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Lung Injury After One-Lung Ventilation: A Review of the Pathophysiologic Mechanisms Affecting the Ventilated and the Collapsed Lung

Lohser, Jens MD, MSc, FRCPC*; Slinger, Peter MD, FRCPC

doi: 10.1213/ANE.0000000000000808
Cardiovascular Anesthesiology: Review Article
Continuing Medical Education

Lung injury is the leading cause of death after thoracic surgery. Initially recognized after pneumonectomy, it has since been described after any period of 1-lung ventilation (OLV), even in the absence of lung resection. Overhydration and high tidal volumes were thought to be responsible at various points; however, it is now recognized that the pathophysiology is more complex and multifactorial. All causative mechanisms known to trigger ventilator-induced lung injury have been described in the OLV setting. The ventilated lung is exposed to high strain secondary to large, nonphysiologic tidal volumes and loss of the normal functional residual capacity. In addition, the ventilated lung experiences oxidative stress, as well as capillary shear stress because of hyperperfusion. Surgical manipulation and/or resection of the collapsed lung may induce lung injury. Re-expansion of the collapsed lung at the conclusion of OLV invariably induces duration-dependent, ischemia-reperfusion injury. Inflammatory cytokines are released in response to localized injury and may promote local and contralateral lung injury. Protective ventilation and volatile anesthesia lessen the degree of injury; however, increases in biochemical and histologic markers of lung injury appear unavoidable. The endothelial glycocalyx may represent a common pathway for lung injury creation during OLV, because it is damaged by most of the recognized lung injurious mechanisms. Experimental therapies to stabilize the endothelial glycocalyx may afford the ability to reduce lung injury in the future. In the interim, protective ventilation with tidal volumes of 4 to 5 mL/kg predicted body weight, positive end-expiratory pressure of 5 to 10 cm H2O, and routine lung recruitment should be used during OLV in an attempt to minimize harmful lung stress and strain. Additional strategies to reduce lung injury include routine volatile anesthesia and efforts to minimize OLV duration and hyperoxia.

From the *Department of Anesthesiology, Pharmacology and Therapeutics, University of British Columbia, Vancouver General Hospital, Vancouver, British Columbia, Canada; and Department of Anesthesia, University of Toronto, Toronto General Hospital, Toronto, Ontario, Canada.

Accepted for publication March 3, 2015.

Funding: None.

The authors declare no conflicts of interest.

Reprints will not be available from the authors.

Address correspondence to Jens Lohser, MD, MSc, FRCPC, Department of Anesthesiology, Pharmacology and Therapeutics, University of British Columbia, Vancouver General Hospital, Room 2449, 899 W 12th Ave., Vancouver, British Columbia, V5Z 1M9 Canada. Address e-mail to jens.lohser@vch.ca.

The pathophysiologic mechanisms that underlie the creation of acute lung injury (ALI) after 1-lung ventilation (OLV) are different for the ventilated and collapsed lung. In this review, we will describe the mechanisms known to be involved in the creation of lung injury in the operating theater and critical care units and then relate them to the setting of OLV, examining each lung in isolation. Strategies to reduce lung injury and the relevant supportive evidence are discussed at the conclusion of the review.

OLV has enabled increasingly complex intrathoracic surgery and is a de facto necessity with the increased use of minimally invasive techniques. However, OLV is associated with postoperative pulmonary complications in 20% of lung resections.1 Historically feared for its high rate of hypoxemia, OLV is now recognized to be a risk factor for ALI.2 Postthoracotomy ALI occurs in 4% to 15% of patients, with an escalating incidence from minor (wedge) resections, to major lung resections (lobectomy, pneumonectomy).1 ALI and acute respiratory distress syndrome (ARDS) are the leading cause of death after thoracic surgery3–5 and significantly reduce 1-year survival (56% vs 92%).4 The most recent ARDS consensus criteria have replaced the formal diagnosis of ALI with the term “mild ARDS” to emphasize the fact that it represents the same disease spectrum.6 In addition, the oxygenation criteria now demand the use of positive end-expiratory pressure (PEEP) or continuous positive airway pressure (CPAP) ≥5 cm H2O, whether invasively or noninvasively.6 These changes will bring about a lesser incidence of the disease, albeit with a greater acuity, illustrated by a recent study of ARDS after lung resections using the aforementioned criteria, which demonstrated an incidence of 2% with a mortality of 54%.7 For the purpose of this review, we will continue to use the term ALI but focus on histopathologic and biochemical end points of the diagnosis.

Ventilator-induced lung injury is a major contributor in the creation of ARDS, and its basic pathophysiologic mechanisms need to be appreciated to understand their relative contribution during OLV-induced lung injury (Fig. 1). Regional lung overdistension, the end-inspiratory lung volume, and tidal recruitment are the main recognized factors in the 2-lung ventilation setting.8 Physical forces are exerted onto the alveolus both at high and at low lung volumes, which often coexist in different regions of the lung, and may result in alveolar damage and subsequent inflammatory response (Fig. 1).8 The alveolar-capillary membrane and, in particular, the endothelial glycocalyx, a complex layer of membrane-bound proteins on the luminal surface of the vascular endothelium, appears to play a central role in lung injury.9 The glycocalyx regulates oncotic pressure, modulates plasma−endothelial cell interactions, and prevents leukocyte and platelet adhesion to the endothelium in the unactivated state.10 Breakdown of the glycocalyx is present in all types of lung injury11 and is an integral component of inflammation, capillary leak, and edema formation.9

Figure 1

Figure 1

Protective low tidal volume (Vt) ventilation mitigates lung injury and reduces mortality in ARDS12,13 and has been shown to decrease pulmonary and extrapulmonary complications after nonthoracic surgery in patients with healthy lungs.14 Whether this benefit derives from ensuring “ open lung” ventilation (the process of avoiding atelectasis and maintaining lung expansion near normal functional residual capacity [FRC] with alveolar recruitment and PEEP),15 or the use of low Vt remains a topic of debate.16 Protective OLV techniques appear similarly effective in reducing the incidence of postthoracotomy ALI,17 but studies with end point reductions in mortality are lacking, and most investigations are focused on surrogate markers, such as inflammatory cytokines.

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PHYSIOLOGIC CONSIDERATIONS

Lung Volumes

The breach of the pleural interface, which occurs during thoracotomy and thoracoscopy, significantly alters intrathoracic lung volumes. Of particular importance is the disruption of the normal relationship between FRC and closing capacity, which underlies gas exchange abnormalities during anesthesia in general and intrathoracic surgery in particular. Closing capacity is an intrinsic property of the lung, whereas FRC hinges on the interplay of the inward elastic recoil of the lung parenchyma and the outward recoil of the chest wall. FRC decreases by 40% with the induction of general anesthesia18 but ceases to exist once the surgical pneumothorax is established. The collapsing lung is released from the outward “spring” of the chest wall and collapses toward residual volume. Although the ventilated lung retains intact pleural attachments, it loses mediastinal and diaphragmatic support. Because of the compressive forces of abdominal and mediastinal contents, the ventilated lung therefore depends on positive airway pressure to stay above residual volume. The end-expiratory lung volume of the ventilated lung therefore becomes dependent on the respiratory rate, Vt, inspiratory/expiratory ratio, and PEEP chosen by the anesthesiologist.19,20 The loss of a stable end-expiratory lung volume is easily appreciated in computed tomography images of a pig OLV model where, even in the presence of PEEP, 80% of the ventilated lung is poorly aerated or atelectatic at end expiration (Fig. 2, A and C).21 Given that closing capacity commonly exceeds FRC in awake, older patients, particularly those in the supine position,22 it can therefore be assumed that a substantial portion of the ventilation during OLV occurs below closing capacity, unless active measures to restore the end-expiratory lung volume are taken.

Figure 2

Figure 2

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Lung Mechanics

The focus in lung protection increasingly is being placed on concepts such as lung stress and strain which, in our opinion, are particularly relevant to the lung injury associated with OLV. The fibrous network of the lung consists of elastin fibers responsible for the elastic recoil and collagen fibers, which provide a “stop-length” at total lung capacity.23 Lung cells are anchored to the fibrous skeleton and do not bear the full force of distention but may activate the inflammatory cascade if subjected to abnormal stretch.23 The fiber tension corresponds to lung “stress,” which, during mechanical ventilation, is represented by transpulmonary pressure and may be calculated as airway pressure minus pleural pressure. The elongation of the fibers from their resting position is called lung “strain” and can be thought of as ΔVt/FRC. Stress and strain are mathematically linked by the elastance of the respiratory system (lung and chest wall), which represents the reciprocal of respiratory system compliance.23

CV

CV

Lung stress and strain are global values and therefore not reflective of the regional risk of lung injury. Heterogeneity between lung units, in particular the interface between atelectatic and normally expanded alveoli, has been described as a stress modifier,24 which is of particular importance during OLV, given that atelectasis is prevalent in the ventilated lung (Fig. 2). The ventilated lung is overdistended during OLV, particularly at high Vt, as illustrated by mediastinal shift in Figure 2, B and D, and Figure 3A, which may expose the lung to excess strain. High lung strain is known to produce an inflammatory response in patients with ARDS25 and correlates with lung injury after short-term, 2-lung ventilation in healthy patients.18 Stress and strain can be determined in critical care, with the measurement of esophageal pressures (as a surrogate for pleural pressure) and FRC. Unfortunately, this is not routinely possible in the operating room, and standard ventilation parameters (Vt, airway pressures) are not reflective of lung stress or strain in mechanically ventilated patients.26 Even low Vt ventilation is capable of producing high strain in the setting of low end-expiratory lung volumes.26 OLV therefore creates a milieu of high lung strain, given the markedly reduced end-expiratory lung volumes secondary to the loss of a stable FRC, coupled with the traditional use of relatively large and nonphysiologic Vts.

Figure 3

Figure 3

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Hypoxic Pulmonary Vasoconstriction

It is unknown whether hypoxic pulmonary vasoconstriction (HPV) is a contributing factor in lung injury creation; however, the markers of ischemia−reperfusion injury are present in the collapsed lung after reventilation. The importance of HPV in the diversion of blood flow to the ventilated lung during OLV relative to other factors (nonventilated lung collapse, gravity, surgical manipulation, etc.) has been difficult to quantify because of the interconnected nature of all relevant factors. Models in animals have led to contradictory claims, likely because of interspecies differences in potencies of the HPV response and differences in study protocols from clinical 1-lung anesthesia, involving lobar hypoxia, closed chest preparations, or awake subjects as models.29 Even among human subjects, there is a large interindividual variability of the HPV response.29 The effect of HPV during OLV may have been underestimated by the use of blood flow during 2-lung ventilation as a baseline. Blood flow to the collapsing lung transiently increases at the start of OLV because of the sudden airway pressure differential between the ventilated and the nonventilated lung.30 This increased blood flow will then be diverted back to the ventilated lung because of HPV and lung collapse. Within 5 minutes of the onset of OLV, blood flow to the nonventilated lung will start to decrease.31 Extrapolating from the most valid animal models, it is likely that the perfusion of the nonventilated lung is decreased by approximately 50%, with HPV being responsible for half of this decrease.9

HPV was thought previously to be a simple on/off reflex of pulmonary arteriolar vasoconstriction, largely under the control of the alveolar oxygen tension. It is now appreciated that HPV is a much more complex physiologic process.29 The HPV reflex seems to be subject to preconditioning, because the onset of HPV will occur more quickly and more profoundly on repeated exposure to alveolar hypoxemia.29 Of interest to the anesthesiologist is the fact that onset and offset of HPV occur in a 2- or 3-stage fashion (Fig. 3C), possibly not reaching their maximal effect for 6 to 8 hours.28 Once HPV is fully established, it will not relax completely for several hours (Fig. 3, B and C). This delayed offset is particularly relevant for procedures that require bilateral sequential OLV and may explain the clinical observation of more profound desaturation during OLV of the second lung.

HPV is inhibited by volatile anesthetics in a dose-dependent fashion. However, the modern volatile anesthetics (isoflurane, sevoflurane, and desflurane) are only weak inhibitors of HPV compared with the older volatile anesthetics (halothane, enflurane).2 The newer volatile anesthetics also do not cause clinically relevant decreases in OLV oxygenation at dosages <1 minimal alveolar concentration compared with IV anesthetics.31 Alkalosis caused by hyperventilation is a potent inhibitor of HPV and interferes with blood flow redistribution during OLV.2 Conversely, acidosis caused by hypoventilation will contribute to vasoconstriction in both lungs even during OLV, but there is no evidence that it improves the blood flow redistribution between the lungs. The increase in pulmonary vascular resistance associated with severe hypercapnia may adversely affect right ventricular function, and cardiac output, which may exacerbate both mixed venous and arterial oxygen desaturation during OLV.2

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MECHANISMS OF LUNG INJURY IN THE VENTILATED LUNG

Injury at High Lung Volumes (Volutrauma)

Excessive end-inspiratory lung volumes may be reached because of large Vt (Fig. 2D) or air trapping in the setting of inadequate expiratory-time or excess PEEP. The detrimental effects of excessive Vt during OLV are well documented. OLV with 12 mL/kg resulted in increased extravascular lung water after pneumonectomy in sheep.32 OLV with 10 mL/kg produced lung overdistension and lung weight gain relative to protective ventilation in rabbits33 and diffuse alveolar damage and leukocyte sequestration after only 90 minutes in pigs (Fig. 4).27 The alveolar damage after OLV with 10 mL/kg was 3-fold greater than after 2-lung ventilation with the same settings.34 Large Vt OLV does produce end-inspiratory lung overdistension (Fig. 2), a recognized risk factor of lung injury.27,35 On the basis of an ex vivo rat lung model, it is the degree of overinflation that determines the degree of lung injury not the time spent at the particular volume.36

Figure 4

Figure 4

Clinical cohorts similarly show an association between high Vt and ALI. In a group of 146 pneumonectomies, any increase in Vt of 1 mL/kg predicted body weight increased the odds ratio of ALI by 3.37 (95% confidence interval, 1.65−6.86).37 Similarly, respiratory failure after pneumonectomy was associated with greater Vt (8.3 vs 6.7 mL/kg).38 Multiple randomized, control trials of patients undergoing esophagectomy or lung resection with low Vt OLV (5 mL/kg PEEP 5) or high Vt OLV (8−10 mL/kg PEEP 0) demonstrated a lessened cytokine response with protective ventilation settings.39–41 More importantly, randomized control trials have demonstrated that high Vt OLV is associated with a worse oxygenation index 18 hours postoperatively39 and increased pulmonary complications.39,42

High ventilating pressures achieved during high Vt OLV are similarly harmful. Postpneumonectomy pulmonary edema was shown to be associated with increased peak airway pressures.43 Each increase of 1 cm H2O in peak airway pressures was associated with an odds ratio of 2.32 for ALI in a retrospective analysis of 146 pneumonectomies (95% confidence interval, 1.46−3.67; actual 28.9 vs 27.2 cm H2O).37 Elevated plateau pressures were implicated in a retrospective trial, where a ventilator hyperpressure index (product of inspiratory plateau pressure >10 cm H2O and the duration of OLV) was strongly associated with an increased risk of ALI (odds ratio 3.53, 95% confidence interval, 1.71−8.45).44 Although high peak pressures need to be avoided during OLV, the actual values are exaggerated by the increased airflow resistance of lung isolation devices.45 Pressure-control ventilation markedly reduces peak airway pressures measured proximally by the ventilator,46 but the intrabronchial pressure differences between pressure- and volume-control ventilation are small and likely not clinically significant.47 Protective ventilation settings decrease airway pressures, as illustrated in a crossover trial in which the authors compared rate-compensated OLV with 5 mL/kg with traditional OLV with 10 mL/kg in the same patients, where peak and plateau airway pressures decreased significantly from 27 to 21 cm H2O and 22 to 18 cm H2O, respectively.48

This finding begs the question: Which contributes more to lung injury during OLV, large Vts or high airway pressures? There is no simple or clear answer to this question because it is difficult to separate the effects of large Vts from high airway pressures in the clinical context of OLV. Studies in animals suggest that it is the volume, primarily lung overdistension at end-inspiration, which causes lung injury.35 In the clinical arena, safe volumes and pressures during OLV are determined primarily by intrinsic patient factors, such as lung compliance, elastic recoil, and predisposition to auto-PEEP.35,49 A Vt that may be acceptable for a healthy patient during OLV may produce excessively high airway pressures in a patient with pulmonary fibrosis. Conversely, relatively normal Vts and airway pressures may result in markedly increased end-inspiratory lung volumes secondary to air trapping in patients with severe emphysema.2,50

Alveolar recruitment maneuvers intentionally create high alveolar pressures to expand low compliance alveolar units, which may result in regional overdistension in high compliance units.51 Recruitment maneuvers are considered an integral part of lung protective ventilation and advocated during routine OLV.52 However, re-expansion of collapsed alveoli may be harmful, as stress is amplified at the interface between aerated and collapsed alveoli resulting in opening pressures of up to 140 cm H2O in collapsed alveoli.23,53 A recent study argued against substantial harm from recruitment maneuvers. Healthy pigs received repeated recruitment maneuvers (40 cm H2O for 10 seconds) during either OLV or 2-lung ventilation. Only the OLV group exhibited a proinflammatory cytokine response, leading the authors to conclude that it is OLV not lung recruitment that is harmful.54 This, however, does not rule out the possibility that recruitment maneuvers may not exacerbate the lung injury during OLV. Preventing alveolar collapse and maintaining open lung ventilation with sufficient PEEP may reduce the need for repeated recruitment maneuvers.55,56

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Injury at Low Lung Volumes (Atelectrauma/Tidal Recruitment)

Dependent lung tissue is prone to atelectasis during general anesthesia, secondary to extrinsic lung compression and oxygen absorption in areas with low ventilation/perfusion ratios.57,58 Even short-term exposure to high fraction of inspired oxygen (FIO2) during the induction of anesthesia causes significant absorption atelectasis.56 Atelectasis is prevalent in the ventilated lung during OLV, as demonstrated by the marked oxygenation benefit achievable with lung recruitment.59 Atelectasis predisposes the patient to lung injury as a result of worsened lung compliance and oxygenation, which demand greater ventilating pressures and increased FIO2.56 In addition, tidal recruitment, the process of repeated alveolar opening during inspiration and recollapse during expiration, is known to result in alveolar barotrauma and accentuate existing lung injury.56,60 Ex vivo studies in rats have demonstrated that cyclic alveolar recruitment/collapse creates more lung injury than simple atelectasis.36 Tidal recruitment exists during OLV in pigs, despite lung recruitment, low FIO2, and PEEP (Fig. 2), illustrating the propensity of the ventilated lung to collapse toward residual volume as discussed.21 Although OLV with Vt 5 mL/kg maintained tidal recruitment at levels comparable with 2-lung ventilation before and after recruitment, high Vt OLV (10 mL/kg) increased tidal recruitment by 50% and was associated with substantially worse lung function after OLV (Fig. 2, E and F).21

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Hyperperfusion/Capillary Shear Stress

Capillary stress failure is described as the disruption of the capillary endothelium, alveolar epithelium, or sometimes all layers.61 Capillary stress failure is a recognized mechanism involved in ventilator-induced lung injury and may occur because of increased vascular shear stress or lung overinflation.61 In a rabbit lung model, high pulmonary blood flow was more harmful than high capillary perfusion pressure. Lungs exposed to high pulmonary flow displayed more pulmonary edema and hemorrhage and experienced larger decreases in compliance plus larger increases in vascular resistance.62 The combination of high pulmonary perfusion pressures and high alveolar pressures is more damaging to the endothelium and epithelium than either in isolation.63 In lungs exposed to harmful ventilation, a 50% increase in pulmonary blood flow, akin to flow increases seen during OLV, results in worse lung compliance, lung weight gain, and alveolar hemorrhage compared with low flow conditions.64 Pulmonary blood flow redistribution during OLV occurs due to HPV,29 gravity (in the lateral position), and surgical manipulation of the collapsed lung.65 OLV in pigs was shown to produce near-complete diversion of pulmonary blood flow to the ventilated lung during OLV (Fig. 3A) and also persistent hyperperfusion (of the ventilated lung) 45 minutes after the resumption of 2-lung ventilation (Fig. 3B).27 Histopathologic evidence of increased interstitial edema and microhemorrhage in the ventilated lung after OLV support the fact that hyperperfusion is damaging to the capillaries (Fig. 4).27 One of the mechanism may be transcription-dependent changes in the glycocalyx (mechanotransduction), which have been shown to occur in response to high capillary vascular pressures and result in increased vascular permeability.9,66

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Biotrauma

OLV-induced injury to the alveolar-capillary membrane results in all facets of lung injury, including cytokine release, recruitment of inflammatory cells, and flooding of the alveolus. Prolonged overexpression of inflammatory mediators and prolonged activation of neutrophils are important in promoting parenchymal cell death67 and deterioration of the glycocalyx.41 Exhaled breath condensate pH levels, a validated biomarker of lung inflammation in respiratory disease, drop rapidly during OLV.68 The increase in inflammatory markers is significantly more pronounced in the ventilated lung after OLV than after comparable periods of 2-lung ventilation.69,70 Cytokine increases are greater after high Vt OLV (10 mL/kg) than protective OLV (5 mL/kg).41 Inflammatory cells are recruited into the alveolus during OLV in pigs34 and humans,41,70 particularly if ventilated with nonprotective high Vt OLV.39–41

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Oxidative Injury

Oxidative injury because of reactive oxygen species is a well-described component of ARDS.67 Prolonged exposure to high FIO2 in healthy volunteers elicits capillary leak of albumin into the alveolus67 and is associated with oxidative stress and histopathologic changes similar to ALI.71 Lung re-expansion after OLV elicits severe oxidative stress, particularly in patients with lung cancer.72 Increasing OLV duration results in worsening oxidative stress upon lung re-expansion (Fig. 5A)72 and is associated with respiratory failure.73 The presence of reactive oxygen species after pneumonectomy indicates that oxidative stress also is present in the ventilated lung, presumably because of the high FIO2 (Fig. 5B).74 In an animal model of OLV, oxidative stress markers of lung injury were exacerbated by hyperoxia (FIO2 1.0, PaO2 400) relative to normoxemia (FIO2 0.5, PaO2 100).75 Exposure to high perioperative FIO2 has been found to be associated with significantly reduced long-term survival after nonthoracic cancer surgery, with lung injury because of reactive oxygen species being the presumed culprit.76,77 Given that most thoracic procedures are cancer operations and high FIO2 is required, it is plausible, but unproven, that this finding may translate to the OLV setting.

Figure 5

Figure 5

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MECHANISMS OF LUNG INJURY IN THE COLLAPSED LUNG

Atelectasis/Recruitment

Dense lung collapse after prolonged lung isolation may in itself not be harmful to the lung. Although multiday lung collapse results in increased reactive oxygen species and edema of the alveolar-capillary membrane in the collapsed rat lung,79 3 hours of lung collapse did not result in cytokine release in either a nonperfused rat lung model or an in vivo rat OLV model.36,80 Lung expansion from the atelectatic state, however, exposes the alveolar units to significant mechanical stress and strain23 and creates high shear forces to adjacent alveoli.53,81 Lung recruitment after complete lung collapse does induce inflammatory cytokine production in the collapsed lung. Even in the absence of HPV, lung recruitment after 55 minutes of lung collapse resulted in increased expression of proinflammatory cytokines tumor necrosis factor-α and interleukin-1β.82 Lung re-expansion and reventilation after 1 or 3 hours of OLV in an in vivo rat lung model resulted in cytokine release, protein extravasation, and neutrophil recruitment into the alveolus.80 Neutrophil infiltration and alveolar structural damage increases with the duration of lung collapse.78

The type of lung recruitment may affect the extent of injury. Cycling recruitment maneuvers with stepwise increases in peak pressure and PEEP are less harmful in the 2-lung ventilation setting, particularly if pressures are built up slowly.83 Vital capacity maneuvers or sustained pressure holds, the most widely practiced recruitment maneuver in the operating room, appear to be more harmful to the alveolar-capillary membrane.84 Sustained pressure holds additionally may cause hemodynamic instability because of acute increases in right ventricular afterload.85 The aforementioned issues have led to recommendations in critical care to abandon vital capacity maneuvers in favor of cycling maneuvers.85

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Hypoperfusion/Ischemia−Reperfusion Injury

The addition of ischemia to the lung collapse model results in marked worsening of the lung injury based on increased levels of tumor necrosis factor-α, decreases in nitric oxide metabolites, increased microvascular permeability, and lung edema.86 Organ ischemia induces capillary leak because of near-complete loss of the glycocalyx in guinea pig hearts.87 Ischemia−reperfusion injury and exposure to inflammatory mediators induce further deterioration of the glycocalyx (Fig. 6B).88 Although lung injury in the setting of complete lung ischemia is not surprising, even hypoperfusion because of HPV induces hypoxemic changes. Before reventilation after prolonged pneumothorax in rats, the collapsed lung tissue has increased levels of reactive oxygen species79 and hypoxia-induced gene expression.89 The same is true after clinically relevant durations of lung collapse in rat models78 and patients, as reventilation after a period of clinical OLV substantially increased exhaled hydrogen peroxide concentrations in breath condensate, myeloperoxidase levels in bronchoalveolar lavage samples, and systemic markers of oxidative stress.72,90,91 These findings are more pronounced in patients with cancer, who have a higher oxidative burden and may have less antioxidant capacity.72 The duration of OLV determines the amount of oxidative stress for 12 hours after OLV (Fig. 5).72,73 One hour of OLV creates a 3-fold increase in oxidative stress from baseline. Oxidative stress is lower after pneumonectomy and in patients managed with 2-lung ventilation, which confirms that lung re-expansion is the primary culprit.72 Oxidative stress predominates in the re-expanded collapsed lung78 and is greater after lobectomy than wedge resection, likely because of the difference in OLV duration (Fig. 5C).74 Unilateral pulmonary edema of the previously collapsed lung has been described in 25% of patients undergoing minimally invasive cardiac procedures and was associated with increased morbidity (ventilator support, hemodynamic support, critical care length of stay, hospital length of stay) and increased mortality.92 Patient risk factors included pulmonary hypertension, right ventricular dysfunction, and increased cardiopulmonary bypass times, which may argue for an increased role of ischemia−reperfusion in this surgical setting.92 Reduced oxygen fractions during reventilation may potentially attenuate the reperfusion injury caused by recruitment from the collapsed state, as hyperoxia worsens reperfusion injury after gut ischemia in pigs93 and liver ischemia in mice.94

Figure 6

Figure 6

Relative hypoperfusion continues after the collapsed lung has been recruited (Fig. 3B) and may be the result of microatelectasis, residual HPV, or lung trauma secondary to surgical resection.27 Nitric oxide levels, which counteract HPV, decrease at a steady rate throughout OLV in an intact, perfused pig model and reach a nadir at reventilation.79,95 Histologic analysis demonstrates vascular congestion and alveolar wall thickening persisting for 1 hour after reventilation.95

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Biotrauma

Inflammatory cytokine levels are increased in bronchoalveolar lavage samples of the collapsed lung after lung resection surgery, particularly with increasing OLV duration.96 The bronchoalveolar lavage cytokine response is stronger in the previously collapsed lung than the contralateral ventilated lung, even in the absence of surgical manipulation, as demonstrated after esophagectomy.97,98 Dense atelectasis and lung re-expansion appear responsible, given that the cytokine response starts on reinflation, is most pronounced postoperatively, and can be blunted with CPAP (Fig. 7, B and D).98

Figure 7

Figure 7

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Surgical Trauma/Manipulation

Surgical trauma varies depending on whether the lung is retracted or resected. Manipulation causes diffuse alveolar damage consisting of interstitial edema, microhemorrhage, microatelectasis, and neutrophil infiltration (Fig. 4, A and C).27,34 The degree of injury is dependent on the amount of manipulation and can be as significant as the ventilator-induced lung injury to the ventilated side.34

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Systemic Factors Affecting Both Lungs

The activation of neutrophils and the release of proinflammatory cytokines and reactive oxygen species are not localized phenomena but result in systemic effects and potential crosstalk with the contralateral lung. In a rat model of OLV, protein extravasation in the ventilated lung coincided with cytokine release upon lung expansion of the collapsed lung.80 The crosstalk is equally illustrated by the fact that CPAP application to the collapsed lung reduced alveolar levels of inflammatory cytokines in the contralateral ventilated lung during esophagectomy (Fig. 7, A–D).98

Aside from cytokine crosstalk, there are multiple factors that may influence lung injury, including ischemia−reperfusion injury, surgical trauma, parenteral fluids, and lymphatic disruption. Reactive oxygen species are routinely generated in the collapsed lung upon reventilation and reperfusion (Fig. 5B). Systemic release of these reactive oxygen species causes systemic lipid peroxidation, as evidenced by urinary excretion of malon dialdehyde.90 Reactive oxygen species release because of lung or gut ischemia−reperfusion is associated with ALI in animal models, which may be a direct effect100 or mediated via cytokine release.101,102 The frequent perioperative gastric and jejunal ischemia during esophagectomy may therefore explain the increased risk of lung injury after these procedures.103 Surgical trauma modulates the inflammatory response, as demonstrated by the fact that the thoracoscopic approach produces less acute phase reactants, inflammatory cytokines, and reactive oxygen species compared with the thoracotomy approach.104,105 Overhydration has long been considered a risk factor for lung injury after OLV,106 although the association was later called into question.107,108 ALI is associated with larger perioperative fluid loads.44,109 Shedding of the endothelial glycocalyx in response to atrial natriuretic peptide release brought on by hypervolemia110 and mechanotransduction of the glycocalyx in response to capillary shear stress9,66 may be some of the underlying mechanisms to explain the harmful effects of overhydration.

Lung resection results in disruption of lymphatic flow, which may impair fluid clearance.107,111 Because lymphatic drainage of the left chest occurs via lymphatic vessels in the left and right thorax, lung resection in either thoracic cavity will affect left lung drainage.111 Lymphatic flow may confer resistance to lung injury, as thoracic duct ligation worsened histologic lung injury in a rat model of gut ischemia-reperfusion,112 and lymphatic disruption has been associated with an increased risk of ALI/ARDS.113 Finally, preoperative chemotherapy and radiotherapy have been shown to be associated with post-lung resection ALI,114 and transfusion-related lung injury may compound OLV-mediated injury.115,116

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Prevention of OLV-Associated Lung Injury

Anesthetic technique may influence the severity of lung injury after OLV. Protective OLV and volatile anesthesia appear effective in reducing adverse outcomes in both retrospective3 and prospective trials (Table 1). Prospective, randomized OLV trials in which the author explores lung injury−avoidance techniques are limited but reaffirm strategies based on animal models and critical care data (Table 1).

Table 1

Table 1

Volatile anesthetics have immune-modulating effects.123 Studies suggest that volatile anesthetics act as pre- and postconditioning agents and induce lung protection, by inhibiting the expression of proinflammatory mediators.124 In animal models, preconditioning with isoflurane reduced polymorphonuclear leukocyte recruitment and microvascular protein leakage,125 whereas postconditioning with sevoflurane attenuated lung damage and preserved lung function.126 Sevoflurane and desflurane attenuated the inflammatory reaction in patients undergoing thoracic surgery with OLV relative to propofol (Fig. 7, E and F)70,96,99 and resulted in fewer adverse events. Volatile anesthetics may affect lung injury by protecting the glycocalyx of the pulmonary capillaries.9 In animal models, sevoflurane reduced the ischemia-reperfusion injury to the endothelial glycocalyx (Fig. 6, B and C).88,127 Although volatile agents appear to be superior to IV anesthesia with propofol, based on biochemical and histologic profiles, the choice of anesthetic maintenance agent has not yet been proven to substantially affect clinical outcomes.128

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OLV: Best Practice Recommendations

Protective OLV results in reduced ALI, critical care admissions, and hospital length of stay.3 Anesthesiologists have been slow to adopt protective ventilation strategies for patients with severe lung injury and often deviate from established protective settings in critical care patients upon transfer to the operating theater.129 The acceptance of protective ventilation strategies for OLV is undefined, but we hope that this review will help ensure its implementation.

OLV is nonphysiologic and results in microscopic and biochemical injury, even if managed with lung protective strategies. OLV therefore should be “administered” only when required and in the smallest “dose” (i.e., duration) necessary. OLV is not essential for all intrathoracic procedures, and high-frequency jet ventilation or 2-lung ventilation with intermittent apnea may be a suitable alternative in select cases, particularly for non-lung surgery. High-frequency jet ventilation is an effective alternative to OLV for minimally invasive coronary bypass procedures,130 transthoracic esophagectomy,131 and even some lung resection procedures.132,133 Although not formally studied, the avoidance of lung collapse, pulmonary flow redistribution, and oxidative stress should, in theory, result in a lower risk of lung injury.

Although the correlation between parenteral fluid and ALI is not clear, overhydration must be avoided, because it worsens lung injury.108,110 Other interventions have been proposed but are considered experimental at this point. They include remote limb ischemia,120 statin therapy,122 lidocaine infusions,134 and parenteral sivelestat (neutrophil elastase inhibitor).121 Similarly, stabilization of the glycocalyx has been achieved with hydrocortisone and antithrombin, which may point toward future prophylactic interventions.87,135

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Before OLV

Optimization of lung compliance lessens inflammatory cytokine release, likely because of reduced mechanical stress.119 Under anesthesia, this entails lung recruitment, PEEP titration, and consideration for bronchodilation and bronchial toilet. Recruitment maneuvers should be routinely provided to all patients after general anesthesia induction and endotracheal intubation,136 but caution needs to be exercised in patients with significant emphysema or marked hypovolemia.52 As previously stated, this may occur via vital capacity maneuvers (30−40 cm H2O for 10−40 seconds) or with the use of programmed ventilator cycling maneuvers. The theory behind cycling maneuvers is beyond the scope of this article; however, they essentially consist of stepwise increases in PEEP and driving pressure under pressure-control ventilation up to a maximal plateau pressure of 40 cm H2O and PEEP of 20 cm H2O over a period of 2 to 5 minutes.136 Routine lung recruitment before OLV provides a sustained oxygenation benefit for OLV137 and improves lung compliance and CO2 elimination,138 all of which facilitate protective ventilation.52 Lung isolation should only be established when necessary to minimize its duration.

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During OLV: Collapsed Lung

CPAP should be considered to avoid dense atelectasis and minimize the shunt fraction. The incomplete lung collapse associated with CPAP is compatible with many chest wall and peripheral lung procedures. Even during thoracoscopic procedures, low-level CPAP of 2 cm H2O has been shown to be feasible without impairing surgical exposure.139 This approach has been shown to reduce HPV and attenuate inflammatory cytokine release in models of animal OLV 89 and during clinical esophagectomy (Fig. 7).98 The use of an air−oxygen mixture before OLV will delay lung collapse,140 which may be preferable in cases in which incomplete lung collapse is not detrimental. It would appear sensible to minimize active suctioning of the lung, which may produce negative pressure trauma, although this has never been formally investigated.

Lung recruitment at the end of OLV harms the collapsed lung because of volume, pressure, and oxygen effects. The impact of recruitment maneuvers on the alveolar−capillary membrane may be minimized by the use of slow airway pressure increases83 and cycling maneuvers.85 The use of lower FIO2 during recruitment maneuvers may reduce the creation of reactive oxygen species, but this has not been studied in the OLV setting.93

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During OLV: Ventilated Lung

Protective ventilation is essential to reduce lung injury. Low Vt ventilation based on predicted body weight should be routine. Predicted body weight is readily calculated on the basis of existing formulas13 and is crucial to avoid the use of excess Vt, which is common particularly in women and patients with obesity.141,142 Vts should be restricted to 4 to 5 mL/kg predicted body weight, with the acknowledgment that lung strain may still be excessive depending on the end-expiratory lung volume. We previously considered Vt 6 mL/kg to be protective2,115 and still believe that this is preferable to 10 mL/kg. However, Vt 6 mL/kg corresponds to the same harmful lung stretch observed during 2-lung ventilation at 12 mL/kg143 and should therefore likely be avoided particularly during OLV of the smaller left lung.

PEEP must be routine for lung injury prevention to restore end-expiratory lung volume toward FRC and minimize tidal recruitment and lung strain. The most appropriate PEEP level depends on individual respiratory mechanics and is ideally chosen based on optimal lung compliance. In a recent PEEP decrement trial, optimal PEEP during OLV with Vt 5 to 7 mL/kg averaged 10 cm H2O in patients with relatively normal lung function.117 This illustrates that the stabilization of the end-expiratory lung volume in the ventilated lung likely requires greater PEEP levels than commonly used in clinical practice. Lung recruitment and PEEP titration should be repeated in case of deteriorating oxygenation or lung compliance.52,59

Respiratory rate and minute ventilation targets should be relaxed to allow mild hypercapnia, which attenuates ALI primarily by reducing mechanical stress, and also appears to down-regulate cytokine release in animal models.144,145 Extreme hypercapnia (PaCO2 >70) may be associated with impaired right ventricular function and cardiovascular instability.146,147 Mild hypercapnia (PaCO2 40−60), however, is well tolerated,148–150 unless there is preexisting marked right ventricular dysfunction or primary pulmonary arterial hypertension. High FIO2 may be necessary at the onset of OLV but should be reduced after approximately 20 to 30 minutes of OLV, when the nadir in oxygenation has been reached.151 Further reductions may be possible, as shunt decreases with the strengthening of HPV and the resection of lung tissue. Oxygen fractions as low as 0.4 have been shown to provide adequate oxygenation for OLV in the lateral decubitus position.152

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After OLV

Histologic and biochemical lung injury is invariably present after OLV, which necessitates the avoidance of additional iatrogenic injury. Because of the presence of reactive oxygen species, hyperoxia must be avoided and oxygen titrated to effect on resumption of 2-lung ventilation and continuing into the postoperative period.93,94 Protective 2-lung ventilation should be instituted after OLV to attenuate the inflammatory changes associated with early lung injury.153 Post-extubation noninvasive pressure ventilation has been shown to improve lung mechanics, and oxygenation and may be warranted in patients at high risk for respiratory dysfunction. Whether noninvasive ventilation is capable of reducing lung injury or progression to respiratory failure in this setting is unclear.154

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CONCLUSIONS

The lung injury of OLV involves the entire alveolar−capillary unit, with trauma to both the alveolar epithelium and the vascular endothelium. Lung injury occurs in both lungs but for different reasons. The ventilated lung is primarily affected by hyperperfusion and ventilator-induced lung injury, whereas the collapsed lung is exposed to ischemia−reperfusion injury and shear stress on reventilation. There appears to be substantial crosstalk because of reactive oxygen species and cytokines released into the circulation, which may cause injury in the contralateral lung. Multiple pathways appear to converge in damage to the endothelial glycocalyx which, in turn, facilitates vascular leakage and cell migration. Given the multifactorial nature of ALI creation, it is not surprising that no single intervention has proven beneficial. Any OLV is nonphysiologic and will result in histologic lung injury. Protective OLV should be routine and consists of Vt 4 to 5 mL/kg predicted body weight and PEEP 5 to 10 cm H2O, with an emphasis on open lung ventilation with lung recruitment preceding OLV and repeated as necessary. Protective ventilation with volatile agents may reduce the risk of ALI and appears to improve patient outcomes but cannot eliminate the risk completely. Research on anti-inflammatory agents and glycocalyx stabilizers holds promise for future prophylactic interventions.

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DISCLOSURES

Name: Jens Lohser, MD, MSc, FRCPC.

Contribution: This author helped write the manuscript.

Attestation: Jens Lohser approved the final manuscript.

Name: Peter Slinger, MD, FRCPC.

Contribution: This author helped write the manuscript.

Attestation: Peter Slinger approved the final manuscript.

This manuscript was handled by: Martin J. London, MD.

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ACKNOWLEDGMENTS

The authors thank Dr. William R. Henderson (Associate Professor, Department of Respirology and Critical Care, University of British Columbia) for his thoughtful comments on the manuscript.

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REFERENCES

1. Licker MJ, Widikker I, Robert J, Frey JG, Spiliopoulos A, Ellenberger C, Schweizer A, Tschopp JM. Operative mortality and respiratory complications after lung resection for cancer: impact of chronic obstructive pulmonary disease and time trends. Ann Thorac Surg. 2006;81:1830–7
2. Lohser J. Evidence-based management of one-lung ventilation. Anesthesiol Clin. 2008;26:241–72
3. Licker M, Fauconnet P, Villiger Y, Tschopp JM. Acute lung injury and outcomes after thoracic surgery. Curr Opin Anaesthesiol. 2009;22:61–7
4. Fernández-Pérez ER, Sprung J, Afessa B, Warner DO, Vachon CM, Schroeder DR, Brown DR, Hubmayr RD, Gajic O. Intraoperative ventilator settings and acute lung injury after elective surgery: a nested case control study. Thorax. 2009;64:121–7
5. Iglesias M, Martinez E, Badia JR, Macchiarini P. Extrapulmonary ventilation for unresponsive severe acute respiratory distress syndrome after pulmonary resection. Ann Thorac Surg. 2008;85:237–44
6. Ranieri VM, Rubenfeld GD, Thompson BT, Ferguson ND, Caldwell E, Fan E, Camporota L, Slutsky AS. Acute respiratory distress syndrome: the Berlin Definition. JAMA. 2012;307:2526–33
7. Choi S, Lee J, Park Y, Lee CH, Lee SM, Yim JJ, Kim Y, Han S, Yoo CG, Bae W. Clinical outcomes of acute respiratory distress syndrome after pulmonary resection in lung cancer patients. Am J Respir Crit Care Med. 2014;189:A4479
8. Slutsky AS, Ranieri VM. Ventilator-induced lung injury. N Engl J Med. 2013;369:2126–36
9. Collins SR, Blank RS, Deatherage LS, Dull RO. Special article: the endothelial glycocalyx: emerging concepts in pulmonary edema and acute lung injury. Anesth Analg. 2013;117:664–74
10. Woodcock TE, Woodcock TM. Revised Starling equation and the glycocalyx model of transvascular fluid exchange: an improved paradigm for prescribing intravenous fluid therapy. Br J Anaesth. 2012;108:384–94
11. Schmidt EP, Li G, Li L, Fu L, Yang Y, Overdier KH, Douglas IS, Linhardt RJ. The circulating glycosaminoglycan signature of respiratory failure in critically ill adults. J Biol Chem. 2014;289:8194–202
12. Amato MB, Barbas CS, Medeiros DM, Magaldi RB, Schettino GP, Lorenzi-Filho G, Kairalla RA, Deheinzelin D, Munoz C, Oliveira R, Takagaki TY, Carvalho CR. Effect of a protective-ventilation strategy on mortality in the acute respiratory distress syndrome. N Engl J Med. 1998;338:347–54
13. The Acute Respiratory Distress Syndrome Network. . Ventilation with lower tidal volumes as compared with traditional tidal volumes for acute lung injury and the acute respiratory distress syndrome. N Engl J Med. 2000;342:1302–1308
14. Futier E, Constantin JM, Paugam-Burtz C, Pascal J, Eurin M, Neuschwander A, Marret E, Beaussier M, Gutton C, Lefrant JY, Allaouchiche B, Verzilli D, Leone M, De Jong A, Bazin JE, Pereira B, Jaber SIMPROVE Study Group. . A trial of intraoperative low-tidal-volume ventilation in abdominal surgery. N Engl J Med. 2013;369:428–37
15. Reis Miranda D, Gommers D, Struijs A, Dekker R, Mekel J, Feelders R, Lachmann B, Bogers AJ. Ventilation according to the open lung concept attenuates pulmonary inflammatory response in cardiac surgery. Eur J Cardiothorac Surg. 2005;28:889–95
16. Hedenstierna G, Edmark L, Perchiazzi G. Postoperative lung complications: have multicentre studies been of any help? Br J Anaesth. 2015;114:541–3
17. Licker M, Diaper J, Villiger Y, Spiliopoulos A, Licker V, Robert J, Tschopp JM. Impact of intraoperative lung-protective interventions in patients undergoing lung cancer surgery. Crit Care. 2009;13:R41
18. Di Marco F, Bonacina D, Vassena E, Arisi E, Apostolo A, Banfi C, Centanni S, Agostoni P, Fumagalli R. The effects of anesthesia, muscle paralysis, and ventilation on the lung evaluated by lung diffusion for carbon monoxide and pulmonary surfactant protein B. Anesth Analg. 2015;120:373–80
19. Larsson A, Malmkvist G, Werner O. Variations in lung volume and compliance during pulmonary surgery. Br J Anaesth. 1987;59:585–91
20. Slinger PD, Kruger M, McRae K, Winton T. Relation of the static compliance curve and positive end-expiratory pressure to oxygenation during one-lung ventilation. Anesthesiology. 2001;95:1096–102
21. Kozian A, Schilling T, Schütze H, Senturk M, Hachenberg T, Hedenstierna G. Ventilatory protective strategies during thoracic surgery: effects of alveolar recruitment maneuver and low-tidal volume ventilation on lung density distribution. Anesthesiology. 2011;114:1025–35
22. Craig DB, Wahba WM, Don HF, Couture JG, Becklake MR. “Closing volume” and its relationship to gas exchange in seated and supine positions. J Appl Physiol. 1971;31:717–21
23. Gattinoni L, Pesenti A. The concept of “baby lung.” Intensive Care Med. 2005;31:776–84
24. Gattinoni L, Carlesso E, Langer T. Towards ultraprotective mechanical ventilation. Curr Opin Anaesthesiol. 2012;25:141–7
25. González-López A, García-Prieto E, Batalla-Solís E, Amado-Rodríguez L, Avello N, Blanch L, Albaiceta GM. Lung strain and biological response in mechanically ventilated patients. Intensive Care Med. 2012;38:240–7
26. Chiumello D, Carlesso E, Cadringher P, Caironi P, Valenza F, Polli F, Tallarini F, Cozzi P, Cressoni M, Colombo A, Marini JJ, Gattinoni L. Lung stress and strain during mechanical ventilation for acute respiratory distress syndrome. Am J Respir Crit Care Med. 2008;178:346–55
27. Kozian A, Schilling T, Fredén F, Maripuu E, Röcken C, Strang C, Hachenberg T, Hedenstierna G. One-lung ventilation induces hyperperfusion and alveolar damage in the ventilated lung: an experimental study. Br J Anaesth. 2008;100:549–59
28. Dorrington KL, Clar C, Young JD, Jonas M, Tansley JG, Robbins PA. Time course of the human pulmonary vascular response to 8 hours of isocapnic hypoxia. Am J Physiol. 1997;273:H1126–34
29. Sylvester JT, Shimoda LA, Aaronson PI, Ward JP. Hypoxic pulmonary vasoconstriction. Physiol Rev. 2012;92:367–520
30. Cannon D, Kalso EJ, Sykes MK. Effects of the pattern of ventilation and of an increase in cardiac output on the distribution of blood flow to a hypoxic lung lobe. Br J Anaesth. 1988;60:81–90
31. Gong Q, Yang Z, Wei W. The changes of pulmonary blood flow in non-ventilated lung during one lung ventilation. J Clin Monit Comput. 2010;24:407–12
32. Kuzkov VV, Suborov EV, Kirov MY, Kuklin VN, Sobhkhez M, Johnsen S, Waerhaug K, Bjertnaes LJ. Extravascular lung water after pneumonectomy and one-lung ventilation in sheep. Crit Care Med. 2007;35:1550–9
33. Gama de Abreu M, Heintz M, Heller A, Széchényi R, Albrecht DM, Koch T. One-lung ventilation with high tidal volumes and zero positive end-expiratory pressure is injurious in the isolated rabbit lung model. Anesth Analg. 2003;96:220–8
34. Kozian A, Schilling T, Röcken C, Breitling C, Hachenberg T, Hedenstierna G. Increased alveolar damage after mechanical ventilation in a porcine model of thoracic surgery. J Cardiothorac Vasc Anesth. 2010;24:617–23
35. Dreyfuss D, Saumon G. Role of tidal volume, FRC, and end-inspiratory volume in the development of pulmonary edema following mechanical ventilation. Am Rev Respir Dis. 1993;148:1194–203
36. Chu EK, Whitehead T, Slutsky AS. Effects of cyclic opening and closing at low- and high-volume ventilation on bronchoalveolar lavage cytokines. Crit Care Med. 2004;32:168–74
37. Jeon K, Yoon JW, Suh GY, Kim J, Kim K, Yang M, Kim H, Kwon OJ, Shim YM. Risk factors for post-pneumonectomy acute lung injury/acute respiratory distress syndrome in primary lung cancer patients. Anaesth Intensive Care. 2009;37:14–9
38. Fernández-Pérez ER, Keegan MT, Brown DR, Hubmayr RD, Gajic O. Intraoperative tidal volume as a risk factor for respiratory failure after pneumonectomy. Anesthesiology. 2006;105:14–8
39. Shen Y, Zhong M, Wu W, Wang H, Feng M, Tan L, Wang Q. The impact of tidal volume on pulmonary complications following minimally invasive esophagectomy: a randomized and controlled study. J Thorac Cardiovasc Surg. 2013;146:1267–73
40. Michelet P, D’Journo XB, Roch A, Doddoli C, Marin V, Papazian L, Decamps I, Bregeon F, Thomas P, Auffray JP. Protective ventilation influences systemic inflammation after esophagectomy: a randomized controlled study. Anesthesiology. 2006;105:911–9
41. Schilling T, Kozian A, Huth C, Bühling F, Kretzschmar M, Welte T, Hachenberg T. The pulmonary immune effects of mechanical ventilation in patients undergoing thoracic surgery. Anesth Analg. 2005;101:957–65
42. Yang M, Ahn HJ, Kim K, Kim JA, Yi CA, Kim MJ, Kim HJ. Does a protective ventilation strategy reduce the risk of pulmonary complications after lung cancer surgery? A randomized controlled trial. Chest. 2011;139:530–7
43. van der Werff YD, van der Houwen HK, Heijmans PJ, Duurkens VA, Leusink HA, van Heesewijk HP, de Boer A. Postpneumonectomy pulmonary edema. A retrospective analysis of incidence and possible risk factors. Chest. 1997;111:1278–84
44. Licker M, de Perrot M, Spiliopoulos A, Robert J, Diaper J, Chevalley C, Tschopp JM. Risk factors for acute lung injury after thoracic surgery for lung cancer. Anesth Analg. 2003;97:1558–65
45. Slinger PD, Lesiuk L. Flow resistances of disposable double-lumen, single-lumen, and Univent tubes. J Cardiothorac Vasc Anesth. 1998;12:142–4
46. Montes FR, Pardo DF, Charrís H, Tellez LJ, Garzón JC, Osorio C. Comparison of two protective lung ventilatory regimes on oxygenation during one-lung ventilation: a randomized controlled trial. J Cardiothorac Surg. 2010;5:99
47. Rozé H, Lafargue M, Batoz H, Picat MQ, Perez P, Ouattara A, Janvier G. Pressure-controlled ventilation and intrabronchial pressure during one-lung ventilation. Br J Anaesth. 2010;105:377–81
48. Végh T, Juhász M, Szatmári S, Enyedi A, Sessler DI, Szegedi LL, Fülesdi B. Effects of different tidal volumes for one-lung ventilation on oxygenation with open chest condition and surgical manipulation: a randomised cross-over trial. Minerva Anestesiol. 2013;79:24–32
49. Slinger PD, Johnston MR. Preoperative assessment for pulmonary resection. Anesthesiol Clin North America. 2001;19:411–33
50. Ducros L, Moutafis M, Castelain MH, Liu N, Fischler M. Pulmonary air trapping during two-lung and one-lung ventilation. J Cardiothorac Vasc Anesth. 1999;13:35–9
51. Tusman G, Böhm SH. Prevention and reversal of lung collapse during the intra-operative period. Best Pract Res Clin Anaesthesiol. 2010;24:183–97
52. Tusman G, Bohm SH, Suarez-Sipmann F. Alveolar recruitment maneuvers for one-lung ventilation during thoracic anesthesia. Current Anesth Rep. 2014;4:160–169
53. Mead J, Takishima T, Leith D. Stress distribution in lungs: a model of pulmonary elasticity. J Appl Physiol. 1970;28:596–608
54. Schilling T, Kretzschmar M, Hachenberg T, Hedenstier-Na G, Kozian A. The immune response to one-lung-ventilation is not affected by repeated alveolar recruitment manoeuvres in pigs. Minerva Anestesiol. 2013;79:590–603
55. Farias LL, Faffe DS, Xisto DG, Santana MC, Lassance R, Prota LF, Amato MB, Morales MM, Zin WA, Rocco PR. Positive end-expiratory pressure prevents lung mechanical stress caused by recruitment/derecruitment. J Appl Physiol (1985). 2005;98:53–61
56. Duggan M, Kavanagh BP. Atelectasis in the perioperative patient. Curr Opin Anaesthesiol. 2007;20:37–42
57. Brismar B, Hedenstierna G, Lundquist H, Strandberg A, Svensson L, Tokics L. Pulmonary densities during anesthesia with muscular relaxation—a proposal of atelectasis. Anesthesiology. 1985;62:422–8
58. Klingstedt C, Hedenstierna G, Baehrendtz S, Lundqvist H, Strandberg A, Tokics L, Brismar B. Ventilation-perfusion relationships and atelectasis formation in the supine and lateral positions during conventional mechanical and differential ventilation. Acta Anaesthesiol Scand. 1990;34:421–9
59. Tusman G, Böhm SH, Sipmann FS, Maisch S. Lung recruitment improves the efficiency of ventilation and gas exchange during one-lung ventilation anesthesia. Anesth Analg. 2004;98:1604–9
60. Koh WJ, Suh GY, Han J, Lee SH, Kang EH, Chung MP, Kim H, Kwon OJ. Recruitment maneuvers attenuate repeated derecruitment-associated lung injury. Crit Care Med. 2005;33:1070–6
61. West JB. Invited review: pulmonary capillary stress failure. J Appl Physiol (1985). 2000;89:2483–9
62. López-Aguilar J, Piacentini E, Villagrá A, Murias G, Pascotto S, Saenz-Valiente A, Fernández-Segoviano P, Hotchkiss JR, Blanch L. Contributions of vascular flow and pulmonary capillary pressure to ventilator-induced lung injury. Crit Care Med. 2006;34:1106–12
63. Hotchkiss JR Jr, Blanch L, Naveira A, Adams AB, Carter C, Olson DA, Leo PH, Marini JJ. Relative roles of vascular and airspace pressures in ventilator-induced lung injury. Crit Care Med. 2001;29:1593–8
64. Broccard AF, Hotchkiss JR, Kuwayama N, Olson DA, Jamal S, Wangensteen DO, Marini JJ. Consequences of vascular flow on lung injury induced by mechanical ventilation. Am J Respir Crit Care Med. 1998;157:1935–42
65. Ishikawa S, Shirasawa M, Fujisawa M, Kawano T, Makita K. Compressing the non-dependent lung during one-lung ventilation improves arterial oxygenation, but impairs systemic oxygen delivery by decreasing cardiac output. J Anesth. 2010;24:17–23
66. Dull RO, Cluff M, Kingston J, Hill D, Chen H, Hoehne S, Malleske DT, Kaur R. Lung heparan sulfates modulate K(fc) during increased vascular pressure: evidence for glycocalyx-mediated mechanotransduction. Am J Physiol Lung Cell Mol Physiol. 2012;302:L816–28
67. Tang SS, Redmond K, Griffiths M, Ladas G, Goldstraw P, Dusmet M. The mortality from acute respiratory distress syndrome after pulmonary resection is reducing: a 10-year single institutional experience. Eur J Cardiothorac Surg. 2008;34:898–902
68. Bastin AJ, Sato H, Davidson SJ, Quinlan GJ, Griffiths MJ. Biomarkers of lung injury after one-lung ventilation for lung resection. Respirology. 2011;16:138–45
69. Zingg U, Forberger J, Frey DM, Esterman AJ, Oertli D, Beck-Schimmer B, Zollinger A. Inflammatory response in ventilated left and collapsed right lungs, serum and pleural fluid, in transthoracic esophagectomy for cancer. Eur Cytokine Netw. 2010;21:50–7
70. Schilling T, Kozian A, Kretzschmar M, Huth C, Welte T, Bühling F, Hedenstierna G, Hachenberg T. Effects of propofol and desflurane anaesthesia on the alveolar inflammatory response to one-lung ventilation. Br J Anaesth. 2007;99:368–75
71. Jordan S, Mitchell JA, Quinlan GJ, Goldstraw P, Evans TW. The pathogenesis of lung injury following pulmonary resection. Eur Respir J. 2000;15:790–9
72. Misthos P, Katsaragakis S, Milingos N, Kakaris S, Sepsas E, Athanassiadi K, Theodorou D, Skottis I. Postresectional pulmonary oxidative stress in lung cancer patients. The role of one-lung ventilation. Eur J Cardiothorac Surg. 2005;27:379–82
73. Misthos P, Katsaragakis S, Theodorou D, Milingos N, Skottis I. The degree of oxidative stress is associated with major adverse effects after lung resection: a prospective study. Eur J Cardiothorac Surg. 2006;29:591–5
74. Williams EA, Quinlan GJ, Goldstraw P, Gothard JW, Evans TW. Postoperative lung injury and oxidative damage in patients undergoing pulmonary resection. Eur Respir J. 1998;11:1028–34
75. Olivant Fisher A, Husain K, Wolfson MR, Hubert TL, Rodriguez E, Shaffer TH, Theroux MC. Hyperoxia during one lung ventilation: inflammatory and oxidative responses. Pediatr Pulmonol. 2012;47:979–86
76. Meyhoff CS, Jorgensen LN, Wetterslev J, Christensen KB, Rasmussen LSPROXI Trial Group. . Increased long-term mortality after a high perioperative inspiratory oxygen fraction during abdominal surgery: follow-up of a randomized clinical trial. Anesth Analg. 2012;115:849–54
77. Meyhoff CS, Jorgensen LN, Wetterslev J, Siersma VD, Rasmussen LSPROXI Trial Group. . Risk of new or recurrent cancer after a high perioperative inspiratory oxygen fraction during abdominal surgery. Br J Anaesth. 2014;113(Suppl 1):i74–81
78. Tekinbas C, Ulusoy H, Yulug E, Erol MM, Alver A, Yenilmez E, Geze S, Topbas M. One-lung ventilation: for how long? J Thorac Cardiovasc Surg. 2007;134:405–10
79. Sivrikoz MC, Tunçözgür B, Cekmen M, Bakir K, Meram I, Koçer E, Cengiz B, Elbeyli L. The role of tissue reperfusion in the reexpansion injury of the lungs. Eur J Cardiothorac Surg. 2002;22:721–7
80. Leite CF, Calixto MC, Toro IF, Antunes E, Mussi RK. Characterization of pulmonary and systemic inflammatory responses produced by lung re-expansion after one-lung ventilation. J Cardiothorac Vasc Anesth. 2012;26:427–32
81. Tremblay LN, Slutsky AS. Ventilator-induced lung injury: from the bench to the bedside. Intensive Care Med. 2006;32:24–33
82. Funakoshi T, Ishibe Y, Okazaki N, Miura K, Liu R, Nagai S, Minami Y. Effect of re-expansion after short-period lung collapse on pulmonary capillary permeability and pro-inflammatory cytokine gene expression in isolated rabbit lungs. Br J Anaesth. 2004;92:558–63
83. Silva PL, Moraes L, Santos RS, Samary C, Ornellas DS, Maron-Gutierrez T, Morales MM, Saddy F, Capelozzi VL, Pelosi P, Marini JJ, Gama de Abreu M, Rocco PR. Impact of pressure profile and duration of recruitment maneuvers on morphofunctional and biochemical variables in experimental lung injury. Crit Care Med. 2011;39:1074–81
84. Silva PL, Moraes L, Santos RS, Samary C, Ramos MB, Santos CL, Morales MM, Capelozzi VL, Garcia CS, de Abreu MG, Pelosi P, Marini JJ, Rocco PR. Recruitment maneuvers modulate epithelial and endothelial cell response according to acute lung injury etiology. Crit Care Med. 2013;41:e256–65
85. Marini JJ. Recruitment by sustained inflation: time for a change. Intensive Care Med. 2011;37:1572–4
86. Liu R, Ishibe Y, Ueda M. Isoflurane-sevoflurane administration before ischemia attenuates ischemia-reperfusion-induced injury in isolated rat lungs. Anesthesiology. 2000;92:833–40
87. Chappell D, Jacob M, Hofmann-Kiefer K, Bruegger D, Rehm M, Conzen P, Welsch U, Becker BF. Hydrocortisone preserves the vascular barrier by protecting the endothelial glycocalyx. Anesthesiology. 2007;107:776–84
88. Chappell D, Heindl B, Jacob M, Annecke T, Chen C, Rehm M, Conzen P, Becker BF. Sevoflurane reduces leukocyte and platelet adhesion after ischemia-reperfusion by protecting the endothelial glycocalyx. Anesthesiology. 2011;115:483–91
89. Nagamine Y, Ota S, Baba Y, Goto T, Kurahashi K, Tojo K. Alveolar hypoxia during one-lung ventilation leads to Hif-1 activation and lung inflammation in the non-ventilated lung. Am J Respir Crit Care Med. 2013;187:A1231
90. Lases EC, Duurkens VA, Gerritsen WB, Haas FJ. Oxidative stress after lung resection therapy: a pilot study. Chest. 2000;117:999–1003
91. Cheng YJ, Chan KC, Chien CT, Sun WZ, Lin CJ. Oxidative stress during 1-lung ventilation. J Thorac Cardiovasc Surg. 2006;132:513–8
92. Tutschka MP, Bainbridge D, Chu MW, Kiaii B, Jones PM. Unilateral postoperative pulmonary edema after minimally invasive cardiac surgical procedures: a case-control study. Ann Thorac Surg. 2015;99:115–22
93. Douzinas EE, Kollias S, Tiniakos D, Evangelou E, Papalois A, Rapidis AD, Tsoukalas GD, Patsouris E, Roussos C. Hypoxemic reperfusion after 120 mins of intestinal ischemia attenuates the histopathologic and inflammatory response. Crit Care Med. 2004;32:2279–83
94. Zangl Q, Martignoni A, Jackson SH, Ohta A, Klaunberg B, Kaufmann I, Lukashev D, Ward JM, Sitkovsky M, Thiel M, Choukèr A. Postoperative hyperoxia (60%) worsens hepatic injury in mice. Anesthesiology. 2014;121:1217–25
95. Yin K, Gribbin E, Emanuel S, Orndorff R, Walker J, Weese J, Fallahnejad M. Histochemical alterations in one lung ventilation. J Surg Res. 2007;137:16–20
96. De Conno E, Steurer MP, Wittlinger M, Zalunardo MP, Weder W, Schneiter D, Schimmer RC, Klaghofer R, Neff TA, Schmid ER, Spahn DR, Z’graggen BR, Urner M, Beck-Schimmer B. Anesthetic-induced improvement of the inflammatory response to one-lung ventilation. Anesthesiology. 2009;110:1316–26
97. Cree RT, Warnell I, Staunton M, Shaw I, Bullock R, Griffin SM, Baudouin SV. Alveolar and plasma concentrations of interleukin-8 and vascular endothelial growth factor following oesophagectomy. Anaesthesia. 2004;59:867–71
98. Verhage RJ, Boone J, Rijkers GT, Cromheecke GJ, Kroese AC, Weijs TJ, Borel Rinkes IH, van Hillegersberg R. Reduced local immune response with continuous positive airway pressure during one-lung ventilation for oesophagectomy. Br J Anaesth. 2014;112:920–8
99. Schilling T, Kozian A, Senturk M, Huth C, Reinhold A, Hedenstierna G, Hachenberg T. Effects of volatile and intravenous anesthesia on the alveolar and systemic inflammatory response in thoracic surgical patients. Anesthesiology. 2011;115:65–74
100. Koike K, Moore EE, Moore FA, Read RA, Carl VS, Banerjee A. Gut ischemia/reperfusion produces lung injury independent of endotoxin. Crit Care Med. 1994;22:1438–44
101. Tyvold SS, Solligård E, Gunnes S, Lyng O, Johannisson A, Grønbech JE, Aadahl P. Bronchial microdialysis of cytokines in the epithelial lining fluid in experimental intestinal ischemia and reperfusion before onset of manifest lung injury. Shock. 2010;34:517–24
102. Narita K, Kuwabara Y, Fujii Y. Lung injury after intestinal ischemia-reperfusion may be avoided by the reduced absorption of locally produced cytokines. Surg Today. 2004;34:937–42
103. Baudouin SV. Lung injury after thoracotomy. Br J Anaesth. 2003;91:132–42
104. Craig SR, Leaver HA, Yap PL, Pugh GC, Walker WS. Acute phase responses following minimal access and conventional thoracic surgery. Eur J Cardiothorac Surg. 2001;20:455–63
105. Yim AP, Wan S, Lee TW, Arifi AA. VATS lobectomy reduces cytokine responses compared with conventional surgery. Ann Thorac Surg. 2000;70:243–7
106. Zeldin RA, Normandin D, Landtwing D, Peters RM. Postpneumonectomy pulmonary edema. J Thorac Cardiovasc Surg. 1984;87:359–65
107. Slinger PD. Perioperative fluid management for thoracic surgery: the puzzle of postpneumonectomy pulmonary edema. J Cardiothorac Vasc Anesth. 1995;9:442–51
108. Slinger PD. Postpneumonectomy pulmonary edema: good news, bad news. Anesthesiology. 2006;105:2–5
109. Ashes C, Slinger P. Volume management and resuscitation in thoracic surgery. Curr Anesthesiol Rep. 2014;4:386–96
110. Bruegger D, Jacob M, Rehm M, Loetsch M, Welsch U, Conzen P, Becker BF. Atrial natriuretic peptide induces shedding of endothelial glycocalyx in coronary vascular bed of guinea pig hearts. Am J Physiol Heart Circ Physiol. 2005;289:H1993–9
111. Nohl-Oser HC. An investigation of the anatomy of the lymphatic drainage of the lungs as shown by the lymphatic spread of bronchial carcinoma. Ann R Coll Surg Engl. 1972;51:157–76
112. Amorim MB, Fantozzi ET, Da Silva FYR, Oliveira-Filho RM, Vargaftig BB, Tavares-de-Lima ACW. Lymphatic system influence on acute lung injury after intestinal ischemia/reperfusion in female rats. Am J Respir Crit Care Med. 2014;189:A5005
113. Grichnik KP, D’Amico TA. Acute lung injury and acute respiratory distress syndrome after pulmonary resection. Semin Cardiothorac Vasc Anesth. 2004;8:317–34
114. Parquin F, Marchal M, Mehiri S, Hervé P, Lescot B. Post-pneumonectomy pulmonary edema: analysis and risk factors. Eur J Cardiothorac Surg. 1996;10:929–32
115. Della Rocca G, Coccia C. Acute lung injury in thoracic surgery. Curr Opin Anaesthesiol. 2013;26:40–6
116. Triulzi DJ. Transfusion-related acute lung injury: current concepts for the clinician. Anesth Analg. 2009;108:770–6
117. Ferrando C, Mugarra A, Gutierrez A, Carbonell JA, García M, Soro M, Tusman G, Belda FJ. Setting individualized positive end-expiratory pressure level with a positive end-expiratory pressure decrement trial after a recruitment maneuver improves oxygenation and lung mechanics during one-lung ventilation. Anesth Analg. 2014;118:657–65
118. Qutub H, El-Tahan MR, Mowafi HA, El Ghoneimy YF, Regal MA, Al Saflan AA. Effect of tidal volume on extravascular lung water content during one-lung ventilation for video-assisted thoracoscopic surgery: a randomised, controlled trial. Eur J Anaesthesiol. 2014;31:466–73
    119. Ju NY, Gao H, Huang W, Niu FF, Lan WX, Li F, Gao W. Therapeutic effect of inhaled budesonide (Pulmicort® Turbuhaler) on the inflammatory response to one-lung ventilation. Anaesthesia. 2014;69:14–23
    120. Li C, Xu M, Wu Y, Li YS, Huang WQ, Liu KX. Limb remote ischemic preconditioning attenuates lung injury after pulmonary resection under propofol-remifentanil anesthesia: a randomized controlled study. Anesthesiology. 2014;121:249–59
    121. Lee SK, Son BS, Hwang JJ, Kim KD, Kim do H. The use of neutrophil elastase inhibitor in the treatment of acute lung injury after pneumonectomy. J Cardiothorac Surg. 2013;8:69
    122. Shyamsundar M, McAuley DF, Shields MO, MacSweeney R, Duffy MJ, Johnston JR, McGuigan J, Backman JT, Calfee CS, Matthay MM, Griffiths MJ, McDowell C, Elborn SJ, O’Kane CM. Effect of simvastatin on physiological and biological outcomes in patients undergoing esophagectomy: a randomized placebo-controlled trial. Ann Surg. 2014;259:26–31
    123. Slinger P, Kilpatrick B. Perioperative lung protection strategies in cardiothoracic anesthesia: are they useful? Anesthesiol Clin. 2012;30:607–28
    124. Fujinaga T, Nakamura T, Fukuse T, Chen F, Zhang J, Ueda S, Hamakawa H, Omasa M, Sakai H, Hanaoka N, Wada H, Bando T. Isoflurane inhalation after circulatory arrest protects against warm ischemia reperfusion injury of the lungs. Transplantation. 2006;82:1168–74
    125. Reutershan J, Chang D, Hayes JK, Ley K. Protective effects of isoflurane pretreatment in endotoxin-induced lung injury. Anesthesiology. 2006;104:511–7
    126. Voigtsberger S, Lachmann RA, Leutert AC, Schläpfer M, Booy C, Reyes L, Urner M, Schild J, Schimmer RC, Beck-Schimmer B. Sevoflurane ameliorates gas exchange and attenuates lung damage in experimental lipopolysaccharide-induced lung injury. Anesthesiology. 2009;111:1238–48
    127. Annecke T, Rehm M, Bruegger D, Kubitz JC, Kemming GI, Stoeckelhuber M, Stoekelhuber M, Becker BF, Conzen PF. Ischemia-reperfusion-induced unmeasured anion generation and glycocalyx shedding: sevoflurane versus propofol anesthesia. J Invest Surg. 2012;25:162–8
    128. Módolo NS, Módolo MP, Marton MA, Volpato E, Monteiro Arantes V, do Nascimento Junior P, El Dib RP. Intravenous versus inhalation anaesthesia for one-lung ventilation. Cochrane Database Syst Rev. 2013;7:CD006313
    129. Blum JM, Maile M, Park PK, Morris M, Jewell E, Dechert R, Rosenberg AL. A description of intraoperative ventilator management in patients with acute lung injury and the use of lung protective ventilation strategies. Anesthesiology. 2011;115:75–82
    130. Ender J, Brodowsky M, Falk V, Baunsch J, Koncar-Zeh J, Kaisers UX, Mukherjee C. High-frequency jet ventilation as an alternative method compared to conventional one-lung ventilation using double-lumen tubes during minimally invasive coronary artery bypass graft surgery. J Cardiothorac Vasc Anesth. 2010;24:602–7
    131. Buise M, van Bommel J, van Genderen M, Tilanus H, van Zundert A, Gommers D. Two-lung high-frequency jet ventilation as an alternative ventilation technique during transthoracic esophagectomy. J Cardiothorac Vasc Anesth. 2009;23:509–12
    132. Lohser J, McLean SR. Thoracoscopic wedge resection of the lung using high-frequency jet ventilation in a postpneumonectomy patient. A A Case Rep. 2013;1:39–41
    133. Misiolek H, Knapik P, Swanevelder J, Wyatt R, Misiolek M. Comparison of double-lung jet ventilation and one-lung ventilation for thoracotomy. Eur J Anaesthesiol. 2008;25:15–21
    134. Garutti I, Rancan L, Simón C, Cusati G, Sanchez-Pedrosa G, Moraga F, Olmedilla L, Lopez-Gil MT, Vara E. Intravenous lidocaine decreases tumor necrosis factor alpha expression both locally and systemically in pigs undergoing lung resection surgery. Anesth Analg. 2014;119:815–28
    135. Chappell D, Dörfler N, Jacob M, Rehm M, Welsch U, Conzen P, Becker BF. Glycocalyx protection reduces leukocyte adhesion after ischemia/reperfusion. Shock. 2010;34:133–9
    136. Tusman G, Belda JF. Treatment of anesthesia-induced lung collapse with lung recruitment maneuvers. Current Anaesth Crit Care. 2010;21:244–249
    137. Park SH, Jeon YT, Hwang JW, Do SH, Kim JH, Park HP. A preemptive alveolar recruitment strategy before one-lung ventilation improves arterial oxygenation in patients undergoing thoracic surgery: a prospective randomised study. Eur J Anaesthesiol. 2011;28:298–302
    138. Unzueta C, Tusman G, Suarez-Sipmann F, Böhm S, Moral V. Alveolar recruitment improves ventilation during thoracic surgery: a randomized controlled trial. Br J Anaesth. 2012;108:517–24
    139. El-Tahan MR, El Ghoneimy YF, Regal MA, El Emam H. Comparative study of the non-dependent continuous positive pressure ventilation and high-frequency positive-pressure ventilation during one-lung ventilation for video-assisted thoracoscopic surgery. Interact Cardiovasc Thorac Surg. 2011;12:899–902
    140. Ko R, McRae K, Darling G, Waddell TK, McGlade D, Cheung K, Katz J, Slinger P. The use of air in the inspired gas mixture during two-lung ventilation delays lung collapse during one-lung ventilation. Anesth Analg. 2009;108:1092–6
    141. Fernandez-Bustamante A, Wood CL, Tran ZV, Moine P. Intraoperative ventilation: incidence and risk factors for receiving large tidal volumes during general anesthesia. BMC Anesthesiol. 2011;11:22
    142. Gajic O, Dara SI, Mendez JL, Adesanya AO, Festic E, Caples SM, Rana R, St Sauver JL, Lymp JF, Afessa B, Hubmayr RD. Ventilator-associated lung injury in patients without acute lung injury at the onset of mechanical ventilation. Crit Care Med. 2004;32:1817–24
    143. Wolthuis EK, Choi G, Dessing MC, Bresser P, Lutter R, Dzoljic M, van der Poll T, Vroom MB, Hollmann M, Schultz MJ. Mechanical ventilation with lower tidal volumes and positive end-expiratory pressure prevents pulmonary inflammation in patients without preexisting lung injury. Anesthesiology. 2008;108:46–54
    144. Whynot S, Xu Z, Zhang H, Slutsky AS, Chappe V, Henzler D, Ismaiel N. Protective ventilation attenuates lung injury by combined mechanisms of reduced mechanical stress and hypercapnia in a rat model of ARDS. Am J Respir Crit Care Med. 2014;189:A3100
    145. Laffey JG, Tanaka M, Engelberts D, Luo X, Yuan S, Tanswell AK, Post M, Lindsay T, Kavanagh BP. Therapeutic hypercapnia reduces pulmonary and systemic injury following in vivo lung reperfusion. Am J Respir Crit Care Med. 2000;162:2287–94
    146. Mekontso Dessap A, Charron C, Devaquet J, Aboab J, Jardin F, Brochard L, Vieillard-Baron A. Impact of acute hypercapnia and augmented positive end-expiratory pressure on right ventricle function in severe acute respiratory distress syndrome. Intensive Care Med. 2009;35:1850–8
    147. Morisaki H, Serita R, Innami Y, Kotake Y, Takeda J. Permissive hypercapnia during thoracic anaesthesia. Acta Anaesthesiol Scand. 1999;43:845–9
    148. Sticher J, Müller M, Scholz S, Schindler E, Hempelmann G. Controlled hypercapnia during one-lung ventilation in patients undergoing pulmonary resection. Acta Anaesthesiol Scand. 2001;45:842–7
    149. Zollinger A, Zaugg M, Weder W, Russi EW, Blumenthal S, Zalunardo MP, Stoehr S, Thurnheer R, Stammberger U, Spahn DR, Pasch T. Video-assisted thoracoscopic volume reduction surgery in patients with diffuse pulmonary emphysema: gas exchange and anesthesiological management. Anesth Analg. 1997;84:845–51
    150. Thorens JB, Jolliet P, Ritz M, Chevrolet JC. Effects of rapid permissive hypercapnia on hemodynamics, gas exchange, and oxygen transport and consumption during mechanical ventilation for the acute respiratory distress syndrome. Intensive Care Med. 1996;22:182–91
    151. Ishikawa S. Oxygenation may improve with time during one-lung ventilation. Anesth Analg. 1999;89:258–9
    152. Bardoczky GI, Szegedi LL, d’Hollander AA, Moures JM, de Francquen P, Yernault JC. Two-lung and one-lung ventilation in patients with chronic obstructive pulmonary disease: the effects of position and F(IO)2. Anesth Analg. 2000;90:35–41
    153. Ranieri VM, Suter PM, Tortorella C, De Tullio R, Dayer JM, Brienza A, Bruno F, Slutsky AS. Effect of mechanical ventilation on inflammatory mediators in patients with acute respiratory distress syndrome: a randomized controlled trial. JAMA. 1999;282:54–61
    154. Jaber S, Antonelli M. Preventive or curative postoperative noninvasive ventilation after thoracic surgery: still a grey zone? Intensive Care Med. 2014;40:280–3
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