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Airway management

A comparison of the disconnection technique with continuous bronchial suction for lung deflation when using the Arndt endobronchial blocker during video-assisted thoracoscopy

A randomised trial

El-Tahan, Mohamed R.

Author Information
European Journal of Anaesthesiology (EJA): June 2015 - Volume 32 - Issue 6 - p 411-417
doi: 10.1097/EJA.0000000000000194
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Abstract

Introduction

Most Middle Eastern and British thoracic anaesthesiologists (100 and 98%, respectively) are using a double-lumen endobronchial tube (DLT) as the first-choice lung separation technique,1,2 although tracheal intubation with a single lumen tube (SLT) may be easier. This reticence to use SLTs may be due to the nonavailability and higher acquisition cost of endobronchial blockers and the lack of familiarity with their use by anaesthesiologists. In addition, the use of an endobronchial blocker results in a longer time required for collapse of the operative lung.3 In a comparison study, the wire-guided Arndt endobronchial blocker (Cook Critical Care, Bloomington, Indiana, USA) was associated with a significantly longer time for lung collapse than the Univent tube (approximately 26 vs. 19 min respectively). This may be due to the narrower inner lumen of the endobronchial blocker (1.4 vs. 2.0 mm, respectively). This slower lung collapse may preclude its widespread acceptance for video-assisted thoracoscopic surgery (VATS), as it results in delayed insertion of the trocars.

There are different techniques described to accelerate lung collapse during the use of the Arndt endobronchial blocker. These include the disconnecting of the SLT from the ventilator and allowing both lungs to collapse before inflation of the bronchial blocker cuff4,5 or bronchial suction. The suction can either be through the fibreoptic bronchoscope (FOB) after deflation of the bronchial cuff and cessation of ventilation before reinflation of the bronchial cuff, or through a barrel of a 3 ml syringe attached to the suction port of the bronchial blocker.3 The use of a modified disconnection technique with the use of a Fuji endobronchial blocker during VATS for pneumothorax has been shown to have a comparable degree of lung collapse as that achieved with the use of a DLT.5 However, compared with the bronchial suction, the disconnection technique may carry a risk of blood or infected secretions contaminating the dependent lung.6

To the best of our knowledge, the comparison of the efficacy of disconnection and bronchial suction techniques to accelerate the lung deflation during the use of Arndt blocker for thoracoscopic surgery has not yet been studied. We hypothesised that that the use of bronchial suction through the suction port of the Arndt bronchial blocker would be associated with comparable time to optimum lung collapse as that seen with the disconnection technique.

Materials and methods

Ethical approval for this study was provided by the Ethical Committee (Number 2014-01-278), University of Dammam, Saudi Arabia, Chairperson Professor Abdulsalam Al-Sulaiman, on 23 February 2014. The study was registered with www.clinicaltrials.gov (ref. NCT02030795). Following written informed consent, 58 patients aged 18 to 70 years, American Society of Anesthesiologists’ (ASA) physical status II/III, scheduled for elective VATS for spontaneous pneumothorax, in whom one-lung ventilation (OLV) was needed, were included in this randomised, prospective double-blind study. Exclusion criteria were as follows: New York Heart Association (NYHA) heart failure class II to IV; forced expiratory volume in 1 s (FEV1) or forced vital capacity (FVC) less than 50% of predicted values; severe asthma; pregnancy; BMI more than 35 kg m−2; anticipated difficult intubation (Mallampatti score ≥3); patients requiring absolute lung separation (due to massive bleeding, pus or alveolar proteinosis); known lesions along the path of the bronchial blockers; preoperative ventilatory support; pneumothorax caused by thoracic surgery or trauma; emergency surgery; previous pneumonectomy, bilobectomy, lobectomy or tracheostomy; and a calculated ipsilateral percentage pneumothorax size more than 20% as estimated by helical computed tomography (CT)-derived Collins’ formula.7

Standard monitoring and state and response entropy (GE Healthcare, Helsinki, Finland) were employed in all patients. Invasive blood pressure monitoring was achieved by cannulation of the radial artery. The anaesthetic technique was standardised in all studied patients. After preoxygenation, general anaesthesia was induced with propofol 1.5 to 3 mg kg−1 and a target-controlled infusion (TCI) of remifentanil, at an effect-site concentration (Ce) of 4 ng ml−1, was titrated to achieve state entropy values of less than 50 and a difference between response and state entropy of less than 10. Cisatracurium (0.2 mg kg−1) was given to facilitate tracheal intubation with an SLT (size 8.0 mm for women and 8.5 mm for men). A 9.0-F, 78 cm Arndt endobronchial blocker with a ‘spherical’-shaped balloon was advanced through the blocker port of its special multiport connector and the wire loop was coupled with a paediatric FOB that had been introduced through the fibreoptic port. The Arndt endobronchial blocker was introduced to the targeted bronchus and the correct position was confirmed with a FOB. The optimal position in the right or left bronchus was achieved when the outer surface of the blocker balloon was seen with the FOB at least 1 cm below the tracheal carina. If any patient had an ‘early take-off’ of the right upper lobe bronchus then that precluded the use of a single Arndt endobronchial blocker for a right mainstem bronchus blockade and the patient was excluded. Anaesthesia was maintained with sevoflurane (0.7 to 1.5% minimum alveolar concentration) and remifentanil Ce of 2 to 4 ng ml−1 titrated to maintain mean arterial blood pressure (MAP) and heart rate 20% less than baseline values and the entropy values as previously described. Intermittent boluses of cisatracurium were used to maintain neuromuscular blockade. Two-lung ventilation (TLV) was instituted using an inspired oxygen fraction (FiO2) of 0.4 in air, tidal volume 8 ml kg−1, inspiratory to expiratory (I:E) ratio 1 : 2.5, positive end expiratory pressure (PEEP) 5 cmH2O and respiratory rate adjusted to achieve an arterial carbon dioxide tension (paCO2) of 4.7 to 6 kPa. After positioning the patient in the lateral decubitus position, the position of the blocker was reconfirmed and the blocker cuff was inflated under direct FOB visualisation with 5 to 8 ml of air in order to create a seal: Time = 0 (T0). The wire loop was then removed.

At least 5 min before initiation of OLV, the FiO2 was increased to 1.0. After the application of surgical drapes by a nonblinded surgeon who was not involved in scoring the degree of lung collapse, patients were randomised to one of two groups by drawing sequentially numbered sealed opaque envelopes containing a computer-generated randomisation code. In the disconnection group, the blocker cuff was deflated, the SLT was disconnected from the ventilator for 60 s allowing the surgical lung to collapse, then the cuff was reinflated with the same amount of air as previously determined and the ventilator was reconnected to the SLT. In the bronchial suction group, the barrel part of a 1 ml syringe was attached to the suction port of the bronchial blocker and was then connected to a vacuum source (-30 cmH2O) until the assessing surgeon determined that total lung collapse had been achieved. During OLV, the dependent lung was ventilated with a FiO2 of 1.0 and a tidal volume of 6 ml kg−1. All other ventilator parameters (I:E ratio, PEEP and respiratory rate) were maintained as for TLV. The dependent lung was recruited at 30 min intervals by increasing the inspiratory pressure to 40 cmH2O for 10 s.

The VATS procedure began with the exploration of the pleural cavity using a 30° video thoracoscopic camera through a 1.5 cm single skin incision with the use of one to three trocars that enabled the thoracoscopic instruments to move the lung. After the pleurotomy, when the lung could be seen, the surgeon scored the quality of lung collapse after pleural opening, and again at 20, 40 and 60 min after the initiation of OLV using a four-point ordinal scale:3,8 1, extremely poor – no collapse of lung; 2, poor – partial collapse with interference with surgical exposure; 3, good – total collapse, but the lung still had residual air; and 4, excellent – complete collapse with perfect surgical exposure. The feasibility of this scale was investigated during six surgical procedures not included in the study. Further manoeuvres were performed to facilitate lung collapse if the surgeon ranked the lung collapse as poor or extremely poor. A FOB was used to diagnose and correct the problem. The bronchial blocker cuff was deflated, ventilation stopped and bronchial suction with the FOB was performed. The bronchial blocker cuff was then reinflated.3

Intraoperative hypoxaemia, defined as a decrease in peripheral blood oxygen saturation (SpO2) below 90%, was treated with the application of low-level continuous positive airway pressure (CPAP) at 2 cmH2O.

At the end of surgery, the nondependent lung was re-expanded and the remifentanil infusion and sevoflurane were discontinued after chest and skin closure, respectively. Residual neuromuscular blockade was antagonised. Postoperative analgesia was provided with patient-controlled morphine analgesia, lornoxicam and paracetamol.

The primary outcome was the time needed for complete lung collapse; measured from the start of OLV after inflation of the bronchial blocker's cuff (T0) to the time of total lung collapse (score 3 to 4), graded via video view, by the surgeon who was blinded to the lung collapse technique. The time required to open the pleura was also recorded (T0 to pleural opening). Secondary outcome variables included the quality of lung collapse; the overall surgeon satisfaction with surgical conditions as assessed using a visual analogue scale (0, unsatisfied to 10, very satisfied); the number of times that the FOB was required to assure proper position or to perform further bronchial suction; the number of bronchial blocker malpositions; the number of secondary dislodgements of the bronchial blocker after turning the patient into the lateral decubitus position; intraoperative hypoxaemia or need for CPAP during OLV; and perioperative complications such as pulmonary oedema, respiratory failure or cardiovascular events. An independent investigator who was blinded to patient allocation and not involved in patient management collected patients’ data. The experienced attending thoracic anaesthesiologists who gave the anaesthetic and placed the Arndt endobronchial blocker were not blinded to group assignment and not involved in data collection. All surgical procedures were performed by the same surgeons who were blinded to the lung collapse technique and were absent from the operating room during placement of the bronchial blocker and deflation of the lung. The patient's head and the bronchial blocker were masked with an opaque screen to ensure the blinding of the assessor surgeon.

Statistical analysis

A previous study showed that the mean (SD) time to loss of CO2 trace on capnograph (which is the time taken to collapse both lungs before initiating OLV) was 32.3 (7) s.5 A-priori power analysis indicated that a sample size of 26 patients was sufficiently large to detect a 20% difference in the mean of time to lung collapse with the use of an Arndt endobronchial blocker, with a type I error of 0.05 and power of 90%. In order to compensate for an anticipated 10% dropout rate during the study, we aimed to recruit 29 patients to each group.

Data were tested for normality using the Kolmogorov–Smirnov test. Repeated measure analysis of variances (ANOVAs) was done. Unpaired Student's t-test was used to compare the parametric values in the two groups. Mann–Whitney U test was performed to compare the nonparametric values of the two groups. Chi-square test was used for categorical data. Spearman rank order correlation analysis was used to evaluate the relationship between the time to total lung collapse and the presence of COPD. Data were expressed as mean (SD), median (IQR) or number (%). A value of P less than 0.05 was considered to be statistically significant.

Results

All 58 patients who were enrolled (29 in the disconnection group and 29 in the bronchial suction group) completed the study (Fig. 1). The patients’ demographic and clinical characteristics, all of which were similar in the two groups, are presented in Table 1. No patient in the study had an early take-off of the right upper lobe bronchus that precluded the proper positioning of the Arndt endobronchial blocker.

Fig. 1
Fig. 1:
Patient flow diagram.
Table 1
Table 1:
Patient characteristics

Compared with the disconnection technique, the use of bronchial suction was associated with a significantly shorter time to complete lung collapse [93 (95% confidence interval, 95% CI 81.3 to 103.7) vs. 197 (95% CI 157.4 to 237) s, respectively; P < 0.001] (Table 2).

Table 2
Table 2:
Clinical outcomes

The use of bronchial suction through the lumen of the Arndt endobronchial blocker resulted in a comparable time required for pleural opening (P = 0.896), overall surgeon satisfaction (P = 0.903) (Table 2) and surgical rating scales at all observation times (P > 0.244) (Fig. 2) as compared with the disconnection technique.

Fig. 2
Fig. 2:
Distribution of the intraoperative modified surgical rating obtained during the use of disconnection technique (a) and during the use of bronchial suction (b). Data are presented as percentages.P < 0.05 compared with the disconnection technique.

No patient in the bronchial suction group needed further manoeuvres to collapse the surgical lung. Two patients needed FOB bronchial suctioning in the disconnection group. The two groups were also similar in terms of the number of patients requiring additional repositions (P = 0.436) and the number of dislodgements after positioning in the lateral decubitus position (P = 0.317) (Table 2).

One patient in the disconnection group developed intraoperative hypoxaemia that required the use of CPAP. There were no incidents of perioperative pulmonary oedema, respiratory failure or cardiovascular events.

The presence of COPD showed a significant positive correlation with the time to total lung collapse (Spearman r 0.564; P < 0.001).

Discussion

Compared with a disconnection technique, the present study showed that, bronchial suction through the suction port of the Arndt endobronchial blocker during VATS for spontaneous pneumothorax was associated with a shorter time to complete lung collapse and comparable overall surgeon satisfaction, surgical rating scales, numbers of repositions and dislodgements, incidence of intraoperative hypoxaemia, need for CPAP and perioperative complications. The presence of COPD was an independent factor that could delay the time to total lung collapse.

There is an increase in the need for OLV in order to allow procedures such as oesophageal surgery, spinal surgery, thoracic sympathectomy, minimally invasive-cardiac surgery and whole lung lavage in patients with alveolar proteinosis. All these interventions require excellent lung deflation for optimum surgical exposure, thus facilitating the surgeon's dissection and reducing both the operating time and incidence of postoperative complications.9

Two main techniques can be used to achieve lung isolation during VATS; a DLT or a bronchial blocker inserted through a SLT. There is no consensus on the best technique for lung isolation for VATS. The bronchial blocker provides equivalent surgical exposure to left-sided DLTs during left-sided VATS.3,10 However, bronchial blockers require longer to position initially, and are associated with more frequent intraoperative repositioning.10 These problems may be reduced once the learning curve process is achieved.11 Double-lumen tubes, when compared with SLTs, can be more difficult to insert in patients with abnormal upper or lower airway anatomy and in those with difficult airways. In addition, DLTs have the potential to cause more frequent postoperative complications, such as sore throat, hoarseness and airway oedema because of their larger outer diameter, distal curvature and greater rigidity.9,12,13

Another potential problem with a bronchial blocker is the longer time required to collapse the lung compared with a DLT. This could impair surgical exposure and prolong the duration of the VATS procedure. Campos and Kernstine3 showed that the Arndt endobronchial blocker took longer to achieve lung collapse (26 : 02 min:s) than a DLT (17 : 54 min:s) or Univent endobronchial blocker (19 : 28 min:s) (P < 0.006). The lumen of the Arndt endobronchial blocker is narrower than the Univent endobronchial blocker (1.4 vs. 2.0 mm) and may not be large enough to allow air evacuation. Several methods have been described to expedite lung collapse during the use of bronchial blockers’ including denitrogenation of the lung with an FiO2 of 1.0,14 filling the lung with 50% nitrous oxide,14,15 and disconnection4,5,12 and suction techniques.3

This study found that, when compared with a disconnection technique, bronchial suction was associated with a 53.1% shorter time to achieve complete lung collapse. Young et al.5 have reported that, compared with the use of wider lumen Fuji uniblockers (2.0 mm) without disconnection, the disconnection technique was associated with a shorter time to lung collapse. That study, however, included fewer patients, was not powered to test the differences in time to complete lung collapse and the study period for lung collapse was limited to 10 min after initiation of OLV. The definition of time to lung collapse varies from one study to another, from the start of OLV3 or from the opening of pleura.16 In the present study, although the time to lung collapse was defined from the start of OLV, both groups took a similar time to pleural opening.

On the basis of a previous study,17 the variable cost of patient care in the operating room was calculated at the author's centre to be equivalent to US$ 29 min−1. The use of bronchial suction during OLV was associated with a shorter time to complete lung collapse and this lowered operating room costs by US$ 77. However, this reduction in the costs could not compensate for the high cost of Arndt endobronchial bronchial blocker (US$ 290 per blocker at the author's institution). Furthermore, the disconnection technique should not be used for cases carrying a risk of blood or infected secretions contaminating the dependent lung.4,6 In these situations, which were excluded from the study, bronchial suction may be a well tolerated and effective choice to achieve lung collapse.

The ideal disconnection time needed for complete lung collapse remains controversial, with studies suggesting a time of 15 to 60 s.4,5,18 In a study that assessed the disconnection time using a capnograph, a disconnection time of 32 s was suggested.5 On the basis of previous studies,4,18 we choose a disconnection time of 60 s in order to expedite lung collapse.

The level of suction needed to accelerate the rate of lung collapse varies among clinicians.15 The failure of suction to improve lung collapse with the use of Arndt endobronchial blocker in the study of Narayanaswamy et al.10 may be explained by the low level of suction used (−20 cmH2O). Higher suction pressures have the potential to cause injury to airway mucosa19 or life-threatening hypoxaemia and pulmonary oedema.20 Applying a negative pressure even for short periods through a closed/sealed lung might cause harmful negative pressure unilateral lung oedema.20 We chose to use a suction of -30 cmH2O in this study. This was associated with a similar incidence of intraoperative hypoxaemia during OLV compared with the disconnection technique, although the study was not powered to test this difference. Further studies are needed to test the effect of using bronchial suction technique on extravascular water content index.

In the present study, compared with the disconnection technique, bronchial suction did not improve overall surgeon satisfaction or the surgical rating scales, as determined by an objective assessment. Other investigators have found that, once lung isolation was achieved, the overall quality of lung collapse was equivalent for the Arndt endobronchial blocker, Cohen Flexi-tip blocker, Fuji Uni-blocker and a left-sided DLT.10Although another study reported more patients had fair/poor lung collapse at pleural opening after the use of a disconnection technique for 60 s in conjunction with the Arndt endobronchial blocker, compared with Cohen Flexi-tip blocker and left-sided DLT (7 vs. 2 and 1, respectively), this study included fewer patients and paired intergroup comparisons did not reach statistical significance.4

In the current study, the manoeuvres to accelerate lung collapse (denitrogenation of the lung before the start of OLV and bronchoscopic suctioning if necessary) were standardised in all patients. No patient in the bronchial suction group needed further manoeuvres to collapse the surgical lung. Furthermore, we found no significant differences between the two groups in the number of patients requiring additional repositions or the number of dislodgements after positioning in the lateral decubitus position.

The present study had several limitations. First, the method of assessing lung collapse using the surgeon's rating scale was less objective than the measurement of the distance of lung collapse away from the chest wall, although the latter measure could be influenced by the size of the patient's thorax.14 Moreover, the most clinically relevant assessment of the surgical access is the surgeon's clinical impression and this was considered in the present study.14 Second, the study was not designed to test the incidence of contamination of the nondependent lung with secretions or blood. Third, the inclusion of the DLTs, to serve as the control arm for the studied groups, was not used. That is because other investigators have reported that the disconnection technique had comparable quality of lung collapse with the use of DLTs.5 Thus, the disconnection technique that was used served as the comparative control arm for the bronchial suction group.

In conclusion, the use of continuous bronchial suction through the lumen of the Arndt endobronchial blocker offers an effective method to accelerate lung collapse prior to VATS. Further larger studies are needed to address the efficacy of the continuous bronchial suction on the prevention of the contamination of the nondependent lung with blood or infected secretions compared with the disconnection technique.

Acknowledgements relating to this article

Assistance with the study: the author wishes to express his appreciation to the Thoracic Anesthesia Team, the Thoracic Surgical Team, Dr Yasser El Ghoneimy and Dr Mohamed Regal for their involvement and participation in this study.

Financial support and sponsorship: none.

Conflicts of interest: none.

Presentation: preliminary data from this study were accepted as an oral presentation at the joint European Association of Cardiothoracic Anaesthesiologists (EACTA) Annual Meeting and 14th International Congress on Cardiovascular Anesthesia (ICCVA), 17 to 19 September 2014, Florence, Italy.

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