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Is Bronchoscopy Indicated in the Management of Atelectasis?: Con: Bronchoscopy

Raoof, Suhail M.D.

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Nassau University Medical Center, East Meadow, New York, U.S.A.

Address reprint requests to Dr. Suhail Raoof, Nassau University Medical Center, 2201 Hempstead Turnpike, East Meadow, NY 11554 U.S.A.; e-mail: sraoof@numc.edu

Healthy individuals change their body position approximately every 11.6 minutes while sleeping. 1 Critically ill patients may remain immobilized for extended periods of time. Despite repositioning these patients every 2 hours, adverse effects are observed in many organ systems of the body, especially the lungs. 2 One such effect is atelectasis of the lungs.

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MECHANISM OF DEVELOPMENT OF ATELECTASIS

In a supine position, the abdominal contents push the diaphragm upwards. The cephalad movement of the diaphragm may result in closure of the alveoli in the dependent lung zones, reducing functional residual capacity. Critical illness, hypoxemia, and the presence of an endotracheal or tracheostomy tube may impair mucociliary clearance mechanisms. Pooling of mucus in the dependent lung zones may also result in development of atelectasis. 3

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EFFECTS

Creation of areas with low ventilation and relatively preserved perfusion results in a shunt with attendant hypoxemia. Atelectasis causes a decrease in compliance of affected alveolar units. Thus, a greater critical level of opening pressure with each breath is required to restore patency of the atelectatic lung units. Pooled secretions may allow proliferation of bacteria, which in turn may increase the risk of development of nosocomial pneumonia.

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PATTERNS OF LUNG INVOLVEMENT

The lower lobes are involved most frequently. In a group of 23 patients with acute spinal cord injury, 22 patients had atelectasis and pneumonia involving the lower lobes. 4 In 309 postoperative or critically ill patients, the left lower lobe was the most common site of accumulated secretions. 5 Various reasons implicated in the preferential involvement of lower lobes in critically ill patients are discussed in Table 1 and Fig. 1.

TABLE 1

TABLE 1

FIG. 1.

FIG. 1.

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TREATMENT MODALITIES

Several modalities have been used to remove retained secretions (Table 2).

TABLE 2

TABLE 2

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Postural Drainage

This modality deploys 11 positions of the patient to assist drainage of respiratory secretions with gravity. Several studies have demonstrated the benefits of postural drainage on mucus and peripheral lung clearance. 6,7 Stiller et al. 7 demonstrated that in a group of 14 patients with lobar atelectasis, the group (n = 7) receiving positioning, vibrations, hyperinflation, and suction showed resolution in 60.1% patients in contrast to 7.6% resolution in the group (n = 7) receiving hyperinflation and suction only. Positioning involved laying the patient with the involved lung uppermost, for at least 20 minutes. Treatment cycles were repeated hourly for 6 hours.

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Coughing and Breathing Exercises

Coughing may clear airway secretions up to the fourth-generation segmental bronchi. 8 Spontaneous coughing mechanisms may be impaired in critically ill patients because of the presence of an endotracheal tube, respiratory muscle weakness, pain, and an impaired level of consciousness. Mechanisms to assist in coughing include compression of the trachea at the suprasternal notch, asking the patient to make repeated exhalation maneuvers from maximal inspiration, controlling pain that prevents the patient from coughing forcefully, and supporting thoracic and abdominal incisions during coughing.

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Intermittent Positive Pressure Breathing

Atelectatic lung units may need high distending pressures to regain patency. Intermittent positive pressure breathing, administered by a mask or mouthpiece and nose clips every 1 to 2 waking hours for 15 to 30 minutes, is recommended by some authors for use in refractory atelectasis. 9 Selection criteria proposed are refractory atelectasis and reduced inspiratory capacity of less than 1 L and a vital capacity of less than 10 mL/kg in an adult. 9

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Percussion and Vibrations with Kinetic Therapy (KT)

Percussions may be delivered both manually and mechanically. Energy waves are transmitted through the chest wall and serve to dislodge secretions from the bronchial walls.

KT is defined as the continuous turning of a patient slowly along the longitudinal axis to ≥ 40° onto each side. 10 In a study by Raoof et al. 11 of 24 patients with segmental, lobar, or whole-lung atelectasis, 17 in the test group received KT (45° rotation to each side) and percussion therapy (P; 20 minutes every 4 hours at 9 beats/second). The remaining seven patients (control group) received manual repositioning and manual percussion every 2 hours. Two patients in the control group (28.6%) and eight patients in the test group (47.1%) were intubated and ventilated mechanically. Suctioning in both groups was performed via either the endotracheal tube or nasotracheal silastic catheters.

The groups were matched in terms of age, smoking history, primary diagnosis, medication usage, extent of atelectasis, and partial pressure of oxygen in arterial blood to fraction of inspired oxygen (PaO2/FIO2) ratio at baseline. The test group had a slightly higher APACHE II score (16 ± 4 points vs. 11 ± 5 points). The test group demonstrated complete or partial resolution of atelectasis in 14 of 17 patients (82.3%). Chest roentgenograms of a representative patient in the KT+P group are depicted in Fig. 2. The control group, on the other hand, demonstrated resolution of atelectasis in only one of seven patients (14.3%). It took a median duration of 4 days to bring about resolution of atelectasis using KT+P. The results of this study are summarized in Table 3.

TABLE 3

TABLE 3

FIG. 2.

FIG. 2.

In the study, none of the test patients underwent bronchoscopy for resolution of atelectasis, whereas 42.9% control subjects underwent bronchoscopy. Three patients each in the test and control groups were advised bronchoscopy; however, consent could not be obtained in each of the six patients. If bronchoscopy was performed in all patients who failed noninvasive techniques to resolve atelectasis, 17.6% of patients in the test group versus 85.7% of patients in the control group would have required bronchoscopy. It can be projected from this study, that approximately 68% of all bronchoscopies may have been avoided in patients with atelectasis treated with KT+P. In addition, the KT+P group demonstrated a PaO2/FIO2 ratio that was significantly higher (P < 0.03) at days 3, 7, and 14 compared with the control group.

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Manual Lung Inflation

With this treatment option, the patient is disconnected from the ventilator and is connected to a manual resuscitation bag. The lungs are inflated with large tidal volumes. High expiratory flows generated from the state of hyperinflation help to mobilize secretions. Different studies have shown no improvement 12 in lung compliance or oxygenation or an increase in lung compliance for as long as 2 hours in patients without pulmonary disease when hyperinflation was used with percussion. 13

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Air Insufflation

Several studies have demonstrated that despite chest physiotherapy or bronchoscopy, the atelectatic segments may not expand. Kubota et al. 14 and Susini et al. 15 devised a curve-tipped catheter and a small-caliber balloon-tipped catheter respectively. The catheter was introduced through the nares or through an endotracheal tube. Fluoroscopic visualization was used in one study 15 while advancing the catheter. In that study, a 60-mL syringe was used to insufflate the atelectatic lobe. Compiling the data from these two studies, nonbronchoscopic techniques resulted in complete reexpansion of the atelectatic segments in 17 of 20 patients (85%) and partial reexpansion in the remaining three patients.

In summary, several studies have demonstrated that chest physiotherapy is an effective modality for the treatment of acute lobar atelectasis. The rate of resolution of atelectasis may be increased significantly by the combined and intensive application of these manual and mechanical therapies. 7 Manual chest physiotherapy, however, is labor intensive and may take up a substantial amount of health care providers' time. With the availability of specialty beds with the capability of providing lateral rotation to more than 40° on each side and percussion therapy, atelectasis may be resolved in a large number of patients without resorting to invasive techniques such as bronchoscopy. 11

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FLEXIBLE BRONCHOSCOPY (FFB) FOR ATELECTASIS

Atelectasis, in the majority of patients, may be resolved with conventional chest physiotherapy. 14 Indeed, Marini et al. 16 showed no significant difference in the resolution of volume loss in postoperative patients receiving bronchoscopy or chest physical therapy. In the case of a lack of response to physical therapy (usually 24 to 48 hours), 17 or worsening atelectasis, bronchoscopy may be considered. FFB resulted in improvement in aeration on chest roentgenogram in 41% of 90 bronchoscopies performed for retained secretions. Clinical improvement was seen in only 19% patients. 18 A plausible explanation of the poor response is depicted in Fig. 3. In critically ill patients, for various reasons, there is a reduction in tidal volume and vital capacity. Reduction of functional residual capacity below closing volume results in closure of small airways, depletion of surfactant, and reabsorption of alveolar gases. This may result in the presence of air bronchograms in the subsegmented bronchi or beyond. Presence of distal air bronchograms connotes absence of secretions and hence failure of response to bronchoscopy. 17,19

FIG. 3.

FIG. 3.

When FFB is combined with vibrations and chest physiotherapy, the rate of complete resolution of atelectasis is approximately 71%. Partial improvement was noted in another 18% patients. 20

Another indication for FFB may be severe hypoxemia. Some authors have arbitrarily chosen a PaO2/FIO2 ratio of ≤ 100 as an indication for performing urgent FFB. 21

The complications associated with performing FFB for atelectasis are summarized in Table 4. 22

TABLE 4

TABLE 4

FFB is an invasive procedure that may be associated with complications in critically ill patients. The overall complications associated with FFB not involving transbronchial biopsy was 3 of 141 procedures (2.1%). 20 Hypoxemia, defined as an oxygen saturation of less than 90%, was observed in 29 of 147 procedures (19.7%) performed in mechanically ventilated patients.

The degree of hypoxemia during FFB may be as much as 20 mmHg. 23 The duration of hypoxemia may persist for 2 to 4 hours. However, the greater the amount of normal saline instilled for lavage during FFB, the more frequent the hypoxemia (as much as 23% of patients) 24 and the longer its duration (as long as 8 hours). 25 The issue of hypoxemia may assume greater clinical relevance in elderly patients who are hypoxemic to begin with and who have an advance directive that intubation and mechanical ventilation not be instituted.

An augmentation of cardiac output, mean arterial pressure, heart rate, and mean pulmonary artery occlusion pressure occurs during FFB. These effects are most pronounced during suctioning and usually last for approximately 15 minutes. 26 Significant atrial and ventricular arrhythmias were reported in 11% of patients in one series. 27

During passage of the bronchoscope and intrabronchial suctioning, irritant receptors in lower airways may be stimulated and may result in bronchospasm. 23 This may be particularly profound in the asthmatic, intubated patient with diffuse mucus plugging.

Cardiopulmonary arrest is rare, with an incidence of 0.01 to 0.5%. 22,28

In a study by Matsushima et al. 29 the passage of a standard 5.9-mm bronchoscope through an 8-mm cuffed endotracheal tube increased airway resistance approximately 11-fold. This may result in the development of dangerous intrinsic PEEP (average, 10.4 ± 9.3 cm H2O). It is therefore recommended by most investigators that extrinsic PEEP be discontinued before performing FFB. 26

In critically ill patients, the nose, oropharynx, or endotracheal tube may be colonized with pathogenic bacteria. The potential for the bronchoscope to act as a vehicle for translocation of these bacteria to the distal airways and result in nosocomial pneumonia is intuitively obvious.

Obtaining consent for a bronchoscopy may be difficult in specific subsets of patients. In 24 patients with atelectasis and respiratory failure, Raoof et al. 11 could not get consent or the Do Not Resuscitate order rescinded for performing bronchoscopy in six patients (25%).

In an editorial written by Prakash, 30 several risk factors were identified that predict complications during bronchoscopy. These include unstable angina, uncontrolled arrhythmias, refractory hypoxia, severe hypercarbia, severe bullous emphysema, severe asthma, severe coagulopathy, mechanical ventilation, high positive end-expiratory pressure, and lack of patient cooperation. Some or many of these factors may be present in patients undergoing bronchoscopy for atelectasis.

The actual cost of performing a bronchoscopy varies from hospital to hospital. The data are not readily available. An approximate estimation of costs was performed in a county hospital in New York in 1997. Assuming that an average bronchoscopy for resolving atelectasis takes 1 hour of the attending physician's time and 1.5 hours each of the pulmonary fellow's and bronchoscopy nurse's time, adding equipment used and sterilizing expenses, the cost for performing a bronchoscopy was estimated at $300 (US). The costs of renting specialty beds in the same hospital to provide KT+P were $180 (US)/day. 11 The expenses incurred in delivering manual chest percussion and suctioning and two hourly patient rotations is difficult to calculate. Knowledge of costs incurred in individual settings may be an important factor in choosing the procedure of choice.

Based on the current data, a proposed algorithm for management of pulmonary atelectasis is outlined in Fig. 4.

FIG. 4.

FIG. 4.

In conclusion, atelectasis is a common occurrence in critically ill patients. Atelectasis has notable effects on lung mechanics and gas exchange. If the reason for development of atelectasis is retained secretions, bronchoscopy may be preferred to less invasive techniques in the severely hypoxemic individual. If distal air bronchograms (subsegmental bronchi and beyond) are seen, patients may have alveolar collapse without retained secretions. In such cases, bronchoscopy is unlikely to be beneficial. The usefulness of bronchoscopy in resolving atelectasis is comparable with chest physical therapy (either manual or mechanical). Finally, bronchoscopy is an invasive procedure that has substantially more complications than chest physical therapy.

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