Expanding unilateral lung collapse using airway pressure release ventilation applied independently to the collapsed lung through the double-lumen endotracheal tube.

Unilateral lung collapse (ULC) is a clinical challenge in the intensive care unit and requires sophisticated treatment approaches, especially if the collapse continued over several hours. If not responded to ordinary measures such as postural drainage and bronchoscopy, it may require insertion of a double-lumen endotracheal tube and independent lung ventilation or high-pressure manual re-expansion of the collapsed lung which may result in lung injury. In this article, a safe and gradual re-expansion method using airway pressure release ventilation is presented for the treatment of a ULC. Copyright:

INTRODUCTION

Unilateral lung collapse (ULC) caused by the obstruction of a main stem bronchus is not uncommon in the intensive care unit and postoperative period, with a prevalence ranges from 2% to 40%.[12] ULC usually responds well to bronchoscopy, nebulized mucolytic agents, incentive spirometry, physiotherapy, and postural drainage.[3] After obstruction of a main stem bronchus, the alveolar air space becomes progressively deflated because of gradual absorption, and if not treated early it may lead to total ULC which may not respond easily to conventional treatments.[4] In the intubated patients since the collapsed lung has a very poor compliance, most of the tidal volume diverts to the normal lung causing overinflation injury which necessitates using the advanced method of lung recruitment selectively applied to the affected lung. Using a double-lumen endotracheal tube facilitates the isolation of lungs and allows for manual inflation of collapsed lung using high pressure without affecting the healthy lung. Rapid re-expansion of the collapsed lung by forceful application of positive pressure to the collapsed lung may lead to adverse complications such as barotrauma, bronchospasm, lung edema, and pneumothorax.[5] A relatively safe approach for expanding the lung is to use independent lung ventilation (ILV) using two ventilators with different setting customized to each lung.[6] In this article, we have reported a case of total ULC treated successfully using the ventilation mode of airway pressure release ventilation (APRV).

CASE REPORT

A 49-year-old male patient with multiple trauma admitted to the intensive care unit after emergency laparotomy for the removal of a ruptured spleen. The patient was receiving mechanical ventilation through a well-positioned tracheal tube. In the next post-operative day, oxygen saturation decreased and on auscultation respiratory sounds cannot be heard over the left hemothorax, which persisted after endotracheal suctioning. The depth of tracheal tube insertion was checked and appeared to be appropriate for the patient (21–22 cm). A portable chest X-ray showed complete collapse of the left lung. The appropriate position of the tracheal tube was confirmed in the chest X-ray. The preoperative chest X-ray showed no evidence of lung collapse and both lung fields were normal on auscultation as documented in patient's history. Therefore, we concluded that the collapse was developed during or after surgical operation. To treat lung collapse in addition to tracheal suction, the patient positioned on the right side and a nebulization of N-acetylcysteine 20% 3 ml Q8h administered and tidal volume reduced to 300 ml to prevent overinflation of the right lung. After 2 days, fiberoptic bronchoscopy was performed to open the bronchial obstruction and to expend the lung which proved to be ineffective. In the fifth postoperative day, the left lung was still totally collapsed in the chest X-ray [Figure 1], and it was decided to recruit the left lung using ILV. At this time, oxygen saturation was 88–90% with an FiO2 of 1.0, lung compliance 30 ml/cmH2O, and peak airway pressure 18 cmH2O. After sedation with midazolam 5 mg and fentanil 100 μg cisatracurium 15 mg was administered as muscle relaxant to facilitate insertion of double-lumen tube. Then pharynx was suctioned, single-lumen tracheal tube was removed and a size 36F left-sided double lumen tube was inserted without difficulty. Ventilation of the right lung continued as before. For the left lung initially manual ventilation with a bag-valve was tried, but it soon appeared to be stiff and resistant to expansion. Therefore, after 30 min of bag-valve trial, the left lung connected to a second ventilator using APRV with the setting showed in Table 1. Patient's spontaneous ventilation was returned at this point and preserved throughout the procedure. Fifteen minutes after start of APRV mode for the left lung, oxygen saturation and left lung compliance started to rise from the initial value of 90% and 30 ml/cmH2O toward a final value of 98% and 28 ml/cmH2O after 2 h respectively. A second chest X-ray showed re-expansion of the left lung [Figure 2]. At this point, double-lumen tube was replace with a single-lumen tracheal tube and ventilation of both lungs continued using PSIMV mode with a pressure of 12 cmH2O and a PEEP of 10 cmH2O which resulted in an exhaled tidal volume of 600–640 ml. FiO2 gradually reduced to 40% and total lung compliance increased to 52 ml/cmH2O after 4 h. During the whole period, hemodynamic status was stable. Final blood gas values were appropriate, and the rest of the clinical course had no significant event and control X-rays showed fully expanded lungs. The patient was extubated the next day and discharged from the intensive care unit after another 2 days.

Figure 1

Chest X-ray before insertion of double-lumen endotracheal tube, showing collapse of the left lung

Table 1

Ventilatory setting of the patient

Setting	Value
Normal lung (right)
Mode	SIMV
Tidal volume (ml)	300
Set rate (bpm)	12
PEEP (cmH2O)	8
Collapse lung (left)
Mode	APRV
P high (cmH2O)	30
P low (cmH2O)	0
T high (s)	8
T low (s)	0.5

APRV=Airway pressure release ventilation; SIMV=Synchronized intermittent mandatory ventilation, PEEP=Positive end-expiratory pressure

Figure 2

Chest X-ray 2 h after the application of airway pressure release ventilation to the collapsed lung

DISCUSSION

During ILV lungs are separated anatomically and physiologically. Each lung ventilates using a separate ventilator with setting tailored to the characteristics of each individual lung.

In this article, a new method for safe and soft recruitment of collapsed lung is presented. APRV is a pressure controlled mode which applies a continuous distending airway pressure higher than the baseline pressure over several seconds with brief releases at set points to facilitate tidal exhalation. APRV is mainly used as a rescue mode in acute respiratory distress syndrome resistant to conventional mechanical ventilation. In this mode, the ratio of inspiration to expiration is high (inverse ratio ventilation) and the continuous distending pressure progressively re-expands the atelectatic areas of the lung. Therefore, it is a safe and gradual method of lung recruitment compared to invasive approaches of applying very high distending pressure in short time periods with potential volutrauma.

The exact cause of lung collapse in this case is not evident, but postoperative lung collapse is usually caused by impaired ventilation, retained secretions, decreased compliance of lung, postoperative pain that interferes with effective breathing and coughing, and malposition of tracheal tube into a main stem bronchus.[7]

Since ILV through a double-lumen endotracheal tube is inherently invasive, it should not be used as the first measure for the treatment of ULC. In this case, ordinary treatments consisting of postural drainage, chest physiotherapy, and fiberoptic brochoscopy were not effective.

Previously, Purtuloglu et al.[5] used a mixture of Bi-level positive airway pressure and manual lung inflation using a bag-valve unit for 24 h; both were applied with relatively high distending pressure of 32 and 40 cmH2O, respectively. Although the APRV method used in our case used a lower pressure and expanded the lung in a shorter period of time, controlled clinical trials are necessary to determine the best distending pressure and duration of application.

In conclusion, selective application of APRV to one lung using ILV strategy may be considered a safe, effective and practical method for recruitment of collapsed unilateral lung in intubated patients. Double-lumen tracheal tubes are available in operating rooms and intensive care units. With a little experience, it can be used by intensivist to perform ILV for cases of ULC resistant to ordinary treatments. The insertion of double-lumen tube is more difficult than single lumen tubes, and therefore, patients must be anesthetized or deeply sedated and receive neuromuscular blockade to facilitate the tube insertion and prevent complications.

Financial support and sponsorship

Nil.

Conflicts of interest

There are no conflicts of interest.