High frequency oscillatory ventilation in bronchial air leaks
Introduction
High frequency oscillatory ventilation (HFOV) maintains a constant mean airway pressure (MAP) by applying a bias flow throughout the ventilator circuit. Gas exchange is maintained by oscillating this bias flow¹. The rate of bias flow is
changed to keep the MAP constant. In pneumothoraces with air leaks it is possible to ventilate patients effectively as long as the amount of the leak does not exceed the bias flow.
In this report we describe two cases with bronchial leaks and persistent pneumothoraces that were ventilated with HFOV.
Fact
Case 1. 68-year-old male patient, undergone oesophagectomy and gastric pull- up operation. The patient was admitted with acute respiratory failure and sepsis due to empyema. Upon commencing positive pressure ventilation, the patient
developed bilateral subcutaneous emphysema. A new left pneumothorax was identified on the chest computed tomography scan (figure 1). Thoracic drainage failed to expand the lung and conventional ventilation failed to improve gas exchange due to leaks around the chest tube.
Case 2. 17-year-old female trauma victim. She was admitted to the ICU postoperatively after lung laceration repair. The patient had cardiac arrest before admission to the ER. The patient had a PaO2/Fi02 ratio of 100 on admission and effective ventilation was not possible due to air leaks from two thoracic drains (figure 2).
Both patients were ventilated with HFOV (MEK-SUM 3, S. Korea, Seul, MEK ICS) with improvement of gas exchange.
For case 1, HFOV was initiated within three hours after the development of pneumothorax. Initial settings were adjusted according to arterial blood gas (ABG) results (Table 1). Once patient's oxygenation improved after 4 days of
HFOV, he was placed back on conventional ventilation. Case 2 was placed on HFOV within the first hour of arriving to ICU and initial settings were adjusted according to the ABG (Table 2).
After 6 days of HFOV, an attempt to start conventional ventilated failed with worsened oxygenation and HFOV recommenced. After another 11 days of HFOV, she was placed on conventional ventilation and adequate gas exchange was achieved. Case 1 passed away on 21st day of admission with septic shock stemming from empyema due to anastomosis leak into the pleura. Case 2 died on 51th day of admission from severe brain injury.
Discussion:
In this report we describe two cases with bronchial leaks and persistent pneumothoraces that were ventilated with HFOV. The early initiation of HFOV resulted in rapid control of bilateral air leaks and sustain improvements in
oxygenation. HFOV has been safely and effectively used for adults with severe acute respiratory distress syndrome (ARDS)2,³. Recent trials, however, showed no benefit in outcomes 4,5,6. There have been some reports on effective use of HFOV in trauma and non-trauma patients with refractory hypoxaemia. Briggs et al.