882: A CASE OF VENTILATOR MALFUNCTION-INDUCED PNEUMOTHORAX

Abstract

Introduction: Mechanical ventilation is one of the major advances in modern medicine, used in multiple conditions including respiratory or cardiac failure. Ventilator associated lung injuries are not uncommon and are associated with high airway volumes or pressures. This case highlights a patient with no pulmonary concerns, on minimal vent settings who developed a pneumothorax from an uncommon issue with the ventilator. Description: The patient is an adult male with no known prior diagnosis, brought in from a shelter with concerns for encephalopathy from drug overdose. In the ED he had a temp 105.8F and was obtunded. He was intubated for severe encephalopathy. Initial ICU CXR was unremarkable with ET tube in good position. Vent settings: AC-VC,TV 450/RR20/FiO2 40/PEEP 5 for IBW 72kg.On day 2,it was observed that the ET tube end adaptor kept popping out causing the vent alarms to go off. Changing the adaptor and later the ET tube did not resolve the issue. The ventilator then detected low exhaled volumes with alarm messages “Low tidal volume” and “airway obstruction”. His peak/plateau pressures also became high. Both were normal the day prior. New findings of poor air entry in the right lung was later noted with ultrasound demonstrating absence of lung slide and CXR confirming pneumothorax. Chest tube was placed with lung expansion confirmed. Despite this the vent still showed low expiratory volumes with alarm messages of airway obstruction and high airway pressures. The vent circuit was changed and other vent settings were tried but failed. Finally the vent itself was changed and his readings immediately normalized and alarms ceased. Retrospective analysis revealed the vent had a faulty exhalation valve preventing air return from the circuit, causing buildup of inspiratory volumes, high airway pressures and pneumothorax. Discussion: Ventilators are frequently tested to mitigate malfunction. Most have self-diagnostic software but this is not infallible. It is rare but not unheard of for a ventilator fault to cause a number of varied pathologies which in this case resulted in a pneumothorax. We seldom consider the vent as the cause in maladaptive respiratory scenarios. Though “faulty device” may be low on our differentials, it should never be off it when troubleshooting an alarming ventilator.