Too Much of a Good Thing: Iatrogenic Pediatric Pneumothorax from Engagement of the Oxygen Flush Valve

Iatrogenic pneumothorax during anesthesia remains uncommon but can occur as a result of elevated airway pressures in the setting of anesthesia and airway management. Infants, because of their small size and highly compliant chest, are at greater risk of lung trauma from even briefly elevated airway pressures.¹  The oxygen flush valve is sometimes used to rapidly refill the bag for manual ventilation or the ventilator bellows. When open, it delivers oxygen at high pressure at a rate of 35 to 75 l/min.²  If the valve is open during mechanical ventilation, the airway pressure can reach as high as 70 cm H₂O as the pressure-limiting valve of an operating room ventilator is usually set at 70 cm H₂O. If it is open in spontaneous breathing mode or during manual bag ventilation, the airway pressure can reach 68 cm H₂O if the adjustable pressure-limiting valve is completely closed or dysfunctional. The Supplemental Digital Content (https://links.lww.com/ALN/C758) demonstrates that air pressure can reach 68 cm H₂O within 2.6 s when the oxygen flush valve is pushed with a pediatric bag and the adjustable pressure-limiting valve is closed. Such high pressures can occur with a single flush and resulted in a pneumothorax in this infant (fig.; R indicates right). As many anesthesia machines may allow the oxygen flush valve to function during mechanical ventilation, a flush to refill the ventilator bellows can render airway pressures as high as 70 cm H₂O and lead to catastrophic harm in children.³  Therefore, refilling the bellows or the manual ventilation bag by pushing the oxygen flush valve should be discouraged.