Iatrogenic Pediatric Pneumothorax: Comment.

Abstract

We would like to address the concerns raised by Pecorella et al. in their recent “Images in Anesthesiology” publication entitled “Too Much of a Good Thing: Iatrogenic Pediatric Pneumothorax from Engagement of the Oxygen Flush Valve.”1We agree that if the adjustable pressure-limiting valve is fully closed during manual ventilation and the oxygen flush is engaged, then high pressures can rapidly develop in the circuit, which will then be delivered to the patient. However, it is worth clarifying when it is safe to use the oxygen flush valve—whether in manual or mechanical ventilation mode—even in pediatric patients. The answer depends on the type of anesthesia machine being used and the adjustable pressure-limiting valve setting.The oxygen flush valve provides a way to rapidly deliver oxygen into the common gas outlet, bypassing the flowmeter and vaporizer. It is a key component of modern anesthesia machines that has consistent design standards.2 Use of the valve can be helpful in instances where large leaks are encountered (e.g., difficult mask seal, circuit disconnect, or open airway procedures). The oxygen flush valve has also been described for use in jet ventilation should other oxygen sources not be available.3,4 All modern anesthesia machines provide easy access to an oxygen flush valve because there may be instances in which rapid oxygen delivery is needed.The safety issue raised in the original article may be machine-specific. The machine depicted in the original article’s supplemental video appears to be a machine with a bellows-driven ventilator circuit. Most modern anesthesia machines have built-in pressure release valves and fresh gas decoupling. Thus, during mechanical ventilation, if excess flow (and subsequently pressure) develops in the circuit, it is shunted out via the valve, protecting the patient. These valves prevent both excessive positive pressure (by releasing pressure beyond a certain threshold) and negative pressure from developing (by entraining room air).5 However, these safety features may vary depending on the make and model and ventilator type (e.g., bellows-, piston-, or turbine-driven ventilator). At our institution, we use an anesthesia machine that uses a turbine-driven ventilator with fresh gas decoupling. We confirmed that during mechanical ventilation, the delivered ventilation pressures are entirely unaffected by engagement of the oxygen flush valve. With respect to manual ventilation, it is rare to fully close or set the adjustable pressure-limiting valve greater than 40 cm H2O in the pediatric population. Even if the valve is set this high, after completion of manual ventilation, we recommend routinely resetting the adjustable pressure-limiting valve to 0 cm H2O to avoid build-up of pressure in the circuit if manual ventilation is resumed.The authors declare no competing interests.