A FEW FACTS ABOUT THE ADJUSTABLE PRESSURE LIMITING (APL) VALVE [📖]

🔗 When fully opened the APL valve maintains a pressure of around 1.5 cm of H2O 

🔗 As we close the APL valve, the pressure builds up inside and there is a safety overpressure release valve is incorporated in modern APL valves, to avoid this rising to dangerous levels. This system starts opening at  a pressure of 30 cm of H2O and fully opens at 60 cm of H2O and at this point, allows the gases to escape at a rate of 50L/ min 

🔗 When the patient inspires, the APL valve , if intact, should not allow entrainment of air from the environment 

🔗As the modern reservoir bags are less compliant, compared to the older latex ones, the importance of overpressure relief valves has increased

🔗 As the APL valve will always produce a small resistance to expiration, even when maximally loosened, it helps to maintain PEEP

#Anesthesia , #Anaesthesia