At what oxygen pressure does the mechanical Ohmeda system shut off N2O flow?

• A. 20 psi
• B. 15 psi
• C. 10 psi
• D. 5 psi

Answer: (C)

The mechanical Ohmeda system is designed to ensure patient safety by preventing the administration of nitrous oxide (N2O) to patients when oxygen supply is insufficient. The system incorporates a pressure-sensitive mechanism that monitors the oxygen pressure in the tank. If the oxygen pressure falls below a critical threshold, specifically at 10 psi, the system automatically shuts off the flow of nitrous oxide. This feature is crucial because it prevents the potential risks and complications that could arise from administering N2O in the absence of adequate oxygen, which could lead to hypoxia. The choice of 10 psi reflects a balance between allowing sufficient oxygen flow for safe anesthesia while also ensuring that N2O is not delivered when oxygen levels are critically low. Thus, understanding the 10 psi threshold is vital for anyone working with anesthesia machines, as it is a key safety mechanism in preventing hazardous conditions during procedures.