Breathing Systems And The Anesthesia Machine

Explanation
The World Health Organization requires that compressed-gas cylinders containing N20 for medical use be painted blue. Size "E" compressed-gas cylinders completely filled with N20 contain approximately 1590 L of gas

Explanation
US Manufacturer's require that all compressed-gas cylinders containing O2 for medical use be painted green. A compressed-gas cylinder completely filled with O2 has a pressure of approximately 2000psi and contains approximately 625L of gas. According to Boyle's Law the volume of gas remaining in a closed container can be estimated by measuring the pressure within the container. Therefore, when the pressure gauge on a compressed-gas cylinder containing O2 shows a pressure of 1600 psi, the cylinder contains 500L of O2. At a gas flow of 2L/min, O2 could be delivered from the cylinder for approximately 250 minutes.

Explanation
To summarize the relative efficiency of different Mapleson systems with respect to prevention of rebreathing, during spontaneous ventialtion, A>DFE>BC. During controlled ventilation, DFE>BC>A
Remember "A Dog Can Bite" (Usually a spontaneous event)
"Dead Babies can't assist" (controlled)

Explanation
Agent-specific Vaporizers, are designed for each volatile anesthetic. However, volatile anesthetics with identical saturated vapor pressures could be used interchangeably with accurate delivery of the volatile anesthetic.
Agent Vapor Pressure at 20C
Halothane 243
Enflurane 172
Sevoflurane 160
Isoflurane 240
Desflurane 669
Methoxyflurane 23

Explanation
It has been demonstrated that, in the presence of a flow meter leak, a hypoxi mixture is less likely to occur if the O2 flowmeter is located downstream from all other flowmeters. A potentially dangerous arrangement has the nitrous oxide flowmeter located in teh deownstream position. A hypoxi miture can result, because a substantial portion of O2 flow passes through the leak, and all the nitrous oxide is directed to the common outlet. A safer configuration has the O2 flowmeter located in the downstream position. A portion of the nitrous oxide flow escapes through the leak and the remainder goes toward the common outlet. A hypoxic mixture is less likely, because all the O2 flow is advanced by the nitrous oxide. A leak in the O2 flow tube can produce a hypoxic mixture even when O2 is located in the downstream position.