Unit 6 Equipment and Monitors Flashcards
What components are present in the higher pressure system of the anesthesia machine?
begins at the cylinder and ends at cylinder regulators. Components include: hanger yoke, yoke block with check valves, cylinder pressure gauge, cylinder pressure regulators
What is the gas pressure in the high pressure system?
cylinder pressure
What components are present in the intermediate pressure system?
Begins at pipeline and ends at flowmeter valve. Components include: pipeline inlets, pressure gauges, ventilator power outlet, O2 pressure failure system, O2 2nd stage regulator, O2 flush valve, flowmeter valve
What components are present in the lower pressure system of gas machine?
flowmeter tubes (Thorpe Tubes)
vaporizers
check valves (if present)
common gas outlet
What are the five tasks of O2 in the anesthesia machine?
- O2 pressure failure alarm
- O2 pressure failure device (failsafe)
- O2 flowmeter
- O2 flush valve
- Ventilator drive gases (if pneumatic bellows)
Describe the pin index safety system (PISS).
Pin configuration on each hanger yoke assembly is different for each gas tank.
Goal is to prevent inadvertent misconnections. Note: having more than one washer may bypass the PISS system.
Describe the Diameter Index System (DISS).
Each gas hose and connector are sized and threaded for each individual gas line.
Goal is to prevent inadvertent misconnections of gas hoses.
What are the max pressure and volumes for cylinders of air, O2, N2O?
Air (yellow) = 625L, 1900 PSI, PIN 1,5
O2 (green) = 660L, 1900 PSI, PIN 2,5
N2O (blue) = 1590L, 745 PSI, PIN 3,5
Bourbon pressure gauge on O2 cylinder reads 500 psi. If flow rate 4L/min, how long with this cylinder provide O2 to patient?
660L/1900PSI = x/500PSI = 174L 174L/(4L/min) = 43.5 min.
Is it ever safe to use an O2 cylinder in the MRI suite?
only if made of non-magnetic material such as aluminum.
MRI cylinders have 2 colors: silver tank with only the top covered with either yellow (air), green (O2), blue (N2O).
List 3 safety relief devices that prevent a cylinder from exploding when the ambient temperature increases.
gas cylinders should never be exposed to temps > 130 F (57 C).
- fusible plug made of Wood’s metal (melts at high temps)
- frangible disk that ruptures under pressure
- valve that opens at elevated pressures.
Give 1 example of how the O2 pressure failure device (failsafe) might permit the delivery of a hypoxic mixture.
if there is a pipeline crossover, the pressure of 2nd gas will produce pressure to defeat the failsafe device.
Give 4 examples of how the hypoxia prevention (proportioning device) might allow the delivery of a hypoxic mixture.
- O2 pipeline crossover
- leaks distal to the flowmeter valves
- administration of a third gas (helium)
- defective mechanic or pneumatic components
What is the difference between O2 pressure failure device and the hypoxia prevention safety device?
O2 pressure failure device = failsafe device that shuts off and/or proportionally reduces N2O flow if O2 pressure drops < 20 psi.
Hypoxia prevention safety device is a proportioning system that prevents the user from setting a hypoxic mixture with flow control valves. Max N2O = 75%
Describe the structure and function of flowmeters.
annular space is the area between the indicator flow and the side wall of the flow tube. narrow at the base and wide at the top.
It has a variabel orifice that provides constant gas pressure throughout a range of flows.
1. Laminar flow depends of viscosity (Poiseuille)
2. Turbulant flow depends on gas density (Graham).
