Midterm Flashcards
First Anesthesia Delivery System
Ether soaked rag held over the patients mouth & nose
Done by Dr Crawford Long March 30, 1842
Anesthesia Evolution: Ether Inhaler
1846 – Dr William Morton
Anesthesia Evolution: Air with 4% Chloroform
1862 – Joseph Clover
Anesthesia Evolution: ether/nitrous portable administration system
1877- Jospeh Clover
When was the ‘Dräger-Roth’ inhalation anesthetic apparatus introduced
1904
When was the McKesson Nargraf Apparatus created?
1930
Karl Connell creates Connell Apparatus at Columbia University
1937
Name 5 functions of the Anesthesia Machine
Receive gases from central supply system or pressurized cylinders
Control the flow of desired gases & reduce their pressure
Measure a precise amount of gases & load them with anesthetic vapors
Provide gas to patient for breathing
Provide monitoring & safety features
Who Provided minimum standards for design, performance, & safety?
1979 American National Standards Institute (ANSI)
Who Added pre-use checkout, calibrated vaporizers, O2 analyzer, prioritized alarms, alarms enabled by a master switch, airway pressure monitoring, volume monitoring, & capnography
1988 American Society for Testing & Materials (ASTM)
Who Addressed anesthesia workstation of the future
1999 American Society for Testing & Materials (ASTM)
What is the purpose of Noninterchangeable gas-specific connections to pipeline inlets (DISS) with pressure gauges, filter, & check valve
Prevent incorrect pipeline attachments; detect failure, depletion, or fluctuation
What is the purpose of Pin index safety system (PISS) for cylinders with pressure gauges, & at least one oxygen cylinder
Prevent incorrect cylinder attachments; provide backup gas supply; detect depletion
what is the purpose of Low O2 pressure alarm
Detect O2 supply failure at the common gas inlet
What is the purpose of Minimum O2/N2O ratio controller device (hypoxic guard)
Prevent delivery of less than 21% O2
What is the purpose of O2 failure safety device (shut-off or proportioning device)
Prevent administration of N2O or other gases when the O2 supply fails
What is the purpose of O2 must enter the common manifold downstream to other gases
Prevent hypoxia in event of proximal gas leak
What is the purpose of O2 concentration monitor & alarm
Prevent administration of hypoxic gas mixtures in event of a low-pressure system leak; precisely regulate O2 concentration
What is the purpose of Automatically enabled essential alarms & monitors (ex. O2 concentration)
Prevent use of the machine without essential monitors
What is the purpose of Vaporizer interlock device
Prevent simultaneous administration of more than one volatile agent
What is the purpose of Capnography & anesthetic gas measurement
Guide ventilation; prevent anesthetic overdose; help reduce awareness
What is the purpose of O2 flush mechanism that does not pass through vaporizers
Rapidly refill or flush the breathing circuit
What is the purpose of Breathing circuit pressure monitor & alarm
Prevent pulmonary barotrauma & detect sustained positive, high peak, & negative airway pressures
What is the purpose of Exhaled volume monitor
Assess ventilation & prevent hypo- or hyperventilation
What is the purpose of Pulse oximetry, BP, & ECG monitoring
Provide minimal standard monitoring
What is the purpose of Mechanical ventilator
Control alveolar ventilation more accurately & during muscle paralysis for prolonged periods
What is the purpose of the scavenging system
Prevent contamination of the OR with waste anesthetic gases
What are the high pressure components? (4)
Hanger yoke (including filter & unidirectional valve)
Yoke block
Cylinder pressure gauge
Cylinder pressure regulators
What are the Intermediate Pressure Components? (7)
Pipeline inlets & pressure gauges
Gas power outlet
Master switch (pneumatic component)
Oxygen flush valve
Oxygen pressure failure device (fail-safe) & alarm
Oxygen & nitrous oxide second-stage pressure regulators
Flowmeter valves
What parts of the machine still work when it is in standby?
the O2 Flush Button
Suction
Auxillary O2
Others:
gas power outlet, electrical outlets on the back of the machine, & battery recharging circuitry.
What does the 02 Flush Valve do?
The oxygen (O2) flush valve receives oxygen from the pipeline inlet or cylinder pressure regulator & directs a high unmetered flow (between 35 & 75 L/min) directly to the common gas outlet.
Caution: Barotrauma & Gas Dilution
What is the Oxygen Fail-Safe Device/Alarm?
Device that shuts off or proportionally decreases all gases except oxygen or alarms when oxygen pressure has fallen to a dangerous level (usually 19%
What is the Secondary Pressure Regulator?
Reduce intermediate pressure to low pressure (20 psi O2, 38 psi N2O)
Decrease pressure fluctuations
What are the Low Pressure Components? (5)
Hypoxic guard/proportioning systems Flowmeter tubes Vaporizers Check valves (if present) Common gas outlet
What is The function of the Link-25 Proportioning System?
The function of the Link-25 Proportioning System is to minimize the risk of delivering a hypoxic mixture to the patient by maintaining a minimum of oxygen concentration of 25% in the fresh gas supply (hence the name “Link-25”).
True or False: The flowmeters are gas specific
True. Flowmeters are gas specific because they are calibrated for each particular gas density & viscosity. Temperature & pressure changes will affect both density & viscosity of the gas & therefore the accuracy of the indicated flow rate.
What effect will increased altitude have on flowmeters?
Increased altitude (decreased barometric pressure) will result in flow rates that are greater than indicated on the flowmeter.
What is the Common Gas Outlet?
Receive all gases & vapors from machine
Deliver them to breathing system
What is the difference between PSIg and PSIa?
PSIg (Pounds per Square Inch gauge)
Difference between measured pressure & surrounding atmospheric pressure
Most gauges read 0 at atmospheric pressure
PSIa (Pounds per Square Inch absolute)
Based on reference point of 0 pressure for a perfect vacuum
PSIg + local atmospheric pressure
Who Enforces medical gas purity?
Food & Drug Administration (FDA)
Who regulates how gas cylinders are manufactured, labeled, filled, transported, stored, & disposed of?
Department of Transportation (DOT)
Name 3 other regulatory agencies
United States Pharmacopoeia (USP)
National Fire Protection Association (NFPA)
Compressed Gas Association (CGA)
Air is what percent N and O?
N 78%
O 21%
Cylinder gases have to pass through what safety mechanisms?
- A cylinder yoke
- An inlet filter
- A pressure gauge
- A check valve
- A high pressure regulator
What is the Pin Index Safety System (PISS)?
Pin Index Safety System was designed as a safety feature to help ensure that cylinders are not installed on the wrong cylinder yoke. Each particular gas’s cylinder valve has an assigned hole configuration and the cylinder yoke has an assigned pin configuration. Correct installation requires that the pins merge with the holes so that the cylinder can fit tightly into the yoke. It should not be possible to install a cylinder on the wrong yoke because it would not attach properly.
What is the Cylinder (Primary) Regulator?
Function is to lower the high gas pressure as it exits a cylinder & enters the system. Often called Primary Regulators because they are the first regulator the gas encounters when flowing through the machine.
What is the Pressure Relief Valve?
If the pressure in the gas supply module is too high (above approximately 75 psig), the pressure relief valve opens and vents the gas to atmosphere. When the set pressure is exceeded, the pressure in the cylinder forces the spring to the left, and gas flows around the safety valve seat to the discharge channel. The rapid flow of gas through the relief valve may make a loud sound that is easy to identify. When the pressure relief valve is open, gas continues to flow to the breathing circuit as long as there are sufficient gas supplies. When gas supplies are gone, flow to the breathing circuit stops.
What are the dimensions and empty weights(kg) for E and H cylinders?
E = 4.5 x 26 & 14 kg H = 9.25 x 51 & 119 kg
What are the E cylinder capacity(L) and Pressure Values?
Air = 625/1900 02 = 660/2200 N2O = 1590/745 CO2 = 1590/838 He = 500/1600 HeO2 = 500/+ N2 = 610/1900
What are the H cylinder capacity(L) and Pressure Values?
Air = 6550/2200 02 = 6900/2200 N2O = 15800/745 CO2 = He = 6000/2200 HeO2 = N2 = 6400/2200
What are the US and Intl Colors for O2, Air, N2O, He, Heliox, CO2, N2
02 = Green, White Air = Yellow, Black/White N2O = Blue, Blue CO2 = Grey, Grey He = Brown, Brown HeO2 = Brown/Green, Brown/White N2 = Black, Black
True or False: Oxygen, air, & heliox, exist only as gases in portable cylinders.
True.
Oxygen, air, & heliox, exist as gases only in portable cylinders. The “fullness” of the cylinder is directly proportional to the pressure in the cylinder.
How much O2 time is left in cylinder?
Tank pressure = 750 psig Fresh Gas Flow (FGF) = 2L/min Tidal Volume (VT) = 0.7 L Respiratory Rate (RR) = 10 breaths/min
Residual volume in liters (L) in an E-cylinder is calculated by dividing the cylinder pressure in psi by 2200 psi (to cancel out psi) & multiplying by 660 L. In this example, 750 psi is (750/2200) x 660 = 225 L.
The rate of consumption of O2 during mechanical ventilation is the sum of the O2 flow meter setting & the minute ventilation (tidal volume in L x respiratory rate in breaths/min).
In this example, fresh gas flow is 2 L/min O2 & tidal volume is 0.7 L & respiratory rate is 10 breaths/min. Minute volume equals 0.7 x 10 which is 7 L/min & the total O2 consumption is 7 L/min plus 2 L/min or 9 L/min.
Again, the expected time to exhaustion is equal to the residual O2 volume divided by the O2 consumption. Thus the O2 time left is approximately 225 L / 9 L/min = 25 minutes, ignoring the gas sampled by the gas analyzer & leaks.
How much N2O is left in cylinder?
Empty E Cylinder Weight = 14 kg
Current Cylinder Weight = 15 kg
M1V1 = M2V2
M1 = 15 kg – 14 kg = 1 kg V1 = ? L M2 = 44 g V2 = 22.4 L
V1 = (M2/M1) x V2 = (44 g/mol/1000 g) x 22.4 L/mol V1 = 509 L
What safety features do the pipeline gases pass through?
- A pipeline inlet
- An inlet filter
- A pressure gauge
- A check valve
A pressure relief valve vents to atmosphere if the pipeline pressure is too high (approximately 65-75 psig).
What is the Diameter Index Safety System (DISS)?
Pipeline connections to the anesthesia machine use a diameter indexed safety system (DISS) to help prevent incorrect connections. The fitting for each gas has a different diameter. Each fitting is also internally keyed so that the operator cannot make a loose connection with a slightly larger fitting.
With increasing Compressed Gas Association (CGA) number, the small shoulder (MM) of the nipple becomes larger & the large diameter becomes smaller. If assembly of an unmatched body & nipple is attempted, either MM will be too large for small bore (BB) or large shoulder (NN) will be too large for large bore (CC)
What is a Quick Connector?
Quick connectors (automatic quick couplers valves, quick connects, quick-connect fittings, quick couplers) allow apparatus (hoses, flowmeters, etc.) to be connected or disconnected by a single action by using one or both hands without the use of tools or undue force.
Quick connectors are more convenient than DISS fittings but tend to leak more.
Each quick connector consists of a pair of gas-specific male and female components. A releasable spring mechanism locks the components together. Hoses & other equipment are prevented from being inserted into an incorrect outlet by using different shapes &/or different spacing of mating portions.
Quick connectors are not standardized
What is a shutoff valve?
Shutoff (ON-OFF, isolating, section, zone) valves permit specific areas of the piping system to be isolated in the event of a problem as well as for maintenance, repair, testing, or expansion without the whole system being turned OFF. A shutoff valve is required at the outlet from the supply source. This allows the entire supply source to be isolated.
What is the Master Alarm System?
Monitors the central supply & distribution system for all gases
Signals changes in pressure, supply changeovers, & supply/reserve depletion
What is the Area (Local) Alarm System?
Monitors a specific area
Signals pressure changes 20% above/below normal operating pressure
