Vaporizers Flashcards
Sevoflurane is known for ________ induction and awakening
Rapid
Sevoflurane can react with _____ absorbents to form nephrotoxic _______
CO2; compound A
Sevoflurane is often used for what population?
Peds
Sevoflurane is the only inhalation agent that can be used for what?
Inhalation induction
______ elimination of Sevoflurane results in ______ awakening
Rapid; quick
Signature color of Sevoflurane?
Lemon yellow
Desflurane requires ____________?
An electrically heated vaporizer
Desflurane is an airway ______, therefore combine with __ agents during ________.
Irritant; IV; induction
Desflurane can cause _________, therefore use with caution in patients with ___.
tachycardia; CAD
_______ elimination of Desflurane results in _______ awakening
Rapid; quick
Isoflurane was once considered the “____ _______” for _____surgery
gold standard; neuro
Isoflurane can cause _____ ______ ____ ________ through ________ _________ __________/_________.
Coronary artery steal syndrome; significant peripheral vasodilation; hypotension
Isoflurane’s signature color is?
Medium purple
Halothane, once the agent of choice for inhalation induction, has now been replaced by ________.
Sevoflurane
Halothane is a potent _________, therefore good for ________ patients
bronchodilator; reactive airway
Halothane’s effect on what organ causing ________ _______ is a major disadvantage?
Liver; halothane hepatitis
Halothane causes an increased risk of ________ along with __________ or __ use with local anesthetics.
dysrhythmias; catecholamines (DL stimulation); epi
Emergence is significantly _________ with Halothane compared to other inhaled agents. How long?
slower; 30-40 minutes
Nitrous oxide is NOT a ________ _________.
volatile agent
Nitrous oxide is used to ________ inhalation agents
supplement
Nitrous oxide is the only inhalation agent with ________________ activity
sympathomimetic
Nitrous oxide use should not exceed __% (with __% O2)
70; 30
What are two major safety issues with nitrous oxide due to its fast diffusion? How can the latter be prevented?
Diffusion into air-filled spaces and diffusion hypoxia; don’t extubate on nitrous and give high FiO2.
What is a vaporizer?
A device for converting a liquid volatile anesthetic agent into breathable vapor
Components of vaporizers?
Concentration-calibrated dials; sit between flow meters and CGO; agent-specificity; interlocking safety mechanisms
Vapor
gaseous at room temperature at 1 atm (760 mmHg)
What happens to the temperature of remaining liquid in a vaporizer as vaporization increases?
It decreases if heat is not added, causing vaporization to decrease
What is saturated vapor pressure?
The equilibrium pressure of a vapor above its liquid or solid (in a closed container) at a certain temperature; dependent on specific agent and temperature (NOT atmospheric pressure)
Boiling point is…
The temperature at which the vapor pressure equals atmospheric pressure
Latent heat of vaporization
The calories needed to convert 1 gram of liquid to vapor without changing the temperature in the remaining liquid
Specific heat
Calories needed to increase the temperature of 1 gram of a substance by 1 degree Celsius
Vaporizers materials must have a high specific heat in order to minimize temperature change with vaporization (ex., copper kettle)
What are the characteristics of a copper kettle vaporizer (Vernitrol)?
Old school; uses MEASURED-FLOW (oxygen bubbles THROUGH agent; outside of breathing circuit; manual temperature compensation
Copper has a high specific heat and high thermal conductivity
Characteristics of Variable Bypass vaporizer?
Most common contemporary vaporizer; gas is split into CARRIER GAS (enters vaporizing chamber to pick up agent) and gas which bypasses the chamber; wicks/baffles ensure full saturation of carrying gas.
What determines the splitting ratio in a variable bypass vaporizer?
The internal resistance to flow (dial) and the temperature compensating mechanism
In a variable-bypass vaporizer, saturated gas combines with fresh gas at _______ ________ to consistently produce final desired concentration regardless of _____ _____ ____ _____.
vaporizer outlet; total fresh gas flow
Characteristics of TEC 6 vaporizer
Electronic (heated); for desflurane; since des nearly boils at room temperature and would excessively cool liquid des due to volatility (VP 681 @ 1 atm), TEC 6 heats des and injects it into the system to maintain an appropriate concentration controlled by dial internal transducer.
Desflurane vaporizers compensate for ____ and ___; they cannot compensate for ___________.
flow; atm; temperature
TEC 6 requres __ ______ warm-up if left cold and can be _____ during ________.
10 minute; filled; delivery
___________ can cause “No Output” with shutdown in a TEC 6 vaporizer.
Tilting
Aladin Cassette vaporizer characteristics
Once central electronic control mechanism into which different agent cassettes are inserted; when not in use, cassettes are stored in non-electronic ports; no tilt risk; hold less agent; variable bypass for all agents including desflurane (does not require additional heat).
If a sevoflurane (VP: 157) vaporizer was filled with isoflurane (VP: 240), what would happen upon administration? With the reverse scenario?
Overdose; underdose
Six safety mechanisms of vaporizers
Color coding; keyed fillers; low filling port; secured vaporizers; all dials adjust in the same direction (counterclockwise for increase); interlocks
What is a vaporizer interlock?
Safety mechanism that ensures only one vaporizer can be turned on at a time; gas can only enter the vaporizer in the on position, minimizing trace vapor output when off; locked into gas circuit and seated correctly.
What risks are imposed by tipping a vaporizer?
Tilt of >45 degrees can result in overdose if vaporizer is not flushed before use
What safety mechanism can help the CRNA to know if the vaporizer is out of calibration?
Breath to breath analysis
What safety check can show the CRNA circuit leaks?
Negative pressure check
What is pumping, and what mechanism prevents this in newer anesthesia machines?
Back pressure into the vaporizer causing increased concentration of agent in the circuit; one-way valves
What vaporizer models can suffer from electronic dysfunction?
TEC 6 and Aladin
