Anesthetic Equipment Flashcards
the high pressure system of the anesthetic machine runs from and is approximately __________psi
gas cylinder to pressure regulator; 2200 psi
the intermediate pressure system runs from _________ to __________ and is approximately _____ psi
pressure regulator to flow meter; 50-60psi
the ________ marks the start of the low pressure system and drops the pressure to ______ psi
flow meter; 15
by the time the gas gets to the patient it is about what pressure
10 psi or less
the flow of oxygen should be enough to
meet metabolic requirements
what is the purpose of oxygen
carrier gas (we also need it for cellular respiration)
what is a benefit of nitrous oxide over oxygen and why do we not use it at OVC (or often anymore for that matter)
it has a MAC sparing effect; decreases the proportion of oxygen so can decrease oxygen supply during anesthesia
what are the 2 sizes of gas cylinders
E and H
a full tank (E or H) has what pressure
2200 psi
does liquid oxygen (like the tank at ovc) have higher or lower psi than a gas cylinder
lower (approx 130 psi versus 2200 psi)
how do we determine the amount of oxygen in L in an E tank? what is this amount for a full tank
amount (L): psi x 0.3
for a full tank: 2200 psi x 0.3 = 660L
how do we determine the amount of oxygen in L in an H tank? what is this amount for a full tank?
amount (L): psi x 3
for a full tank: 2200 psi x 3 = 6600L
T/F H larger tanks can be grouped to maintain constant supply and avoid frequent changing of regulators
T
1L of liquid oxygen = ___ L of gas
860
T/F 1L of liquid oxygen gives you more L of gas than an entire H tank
F; more than an E tank
1L of liquid oxygen = 860 L
E tank: 660 L
H tank: 6600 L
oxygen comes out of liquid tank at what pressure
50-60 psi
what is the purpose of the Yoke index for E tanks
they prevent attaching the wrong gas tank to your anesthetic machine: pins are specific to the gas tank
what way do you turn to open and close a gas tank
open: to the left (counterclockwise)
close: to the right (clockwise)
what establishes your intermediate pressure system
pressure regulator
what is the role of the flow meter
drives gas to fulfill tidal volume of patient; allows delivery of precise amount of oxygen to meet patient requirements and acts as carrier gas for inhalational anesthetic
the pressure through the flow meter is
15psi
what establishes the low pressure system
flow meter
how do you read a bobbin vs ball
bobbin: from top
ball: from middle
what is the VO2 metabolic requirement of patients (minimum flow of oxygen to maintain aerobic metabolism)
5-10 ml/kg/min
what are the 2 types of rebreathing circuits
circle and F
what is the name for the non-rebreathing circuit
Bain
why do you not need to have soda lime to remove CO2 from a non-rebreathing circuit
because the system uses FGF to drive CO2 out of the system
the FGF for a rebreathing system is _________ ml/kg/min, but it requires a (higher/lower) FGF if the system is semi-closed, which is about ________ ml/kg/min
10-100; higher; 50-100
what is the flow for a non-rebreathing system
200 ml/kg/min
what is the role of the vaporizer
converts liquid anesthetic to gas; allows for precise delivery of the desired concentration
T/F vaporizers have precision: meaning that the output is accurate at dialled concentrations and we can guarantee that is the concentration the animal is receiving
F: does not mean that is what the animal is getting UNTIL it is at equilibrium
anesthetic vaporizers have variable by-pass…. what does this mean?
part of the flow goes into the chamber where the liquid anesthetic is vaporized and part of the flow bypasses the chamber
most vaporizers are in or out of the circuit
out
T/F it is important to maintain room temperature at a constant as the vaporizers cannot accomodate for temperature fluctations
F
vaporizers maintain accurate output despite of FGF between what range of flow
300 mL/min to 10 L/min
do anesthetic vaporizers have low or high resistance and why
high: variable bypass and small tubing
what is the minimum FGF to put a patient on regardless of size
1L/min
what is the role of unidirectional valves
prevent backflow through the opposite limb
unidirectional valves are only used on ____________ systems
rebreating
T/F unidirectional valves are only used with a Bain circuit
F: circle or F circuit
the patients tidal volume is delivered by what parts of the anesthetic machine (i.e where is it breathing the gas from)
from the rebreathing bag and from the anesthetic circuit itself (the hoses)
how is CO2 removed from gases before entering the inspiratory valve
via soda lime: specifically, flow is directed through the soda lime as it leaves the rebreathing bag or before entering the rebreathing bag
how can we manually ventilate a patient
by applying intermittent positive pressure to the rebreathing bag (i.e. by squeezing the rebreathing bag)
how do we select a rebreathing bag size
Vt x 3, which equates to 60 ml/kg (since tidal volume is on average 20ml/kg)
how does soda lime differ before and after use
before: creamy-white, soft, easily crumbled, and moist
after: purple, hard, dry
what does sodalime consist of
active ingredients, water and a pH indicator
soda lime is only applicable to what system
rebreathing
why does a non-rebreathing system not need CO2
uses high FGF to remove CO2 from the system
what is the composition of soda lime (4)
1) 15% water
2) 80% calcium hydroxide
3) 4% sodium hydroxide
4) 1% potassium hydroxide
what should the manometer read if spontaneous breathing? what about if mechanical ventilation is occuring
spontaneous breathing: 0 cm H2O
mechanical ventilation: should rise to 20 cm H2O
what is the role of the oxygen flush valve
delivers emergency O2 to the patient
what is a downside of the oxygen flush valve
it bypasses the flowmeter and the vaporizer so it dilutes the [anesthetic] in the circuit and patient
another con of the oxygen flush valve is it delivers ______% oxygen at _________ flow (_______L/min) and __________ pressure (_______ psi)
100%; high (40-70 L/min); intermediate (50-60 psi)
you should NEVER use an oxygen flush valve on what type of circuit and why
on a non-rebreathing; it delivers high flows directly to animals airway and risks trauma
what is the role of the common gas outlet
outlet for all gases that have passed through/over the vaporizer and through the flow meter; also the exit point for the oxygen flush
the pop-off valve should be _____ for spontaneous ventilation and ____ for mechanical ventilation
open; closed
ventilators have a spill valve that releases pressure during the (inspiratory/expiratory) phase
expiratory
if present, an interface will be located between what
the pop-off valve and the scavenge system
what is the role of the interface
controls the flow of exhaled gases coming from the scavenger and centralizes the scavenging system
