Some courts have defined deviation from manufacturers' instructions as _______ _________negligence
prima facie
components of high- pressure system (exposed to cylinder pressure)
Delivery piping for both nitrous oxide and oxygen uses the ________ _________safety system to prevent misconnections.
diameter index system (DISS)
The ______valve ensures unidirectional forward flow, so that a machine running on cylinder supplies, with the hoses disconnected at the wall outlet, does not leak. The filter is required by the current anesthesia workstation
check valve. At the pipeline inlet, a filter, check valve, and pressure gauge are present
Loss of oxygen pipeline pressure is indicated by the pipeline pressure gauge. In addition, if pressure loss is profound, the oxygen _____-pressure alarm sounds, and the fail-safe valves halt the delivery of all other gases
low-pressure
With complete loss of oxygen pipeline pressure, the anesthetist should
fully open the E cylinder of oxygen,
disconnect the pipeline,
and consider the use of low fresh gas flows and
manual ventilation (using the circle system) to conserve the emergency cylinder supply of oxygen
state 2 reasons why you should disconnect the supply hose from the wall in the event you lose oxygen pipeline pressure
1. in case of a cross-connection of gases (liquid CO2 rather than N20)
2. flow of contaminated contents
In this system, each cylinder valve has a unique arrangement of holes that correspond to its intended contents. The holes mate with pins in the yoke, which is the point where cylinders are attached to the gas machine (E cylinders)
PISS- a means of preventing misconnections; anesthetists should check both pins and washers whenever cylinders are replaced
The ________valve is the most fragile part of the cylinder, so it must be protected during transport.
cylinder valve consists of a body, the port where gas exits, a conical depression (opposite the port) for the securing screw, the holes where the pins on the yoke fit, and safety relief devices
Manufacturers use one or more of the following on cylinder valves: a frangible disk that bursts under pressure, a valve that opens at extreme pressure, or a fusible plug made of ________metal which melts at elevated temperatures.
Wood's
The hanger yoke serves three functions:
it orients cylinders,
provides a gas-tight seal, and
ensures unidirectional flow into the machine
If two cylinders of the same gas are open, _________occurs when gas flows from the cylinder with higher pressure into the cylinder with lower pressure, rather than proceeding toward the flowmeters.
transfilling; Transfilling is a potential fire hazard because filling a cylinder generates heat. The cylinder pressure gauge is a Bourdon-type gauge
The high (but variable) cylinder pressure is converted to a constant downstream pressure ____psi [310 kPa]), set intentionally at slightly less than pipeline pressure, in order to prevent silent depletion of cylinder contents
45 psi [310 kPa];
The _______________ issues regulations for the manufacture, handling, transport, storage, and disposal of cylinders. These regulations have binding legal force
US Department of Transportation
When installing a cylinder, check the labels, "crack" the valve, check that both PISS pins are present, check that only ONE washer is present, place the cylinder in the hanger yoke, observe for the absence of an audible leak, and check for proper gauge pr
The valve is "cracked" to remove dirt from the port
When relying on cylinder supplies in an emergency, one must be able to calculate how long an oxygen cylinder will last.
If oxygen flow is 2 L/min, and the cylinder's oxygen gauge pressure is 500 psi, how long will the cylinder last? 660L/1900PSI= 0.35; 0.35 Xs 500/2L= 87.5 minutes
safe handling of cylinders
Never:
Stand a cylinder upright without support; if a rack or stand is not available, lay it on its side.
� Leave empty cylinders on the machine.
� Leave the plastic cover on the port while installing the cylinder.
� Use more than one washer between a cyl
Cylinder contents must meet the purity requirements for medical gases established by the United States _____________
Pharmacopeia (USP). The contents are also regulated in the United States by the US Food and Drug Administration (FDA).
Nitrous oxide is stored as a ________; therefore, the cylinder pressure of 745 psi (5136 kPa) represents the vapor pressure of liquid nitrous oxide at room temperature. The nitrous oxide cylinder pressure gauge remains at 745 psi until the liquid is gone;
liquid; Thus, nitrous oxide cylinders should be changed if their pressure is less than 745 psi. Rapid removal (more than 4 L/min) from a nitrous oxide cylinder may cause the formation of frost on its wall or freezing of the valve, owing to the loss of the
Medical air is composed of nitrogen ___%, oxygen ___%, and argon (nearly 1%). Carbon dioxide (0.03%) and other gases are present in trace amounts
nitrogen 78%, oxygen 21%
The flowtube is tapered to be _________at its bottom. Thus it may be referred to as a variable orifice flowmeter because the annular opening around the float is larger at higher flows.
narrower; The diameter of the flowtube is tapered, but it is smaller at the bottom than at the top
The flush valve is required by standard to deliver ___ to ___L/min. The purpose of the flush valve is to quickly fill the breathing circuit with oxygen
35-75L; Users should avoid activating the flush while the mechanical ventilator is in the inspiratory phase; during this phase, the ventilator relief valve closes, preventing gas from exiting to the scavenger
Activating the flush bypasses the __________ , and adds 100% oxygen to the breathing circuit
vaporizers
If pipeline oxygen pressure fails, and other gases such as nitrous oxide keep flowing, the patient might receive a hypoxic gas mixture (less than 21% oxygen). Therefore, gas machines incorporate devices that halt the supply of all other gases in the event
fail-safe systems do not analyze oxygen pipeline contents, so they are activated only if oxygen pipeline pressure falls. They do not protect the patient from a crossover, in which oxygen pipeline pressure is intact, but the line does not contain oxygen.
All current anesthesia gas machines incorporate nitrous oxide-oxygen proportioning (hypoxic guard) systems designed to prevent the delivery of hypoxic breathing mixtures.
All link oxygen and nitrous oxide flows, so that final breathing mixtures at the common gas outlet are at least 23% to 25% oxygen. The ratio of nitrous oxide to oxygen is thus kept at no more than 3 to 1.
Systems that warn of trouble with oxygen supply (low pressure alarms) or lessen the chances of hypoxemia (hypoxic guard system, fail-safe system) are based on _________ within the oxygen circuitry of the gas machine.
pressure
The ___________ depends only on the temperature, the vapor pressure of the liquid, and the partial pressure of the vapor above the evaporating liquid�not on the ambient pressure of the remaining gases present
rate of vaporization
As the temperature or the vapor pressure increase, so does the rate of vaporization. As the partial pressure of the vapor above the substance increases, the rate of vaporization will ?
slow;
The rate at which a liquid evaporates relies on only three factors: the vapor pressure of the substance, the partial pressure of the vapor in the container above the liquid, and the temperature.
All gases (except oxygen and, in newer models, air) pass through a fail-safe valve before proceeding to their flowmeters. This valve is held open by pressure in the oxygen circuitry within the anesthesia gas machine. After passing through their respective
common manifold
________________ occurs when gases flow through passages of lower resistance in the CO2 cannister. When this occurs, most of the CO2 absorbent granules are bypassed and the efficiency of the absorber decreases. It can be minimized by gently shaking the ca
Channeling
The mechanical deadspace of a circle system breathing circuit ends where the inspiratory and expiratory streams diverge, which is at the
y-piece (p 248 nHt)
Full saturation of the carrier gas is ensured by means of a series of wicks and baffles with this vaporizer?
variable bypass;
The small portion of the gas flow entering the vaporizing chamber (carrier gas or chamber flow) flows over the liquid and picks up anesthetic vapor.
This vaporizer is heated to 39 degrees Celsius and pressurized to 2 atmospheres
Tec 6 ; fresh gas never flows over, or comes into contact with the liquid agent (as it would in a variable bypass vaporizer). Instead, an appropriate amount of vapor is added to the fresh gas as it flows through the vaporizer.
The end-tidal CO2 monitor, respirometer, and airway pressure monitor can reliably detect a disconnect in the_________ _________ .
breathing circuit;
The end-tidal CO2 monitor will fall abruptly to baseline on a disconnect and the respirometer indicator will stop moving.
What component in a gas-driven ventilator is responsible for producing the 2-3 cm H2O of PEEP seen when mechanical ventilation is applied?
ventilator relief valve
The ______valve and the breathing bag are both eliminated from the circuit when the ventilator is in mechanical ventilation mode.
APL
OSHA advises that no worker should be exposed to more than ____ppm halogenated agents (0.5 ppm if used with nitrous oxide), and no more than 25 ppm nitrous oxide, based on a time-weighted 8-hour average concentration
2 ppm
The five tasks of oxygen in the anesthesia machine are:
supply the fresh gas flowmeter,
power the oxygen flush valve,
activate the oxygen low-pressure alarms,
activate the fail-safe mechanism, and
drive the ventilator bellows
The hospital pipeline delivers oxygen to the anesthesia machine and the operating room at ___ psig.
50
__________is often used in the construction of anesthetic vaporizers because it exhibits high thermal conductivity
high thermal conductivity of copper helps stabilize the temperature of the volatile anesthetic liquid and maintains a more constant vaporization rate
The Mapleson ___ circuit is efficient during controlled ventilation, because fresh gas flow forces alveolar air away from the patient and toward the APL valve
D
This ventilator uses an electric motor to power the ventilator. They do not use driving gas and can mechanically ventilate the patient without depleting a backup oxygen cylinder. It does not use bellows, and does not produce the 2-3 cm H2O PEEP caused by
Piston-driven also exhibits less loss of tidal volume because the piston-design is less compliant than a bellows design
As the partial pressure of the vapor above a liquid in a closed container increases the rate of vaporization will______
The rate at which a liquid evaporates relies on only three factors: the vapor pressure of the substance, the partial pressure of the vapor in the container above the liquid, and the temperature. As the temperature or the vapor pressure increase, so does t
The mechanical deadspace of a circle system breathing circuit effectively ends at the
Y piece
The Tec-6 vaporizer is heated because
desflurane has a high vapor pressure;
Because of its high vapor pressure, the Tec-6 vaporizer is heated to 39 degrees Celsius to produce a controlled vapor output.
The pipeline inlet connections on an anesthesia machine are fitted with ________ system fittings to prevent connection of a gas line to the wrong connector on the machine. They also have a unidirectional check valve.
diameter index safety
There is only one common gas outlet at __-mm outer diameter, 15-mm inner diameter, which is designed to prevent accidental disconnection.
22mm outer and 15mm inner
The Dr�ger Vapor 2000 is similar to the Vapor 19, except that it is removable by hand. It has a unique "T" (transport) setting that allows the vaporizer to be
tipped or transported without liquid anesthetic fouling the control mechanisms (287/246)
In Mapleson A, B, and C, the ______ _____ is located near the face mask and the reservoir bag is located at the opposite end of the circuit
APL valve
Soda lime is an absorbent and is capable of absorbing up to ____L of CO2 per 100 g of absorbent. It consists primarily of calcium hydroxide (80%), along with sodium hydroxide, water, and a small amount of potassium hydroxide.
23 L
Its reactions are as follows: CO2 + H2O ? H2CO3 H2CO3 + 2NaOH ? Na2CO3 + 2H2O + Heat (a fast reaction) Na2CO3 + Ca(OH)2 ? CaCO3 + 2NaOH
(a slow reaction)
The granules commonly used as CO2 absorbent are between __ and ___ mesh; the mesh number corresponds to the number of holes per square inch of a screen.
4 and 8 mesh
Because a fresh gas flow equal to minute ventilation is sufficient to prevent rebreathing, the Mapleson ___ design is the most efficient Mapleson circuit for spontaneous ventilation
A
what is an example of an open type of breathing system?
Patients have access to the atmosphere only in open systems; this is not true in semi-open, semi-closed, or closed systems.
____________ventilation is the minute ventilation minus dead space ventilation (VA = VE ? VD)
alveolar ;
if the patient's minute ventilation is fixed (such as by respiratory depression), increasing dead space decreases alveolar ventilation, and increases arterial CO2 tension
in nonrebreathing circuits the fresh gas flow required to prevent rebreathing is two to three times minute ventilation. This number can be calculated; however, in practice, many use a minimum fresh gas flow of
___L/min.
5L/min;
in the nonrebreathing system (Mapleson) what determines the amount of rebreathing?
FGF determines the amount of rebreathing;
If fresh gas flow is sufficient, no alveolar gas is rebreathed
this circle system has a single-limb, like the Bain, where the inspiratory limb is contained within the expiratory
coaxial circle system
which breathing system has separate inspiratory and expiratory limbs, and prevents rebreathing of CO2
circle system
in the circle system, driving gas compresses the bellows, it propels gas into the inspiratory limb past the inspiratory unidirectional valve, inflating the lungs. Driving gas pressure also closes the ventilator relief valve, which is the route to the scav
The exhaled gases fill the bellows to a small pressure first, then excess gas proceeds to the scavenger via the ventilator relief valve during expiration in a circle system
Gas enters the circle system from the common gas outlet by way of the fresh gas delivery hose, and it exits the circle to the scavenger via the _____ (or the ventilator relief valve if mechanical ventilation is used).
APL valve
State two common reasons for an increase in inspired CO2:
the absorbent granules have been exhausted, or
the unidirectional valves are faulty
If inspired CO2 of more than 1 to 3 mm Hg is detected on the capnograph, the fresh gas flow should be
increased to 5 to 8 L/min; this converts the system to a semi-open configuration, in which rebreathing of exhaled gases is minimized.
If elevated inspired CO2 persists in spite of the higher fresh gas flow, the unidirectional valves are likely to be incompetent. The operator should
remove the expiratory valve (if possible), inspect and dry it, and then reassemble it (while ventilating the patient with an Ambu bag)
soda lime
the reaction takes place on the surface of the granules;
an appropriate water content is important for speed of reactions;
dry granules become exhausted much more quickly than moist granules;
NaOH and KOH are added to increase the reaction;
Fresh CO2 abso
The main constituent of most soda lime absorbents is
calcium hydroxide
are large or small soda lime granules more efficient?
Larger granules have less resistance to gas flow; however, they are also less efficient because their surface area is relatively small with respect to their mass.
Fine granules or soda lime dust would have a great deal of resistance to gas flow, but their
Degradation may produce compound A (sevoflurane), carbon monoxide (the ethyl methyl ethers ________and ________.
soflurane and desflurane;
Degradation is favored by dry absorbent, and the presence and quantity of strong bases (potassium hydroxide more than sodium hydroxide).
______ _______ is produced by desflurane, much more than isoflurane, when these agents are in contact with absorbent granules
Carbon monoxide
Each 100 g of granules has a theoretical capacity to absorb as much as __L of CO2 before the outlet concentration is 1% (7.6 mm Hg), assuming that no channeling occurs.
15L;
The average to maximum production of CO2 by the anesthetized adult is 12 to 18 L/hr (256/297)
when does the ventilator relief valve open?
only opens during the expiratory phase;
A ventilator relief valve (also known as the bellows pop-off valve, spill valve, or overflow valve) maintains circuit volume and pressure by releasing gas to the scavenger, in an amount equal to the fresh gas flow p
what bellow type (standing/hanging) will not fill in the event of a disconnect?
standing will not fill in the event of a D/C; hanging bellows will fill even if there is a D/C
Piston ventilators
do not use driving gas and may be used w/o depleting the oxygen cylinder in case of an 02 pipeline failure;
+/- relief valves are built it;
have no intrinsic PEEP
with this mode of ventilation, the peak inspiratory pressure is uncontrolled, and rises as the patient's compliance decreases or airway resistance increases.
volume control
In any vent mode, if the flow-time waveform shows that expiratory flow is incomplete before the next inspiration (resulting in auto-PEEP), RR should be ___________, or the I:E ratio prolonged (e.g. 1 : 3 instead of 1 : 2).
decreased;
In this mode of ventilation, PIP is limited, and the cycle is controlled by time, with a decelerating flow pattern.
Pressure controlled ventilation;
In a decelerating flow pattern, inspiratory flow is strongest early in inspiration (in order to reach the set pressure quickly), and declines to flow just sufficient to maintain the set pressure later in inspiration.
Inspiratory pressure is controlled rather than volume with this mode of ventilation. Tidal volume is uncontrolled, and increases if compliance increases, or airway resistance falls.
PCV;
what controls the percent of time during expiration that the ventilator is sensitive to spontaneous breaths (the negative pressure generated by the patient's diaphragm) in SIMV
trigger window (301/260)