Equipment EXAM Flashcards
A 34-year-old female is undergoing laparoscopic tubal ligation. Her vital signs are: BP - 110/74 mmHg, P - 70/min, R - 10/min. Her mean arterial pressure is approximately
86 mmHg
The formula for MAP is:
MAP = (SBP) + 2(DBP)/ 3
Why is the MAP formula as it is ?
Because the time spent in diastole is approximately twice the time spent in systole, a time-weighted average is used to calculate mean arterial pressure (MAP).
According to the American Society for Testing and Materials F1850-00 standard, an anesthesia machine must have:
an exhaled volume or ventilatory carbon dioxide monitor
The ASTM F1850-00 standard requires monitoring of breathing system pressures,.
exhaled tidal volume, ventilatory carbon dioxide, anesthetic vapor concentration, inspired oxygen concentration, oxygen supply pressure, arterial saturation, arterial blood pressure and electrocardiogram
In addition, the anesthesia workstation must have a
3-tiered prioritized alarm system.
In the central venous pressure tracing below, ventricular contraction corresponds to:
B. The buldging of the tricupid valve during contraction
The risk of occupational exposure to inhaled anesthetic agents is higher with:
an open scavenger
Unless used correctly, the risk of occupational exposure is higher with
an open interface.
Open scavenging systems require an
active disposal system for effective scavenging.
When calculating the cardiac output using the Fick principle: What must be determined?
Mixed Venous Oxygen content must be determined
The Fick principle states that the
amount of oxygen consumed equals the difference between arterial and mixed venous oxygen content multiplied by the cardiac output.
Ficks’ principle, Therefore cardiac output is equal to:
Oxygen consumption/A-V oxygen content difference
In adults, the distance from the ventricular port to the tip of a pulmonary artery catheter is:
20 cm
The ventricular port on a PA catheter is how far from the tip?
20 cm from the tip;
PA catheter: the distance of the proximal port is
30 cm.
Ventricular arrhythmias are NOT induced by electrosurgical units as a result of the:
frequency of the current applied
In contrast to the current from the line power (60 Hz), electrosurgical units (ESUs) use
ultrahigh frequencies (0.1 - 3 MHz) to avoid the induction of arrhythmias.
ESUs use a large return pad for the
dispersal of exiting electrical current to avoid burns at the exit site.
Inspired and expired gases that can be measured using infrared absorption analysis include:
carbon dioxide, desflurane
Most anesthetic gases and carbon dioxide are now measured by
infrared absorption analysis.
Nonpolar gases such as oxygen and nitrogen do not
absorb infrared light and must be measured by other means.
Process capable of removing or destroying all viable forms of microbial life, including bacterial spores, to an acceptable assurance level.
Sterilization
Process of reducing the number of microbial contaminants to a relatively safe level.
Sanitization
Process capable of destroying most microorganisms but, as ordinarily used, not bacterial spores.
Disinfection
Process that renders inanimate items safe for handling by personnel who are not wearing protective attire.
Decontamination
The normal gradient between PaCO2 and ETCO2 is approximately:
2 - 5 mmHg and reflects alveolar dead space.
Increasing PaCo2 and ETCO2 gradient ?
Any significant reduction in lung perfusion increases alveolar dead space, diluting expired CO2 and increasing the gradient.
During the delivery of an anesthetic in the CT scanning suite, oxygen from the E-cylinder is being used. The patient is intubated and spontaneously ventilating with 94% oxygen and 6% desflurane. Sixty minutes into the case the pressure of the E-cylinder has fallen from 2000 psi to 1100 psi. From this information, the fresh gas flow is estimated to be:
4.8 - 5.2 L/min
The content of oxygen in an E-cylinder is about
660 L when full, at a pressure of 2000 psi.
Flow loop demonstrates reduced flow during both inspiration and exhalation without changes in lung volume.
Indicate Kinking ETT
The effect of methemoglobinemia on the pulse oximetry reading is to:
cause a reading of 85% regardless of the actual saturation
Methemoglobin has the same
absorption coefficient at both red and infrared wavelengths causing a reading of 85% regardless of the actual hemoglobin saturation
For accurate blood pressure measurement, the width of the blood pressure cuff should be:
20 - 50% greater than the diameter of the extremity
The accuracy of any method of blood pressure measurement depends on
proper cuff size.
The cuff’s bladder should extend at least
halfway around the extremity and the width of the cuff should be 20 - 50% greater than the diameter of the extremity
Interchanging the position of the APL valve and the fresh gas inlet transforms a Mapleson A circuit into a:
Mapleson D circuit which is better suited for controlled ventilation
Elevation of the baseline of the capnogram indicates_______caused by
rebreathing. This could be the result of an incompetent expiratory valve or an exhausted carbon dioxide absorber
At or below which of the following pressures is it recommended that the E-cylinder of oxygen be changed?
1000 ps
An incompetent inspiratory valve causes_____How does the graph is affected?
part of the expired gas to flow back into the inspiratory limb and allows these exhaled gases to be inspired with the next breath. This results in a delay in the initiation of Phase IV of the capnogram
Concerning the use of lasers, as wavelength______absorption by water_______
increases: increase
As wavelength increases the energy of the laser light
decreases.
Wavelength and energy of the laser light have a _____relationship
Inversely proportional relationship
As wavelength increases, There is increased absorption by water and
decreased tissue penetration and coagulation.
Corneal damage is more likely with
longer wavelength lasers (CO2 laser)
Retinal damage is more likely with
shorter wavelength lasers (YAG laser).
Advantages of non-diverting (flowthrough) capnographs include:
no aspiration of gas from the circuit
Non-diverting capnographs measure
carbon dioxide passing through an adaptor placed in the breathing circuit. The weight of the sensor can cause traction on the tracheal tube. However, since the sensor is in the gas stream, no aspiration of gas is required.
In order for leakage current to be perceptible to touch, the current must exceed
: 1.0 mA
Most current leaks are
Imperceptible
In order to be felt, leakage current must exceed
1.0 mA
Leakage of 100 mA or greater is capable of
Causing V FIB
Regular atrial rhythm and a regular ventricular rhythm, but no relationship between the P wave and the QRS complex. This rhythm constitutes a______What kind of treatment and intervention is needed?
complete heart block, also known as a 3rd degree block. Immediate treatment is required if cardiac output is reduced and consideration should be given to insertion of a pacemaker.
Small circuit leaks will have little effect on minute ventilation when using a:
pressure-cycled ventilator because cycling will be delayed until the pressure limit is met.
ventilators are no longer approved for use in the anesthesia circuit.
Hanging-bellows ventilators
Some patients are at increased risk for hand ischemia secondary to radial artery catheterization because of an incomplete palmar arch. The approximate percentage of patients with incomplete palmar arch is:
5%
Some patients are at increased risk for hand ischemia secondary to radial artery catheterization because of an
incomplete palmar arch.
About five percent of patients have incomplete palmar arches and
lack adequate collateral blood flow.
As compared to non-rebreathing circuits, disadvantages of the circle system include:
higher system resistance
Disadvantages of the circle system include:
greater size
decreased portability, increased complexity, increased risk of disconnection, increased system resistance and difficulty in predicting inspired gas concentrations during low fresh gas flows.
With a properly functioning carbon dioxide absorber, inspired carbon dioxide levels should be
approach zero in the circle system.
The tracing below is noted during the insertion of a pulmonary artery catheter. As the catheter is advanced further: the diastolic pressure wil
increase
Determinants of bobbin position in the flowmeter include: (Select 2)
gas molecular weight at high-flow rates
changes in atmospheric pressure
At low (laminar) flow rates the bobbin height is determined by
gas viscosity.
At high (turbulent) flow rates the bobbin height is determined by
gas density.
Gas density is directly proportional to the,
molecular weight of the gas (DMW -> Density/molecular weight)
bobbin height during high flows is determined also by
molecular weight.
Problems inherent with the dye-dilution technique of measuring cardiac output include:
background indicator buildup
The dye-dilution technique introduces the problems of
indicator recirculation
arterial blood sampling and background indicator buildup.
The need for a return electrode to the electrocautery can be eliminated if:
bipolar electrodes are used
Bipolar electrodes confine
current propagation to a few millimeters, eliminating the need for a return electrode.
Pulse oximetry changes seen in carbon monoxide poisoning include a(n):
falsely increased SpO2 levels
Because carboxyhemoglobin and oxyhemoglobin absorb light at
660 nm identically, pulse oximeters will register a falsely high reading in patients with carbon monoxide poisoning.
A 53-year-old man is undergoing a laparoscopic cholecystectomy. He is currently receiving 6% desflurane and oxygen at 3 L/min. A ventilator lacking fresh-gas-flow compensation is set to: TV = 700, Rate = 9, I:E = 1:2. This patient’s minute ventilation is:
7.3 L/min. Because the ventilator’s spill valve is closed during inspiration, fresh gas flow contributes to the minute ventilation (MV). With I:E = 1:2, fresh gas flow contributes to the MV 33% of the time. This results in an increase of minute ventilation of 1 L/min. The patients total MV is therefore (0.7 L)(9 breaths/min) + 1 L = 7.3 L.
Central venous pressure measurements should be made:
at the end of exhalation
Measurement of CVP is made with a______What should CVP pressure be measured?
water column or transducer. The pressure should be measured during end expiration.
During exhalation, sticking of the spill valve of the ventilator can result in: .
the application of positive end-expiratory pressure
The ventilator has its own pressure-relief valve, called the
spill valve, which is closed during inspiration and open at the end of exhalation
Sticking of the spill valve results in
abnormally elevated airway pressure during exhalation.
The decline in core temperature during the first hour of general anesthesia is largely due to:
redistribution of heat to cooler peripheral tissues
Temperature decreases during general anesthesia can be grouped into _____phases
3 phases
General Anesthesia decrease in temp: Phase 1
Phase I is usually a decrease of 1 - 2o C that occurs during the first hour and is the result of REDISTRIBUTION of heat to cooler peripheral tissues.
General Anesthesia decrease in temp: Phase 2
Phase II occurs over the next 3 - 4 hours and is a result of heat loss to the environment.
General Anesthesia decrease in temp : Phase 3
During Phase III, a steady-state equilibrium is established between heat production and loss to the environment with little change in core temperature.
What is the purpose of the bimetallic strip, commonly found in variable-bypass vaporizers:
To compensate for: changes in temperature
What happens to the metal strips in response to temperature changes?
expand and contract differently in response to temperature changes and are used to alter the flows in the vaporizer.
In the variable-bypass vaporizer, temperature compensation is achieved by a strip composed of
two different metals welded together.
The sloping of Phase II and III of the capnogram indicates
increased airway resistance and is consistent with bronchospasm or endotracheal tube kinking.
When using the desflurane Tec 6 vaporizer at high elevations:what happens to the PARTIAL PRESSURE
the delivered partial pressure of the agent is decreased
At high elevations, the Tec 6 concentration delivery? what about the partial pressure?
vaporizer continues to deliver the set concentration. However, because of the decrease in the ambient pressure, the partial pressure of desflurane is decreased.
Capnogram demonstrates rebreathing, with a baseline that does not approach zero and is the result of
inadequate fresh gas flow
The intergranular air space of the carbon dioxide absorber is approximately:
50% of the total volume
To guarantee complete absorption, what should the patient’s tidal volume be?
What is the inter-granular air space of the CO2 absorber?
Pt’s TV should not exceed the air space between absorbent granules.
To ensure this, the carbon dioxide absorber has an intergranular air space of roughly 50% of the total volume, or approximately 1000 mL of air space.
Burst suppression patterns become evident when the Bispectral Index is
is below 40
At BIS values below 40, what happens?
cortical suppression becomes discernible in an EEG as a burst suppression pattern.
At sea-level, the capacity of a full E cylinder of air is
625 L
The E cylinder of oxygen contains
660L
For air as for O2, the pressure of the air E cylinder declines in a
linear fashion with use.
The pulse oximeter corrects for the absorption of light by nonpulsating venous blood and tissues by the use of:
identifying arterial pulsations with plethysmography
To eliminate the effects of light absorption from tissues and venous blood, arterial pulsations are identified by
plethysmograph.
During the delivery of an anesthetic in the endoscopy suite, E-cylinders are being used as the gas supply. The anesthetic being delivered is sevoflurane 2% in a 3:2 L/min mixture of nitrous oxide and oxygen. If fresh E-cylinders were present at the start of the case, after 3 hours of anesthetic delivery the expected pressure of the nitrous oxide E-cylinder is:
745; Unlike the oxygen E-cylinder, the nitrous oxide E-cylinder is 90-95% filled with liquid nitrous oxide when full. The tank pressure of 745 psi represents the vapor pressure of liquid nitrous oxide. The cylinder gauge will remain at 745 psig until all of the liquid is gone and at this point the tank is less than 25% full. Since the nitrous oxide E-cylinder contains 1590 L of nitrous oxide, the consumption of 180 L during the described case will not cause any change in the tank pressure.
The nitrous cut-off valve, formerly known as the f
fail-safe valve:
What is the role of the fail safe valve? What is the magic number to accomplish it ?
discontinues nitrous oxide flow if the pressure of oxygen to the machine drops below 20 PSIG
If the pressure from the oxygen supply declines, usually below 20 psig, the shut-off valve will
discontinue the flow nitrous oxide to prevent the accidental delivery of a hypoxic mixture as a result of oxygen supply failure.
Using transesophageal echocadiography (TEE) and the pulse doppler, cardiac output can be determined by measuring 2 things
Aortic flow velocity AND cross-sectional area
A (2D) two-dimensional image from TEE can assess
LV filling, ejection fraction, wall motion abnormalities, contractility and valve areas.
TEE: When used with pulsed doppler to measure aortic blood velocity, an accurate
cardiac output can be determined.
The FDA Universal negative pressure leak test:
should be repeated with each vaporizer individually turned on
The FDA Universal NEGATIVE pressure leak test should be done with the machine, flow control valves and vaporizers
turned off.
Individually, the vaporizers are turned on to look fors.
leaks in the vaporizers themselve
The test only checks the low pressure system of the anesthesia machine and can detect leaks of as little as
30 mL/min.
When using a modified V5 (CS5) lead, the proper lead selection on the monitor is lead:
I
When using a 3-lead ECG monitor and positioning the electrodes in a modified V5 placement, the appropriate lead selection for monitoring is lead
I.
The line isolation monitor: measures the potential for
isolation transformer current flow to the ground
The line isolation monitor measures what exactly?
Potential for Current flow from the isolated power supply to ground.
Electrosurgical units uset. This high frequency causes an increase in circuit
high-frequency alternating current
Electrosurgical units use high-frequency alternating current. This high frequency causes an increase in circuit:
inductance
Increasing frequency in an AC circuit, what does it do?
decreases both capacitance and impedance in the circuit. however, is increased with increased frequency.
The addition of tubing and stopcocks to a transducer measuring arterial blood pressure:
decreases the natural frequency of the system. If the frequency response is too low, the system will be OVERDAMPENED and will not faithfully reproduce the arterial waveform, underestimating the systolic pressure.
The carbon dioxide absorption capacity of 100 grams of soda lime is approximately:
15 - 26 liters
In practice, the absorption capacity of 100 grams of soda lime is about
15 - 23 L of CO2.
In determining the cardiac output from the THERMODILUTION curve, the cardiac output monitor calculates the output by:
determining the area under the curve
Plotting the temperature change as a function of time in measurement of CO produces the
thermodilution curve.
Thermodilution: Cardiac output is determined by the
integration of the area under the curve which is inversely proportional to the cardiac output.
Flowmeter leaks are a substantial hazard because the
flowmeters are located downstream from all machine safety devices except the oxygen analyzer.
Eger et al. demonstrated that, in the presence of a flowmeter leak,
a hypoxic mixture is less likely to occur if the oxygen flowmeter is located downstream from all other flowmeters.
Visual detection of cyanosis usually occurs when the SpO2
falls below: 80%
In contrast to the pulse oximeter, which can detect very small changes in saturation, visual detection of cyanosis occurs only when.
more than 5 g of hemoglobin is desaturated or at about a SpO2 of 80%
Components of the low-pressure circuit in the anesthesia machine include
vaporizers, flowmeters
Components of the low-pressure circuit in the anesthesia machine are found where ? .
distal to the flow valves
Component proximal to the low pressure system?
Oxygen flush valve
Oxygen failure cutoff (fail-safe) valve
Oxygen supply failure alarm
pressure regulators are all proximal to the flow valves in the anesthesia machine.
The vacuum control should be set at ________L/min on an active scavenging system should be adjusted to allow the evacuation of:
10 - 15 L/min. This rate is adequate for periods of high fresh gas flow and yet minimizes the risk of transmitting negative pressure to the breathing circuit.
Automated blood pressure monitors electronically measure blood pressure by
using OSCILLATION AMPLITUDE change in cuff pressure. From this, a microprocessor derives systolic, mean and diastolic pressures
An increase in both peak inspiratory pressure and plateau pressure, with the difference between the two remaining constant, indicates
a change in tidal volume or a change in compliance.
Increases in peak inspiratory pressure with large difference in _____Presure indicates an ______in inspiratory Flow or an________airway resistance
plateau pressure indicates an increase in inspiratory flow or an increase in airway resistance.
The largest P wave voltages are seen in what lead?
II
The electrical axis of lead II is approximately
60o from the rig which is parallel to the electrical axis of the atria, resulting in the largest P wave voltages of any surface lead. Right arm to the left leg,
On the normal capnogram, exhalation of pure dead space gas is seen during phase:
1
The expiratory portion of the capnogram can be divided into 3 phases. EAI
Phase 1 is the EXHALATION OF DEAD SPACE GASES.
Phase 2, sometimes called the transition phase, is the introduction of carbon dioxide as the dead space gases are washed away.
Phase 3 is the ALVEOLAR GAS PLATEAU
Phase 3 often has an upward slope as alveolar units with lower V/Q ratios empty.
Phase 4 –> Inhalation can be seen on the capnogram
The advantage of motor evoked potential as opposed to sensory evoked potentials for spinal cord monitoring is that
motor evoked potentials: monitor the ventral spinal cord
In contrast to SEP’s, MEP’s monitor
the ventral aspect of the spinal cord and can predict postop motor deficit. MEP’s are affected by volatile agents, benzodiazepines, opioids and moderate hypothermia
The oxygen supply from E-cylinders:
has a check valve to prevent cross filling of tanks
The E-cylinder and yoke assembly use a pin-index safety system to eliminate
tank interchange.
The pressure from the E-cylinders is regulated to a pressure below the pipeline pressure to ensure
preferential use of the pipeline gases if the tank is open.
The yoke assembly contains a
check valve to prevent cross filling of tanks and to allow tank exchange while a second tank is in use.
This rhythm strip shows a delta wave characterized by:
short PR interval with an initial up-sloping of the QRS complex,
Pre-excitation syndrome known as
Wolff-Parkinson-White (WPW) syndrome.
Meds avoided in WPW?
Digoxin should be avoided in patients with WPW syndrome.
The pumping effect is most pronounced when there is
less agent in the vaporizing chamber, when carrier gas flow is low, when the pressure fluctuations are high and frequent and when the dial setting is low.
Enhancement of flow direction of the pulmonary artery catheter can be achieved by:
injecting iced saline thorough the catheter
Flow directed flotation of the pulmonary artery catheter can be enhanced by
maneuvers that increase cardiac output, increase venous return or elevate the position of the pulmonary artery.
all improve flow direction.
As a result, deep inspiration, head-up position and right lateral tilt
In addition, the injection of iced saline
stiffens the catheter catheter and reduces coiling thereby improving flow direction.
A 58-year-old male is undergoing a craniotomy in a semi-sitting position. The patient’s head is 30 cm above the radial artery where his blood pressure is being measured. If the patient’s mean arterial pressure at the radial artery is found to be 100 mmHg it can be estimated that the mean pressure at the cranial vault is:
78 mmHg
Because of mercury’s high density (13.7 g/cc), the height of elevation must be multiplied by a conversion factor (1 cmH2O = 0.74 mmHg) Therefore:
30 cm H2O (0.74 mmHg/cm H2O) = 22 mmHg
100 mmHg - 22 mmHg = 78 mmHg
Output from a variable-bypass sevoflurane vaporizer is shown below. Possible causes for the transient reduction in vaporizer output seen at point A include:
introduction of nitrous oxide to the fresh gas flow
Changing the gas composition from 100% oxygen to 70% nitrous oxide may transiently
decrease the anesthetic concentration due to the greater solubility of nitrous oxide in the volatile agent. Changes in temperature and fresh gas flow, within clinical ranges, have little effect on vaporizer output.
When using an arterial catheter to measure blood pressure, the optimum damping coefficient is:
0.6 - 0.7
Catheter-tubing-transducer systems must prevent both
overdamping and underdamping if an accurate waveform is to be displayed
A damping coefficient of
0.6 - 0.7 is optimal. The damping coefficient can be determined by the high-pressure flush test.
Advantages of paramagnetic oxygen analyzers include:
self-calibration
Although the initial cost of paramagnetic sensors is higher, the devices are
self-calibrating and have no consumable parts. In addition, their response time is fast enough to differentiate between inspired and expired oxygen concentrations.
The accuracy of the pulse oximeter is:
greatest at saturations over 70%
Pulse oximeters have their greatest accuracy
(+/- 2 to 3%) in the range of 70 - 100 %.
Signs of a leak in the bellows-in-box ventilator include:
decreased inspired anesthetic concentration
With a leak in the bellows assembly, ventilator driving gas will enter the bellows. This will result in the
dilution of anesthetic agent, increased tidal volume, decreased carbon dioxide levels and increased peak inspiratory pressures.
Duration of the twitch stimuli from a peripheral nerve stimulator is approximately:
200 μs
All stimuli from the peripheral nerve stimulator are
200 μs in duration, of square-wave pattern and of equal intensity.
To prevent rebreathing of carbon dioxide in the classic circle system: (Select 2)
unidirectional valves must separate the patient and reservoir bag, the APL valve cannot be located between the patient and inspiratory valve
To prevent rebreathing in a classic circle system, three rules must be followed: (
1) a unidirectional valve must be located between the patient and the reservoir bag on both the inspiratory and expiratory limbs of the circuit, (2) the fresh gas inflow cannot enter the circuit between the expiratory valve and the patient and (3) the APL valve cannot be located between the patient and the inspiratory valve.
Falsely low blood pressure measurements can occur when: the cuff is
Falsely low blood pressure measurements result when cuffs are too large, ts.
too large; the extremity is above the heart level or after quick deflation
Falsely low blood pressure measurements can occur when: the cuff is
too large; the extremity is above the heart level or after quick deflation
Resuscitation bags are unlike Mapleson non-rebreathing circuits in that resuscitation bags:
incorporate a non-rebreathing valve
A resuscitator is unlike a Mapleson circuit because it contains a
non-rebreathing valve.
High flows of oxygen are required to deliver a
high FiO2 since resuscitator bags entrain room air.
When using a doppler probe and a blood pressure cuff to measure blood pressure:
only systolic pressure can be reliably determined
Although the doppler probe offers more sensitivity than palpation of the artery
systolic pressure can be reliably determined by this method.
When using a pulmonary artery catheter to measure pulmonary artery pressure, system dynamics can be improved by:
using as few stopcocks as possible
minimizing tubing length, eliminating unnecessary stopcocks, removing air bubbles and using low-compliance tubing.
According to the American National Standards Institute, essential features of the anesthesia machine include
an exhaled volume monitor
The galvanic cell measures inspired oxygen concentration by examining the:
the voltage and current produced by the cell
When using a circle system, dead space is:
distal to the Y-piece
In the circle system, dead space occurs only in areas of bidirectional gas flow. If the unidirectional valves are working properly, dead space will
only be distal to the Y-piece.
When using a peripheral nerve stimulator, the most sensitive test of neuromuscular function is: .
a 5-second tetanic stimulus at 100 Hz
Tetany at_______ is a sensitive test of neuromuscular function.
50 or 100 Hz. Sustained contraction for 5 seconds indicates adequate reversal
As stimulus frequency increases, fade is more
pronounced.
As stimulus frequency increases, fade is more
pronounced.
Compliance for standard adult breathing circuits is about:
5 mL/cm H2O
The compliance for standard adult breathing circuits is about 5 mL/cm H2O. Thus, at a peak inspiratory pressure of 20 cm H2O, about 100 mL of set tidal volume is lost to expanding the circuit.
This train-of-four pattern demonstrates no fade, which is consistent with
However, after 1 hour the patient has persistence of the block, which would suggest
depolarizing blockade; reduced metabolism of succinylcholine as is seen with a pseudocholinesterase deficiency.
To obtain the best accuracy in determining the patient’s tidal volume, the spirometer should be placed:
The effects of these factors in measuring tidal volume can be minimized by placing the spirometer at the Y-piece.
at the Y-piece
Because of compliance of the breathing circuits, gas compression losses, ventilator-fresh gas flow coupling and leaks,
substantial differences between set tidal volume and delivered tidal volume may exist.
Because of compliance of the breathing circuits, gas compression losses, ventilator-fresh gas flow coupling and leaks, What may Exist?
substantial differences between set tidal volume and delivered tidal volume may exist.
With proper placement of a central venous catheter, the catheter tip lies:
at the junction of the superior vena cava and right atrium
An open scavenging interface: should only be used with an
active disposal system
An open scavenging interface is open to
the outside atmosphere and requires no pressure relief valves.
Open scavenging interfaces require
active removal to be effective.
Desirable characteristics of a peripheral nerve stimulator, used to assess the level of neuromuscular blockade, include:
the stimulator should vary its output to adjust for changing skin resistance
Spongiform encephalopathies, such as Creutzfeldt-Jakob disease, are caused by prions, which demonstrate resistance to sterilization. Effective methods of prion inactivation include
1:10 hypochlorite sterilization
Prions are notoriously hardy and demonstrate resistance to routine methods of sterilization. Effective inactivation methods include
incineration, prolonged steam sterilization (1320 C for 1 - 4 hours), high-temperature prevacuum sterilization, sodium hydroxide solution, sodium hypochlorite solution and proprietary phenolics.
At 20o C the pressure of the nitrous oxide E-cylinder should not exceed:
745 psigA higher reading implies gauge malfunction, tank overfill, or a cylinder containing the wrong gas.
During general anesthesia for a total hip replacement, periods of asystole are noted during times of electrocautery use (see rhythm strip below). At this time the most appropriate therapy is
to switch to a bipolar electrocautery
The oxygen flush valve delivers oxygen at
45 - 55 psi and a rate of 35 - 70 L/min.
Comparing blood pressure measurements made from the radial artery to measurements made from the dorsalis pedis artery, the dorsalis pedis artery measurements have
an elevated systolic pressure and elevated pulse pressure
Arterial blood pressure is greatly affected by
where the pressure is measured.
As a pulse moves peripherally, what happens to the wave?
wave reflection distorts the pressure waveform, leading to an exaggeration of systolic and pulse pressures.
