VALLEY:Echo/CO2/Ox/PN/Other Flashcards
1
Q
What seven cardiac parameters are observed or estimated with two dimensional transesophageal echocardiography?
A
1) Ventricular wall motion
2) valve motion
(3) estimations of end-diastolic and end-systolic volumes (ejection fraction),
(4) Cardiac output
(5) Blood flow characteristics,
6) intracardiac air
(7) intracardiac masses.
2
Q
refers to the presence of less than normal ventricular motion
A
Hypokinesis
3
Q
Refers to the presence of greater than normal wall motion;
A
Hyperkinesis
4
Q
Absence of wall motion
A
Akinesis
5
Q
ventricle has a paradoxic outward movement.
A
Dyskinesis
6
Q
Identify the two most sensitive monitors for detection of air emboli.
A
Transesophageal echocardiography (TEE) and a Doppler probe secured over the right side of the heart are the most sensitive methods of intracardiac gas detection.
7
Q
Which method is the most sensitive for detecting venous air embolism?
A
Transesophageal echocardiography (TEE). It is 5- 10 times as sensitive as the Doppler technique.
8
Q
TEE provides visual representation of air in the
A
right or left heart. Therefore, smaller and fewer bubbles can be detected by TEE.
9
Q
Transesophageal two-dimensional echocardiography has an additional benefit: What is this benefit?
A
The added benefit of two-dimensional transesophageal echocardiography is evaluation of cardiac function.
10
Q
Transesophageal two-dimensional echocardiography has __________than precordial Doppler ultrasound for
detecting venous air embolism.
A
greater sensitivity
11
Q
What advantage does C02 monitoring have over pulse oximetry or vital sign monitoring?
A
Carbon dioxide monitoring detects acute, complete airway obstruction and extubation more rapidly than pulse oximetry or vital sign monitoring.
12
Q
Identify and describe phase I of the C02 waveform.
A
Phase I of the CO2 waveform reflects late inspiration, during which carbon dioxide levels should be near zero.
13
Q
Identify and describe phase II of the C02
waveform.
A
represents the emptying of connecting airways and the beginning of the emptying of alveoli.
14
Q
During phase 2, As exhalation continues, gas from alveoli
in regions with relatively short conducting airways
A
appears and mixes with dead space gas from regions with relatively long conducting airways, resulting in an increasing C02 level
15
Q
Phase II reflects a
A
mixture of anatomic and alveolar dead-space.
16
Q
Identify and describe phase III of the C02 waveform
A
Phase III is the alveolar plateau. Because of uneven emptying of alveoli, the slope continues to rise gently.
17
Q
Point D shows the best
A
approximation of alveolar C02 (end of expiration, beginning of inspiration, end tidal C02) .
18
Q
Identify and describe phase IV of the C02 waveform.
A
As the patient inhales, C02-free gas enters the patient’s airway, and the C02 level abruptly falls to zero.
19
Q
Phase IV is
A
inspiration.
20
Q
Interpret the a (alpha) angle of the C02 waveform.
A
angle between Phases II and III is called the a (takeoff, elevation) angle.
21
Q
Normal alpha angle _____Degrees
A
100-110 degrees.
22
Q
Angle decreased with obstructive lung disease
A
Alpha (because the dead space volume takes longer to be exhaled)
23
Q
The slope of Phase III depends on the
A
lung’s ventilation-perfusion status.
24
Q
Airway obstruction and PEEP on alpha angle ?
A
cause an increased slope and a larger a angle
25
Interpret the~ (beta) angle of the CO2 waveform.
The angle between the end of Phase III and the descending limb of the capnogram is called the BETA angle.
26
BETA angle Normally, it is approximately _____degrees.
90
27
What issues may INCREASE the BETA angle of the C02 waveform?
increased with rebreathing, malfunctioning inspiratory valves, and with prolonged response time compared
to respiratory cycle time, especially in children.
28
Decrease the BETA angle of the CO2 waverform associated with?
The beta angle will be decreased if the slope of phase III is decreased
29
The capnogram baseline is elevated in the intubated patient who received a volatile agent/N20/narcotic anesthetic. Ventilation is adequate. What are the
most likely causes of the elevated C02 baseline and what do you do?
An elevated C02 waveform baseline indicates the patient is rebreathing, most likely due to a C02 absorbent issue or a malfunctioning unidirectional valve. Increasing fresh gas Row will lower the C02 in the circle system.
30
What three conditions could cause the end-tidal C02 (ETC02) to increase in an intubated patient under general
anesthesia?
ETC02 will increase when: (l) C02 production exceeds ventilation, i.e., as in in hyperthermia; (2) an exogenous source of C02 is present such as C02 insufflation, bicarbonate infusion or rebreathing; (3) alveolar ventilation
decreases
31
An end-tidal C02 (ETC02) partial pressure of< 5 mm-Hg is diagnostic of what?
Esophageal intubation
32
What causes the "rippling" or "feathering"seen on the plateau of the capnogram?
Cardiogenic oscillations produce the feathering pattern associated with the plateau of the capnogram.
33
What will happen to end-tidal C02 (ETC02) if the patient is ventilated and a ventilation:perfusion {V /Q) mismatch
develops?
ETC02 may decrease because the ability to blow off C02 decreases with V/Q mismatching
34
Where on the capnograph tracing is found dead space plus alveolar ventilation?
Dead space plus alveolar ventilation is found throughout expiration on the capnograph tracing
35
What gases are measured by mass spectrometry?
Mass spectrometry measures C02, 02, N2, and inhaled agents (N20, isoflurane, sevotlurane, destlurane, halothane, enflurane).
36
When using a mass spectrometer, what is the primary concern?
The sampling interval, while normally short enough to provide sufficient early warning of most untoward events and physiological changes and detection of some events such as esophageal intubation, may not be short
enough and sampling rate may not be rapid enough
37
What happens to the gas sample drawn from
| a side port into the analyzer compartment of the mass spectrometer?
The gas sample is ionized by an electron beam and passed through a magnetic field.
38
What happens to the ions formed by passing the gas through the electron beam of the mass spectrometer?
The ions formed by passing the gas through the electron beam follow a curved path as they pass through the magnetic field.
39
For mass spectrometer, ions with greater mass to charge rations are
Least deflected and follow the curved path with the greatest radius.
40
For mass spectrometer, ions with smallest mass to charge rations are
are DEFLECTED MOST and follow the curved path with the smallest radius.
41
How is the concentration of a gas determined by the mass spectrometer?
Molecules of different mass are deflected at varying angles when passed through a magnetic field. Detectors are placed at specific locations to the number of molecules hitting the detector, which is then converted to
a concentration of the particular gas.
42
Where should the gas monitor sampling line be placed?
Mass spectrometry sampling should occur from a side port on an elbow inserted between the endotracheal tube or mask and the Y-piece of a circle system.
43
What three general problems can be detected by mass spectrometry?
identify equipment problems, (2) identify ventilatory problems (hypocapnia, hypercapnia, emboli) and (3) warn of vaporizer malfunction
44
List specific problems that can be detected by mass spectrometry as far as anesthesia machine goes?
(I) Error in gas delivery (C02, 02, Nz, and inhaled agent analysis);
2) anesthesia machine malfunction {C02, 0 2, N2, and inhaled agent analysis); (3) disconnection (C02, 02, N2. and inhaled agent analysis);
(4) vaporizer • malfunction or contamination (inhaled agent analysis};
(5) anesthesia circuit leaks (C02 and N1 analysis);
(6) endotracheal tube cuff leak
45
Other things the mass spectometry can help identify?
poor mask or LMA fit {C02 and N2 analysis);
(8) hypoventilation (C02 analysis);
(9) malignant hyperthermia (C02 analysis);
( 10) airway obstruction including kinked endotracheal tube ( C02 analysis); (
11) air embolism (C02 and N1 analysis); (12) circuit hypoxia {02 analysis); (13) vaporizer overdose {agent analysis
46
Can the mass spectrometer detect a ventilation:perfusion (V/Q) mismatch? Explain your answer.
NO. V/Q mismatch is associated with a decrease in PaO2, and the mass spectometer does not assess PaO2.
47
What are two limitations of a mass spectrometer?
l) Long measurement delays may be encountered. (2) Administration of isoproterenol with give HIGH false measurements.
48
What limitation exists when using mass spectrometry with a closed system?
The gas sampling system may withdraw from the system more gas per minute for analysis than the volume of 02 introduced. Hypoxemia could result.
49
A mass spectrometer reads 5% C02 at sea level. What is the partial pressure of CO2? What law is the basis for this
calculation?
(5%/100) x 760 = 38 mm-Hg; 5% C02 exerts a partial pressure of 38 mm-Hg. Dalton's law of partial pressures is the basis for this calculation.
50
Explain how a pulse oximeter works.
Two different wavelengths oflight are used: one is visible red light (660 nm) and the other infrared{(940 nm).
51
Infrared light {940 nm) is absorbed by whereas
oxyhemoglobin
52
Visible red light {660 nm) is absorbed by
deoxyhemoglobin.
53
What ratio is measured with pulse ox?
The ratio of pulsatile to non-pulsatile light absorption
| at each frequency is calculated. The ratio is then correlated to Sp02 through internal calibration.
54
The most common currently used infrared wavelength is
940 nm.
55
What two principles are combined in the pulse oximeter to measure oxygen saturation in arterial blood?
Pulse oximeters combine the principles of oximetry and plethysmography to measure noninvasively oxygen saturation in arterial blood
56
What does a finger plethysmograph detect?
A finger plethysmograph uses a light-emitting diode and a photoelectric cell to detect changes in finger volume
57
The Lambert-Beer law is based on what observation and applies to what monitoring modality?
The Lambert-Beer law is based on the observation that oxygenated hemoglobin and reduced hemoglobin differ in their absorption of red and infrared light.
58
This law forms the basis of pulse oximetry
Lambert-Beer law
59
Identify the two light sources in the photo diode of the pulse oximeter
Red light {660 nanometer wavelength) and infrared light (940 nanometers wavelength).
60
List the absolute and relative contraindications to pulse oximetry.
There are no contraindications to pulse oximetry
61
Why might low or poor perfusion states interfere with accurate pulse oximeter readings?
Pulse oximeters require adequate pulsations to distinguish light absorbed from arterial blood from venous blood and tissue light - this process is called plethysmographic analysis.
62
Pulse oximeter readings may be unreliable or unavailable if
There is loss or diminution of peripheral pulse.
63
List examples of low perfusion states that limit pulse oximetry : Mechanically related
Proximal BP cuff inflation
External pressure
Improper positioning
64
List examples of low perfusion states that limit pulse oximetry : Patient condition
(4) hypotension;
{5) hypothermia;
(6) Raynaud's phenomenon;
(7) cardiopulmonary bypass; (8) low cardiac output; (9) hypovolemia; (10) peripheral vascular disease;
65
Does valsava maneuver affect pulse ox?
Yes such as laboring patients.
66
Factors that lead to falsely low pulse oximeter readings (Sp02 < Sa02). Hgb
versions of hemoglobin, namely methemoglobin when the true Sa02 > 85%, and HbK;
67
Factors that lead to falsely low pulse oximeter readings (Sp02 < Sa02--> DYES?
methylene blue, indigo carmine, isosulfan •
| blue, indocynanine green, and nitrobenzene
68
FACTORS that lead to false low pulse ox nail polish,
especially black, purple, or dark blue; and
69
The pulse oximeter LED generates
heat
70
FACTORS that lead to false low pulse ox anemia,
especially if the hematocrit is <25%; (S) low saturation (Sa02 < 80%)
71
List two factors that lead to falsely high pulse oximeter readings (SP02 > Sa02).
Carboxyhemoglobin (CO poisoning) and methemoglobin-when the true Sa01 < S5% - lead to falsely high pulse oximeter reading
72
Explain how the presence of methemoglobin can lead to both falsely high and falsely low pulse oximeter readings
Methemoglobin absorbs a significant amount of light at both 660 and 940 nm and thus the pulse oximeter detects equal amount of oxy- and deoxyhemoglobin which results in a reading of 8O% to 85%. In other words, in
the presence of significant methemoglobinemia the pulse oximeter reading is essentially "fixed" at 80% to 85%. Therefore, when the true Sa02 is less than 85%, the reading is falsely high and the obverse is true as well.
73
List 5 factors the generally have no significant effect on pulse oximeter readings
(1) polycythemia; (2) skin pigmentation( 4) red henna dye; and, (5) jaundice.
74
Hgb that DOES NOT AFFECT pulse ox?
(3) alternate hemoglobins, specifically HbF, HbS, HbH, and sulfHb;
75
Can the pulse oximeter detect a ventilation: perfusion mismatch? Why or why not?
Yes. Pa02 decreases when a ventilation:perfusion mismatch develops. Since Sa02 decreases when Pa02 decreases below 100 mm Hg, a pulse oximeter can detect a ventilation:perfusion mismatch
76
What is the best monitor to detect a disconnection?
According to Stoelting and MiJler, CAPNOGRAPHY and SPIROMETRY have the highest value in detecting disconnection.
77
The next best monitors for detecting disconnection beside capnography and spirometry
pulse oximetry and the stethoscope
78
What two measurements assess blood oxygen?
Pa02 and Sa02
79
What is the most useful method for monitoring the effects of muscle relaxants during surgery?
The mechanical response elicited by the peripheral nerve stimulator is the most useful method of monitoring neuromuscular blockade
80
Compare and contrast the diaphragm, laryngeal muscles, orbicularis oculi, and thumb muscles as regards response
to and recovery from (i.e., sensitivity) muscle relaxants.
In general, the diaphragm, laryngeal muscles, and orbicularis oculi respond to AND recover from muscle relaxants sooner than the thumb. Try this
mnemonic: "First flaccid, first firm:
81
What is the frequency of stimulation in a train-of-four?
2 Hz (two twitches per second or one every 0.5 seconds).
82
One hertz (Hz) is how many cycles per second? 50 hertz (Hz) is how many cycles per second?
1 Hz = 1 cycle/second. 50 hertz is 50 cycles per second
83
What is post-tetanic potentiation (facilitation)?
Single twitch responses after tetany are transiently enhanced. The enhanced single twitch responses immediately after tetany is post-tetanic potentiation (facilitation).
84
How is tetany produced with a nerve-muscle stimulator?
Tetany is produced by continuous electrical stimulation for five seconds at 50 Hz, which is an intense stimulus for release of acetylcholine at the neuromuscular junction
85
List seven characteristics of nondepolarizin neuromuscular blockade.
1. Decreased twitch height
(2) fade during tetany
(3) train-of-four ratio < 0.7
(4 post-tetanic potentiation, (5)augmentation of block
by other nondepolarizing agents.
86
Characteristics of NDNMB as fas as fasciculations
absence of fasciculations
87
NDNMB as far as acetylcholinesterase inhibitors.
antagonism of block by acetylholinesterase inhibitors
88
What is the best stimulation pattern to determine fade during neuromuscular block?
Double-burst stimulation (DBS} appears to be the best test to determine fade in neuromuscular block
89
In DBS
3,3 2 trains of3 impulses at 50 Hz separated by 750 ms are given
90
The response to DBS is easier to detect
manually,
91
Response to DBS correlates well with
train-of-four ratios (TOF), and the DBS response may reappear earlier than TOF during intense neuromuscular block
92
What percent of receptors are blocked when you have a full return of the train of- four?
70% can still be blocked with full train-of-four. [
93
List seven characteristics of phase I depolarizing blockade.
Decreased twitch height, (2) absence of fade with tetany, (3) slight reduction of twitch height in train-of-four (ratio ofT4:Tl > 0.7}, (4) no post-tetanic potentiation, (5) fasciculations, (and (7)
94
Phase I block and NDNMB
antagonism of block by nondepolarizing muscle relaxants,
95
Augmentation of block by acetylcholinesterase
| inhibitors: What type of block ?
Phase I
96
Fasciculations seen with what type of block?
Phase I
97
Decreased twitch height seen with what type of BLock
Phase I
98
Do the characteristics of phase II block differ from those of a nondepolarizing block when using a peripheral nerve
muscle stimulator?
No. Phase II block is similar to nondepolarizing block. Characteristics of phase II block include fade in train-of-four, fade during tetany, and post-tetanic potentiation (facilitation
99
In a hemiplegic patient, is the twitch elicited by a nerve muscle stimulator depressed more or less on the paralyzed side than on the normal side when non-depolarizing muscle relaxants are present? Explain .
The twitch is less depressed on the paralyzed side, presumably because of up regulation of acetylcholine receptors.
100
Why is a twitch LESS Depressed on the paralyzed side of a patient with hemiplegia?
Because of UPREGULATION of ACH receptors.
101
How is the depth of muscle blockade assessed when there is no detectable train-of-four or tetany?
Post- tetanic count (PTC) is used to evaluate the degree of neuromuscular blockade when there is no reaction to single twitch or train-of-four (TOF) nerve stimulation.
102
How is the post-tetanic count done?
Fifty Hz tetanus is applied for five seconds, followed by
a three-second pause and then stimulation at 1 Hz. The train-of-four and tetanic responses are undetectable but facilitation produces a certain number of visible post-tetanic twitches
103
For a given drug, the number of visible twitches correlates how?
inversely with the time required for the return of single
| twitch or train-of-four responses.
104
Discuss the 5 tests to determine the adequacy of neuromuscular block reversal.
(1) train-of-four > or equal 0.7,
(2) head lift for 5 seconds
(3) adequate tidal volume and/or vital capacity
(4) negative inspiratory pressure of 50 cm H20
(5) hand grasp strength
105
Least sensitive at determine the adequacy of neuromuscular block reversal.
adequate tidal volume and/or vital capacity are the least sensitive tests of adequate NMB reversal (70-80% receptor block remains).
106
Recent research has indicated, however,
| that a TOF > 0.7 does not indicate adequate NMB reversal and the new criterion is TOF
0.8-0.9 to exclude clinically significant neuromuscular
| block.
107
What tests of neuromuscular block correlate well with a TOF > 0.8-0.9?
double-burst stimulation, and holding a tongue depressor blade between the teeth. Double-burst stimulation (DBS) appears to provide a better tactile response to fade, and the DBS3,3 pattern seems to be a more reliable assessment of muscle relaxant reversal (Duke)
108
The ability to hold a tongue depressor between the teeth correlates with a
TOF > or equal to 0.86 and thus is an excellent assessment of adequate neuromuscular block reversal
109
A TOF > or equal 0.9 cannot be determined by
feel; it must be quantitated by mechano-, electro-,
| or acceleromyography.
110
Double-burst stimulation (DBS) appears to provide a better
tactile response to fade, and the DBS3,3 pattern seems to be a more reliable assessment of muscle relaxant reversal
111
How many twitches in a train-of-four should be visible, after administering a nondepolarizing neuromuscular blocker, before endotracheal intubation should be attempted?
The patient should be intubated 30 to 60 seconds after all twitches in the train-of-four have disappeared. No twitches should be seen when the trachea is intubated.
112
What site(s) gives the most reliable approximation of core body temperature?
The lower 25% of the esophagus give a reliable approximation of blood and cerebral temperature
113
Correlates well with esophageal TEMP which is the best is these 2 methods?
The tympanic membrane and aural canal temperatures
| correlate well with esophageal temperature
114
The most accurate reflection of temperature is a
pulmonary artery catheter (PAC) thermistor (never used for this purpose)
115
Where is the ideal placement of the esophageal stethoscope?
lower third of the esophagus.
116
The use of an esophageal stethoscope is contraindicated in patients with either of what two conditions?
The patient who has an esophageal perforation and the patient with liver disease who has or could have esophageal varices. Do not instrument the
esophagus of these patients.
117
Describe the basic operation of a forced-air warmer.
A forced-air warmer (such as the Bair Hugger•, Arizant Healthcare) entrains ambient air through a microbial filter. The air is warmed using an thermostat-controlled electric heater, and then blown through a hose that is connected to an inflatable patient cover.
118
Forced-air warmers are also known as
convection warming devices and warm air blowers.
119
List two standard for forced-air warming devices.
The U.S. standards for forced-air warming devices (2002) are (1) the maximum contact surface temperature shall not exceed 48 °C, and (2) the average contact surface temperature shall not exceed 46 °C during normal
conditions.
120
State advantages afforded by forced-air warmers.
Forced-air warming is safe, simple, effective, and inexpensive
121
Can be warmed before use with a forced-air device.
Fiberoptic laryngoscopes
122
List some disadvantages of forced-air warmers.
Electric power requirements
must occasionally be removed from the patient to
expose covered areas
123
Define perioperative blood salvage (CELL SAVER)
Perioperative blood salvage refers to the recovery of shed blood from the surgical field or wound drains and re-administration to the patient.
124
In most instances, the process involves "washing" of the salvaged material with return of
only the RBC component of blood
125
List seven situations in which intraoperative blood salvage (IBS) may be employed
(1) cardiovascular surgical procedures, (2) aortic
reconstruction, (3) spinal instrumentation, (4) joint arthroplasty, (5) liver transplantation, (6) resection of arteriovenous malformations, and (7) occasionally in the management of trauma patient.
126
Briefly describe the operation of contemporary
| "cell saver" (blood salvage) devices.
Contemporary "cell saver" devices anti-coagulate the salvaged blood as it leaves the surgical field, separate the RBCs from other liquid and cellular elements by centrifugation, and then wash the salvaged RBCs extensively with saline.
127
Cell saver separate the RBCs from other liquid and cellular elements by
CENTRIFUGATION.
128
What is the hematocrit range of the salvaged blood aliquots returned to the patient?
The RBCs are typically returned to the patient suspended in saline in aliquots of 125 or 225 mL with a hematocrit of 45 to 65%.
129
How efficient is the modern cell saver? How many RBCs are salvaged.
Approximately 5O% of RBCs are salvaged, therefore anticipate administration of allogenic blood.
130
What are the contraindications to intraoperative
| blood salvage?
infection, malignant cells, urine, bowel contents, or amniotic fluid in the operative field.
131
Identify expected complications of intraoperative
| blood salvage.
The potential complications of intraoperative blood salvage (IBS) are a function of the reinfusion of materials that might remain after the washing process.
132
Cell saver ,Most of these are in fact removed quite efficiently by contemporary cell salvage
fat microaggregates such as platelets and leukocytes, air, red cell stroma, free hemoglobin, heparin, bacteria, and debris from the surgical field.
133
What coagulopathy is expected after intraoperative
| blood salvage?
Dilutional coagulopathy is to be expected after intraoperative blood salvage because the washing process removes essentially all clotting factors and most platelets.
134
How woul you manage this coagulopathy?
Management is the same as for a dilutional coagulopa·
| thy occurring with administration of homologous or preoperative autologous donation (PAD) blood
135
Briefly describe the basic operation of heat and moisture exchanger (HME).
A heat and moisture exchanger (HME) conserves some exhaled water and heat and returns them to the patient in the inspired gas.
136
The HME is also known as a
```
condenser humidifier
Swedish nose (!).
Artificial nose
nose humidifierpassive humidifier, regenerative humidifier,
moisture exchanger, and vapor condense
```
137
What are the indications for heat and moisture exchanger (HME) use?
increase inspired heat and humidity during both short- and long-term ventilation.
138
HMEs are indicated if the patient is
hypothermic and for use in the neonatal circuit. HMEs may be especially useful in transporting the intubated patients.
139
List two contraindications to heat and moisture exchanger (HME) use
(1) patients with thick and copious, or bloody secretions, (2) patients with a leak that prevents exhaled gas from passing through the HME
