Exam 1 - Clinical Monitoring (airway/neuro/temp) Flashcards

1
Q

What are the two types of gas sampling systems?

A
  • Side-stream/ diverting analyzer
  • Mainstream/ non-diverting analyzer
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2
Q

Which gas sampling system will have more lag time (transit time)?
A. sidestream
B. non-diverting
C. mainstream

A

A. Side-stream/ diverting analyzer

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3
Q

The time taken by the analyzer to react to the change in gas concentration is called:
A. sidestream response
B. transit time
C. rise time
D. mainstream response

A

C. rise time

The mainstream analyzer will have a faster rise time

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4
Q

Side-stream responses are dependent on what sampling tubing factors? select 3.

A. thickness
B. length
C. corrugation
D. inner diameter
E. material
F. gas sampling rate

A

B. Length of tubing
D. Sampling tubing inner diameter
F. Gas sampling rate (50 - 250 mL/min)

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5
Q

Gas sampling challenges with mainstream analyzers include: select 2
A. slower response time
B. leaks in the line
C. secretions or blood in tubing
D. more interfaces for disconnections

A

C. Secretions, Blood
D. More interfaces for disconnections

Water vapor (can block IR waveforms) - a challenge for both mainstream and sidestream

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6
Q

Gas sampling challenges with side-stream analyzers include: select 2.
A. failure of sampling pump or kinked sampling tubing
B. slower response time
C. secretions or blood
D. more interfaces for disconnection

A

A. Kinking of sampling tubing or Failure of sampling pump
B. Slow response time
… could also be leaks in the line

Water vapor (can block IR waveforms) - a challenge for both mainstream and sidestream

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7
Q

The total pressure exerted by a mixture of gases is equal to the sum of the partial pressures exerted by each gas in the mixture. What law is this?

A
  • Dalton’s Law
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8
Q

At sea level, what is the total pressure of all anesthetic gases in the system?

A
  • 760 mmHg
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9
Q

____ is a measure of concentration determined by mass/charge ratio of up to eight different gases administered during inhalational anesthesia.
A. raman spectroscopy
B. infrared analysis
C. mass spectrometry
D. water vapor streaming

A

C. Mass Spectrometry

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10
Q

A high-powered argon laser produces photons that collide with gas molecules in a gas sample. The scattered photons are measured in a spectrum that identifies each gas and concentration. This is called:
A. raman spectroscopy
B. infrared analysis
C. water vapor analysis
D. mass spectrometry

A

A. Raman Spectrometry (Raman Scattering)

No longer in use

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11
Q

What is most commonly used in anesthesia machines to determine the concentration of gas?
A. dispersive infrared analyzers
B. raman scattering
C. mass spectrometry
D. non-dispersive infrared analyzers

A

D. non-dispersive infrared analyzers

measures energy absorbed from narrow band of wavelengths of IR radiation as it passes thru a gas sample!

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12
Q

What gas is NOT measured when using a non-dispersive IR analyzer?
A. CO2
B. nitrous
C. O2
D. volatiles
E. water

A

C. O2; does not absorb IR radiation!

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13
Q

Long story short: How does Infrared Analysis determine concentration of a gases?
A. less light = high concentration
B. less light = lower concentration
C. more light = high concentration

A
  • Gas will enter the sample chamber
  • Each gas has a unique IR transmission spectrum absorption band
  • Strong absorption of IR light occurs at specific wavelengths
  • IR light is transmitted through the gas sample and filtered
  • The amount of IR light that reaches the detector is inversely related to the concentration of the gas being measured

A. Less light = high concentration of gas

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14
Q

T/F: Side-stream analyzers do not account for water vapor.

A

True: Side-stream analyzers report ambient temperature and pressure dry values (ATPD).

only if she asks to remove water vapor in the question then account for it (47 mmHg)

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15
Q

What are the two types of oxygen analyzers?

A
  • Fuel or Galvanic Cell O2 Analyzer (mainstream)
  • Paramagnetic O2 Analyzer (sidestream)
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16
Q

What are the drawbacks of a Fuel/ Galvanic Cell O2 Analyzer? select 2.
A. current is not proportional to PP of O2
B. slow response time
C. more agitation
D. short life span

A

B. Slow response time (30 secs, best to measure O2 in the inspiratory limb)
D. Short life span (months) depending on the length of O2 exposure

current IS proportional to PP of O2 in fuel cell

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17
Q

A paramagnetic O2 analyzer is used in most side-stream sampling multi-gas analyzers. What is the main benefit of this analyzer?
A. less agitation of signal
B. breath-by-breath monitoring which gives rapid response
C. measures current of O2 diffusing
D. longer life span

A

B. Rapid response; breath-by-breath monitoring

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18
Q

Purpose of gas sampling inside the inspiratory limb is to: select 2
A. ensure o2 delivery
B. analyze nitrous delivery
C. analyze hypoxic mixtures
D. ensure CO2 removal

A

A. Ensures oxygen delivery
C. Analyzes hypoxic mixtures

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19
Q

Purpose of gas sampling inside the expiratory limb is:
A. analyze complete deoxygenation
B. ensure CO2 delivery
C. ensure complete denitrogenation
D. ETCO2 above 90%

A

C. Ensure complete pre-oxygenation/ “denitrogenation
so ET O2 above 90% (aka 0.90) = adequate!

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20
Q

What can trigger a low O2 alarm?

A
  • Pipeline crossover
  • Incorrectly filled tanks
  • Failure of a proportioning system
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21
Q

What patient population must we be wary of for high O2 alarms?

A
  • Premature infants (high O2 can cause blindness!)
  • Patients on chemotherapeutic drugs (ex: bleomycin)

Bleomycin has been associated with pulmonary toxicity, which can cause lung damage. Supplemental oxygen may exacerbate this toxicity.

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22
Q

What can airway pressure monitoring detect?

A
  • Circuit disconnections
  • ETT occlusions
  • Kinking in the inspiratory limb
  • Fresh gas hose kink or disconnection
  • Circuit leaks
  • Sustained high-circuit pressure
  • High and low scavenging system pressures
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23
Q

What are the two types of pressure gauges used in airway pressure monitoring?

A
  • Mechanical Pressure Gauges
  • Electronic Pressure Gauges
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24
Q

Mechanical pressure gauges require no power, are always on, and have high reliability. What is a downside of these pressure gauges?
A. don’t turn off ever
B. must be continually scanned
C. loud alarm system
D. only record low data

A

B. Must be continually scanned b/c no alarm system and no recording of data!!

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25
Electrical pressure gauges are built within anesthesia machine and the alarm system is integrated. Why is this important? A. sensitive to small changes B. must be continually scanned C. only pick up huge changes D. no recording of data
A. Sensitive to small changes
26
What is the purpose of the breathing circuit low-pressure alarms?
* Identification of circuit disconnection or leaks * Monitors airway or circuit pressure and compares it with a preset low-pressure alarm limit.
27
Where do most of the circuit disconnections occur at?
* 70% of disconnections occur at the y-piece.
28
What is the normal peak airway pressure?
* 18-20 cmH20 *Low-pressure limit should be set just below this.*
29
What does the sub-atmospheric pressure alarm measure?
* Measure and alerts negative circuit pressure and potential for the reverse flow of gas
30
What can negative pressure cause the patient to have?
* Pulmonary Edema * Atelectasis * Hypoxia
31
What can cause negative pressure on the anesthesia machine?
* Active (suction) scavenging system malfunctions * Pt inspiratory effort against a blocked circuit * Inadequate fresh gas flow * Suction to misplaced NGT/OGT * Moisture in CO2 absorbent
32
What are the causes of high-pressure alarms?
* Obstruction * Reduced compliance * Cough/straining * Kinked ETT * Endobronchial intubation
33
When are continuing pressure alarms triggered?
* Continuing pressure alarms are triggered when circuit pressure exceeds 10 cm H2O for more than 15 seconds * Fresh gas can enter the circuit but can't leave
34
What are causes of continuing pressure alarms?
* Malfunctioning adjustable pressure relief valve * Scavenging system occlusion * Activation of oxygen flush system * Malfunctioning PEEP
35
What is the gold standard for the site of nerve stimulation?
* Ulnar Nerve *The ulnar nerve innervates the adductor pollicis muscle and has the lowest risk of direct muscle stimulation.*
36
What skeletal muscle is the most resistant to depolarizing and nondepolarizing NMBDs?
* Our favorite, the diaphragm *Diaphragm has a shorter onset than adductor pollicis and recovers quicker than peripheral muscles.*
37
What muscle will reflect the extent of the neuromuscular block of the laryngeal adductor and abdominal muscles the best?
* Corrugator Supercilii
38
Define a single twitch stimulation.
* Single stimuli applied from 1.0 Hz (every second) to 0.1 Hz (every 10 seconds)
39
What stimulation will Provide reliable information throughout all phases of neuromuscular blockade w/o a monitoring device?
* Train of Four
40
How do you calculate TOF Ratio?
* 4th Response:1st Response
41
Compare TOF Ratio for partial nondepolarizing block and partial depolarizing block.
* Non-depolarizing block: TOF ratio decreases (fade) and is inversely proportional to the degree of block * Depolarizing block: No fade. The ratio is 1.0. (If fade, phase II block has developed)
42
This stimulation is composed of 2 short bursts of 50 Hz tetanic stimulation separated by 750 ms w/ 0.2 ms duration of each square wave impulse in the burst.
* Double Burst Stimulation *Not used as much in clinical practice*
43
Describe tetanic stimulation.
* Tetanic stimulation given at 50 Hz for 5 seconds
44
Compare tetanic stimulation between non-depolarizer and depolarizer.
* Non-depolarizers - one strong sustained muscle contraction with fade after stimulation * Depolarizer – strong sustained muscle contraction w/o fade
45
What stimulation is used for a deep/surgical blockade?
* Post-tetanic stimulation *Performed every 6 minutes*
46
What kind of blocks are in columns A, B, and C? What kind of nerve stimulation is performed in rows 1 through 4?
47
Describe an intense non-depolarizing block. When does this occur? Reversal?
* Period of no response 3 – 6 minutes after an intubating dose of non-depolarizing NMBD * Reversal with high dose of Sugammadex (16 mg/kg) * Neostigmine reversal impossible
48
Describe a deep non-depolarizing block. Reversal?
* Absence of TOF but the presence of at least one response to post-tetanic count stimulation. * Dose of sugammadex (4 mg/kg) for reversal
49
Describe a moderate non-depolarizing block. Reversal?
* Gradual return of the 4 responses to TOF stimulation appears * Neostigmine reversal after 4/4 TOF * Dose of sugammadex (2 mg/kg) for reversal
50
Describe a phase 1 depolarizing blockade.
* No fade or tetanic stimulation; no post-tetanic facilitation occurs * All 4 responses are reduced, yet equal and then all disappear simultaneously in TOF (ratio is 1.0) * Normal plasma cholinesterase activity
51
Describe a phase 2 depolarizing blockade.
* Fade present in response to TOF and tetanic stimulation; occurrence of post-tetanic facilitation * Response is similar to a non-depolarizing blockade * Abnormal plasma cholinesterase activity
52
What are reliable clinical signs for ETT extubation?
* Sustained head lift for 5 sec * Sustained leg lift for 5 sec * Sustained handgrip for 5 sec * Sustained ‘tongue depressor test’ * Maximum inspiratory pressure
53
What will EEG help identify?
* Identify consciousness/ unconsciousness * **Seizure activity** * Stages of sleep * Coma * Identify inadequate oxygen delivery to the brain (hypoxemia or ischemia)
54
Describe the following EEG factors: -Amplitude -Frequency -Time
* Amplitude – size or voltage of recorded signal * Frequency – number of times per second the signal oscillates or crosses the 0-voltage line * Time – duration of the sampling of the signal
55
What kind of waves are present in alert, attentive patients?
* Beta waves (>13 Hz) * Higher frequency
56
What kind of waves are present when resting and eyes are closed?
* Alpha waves (8-13 Hz) * Present during the beginning of induction (anesthetic effects)
57
What kind of waves are present during depressed, deep anesthesia?
* Theta waves (4-7 Hz) * Delta waves (<4 Hz) * Slower frequency
58
How many channels are used in processed EEG compared to the gold standard EEG?
* 4 channels vs 16 channels
59
How does a BIS monitor estimate anesthetic depth?
* Computer-generated algorithm/weighting system *Note: BIS monitoring has not demonstrated to be superior to end-tidal agent concentration monitoring*
60
What is the BIS range for general anesthesia?
* 40-60
61
What is the most common type of evoked potential monitored intra-op?
* Sensory evoked potential
62
What is sensory-evoked potential?
* Electric CNS response to electric, auditory, or visual stimuli
63
How are sensory-evoked potentials described?
* Latency: time measured from the application of stimulus to the onset or peak of response * Amplitude: size or voltage of recorded signal
64
What are the three types of sensory-evoked potentials?
* Somatosensory-evoked potential (SSEP) * Brainstem auditory-evoked potential (BAEP) * Visual-evoked potential (VEP)
65
What monitors the responses to stimulation of peripheral mixed nerves (containing motor and sensory nerves) to the sensorimotor cortex?
* Somatosensory-Evoked Potential (SSEP)
66
Monitors the responses to click stimuli that are delivered via foam ear inserts along the auditory pathway from the ear to the auditory cortex
* Brainstem Auditory-Evoked Potential (BAEP)
67
What type of latency SSEPs are most commonly recorded intra-op, less influenced by changes in anesthetic drug levels?
* Short-latency
68
Monitors the responses to flash stimulation of the retina using light-emitting diodes embedded in soft plastic goggles through closed eyelids or contact lenses
* Visual-Evoked Potential (VEP)
69
Monitoring the integrity of the motor tracts along the spinal column, peripheral nerves, and innervated muscle
* Motor-Evoked Potentials (MEP)
70
What is the most common MEP?
* Transcranial motor-evoked potentials *Monitors stimuli along the motor tract via transcranial electrical stimulation overlying the motor cortex*
71
Monitors the responses generated by cranial and peripheral motor nerves to allow early detection of surgically induced nerve damage and assessment of the level of nerve function intra-op
* Electromyography *Assesses the integrity of cranial or peripheral nerves at risk during surgery*
72
Where is the primary thermoregulatory control center?
* Hypothalamus
73
What fibers are heat and warmth receptors?
* Unmyelinated C-fibers
74
What fibers are cold receptors?
* A-delta fibers
75
The thermoregulatory response is characterized by what three factors?
* Threshold – temperature at which a response will occur * Gain – the intensity of the response * Response – sweating, vasodilation, vasoconstriction, and shivering
76
What affects the thermoregulatory response?
* Anesthesia type * Age * Menstrual cycle * Drugs/EtOH * Circadian rhythm
77
What is the initial decrease in body temperature with hypothermia in general anesthesia?
* Rapid decrease of approximately 0.5-1.5 °C over 30 mins * Caused by anesthesia-induced vasodilation * Increases heat loss d/t redistribution of body heat
78
How much heat is lost during the slow linear reduction phase with hypothermia in general anesthesia?
* 0.3 °C per hour * Caused by the decrease of the metabolic rate of 20-30% * Heat loss exceeds production * This occurs 1-2 hours after anesthesia has started *Use Bair Hugger to combat heat loss*
79
Describe the plateau phase of hypothermia in general anesthesia.
* Thermal steady state * Heat loss = heat production * Occurs 3-4 hours after anesthesia has started * Vasoconstriction prevents loss of heat from the core, but peripheral heat continues to be lost
80
How is central thermoregulatory control inhibited by neuraxial anesthesia?
* Neuraxial anesthesia decreases the thresholds that trigger peripheral vasoconstriction and shivering
81
Why might there not be a temperature plateau with neuraxial anesthesia?
* Neuraxial anesthesia centrally alters the vasoconstriction threshold * Vasoconstriction of the lower extremity will be inhibited by the nerve block
82
What are the types of heat transfer?
* Radiation * Convection * Evaporation * Conduction
83
Describe Radiation. Which patient population is vulnerable to this type of heat transfer?
* Heat loss to the environment, body surface area (BSA) is exposed to the environment * Approx. 40% of heat loss in pt * Infants have a high BSA/body mass ratio makes them vulnerable
84
Describe Convection.
* Loss of heat to air immediately surrounding the body, approx. 30% * Clothing or drapes decrease heat loss * Greater in rooms with laminar airflow
85
Describe Evaporation
* Latent heat of vaporization of water from open body cavities and respiratory tract. Accounts for approx. 8-10% of heat loss * Sweating is the main pathway
86
Describe Conduction
* Heat loss due to direct contact of body tissues or fluids with a colder material, negligible * Contact between skin and OR table; intravascular compartment and an infusion of cold fluid
87
List complications related to hypothermia
* Coagulopathy * Increase the need for transfusion by 22% * Blood loss by 16% * ↓O2 delivery to tissues * 3x the incidence of morbid cardiac outcomes * Shivering * Decrease drug metabolism * Post-op thermal discomfort
88
Benefits of hypothermia
* Protective against cerebral ischemia * Reduces metabolism… 8% per degree Celsius * Improved outcome during recovery from cardiac arrest * More difficult to trigger MH
89
Peri-Op Temperature Management
* Prioritize airway/heating in pediatrics * Warm IV fluid and blood * Cutaneous warming * Forced air warming (convection method)
90
How can you perform cutaneous warming?
* ↑ Room Temperature (Liver transplant, trauma) * Insulation (blankets reduce heat loss by 30%) * Hot water mattress (safer/effective if placed on top of pt)
91
What is the gold standard monitoring site for temperature?
* Pulmonary Artery
92
What are other monitoring sites for temperature?
* Tympanic membrane (ear) - perforation risk * Nasopharyngeal - prone to error, nose bleeds * Esophagus - place in the distal esophagus, lower third to lower quarter of the esophagus (best site to monitor)
93
OR Temperature
* 65 degree (18°C) to 70 degrees (21°C)