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Principles of Anesthesia I (Summer 2025) > Clinical Monitoring II Exam I > Flashcards

Clinical Monitoring II Exam I Flashcards

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1
Q

What are the two sampling sites depicted by the two arrows?

A
  • Elbow
  • Y-piece
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2
Q

What are the two types of gas sampling systems?

A
  • Side-stream/ diverting analyzer
  • Mainstream/ non-diverting analyzer
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3
Q

Which gas sampling system will have more lag time (transit time)?

A
  • Side-stream/ diverting analyzer
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4
Q

What is rise time in terms of the gas sampling system?

A
  • The time taken by the analyzer to react to the change in gas concentration

The mainstream analyzer will have a faster rise time.

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5
Q

What are gas sampling challenges with mainstream analyzers?

A
  • Water vapor (can block IR waveforms)
  • Secretions
  • Blood
  • More interfaces for disconnections
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6
Q

What are gas sampling challenges with side-stream analyzers? (5)

A
  • Kinking of sampling tubing (can break over time)
  • Leaks in the line
  • Failure of sampling pump
  • Slow response time
  • Water vapor (can block IR waveforms)
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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

Calculate the partial pressure of O2 at room air

A
  • 159.6 mmHg

760 mmHg x 21% = 159.6 mmHg

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10
Q

Calculate the partial pressure of inspired O2 at room air.

A
  • 149.7 mmHg

PIO2 = FIO2 (PB -PH2O)

21% (760 - 47) = 149.7 mmHg

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11
Q

What is mass spectrometry?

A
  • Calculates concentration of up to 8 different gasses aside from CO2
  • Concentration is determined by: molecules of gas present in the sample
  • Calculates partial pressure from fractional percentage
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12
Q

Do side-stream analyzers take into account of water vapors?

A
  • No
  • Side-stream analyzers report ambient temperature and pressure dry values (ATPD).
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13
Q

What are the two types of oxygen analyzers?

A
  • Fuel or Galvanic Cell O2 Analyzer
  • Paramagnetic O2 Analyzer
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14
Q

What are the drawbacks of a Fuel/ Galvanic Cell O2 Analyzer?

A
  • Short life span (months) depending on the length of O2 exposure
  • Battery powered
  • Slow response time (best to measure O2 in the inspiratory limb)
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15
Q

Benefits of a paramagnetic O2 analyzer?

A
  • Rapid response
    • breath-by-breath monitoring
    • Uses magnetic attraction
    • Requires less calibration
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16
Q

Purpose of gas sampling inside the inspiratory limb.

A
  • Ensures oxygen delivery
  • Analyzes hypoxic mixtures
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17
Q

Purpose of gas sampling inside the expiratory limb.

A
  • Ensure complete pre-oxygenation/ “denitrogenation”
  • ET O2 above 90% adequate
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18
Q

What can trigger a low O2 alarm?

A
  • Pipeline crossover (incorrect gas flowing through O2 pipeline)
  • Incorrectly filled tanks
  • Failure of a proportioning system (N2O increasing in the same proportion as O2)
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19
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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20
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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21
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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22
Q

What are the characteristics of mechanical pressure gauges? (4)

A
  • Requires no power, always on, and have high reliability
  • No recording of data - need to write it down
  • No alarm system
  • Must be continually scanned
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23
Q

What are the characteristics of electrical pressure gauges?

A
  • Built within ventilator or anesthesia machine
  • Alarm system integrated
  • Records data w/in machine
  • Sensitive to small changes
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24
Q

Causes of a low PIP alarm

A
  • Pressure does NOT exceed the preset minimum
  • Disconnects, apnea, vent failure, leaks in the system, OGT in lung on suction
  • Only enabled when ventilator is on

Required by AANA/ASA Standards

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25
Where do most of the circuit disconnections occur at?
* 70% of disconnections occur at the y-piece.
26
What is the normal peak airway pressure?
* 18-20 cmH20 *Low-pressure limit should be set just below this.*
27
What can negative pressure cause the patient to have?
* Pulmonary Edema * Atelectasis * Hypoxia
28
What can cause negative pressure on the anesthesia machine? (5)
* 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
29
What are the causes of high-pressure alarms?
Activated if the pressure exceeds a certain limit: * Obstruction * Reduced compliance (ARDS) * Cough/straining * Kinked ETT * Endobronchial intubation **Non-functional in pressure-controlled ventilation**
30
What causes a sustained pressure alarm?
Caused by pressure that remains elevated throughout the respiratory cycle *Circuit pressure exceeds 10cmH2O >15 seconds* Circuit pressure should decrease below 10cmH2O during expiration - Improperly adjusted APL - Activation of O2 flush system - Malfunctioning PEEP (auto-peep) - Breath stacking - Scavenger system occlusion
31
What is the gold standard site of nerve stimulation for recovery?
* Ulnar Nerve *The ulnar nerve innervates the adductor pollicis muscle and has the lowest risk of direct muscle stimulation.*
32
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.*
33
Which nerve/muscle set mirrors the onsent of laryngeal relaxation when stimulated?
- Facial nerve - Orbicularis oculi and **corrugator supercilli**
34
Define a single twitch stimulation.
* Single stimuli applied from 1.0 Hz (every second) to 0.1 Hz (every 10 seconds)
35
Describe stimulus given for TOF monitoring
Supramaximal stimuli every 0.5 seconds for four twitches
36
How do you calculate TOF Ratio?
* 4th Response:1st Response
37
Compare TOF Ratio for partial nondepolarizing block and depolarizing block.
* Non-depolarizing block: TOF ratio decreases (fade) and is inversely proportional to the degree of block (meaning the smaller the ratio, the stronger the block) * Depolarizing block: No fade. The ratio is 1.0. (If fade, phase II block has developed)
38
Describe tetanic stimulation
- Tetanic stimulation given at 50 Hz for 5 seconds - Very painful, limited usefulness
39
Compare tetanic stimulation between non-depolarizing and depolarizing muscle relaxants.
* Non-depolarizers - muscle contraction with fade after stimulation * Depolarizer – strong sustained muscle contraction w/o fade
40
Compare post-tetanic stimulation between depolarizing and non-depolarizing muscle relaxants
- Depolarizing: Post-tetanic stimulation occurs, not facilitation (meaning the post-tetanic twitch is the same strength as the twitches during tetany) - Non depolarizing: Facilitation of post-tetanic twitch (meaning this twitch response is greater than the final tetany twitch)
41
What kind of blocks are in columns A, B, and C? What kind of nerve stimulation is performed in rows 1 through 4?
42
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
43
Describe a deep non-depolarizing block. Reversal?
* Absence of TOF but the presence of at least one response to post-tetanic count stimulation. *Indicates recovery is starting* * Dose of sugammadex (4 mg/kg) for reversal * Neostigmine reversal usually impossible at this point
44
Describe a moderate non-depolarizing block. Reversal practices with neostigmine and sugammadex?
* Gradual return of the 4 responses to TOF stimulation appears * Neostigmine reversal possible after 1/4 TOF * Dose of sugammadex (2 mg/kg) for reversal Reverse even when there are 4/4 twitches
45
Describe a phase 1 depolarizing blockade.
* No fade or 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
46
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
47
What will EEG help identify?
* Identify consciousness/ unconsciousness * **Seizure activity** * Stages of sleep * Coma * Identify inadequate oxygen delivery to the brain (hypoxemia or ischemia)
48
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
49
What kind of waves are present in alert, attentive patients?
* Beta waves (>13 Hz) * Higher frequency
50
What kind of EEG waves are present when resting and eyes are closed?
* Alpha waves (8-13 Hz) * Present during the beginning of induction (anesthetic effects)
51
What kind of waves are present during depressed, deep anesthesia?
* Theta waves (4-7 Hz) * Delta waves (<4 Hz) * Slower frequency
52
How many channels are used in processed EEG compared to the gold standard EEG?
* 4 channels vs 16 channels
53
How does a BIS monitor estimate anesthetic depth? What does the BIS tell us?
- Example of processed EEG - Computer-generated algorithm/weighting system - Delineates unilateral from bilateral changes - Gives us some EMG info - Tells us suppression ratio - 20 to 30 second lag time *Note: BIS monitoring has not demonstrated to be superior to end-tidal agent concentration monitoring*
54
What is the BIS range for general anesthesia?
* 40-60
55
What is the most common type of evoked potential monitored intra-op?
* Sensory evoked potential
56
What is sensory-evoked potential?
* Electric CNS response to electric, auditory, or visual stimuli
57
How are sensory-evoked potentials described (context: refers to the waveforms)?
* Latency: time measured from the application of stimulus to the onset or peak of response * Amplitude: size or voltage of recorded signal
58
What are the four types of sensory-evoked potentials?
* Somatosensory-evoked potential (SSEP) * Brainstem auditory-evoked potential (BAEP) * Visual-evoked potential (VEP) * Motor-evoked potential (MEP)
59
What monitors the responses to stimulation of peripheral mixed nerves (containing motor and sensory nerves) to the sensorimotor cortex?
* Somatosensory-Evoked Potential (SSEP)
60
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) * Uncommon in OR
61
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)
62
Stimulus applied to motor cortex in order to observe a peripheral motor response
* Motor-Evoked Potentials (MEP)
63
What is the most common MEP?
* Transcranial motor-evoked potentials *Monitors stimuli along the motor tract via transcranial electrical stimulation overlying the motor cortex*
64
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*
65
Where is the primary thermoregulatory control center? Mediated by what?
- Hypothalamus - Mediated by dopamine, norepinephrine, ACh, prostaglandins
66
What fibers are heat and warmth receptors?
* Unmyelinated C-fibers
67
What fibers are cold receptors?
* A-delta fibers
68
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
69
What factors could make thermoregulatory response vary?
* Anesthesia type * Age * Menstrual cycle * Drugs/EtOH * Circadian rhythm
70
What is the initial decrease in body temperature with hypothermia in general anesthesia? What causes it?
* 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 to periphery
71
How much heat is lost per hour during the slow linear reduction phase with hypothermia in general anesthesia? When does it occur? What are 2 main causes?
* 0.3 °C per hour * This occurs 1-2 hours after anesthesia has started * Caused by the decrease of the metabolic rate of 20-30% * Heat loss exceeds production *Use Bair Hugger to combat heat loss*
72
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
73
How is central thermoregulatory control inhibited by neuraxial anesthesia?
- Decreases the threshold that triggers vasoconstriction - Induces vasodilation in the periphery → redistributing heat to periphery - Decreases shivering threshold - Sedatives also inhibit thermoregulatory control
74
Describe Radiation. How much heat is lost in this manner? 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 and obese patients lose a greater amount of heat through radiation
75
Describe Convection.
- Refers to rate of air speed in an OR - Neglible loss - Greater in rooms with laminar airflow
76
Describe Evaporation
* Latent heat vaporization of water from open body cavities and respiratory tract. Accounts for approx. 8-10% of heat loss * Sweating is the main pathway
77
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 * Patients are usually on thick foam pads
78
List complications related to hypothermia (8)
* Coagulopathy * Increase need for transfusion by 20% * Blood loss by 16% * ↓O2 delivery to tissues * 3x the incidence of morbid cardiac outcomes * Shivering * Decrease drug metabolism * Post-op thermal discomfort
79
Benefits of hypothermia (4)
* Protective against cerebral ischemia * Reduces metabolism… 8% per degree Celsius * Improved outcome during recovery from cardiac arrest * More difficult to trigger MH
80
Peri-Op Temperature Management
* Prioritize airway/heating in pediatrics * Warm IV fluid and blood * Cutaneous warming * Forced air warming (convection method)
81
How can you perform cutaneous warming?
* ↑ Room Temperature (Liver transplant, trauma, peds) * Insulation (blankets reduce heat loss by 30%) * Hot water mattress (safer/effective if placed on top of pt)
82
What is the gold standard monitoring site for temperature?
* Pulmonary Artery
83
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)
84
OR Temperature
* 65 degree (18°C) to 70 degrees (21°C)
85
PIP should increase or decrease during: Inspiration? Expiration?
- Increases during inspiration - Decreases during expiration
86
When is the posterior tibial nerve used for TOF monitoring?
When the surgical procedure requires the HOB to be away from anesthesia
87
Placement of electrodes correlate with what? Odd numbers go on which hemisphere? Even numbers?
- Placement correlates with anatomy/cortical regions - Odd numbers on left hemisphere - Even numbers on right hemisphere
88
How do volatiles alter the latency and amplitude of evoked potentials?
- N2O affects evoked potentials the most, cannot use - MAC cannot be greater than 0.5, must add IV anesthetic if required

Principles of Anesthesia I (Summer 2025) (23 decks)

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