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Principles of Anesthesia I - Summer 24 > Clinical Monitoring II - Exam 1 (Ericksen) > Flashcards

Clinical Monitoring II - Exam 1 (Ericksen) Flashcards

1
Q

Side-stream (diverting) gas analyzer

A
  • gas taken away from pts airway to the analyzer
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2
Q

Mainstream (non-diverting) gas analyzer

A
  • gas is analyzed at the airway
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3
Q

Gas Analysis

What is the transit time?

A
  • time lag for gas sample to reach analyzer
  • not instantaneous
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4
Q

Gas analysis

What is the rise time?

A

time taken by the analyzer to react to the change in gas concentration

  • ex: ETCO2 fluctuating when pt is getting sleepier - rises and then it levels out
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5
Q

Mainstream sampling

Sampling Challenges

A
  1. Water vapor (condense in airway tubing)
  2. Secretions & blood - clog ETCO2 sample line
  3. more interfaces for disconnections w/ mainstream
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6
Q

Side-stream Sampling

Sampling Challenges

A
  1. Kinking of sampling tubing
  2. water vapor
  3. failure of sampling pump
  4. leaks in line
  5. slow response time
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7
Q

Dalton’s Law states that –

A

the total pressure exerted by a mix of gases is equal to the sum of the partial pressures of each gas

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8
Q

How are gases expressed?

A

partial pressures (mmHg)
Volumes % (PP/Ptot x 100)

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9
Q

What is mass spectrometry?

A
  • looking @ how many gas molecules are present in a expired sample
  • the concenctration deterimined according to mass/charge ratio
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10
Q

What can mass spectrometry tell us?

A
  • what portions of the gas are Sevo, O2, Nitrous, etc.
  • can calculate 8 diff. gases
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11
Q

What is Raman Spectroscopy?

A
  • argon laser produces photons that collide w/ gas molecules in a sample
  • measured in a spectrum that identifies each gas & concentration
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12
Q

What is infrared analysis?

A

the measurement of energy absorbed from narrow band of wavelengths of IR radiation as it passes through a gas sample

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13
Q

What does infrared analysis measure?

A

the concentration of gases - they all have a different fingerprint/band length

CO2, nitrous oxide, water, volatile gases

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14
Q

What type of infrared analyzer is most common?

A

Non-dispersive (keeps it from going everywhere)

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15
Q

Why can infrared analysis not measure O2?

A

O2 does not absorb IR radiation

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16
Q

IR analyzer

Less light getting through =

A

higher concentration of the gas being measured

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17
Q

IR analyzer

more light getting through to detector =

A

Less concentration of the gas being measured

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18
Q

Side-stream analyzers report ________ temperature and ________ ____ dry values.

A

Ambient and Pressure dry

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19
Q

analyzers should report results at ____ temperature and pressure ________ values.

A

Body temp & pressure saturated (BTPS)

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20
Q

Example - calculating PP of a gas

A
  • Ptot - PH2O (FiO2) = PP
  • 30% O2 PP =
  • 760mmHg - 47mmHg (0.30) = 214mmHg

if she does not say anything about H2O vapor, don’t account for H2O vapor

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21
Q

O2 analyzer

What is a fuel cell/galvanic cell?

A
  • located in breathing tube (mainstream)
  • oxygen battery - measure current produced when O2 diffuses across a membrane
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22
Q

Fuel Cell

The current measured by the oxygen battery is proportional to ——?

A

The PP of O2 in the fuel cell

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23
Q

O2 analyzers - Paramagnetic

Why is O2 a highly paramagnetic gas?

A
  • d/t the magnetic energy of unparied electrons in their outer shell orbits
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23
Q

Fuel Cell

Where is it best to monitor the O2 concentration at?

A

In the inspiratory limb - so we know how much O2 the pt is actually getting

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24
Q

O2 analyzers

What does a paramagnetic analyzer detect?

A

the change in sample line pressure from the attraction of O2 by switched magnetic fields

signal changes that happen during the switching of magnetic fields correlate w/ O2 concentration

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25
Q

O2 analyzers

Where is the paramagnetic O2 analyzer mostly used?

A

In side-stream sampling multi-gas analyzers

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26
Q

O2 analyzers

What is the main advantage of the paramagnetic O2 analyzer over the fuel cell?

A
  • rapid-response, breath-by-breath monitoring
  • informs us w/ every breath what we need to do for the pt
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27
Q

O2 sampling inside the inspiratory limb –

A
  • ensures O2 delivery to pt
  • analyzes hypoxic mixtures
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28
Q

O2 sampling inside the expiratory limb –

A
  • ensures complete PREOXYGENATION/denitrogenation
  • ET O2 > 90% adequate - will never be 1.0 (100%)
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29
Q

what does an ET O2 <90% tell us?

A

The pt has lung comorbidities

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30
Q

Low O2 alarm reasons

A
  1. pipeline crossover
  2. incorrectly filled tanks
  3. failure of proportioning system - nitrous on and only so much can go through
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31
Q

Why is a High O2 alarm important?

A
  • important to notify us of high O2 concentration in pts in can be harmful to (free O2 radicals)
    – premature infants
    – pts on chemotherapeutic drugs (bleomycin)
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32
Q

Airway pressure monitoring is a key component in measuring ________.

A

Ventilation

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33
Q

T/F: Airway pressure monitoring can only assess mechanical ventilation.

A

False, it can also assess spontaneous ventilation

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34
Q

What can Airway Pressure Monitoring Detect?

A
  1. circuit disconnects
  2. ETT occlusions
  3. kinking of inspiratory limb
  4. fresh gas hose kink/disconnect
  5. circuit leak
  6. sustained high circuit pressure (collection of H2O vapor, kink)
  7. high & low scavenging system pressures
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35
Q

What are the 2 types of pressure gauges used for airway pressure monitoring?

Which is highly reliable?

A
  1. Mechanical - highly reliable
    * requires monitoring
  2. Electronic
    * has alarm system integrated
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36
Q

What type of Airway Pressure Alarm is required by the AANA/ASA?

A

Breathing circuit low pressure alarm

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37
Q

What is the purpose of the breathing circuit low pressure alarm?

A
  • ID circuit disconnects/leaks
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38
Q

Airway Pressure Monitoring

What should the low pressure limit be set at?

A
  • just below the normal peak airway pressure (20-30cmH2O)
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39
Q

Where do 70% of the disconnections of the breathing circuit occur?

A

At the Y-piece

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40
Q

Airway Pressure Monitoring

What is the sub-atmospheric pressure alarm?

A
  • a negative pressure alarm
  • measures and alerts of negative circuit pressure & potential for reverse flow of gases
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41
Q

What 3 things can negative airway pressures cause?

A
  1. pulmonary edema
  2. atelectasis
  3. hypoxia
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42
Q

What are 5 causes of the sub-atmospheric pressure alarm going off?

A
  1. active (suction) scavenging system malfunctions
  2. pt inspiratory effort against a blocked circuit
  3. inadequate FGF
  4. suction to misplaced NGT/OGT
  5. moisture in CO2 absorbent - prevent suction
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43
Q

When is the high-pressure alarm activated? What pt population is it important in?

A
  • activated if airway pressure exceeds a certain limit
  • pediatrics
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44
Q

Causes of high-pressure alarm activation

A
  1. obstructions
  2. reduced compliance
  3. coughing/straining
  4. kinked ETT
  5. endobronchial intubation
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45
Q

Airway pressure monitoring

What triggers the continuous pressure alarms to be activated?

A
  • circuit pressure > 10cmH2O for > 15 seconds
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46
Q

Causes of the continuous pressure alarm being activated

A
  • turned off vent, flipped to APL valve & forgot to squeeze bag
  • malfunctioning adjustable pressure relief valve
  • scavenging system occlusion
  • activation of oxygen flush system
  • malfunctioning PEEP (comorbidities)
47
Q

Peripheral nerve monitoring

Supramaximal Stimulation

A
  • reaction of a single muscle fiber to a stimulus follows on all-or-none pattern
48
Q

What are the different sites of nerve stimulation?

A
  1. Ulnar - adductor pollicis muscle gold standard
  2. Facial nerve - orbicularis oculi & corrugator supercili muscle where we usually monitor
  3. median nerve
  4. posterior tibial nerve
  5. common peroneal nerve
49
Q

The diaphragm has a ________ onset than the adductor pollicis. But, recovers ________ than peripheral muscles.

A
  1. shorter
  2. faster
50
Q

Does the corrugator supercilii or adductor pollicis reflect NMB of laryngeal & abdominal muscles better?

A
  • Corrugator supercillii
51
Q

What is single twitch stimulation?

What is it used for?

A
  • 1Hz every second - 0.1Hz every 10 seconds
  • used in labs to establish an ED95
52
Q

What is TOF and when do we use it?

A
  • 4 supramaximal stimuli every 0.5 seconds
  • evaluate the TOF count/fade in muscle response
  • reliable assessment of onset and moderate blockade
53
Q

What happens w/ TOF and a partial non-depolarizing block (Roc)

A
  • TOFR decreases (fade)
  • is inversely proportional to degree of block
54
Q

What happens to TOFR and a partial depolarizing block (succ)

A
  • no fade, ratio is 1.0
  • if fade present = phase II block
55
Q

What is Double Burst Stimulation?

A
  • 2-3 short bursts of 50Hz tetanic stimulation separated by 750ms w/ 0.2 ms duration of each square wave impulse in burst
  • DB 3,3 mode
  • DB 3,2 mode
56
Q

What is DBS good for?

A
  • detecting fade
  • not used in clinical practice
57
Q

What is tetanic stimulation?
non-depolarizers response:
depolarizer response:

A
  • 50Hz for 5 seconds
  • non-depolarizers: one strong sustained muscle contraction w/ fade
  • depolarizers: strong sustained muscle contraction w/o fade

* not really used

58
Q

What is post-tetanic stimulation?

A
  • tetanic stimulation (50 Hz for 5 sec)
  • followed by 10-15 single twtiches (1Hz after 3 second post-tetanic stimulation)
  • 9th twitch - may start to see recovery from non-depolarizer
59
Q

What is the post-tetanic response dependent on?

A
  1. degree of block
  2. frequency & duration of tetanic stimulation
  3. lengtho f time b/w end of tetanic & first post-tetanic
  4. frequency of single twitch stimulation
  5. Duration of single twitch stimulation before tetanic stimulation

Can only perform every 6 min

60
Q

What situation is post-tetanic stimulation good for monitoring?

A
  1. deep & surgical blockade - if pt is paralyzed very deep
61
Q

Non-depolarizing intense blockade

Reversal??

A
  • period of no response (3-6 min after intubating dose of NDMB)
  • high dose sugammadex (16mg/kg) reversal
62
Q

Non-depolarizing deep blockade

Reversal??

A
  • absence of TOF, presence of at least 1 response to post-tetanic stimulation
  • reversal - Neostigmine usually impossible, sugammadex (4mg/kg)
63
Q

Non-depolarizing moderate block

Reversal??

A
  • gradual return of 4 responses to TOF
  • reversal: Neostigmine after 4/4 responses, Sugammadex (2mg/kg)
64
Q

What happens in a depolarizing phase I block?

A
  • no fade/tetanic stimulation
  • no post-tetanic facilitation
  • all 4 responses reduced - equal - disappear - come back
65
Q

What happens in a phase II Depolarizing block?

A
  • fade present in TOF and tetanic stimulation
  • occurrence of post-tetanic facilitation
66
Q

clinical tips for NMB & monitoring

A
  • keep pt warm to prevent delaying nerve conduction
  • moderate level block is sufficient for surgery w/ 1-2 responses to TOF
  • reverse when all 4 responses to TOF present
  • check for NM recovery prior to extubation post-reversal
67
Q

Reliable clinical signs for extubation

A
  1. sustained head lift for 5 sec
  2. sustained leg lift for 5 sec
  3. sustained handgrip for 5 sec
  4. sustained tongue depressor test = can they bite down on the depressor around their ETT?
  5. max inspiratory pressure - take deep breath and hold it
68
Q

EEG is a summation of –

A

excitatory & inhibitory postsynaptic potentials in the cerebral cortex
* 16 channels of info

69
Q

What does an EEG identify?

A
  • consciousness/unconsciousness
  • seizures
  • stages of sleep/coma
  • hypoxemia/ischemia
70
Q

EEG

Amplitude

A
  • size/voltage of recorded signal
71
Q

EEG

Frequency

A
  • # of times per second the signal oscillates/crosses the 0-voltage line
72
Q

EEG

Time

A

duration of sampling signal

73
Q

Peri-op uses for EEG

A
  1. indentifies inadequate flow to cerebral cortex
  2. guides an anesthetic-induced reduction of cerebral metabolism
  3. predicts neuro outcome after brain insult
  4. Gauges depth of hypnotic state of pts under GA
74
Q

EEG beta waves

A

> 13Hz
* awake, alert/attentive brain

75
Q

EEG alpha waves

A

8-13Hz
* eyes closed
* anesthetic effects

76
Q

EEG Theta & Delta Waves

A
  • theta (4-7Hz)
  • delta (<4Hz)
  • depressed, slower frequency
77
Q

How many channels does a processed EEG use?

What do we use it for?

A

< 4 channels (2 for each hemisphere)
* delineates unilateral from bilateral changes
– unilateral: regional ischemia d/t carotid clamping
– bilateral: depression from anesthetic drug bolus

78
Q

When do we use a BIS monitor?

A
  • cases where there is concern for neuro deficits
  • estimates anesthetic depth
  • can help prevent intra-op awareness
79
Q

BIS ranges
100:
80:
60:
40:
20:
0:

A
  • 100: Awake - responds to voice
  • 80: responds to loud commands, mild prodding
  • 60: GA - low chance of recall, no response to verbal
  • 40: deep hypnotic state
  • 20: burst suppression
  • 0: flat line
80
Q

What is the most common type of evoked potentials monitored intra-op?

A

Sensory-evoked Responses
* electric most common
* can also have auditory, or visual

81
Q

How do sensory evoked potentials work?

A
  • stimulate sensory pathway and record responses along the path to the cerebral cortex
82
Q

Evoked potentials

Latency

A
  • time measured from application of stimulus to onset/peak of response
83
Q

Evoked potentials

amplitude

A
  • size/voltage of recorded signal
84
Q

Evoked potentials

What is one of the most important things for anesthesia?

A
  • let the tech get their baseline tracing while we are pre-oxygenating
85
Q

What are somatosensory evoked potentials (SSEPs)?

A
  • stimulation to peripheral mixed nerves
  • responses measured in sensorimotor cortex
86
Q

SSEPs

short latency vs. long-latency waveforms

A
  • short latency - more commonly recorded intra-op
    – less affected by anesthetics
  • long-latency: changed by anesthesia
87
Q

SSEPs

What things may alter the appearance of SSEPs?

A
  1. induction
  2. neuro disease
  3. age
88
Q

What are Brainstem Auditory Evoked Potentials (BAEPs)?

A
  1. monitors responses to click stimuli
  2. delivered via foam inserts along auditory path from ear to auditory cortex
89
Q

What are Visual Evoked Potentials (VEP)?

A
  • monitors response to flash stimulation of retina
  • uses light-emitting diodes in soft plastic goggles through closed eyelids or contacts
  • least common technique intra-op
90
Q

What are motor evoked potentials?

A

MEP
* monitors integrity of motor tract along spinal column, peripheral nerves, and innervated muscle

91
Q

What is the most common MEP used?

A

Transcranial motor evoked potential
* via transcranial electrical stimulation overlying motor cortex

92
Q

MEPs

What is electromyography?

A
  • monitors responses generated by cranial and peripheral motor nerves
  • allows early detection of surgically induced nerve damage & assessment of the level of nerve function intra-op
93
Q

What is the primary thermoregulatory control center?

A

Hypothalamus

93
Q

What nerve fibers are the heat/warmth receptors?

A

Unmyelinated C fibers

94
Q

What nerve fibers are the cold receptors?

A

Alpha & delta fibers

95
Q

Thermoregulatory - threshold:

A

the temp at which a response will occur

96
Q

Thermoregulatory - Gain:

A

the intensity of the response

97
Q

Thermoregulatory - Response

A
  • sweating - decreases body temp
  • vasodilation - more heat loss
  • vasoconstriction - less heat loss
  • shivering - increases body temp
98
Q

What 6 things can alter temperature control?

A
  1. anesthesia
  2. age
  3. menstrual cycle
  4. drugs
  5. alcohol
  6. circadian rhythm
99
Q

Hypothermia in GA

initial response

A
  • rapid decrease of 0.5-1.0 degree C
  • c/b anesthesia induced vasodilation (redistribution of body heat)
  • happens over 30min
100
Q

Hypothermia in GA

Slow linear reduction

A
  • 0.3 degree C/hr
  • c/b GA reducing metabolic rate by 20-30%
  • heat loss exceeds production
  • 1-2hrs after anesthesia induction
101
Q

Hypothermia in GA

Plateau phase

A
  • thermal steady state
  • heat loss = production
  • 3-4hrs after anesthesia
  • pt is still losing peripheral heat - but not core (vasoconstriction)
102
Q

Neuraxial Hypothermia

Central thermoregulatory control is inhibited, which means —

A

the threshold (temp) at that triggers peripheral vasoconstriction & shivering is lower
so more heat is lost

103
Q

Neuraxial Hypothermia

What autonomic thermoregulatory defenses are impaired?

A
  1. vasodilation
  2. sweating
  3. vasoconstriction
  4. shivering
104
Q

Neuraxial Hypothermia

What causes the initial decrease in core temp?

A
  • neuraxial blockade induced vasodilation
105
Q

Neuraxial Hypothermia

Will there be a plateau in temp?

A

NO, b/c inhibition of peripheral vasoconstriction

106
Q

Heat Transfer

Radiation

A

Heat loss to the environment (30-40%)
main form of heat loss
* infants vulnerable b/c low BSA

107
Q

Heat Transfer

Convection

A
  • loss of heat to air immediately surrounding the body (30%)
  • greater in rooms w/ laminar flow
108
Q

Heat Transfer

Evaporation

A
  • loss of heat through vaporization of water from open body cavities & resp. tract
  • sweating (DM - blood sugar)
  • ex-lap - pack abd w/ soaked gauze to prevent heat loss
109
Q

Heat Transfer

Conduction

A
  • heat loss d/t direct contact of body tissue or fluids w/ colder material
  • ex: skin and OR table, IV fluids

electricity conduction - touching

110
Q

Hypothermia complications (7 things)

A
  1. Coagulopathy
  2. increases transfusions (22%) and bleeding (16%)
  3. decreases O2 delivery to tissues (vasoconstriction)
  4. 3x rate of morbid cardiac outcomes (BP, HR and catecholamine levels increased)
  5. shivering (increased O2 demand)
  6. decreased drug metabolism - longer DOA NMB
  7. post-op thermal discomfort
111
Q

5 benefits of hypothermia

A
  1. protects against cerebral ischemia
  2. reduces metabolism (8%/degree C)
  3. improved outcomes in cardiac arrest recovery
  4. use in neurosurgery when brain ischemia is unexpected
  5. more difficult to trigger MH
112
Q

Peri-op temp management (4)

A
  1. airway heating & humidification (peds)
  2. warm IV fluids/blood
  3. cutaneous warming
    – increase room temp, insulation, hot water mattress
  4. forced air warming - prevents loss from radiation (uses convection)
113
Q

4 temp monitoring sites

A
  1. pulmonary artery - gold standard
    – correlates w/ other 3
  2. tympanic - approximates hypothalamus temp
  3. nasopharyngeal - brain temp (more error, epistaxis)
  4. distal esophagus - lower 1/3 - 1/4
114
Q

OR temps

A

Children: 70 degrees F/21 C
Adults: 65 degrees F/18 C

Principles of Anesthesia I - Summer 24 (15 decks)

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