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N928 - Basics of Anesthesia > Anesthesia Monitoring > Flashcards

Anesthesia Monitoring Flashcards

1
Q

Why do we monitor patients?

A
  • one of the standards of care
  • assess data indicating - patient status, patient’s response to therapeutic interventions, anesthesia equipment functionality
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2
Q

Standard 9

A
  • monitor, evaluate, and document

- alarms on and audible

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3
Q

documentation requirements

A
  • at least every 5 min
  • BP
  • HR
  • RR
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4
Q

alarms in anesthesia

A
  • reflect changes in patient or equipment status
  • variable pitch
  • threshold alarms on and audible
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5
Q

vigilance

A

state of clinical awareness whereby dangerous conditions are anticipated or recognized and promptly corrected

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6
Q

Standard 9 Required Monitors

A
  • oxygenation
  • ventilation
  • cardiovascular
  • thermoregulation
  • neuromuscular function
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7
Q

Standard 9 oxygenation

A

continuously monitor oxygenation by clinical observation and pulse oximetry; team communicates and collaborates to mitigate risk of fire

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8
Q

Standard 9 ventilation

A
  • continuously monitor ventilation by clinical observation and confirmation of continuous ETCO2 during moderate sedation, deep sedation, or general anesthesia
  • verify intubation of trachea or placement of other artificial airway device by auscultation, chest excursion, and confirmation of expired CO2
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9
Q

oxygenation measurement tools

A
  • oxygen analyzer
  • pulse oximetry
  • skin color
  • color of blood
  • ABG (when indicated)
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10
Q

oxygen analyzer facts

A
  • measures FiO2 - inspired gas from inspiratory limb
  • low concentration alarm if <30% from pipeline
  • calibrate to RA and 100%
  • required for any general anesthetic
  • useful for calculating PaO2 with alveolar gas equation
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11
Q

oxygen analyzer

A

electrochemical sensor, cathode and anode embedded in electrolyte gel separated from oxygen gas by oxygen permeable membrane; O2 reacts with electrodes, generates electrical signal proportional to O2 pressure (mmHg) in sample gas

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12
Q

pulse oximetry

A
  • standard of care for continuous oxygen monitoring
  • early warning for hypoxemia
  • requires pulsatile arterial bed
  • finger, toe, ear lobe, bridge of nose, palm and foot in children
  • continuous measurement of pulse rate and oxygen saturation of peripheral Hgb (SpO2)
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13
Q

mechanism of pulse oximetry

A
  • beer-lambert law
  • oxygenated Hgb absorbs more infrared light (960 nm)
  • deoxygenated Hgb absorbs more red light (660 nm)
  • oximeter calculates O2 saturation –> ratio of infrared and red transmitted to a photodetector; comparison of absorbances of these wavelengths
  • basis of oximetry is change in light absorption during arterial pulsation (pulsation –> increased path length)
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14
Q

factors affecting pulse oximetry accuracy

A
  • high intensity light
  • patient movement
  • electrocautery
  • peripheral vasoconstriction
  • hypothermia
  • cardiopulmonary bypass
  • presence of other Hgb (COHgb –> false high reading; MetHgb –> false low or high)
  • IV injected dyes (methylene blue)
  • hemoglobin < 5 (will not register)
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15
Q

Hypoxia

A

SaO2 less than 90%

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16
Q

what is ventilation

A
  • movement of volume, inhalation/exhalation

- elimination of CO2

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17
Q

ventilation monitors

A
  • continuous auscultation
  • chest excursion (observation)
  • end-tidal capnography
  • spirometry
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18
Q

precordial stethoscope

A
  • position at suprasternal notch or apex of left lung (where heart/lung sounds audible)
  • easily detect changes in breath or heart sounds
  • airway/circuit disconnect
  • endobronchial intubation
  • anesthetic depth/increase HR or contractility
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19
Q

esophageal stethoscope

A
  • soft plastic catheter
  • balloon covered distal openings
  • limited to intubated patients
  • better quality heart and breath sounds
  • incorporated temperature probe
  • place through mouth or nose into esophagus (distal 1/3), to provide core temperature
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20
Q

esophageal stethoscope contraindications

A

esophageal varices or strictures

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21
Q

respiratory gas analysis

A
  • gas sampling line (CO2, O2, volatile anesthetics)
  • allows measurement of volatile anesthetics
  • non-dispersive infrared (NDIR) most common
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22
Q

NDIR

A
  • side stream sampling (continuous gas aspiration)
  • gas absorbs infrared energy at specific wavelength (sp to each gas)
  • complex algorithm and microprocessor
  • multiple narrow band optical filters through which infrared emission passed to determine which gas is present in that mixture
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23
Q

dispersive infrared gas analysis

A

prism or diffraction grading mechanism to separate component wavelengths for each of our agents

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24
Q

how much CO2 does the average adult produce

A

250 mL/min

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25
Q

how can CO2 production change

A
  • patient condition
  • anesthetic depth
  • temperature
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26
Q

side stream sampling

A
  • airway gas aspirated and pumped to measuring device
  • sampling flow rates of 50-250 mL/min
  • limitations –> H2O condensation can contaminate the system and create falsely high readings; lag time between sample aspiration and reading
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27
Q

normal PACO2 and PaCO2 gradient

A

2-10 mmHg

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28
Q

abnormal PACO2-PaCO2 gradient

A
  • gas sampling errors
  • prolonged expiratory phase
  • V/Q mismatch
  • airway obstruction
  • embolic states
  • COPD
  • hypoperfusion
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29
Q

normal ETCO2

A

40 mmHg

indicative of adequate circulation, ventilation, and CO2 production

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30
Q

phase I of capnograph

A
  • corresponds to inspiration
  • anatomic/apparatus dead space devoid of CO2
  • level should be zero unless rebreathing
  • baseline elevated if –> CO2 absorbent exhausted, expiratory valve is missing/incompetent, Bain circuit
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31
Q

phase II of capnograph

A
  • early exhalation/steep upstroke
  • mixing of dead-space with alveolar gas
  • prolonged upstroke associated with –> mechanical obstruction (kinked ETT), slow emptying of lungs (COPD, bronchospasm, asthma)
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32
Q

phase III of capnograph

A
  • CO2 rich alveolar air
  • horizontal with mild upslope
  • steepness is function fo expiratory resistance (COPD, bronchospasm)
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33
Q

beta angle

A

-where the PETCO2 reads, what shows up on the monitor

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34
Q

phase IV of capnograph

A
  • inspiration of fresh gas

- return to baseline

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35
Q

what do we observe in capnograph waveform?

A
  • time
  • amplitude (how high does it go?) - should be 35-40 mmHg
  • frequency
  • slope
  • baseline (how does it look in relation to normal baseline)
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36
Q

mechanical ventilator

A
  • tidal volume - integrated spirometry
  • airway pressure - in circuit pressure gauge, peak inspiratory pressure, sustained elevated pressure
  • disconnect alarm - low airway pressure
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37
Q

Standard 9 cardiovascular

A
  • monitor and evaluate circulation to maintain patient’s hemodynamic status
  • continuously monitor HR and CV status
  • use invasive monitoring as appropriate
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38
Q

electrocardiogram

A
  • standard of care requires continuous display (HR with audible indicator)
  • detects –> cardiac dysrhythmias, conduction abnormalities, myocardial ischemia/ST depression, electrolyte changes, pacemaker function/malfunction
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39
Q

Three-electrode EKG

A
  • typically monitor lead II

- limited in detection of myocardial ischemia

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40
Q

five-electrode EKG

A
  • allows recording of six standard limb leads (I, II, III, aVR, aVL, aVF) and one precordial lead (usually V5)
  • better in detecting myocardial ischemia
  • allows better differential diagnosis of atrial and ventricular dysrhythmias
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41
Q

lead II

A
  • yields max P wave voltage
  • superior detection of atrial dysrhythmias
  • detects inferior wall ischemia/ST depression
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42
Q

V5

A
  • 5th ICS/anterior axillary line

- detection of anterior and lateral wall ischemia

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43
Q

RA (white)

A

R 2nd ICS midclavicular line

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44
Q

LA (black)

A

L 2nd ICS midclavicular line

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45
Q

RL (green)

A

R 5th/6th ICS midclavicular line

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46
Q

LL (red)

A

L 5th/6th ICS midclavicular line

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47
Q

V (brown)

A

4th intercostal space R sternal border (or any of the V leads)

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48
Q

noninvasive arterial BP monitoring (NIBP)

A
  • oscillometric device –> air pump inflates cuff –> microprocessor opens deflation valve –> oscillations sampled
  • easy, accurate
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49
Q

NIBP errors

A
  • surgeon leans on cuff
  • inappropriate cuff size (large –> low reading; small –> high reading)
  • shivering or excessive motion
  • atherslcerosis and HTN –> systolic low, diastolic high compared with invasive arterial pressure
50
Q

invasive arterial BP indications

A
  • any patient requiring BP measurement > minute to minute
  • critically ill
  • anticipated rapid blood loss
  • major procedures - CPB, aortic cross-clamp, intracranial surgery, carotid sinus manipulation
  • frequent ABG
51
Q

CVP monitor indications

A
  • fluid management of hypovolemia and shock
  • infusion of caustic drugs
  • aspiration of air emboli
  • insertion of pacing leads
  • total parenteral nutrition (TPN)
  • venous access in patients with poor peripheral access
52
Q

Pulmonary Artery Catheterization

A
  • poor LV function (EF <0.4, Cl <2 L/min/m2)

- evaluation of response to –> fluids, vasopressors, vasodilators, inotropes

53
Q

PA cath indications

A
  • valvular heart disease
  • recent MI
  • ARDs
  • massive trauma
  • major vascular surgery
54
Q

Standard 9 thermoregulation

A
  • monitor body temp if clinically significant changes in body temperature are intended, anticipated or suspected
  • use active measures to maintain normothermia
  • MH triggering agents used –> monitor for S/S
55
Q

factors affecting temperature

A
  • ambient room temperature
  • scope or length of surgery
  • hypothalamic depression
  • intraoperative fluid replacement
  • vigilance in maintaining core temperature
56
Q

radiation

A

heat radiated from patient into room

57
Q

convection

A

heat loss due to air velocity

58
Q

conduction

A

contact with OR table, blanket

59
Q

evaporation

A

heat loss to dry inspired gases

60
Q

heat loss

A

radiation > convection > conduction > evaporation

61
Q

General anesthesia and temperature regulation

A

body cannot compensate for hypothermia because anesthetics inhibit central thermal regulation by interfering with hypothalamus function (normally plays a role in body temp regulation)

62
Q

hypothermia defintion

A
  • <36 degrees C
  • mild 33-36; reduced enzyme function, coagulopathy
  • moderate = 32; fibrillatory threshold
63
Q

S/S of hypothermia

A
  • shivering
  • dizziness
  • feeling hungry
  • nausea
  • rapid breathing
  • problems speaking
  • confusion
  • coordination difficulties
  • fatigue
  • rapid HR
  • drowsiness
  • weak pulse
  • shallow breathing
64
Q

hypothermia in anesthesia

A
  • heat loss outpaces metabolic heat production
  • anesthesia impairs normal response
  • body temp may decrease 1-4 degrees
  • may delay awakening
  • may cause shivering
65
Q

shivering increases O2 consumption by how much?

A

400%

66
Q

greatest risk for hypothermia

A
  • elderly
  • burn patients
  • neonates
  • patients with spinal cord injuries
67
Q

hyperthermia in anesthesia

A
  • rarely develops under anesthesia
  • late sign of MH
  • other causes –> endogenous pyrogens, thyrotoxicosis or pheo; anitcholinergic blockade of sweating; excessive environmental warming
68
Q

temperature monitoring sites

A
  • esophagus (lower 1/3) accurately reflects blood temperatures
  • nasopharynx
  • rectum (not as reliable)
  • bladder (integrated into foley)
  • tympanic membrane
  • blood (PA cath)
  • skin
69
Q

superficial active warming modalities

A
  • forced air warmer (bair hugger) - most effective; decreases radiant and convective loss; decreases post op shivering and PACU stay
  • warming blanket - water circulating; minimally effective
  • radiant heat unit - no impact on mean body temp
  • heated liquids - IV bags/bottles on patients (dangerous)
70
Q

core active warming modalities

A
  • IV fluid warmers - warmed liquid transfer of heat to infusate; delivers fluids at the highest temperature of any technology
  • gastric lavage - warms body core, impractical intraoperatively
  • peritoneal irrigation - encourage use of warm irrigation during intra-abd procedures
71
Q

passive warming modalities

A
  • ambient temperature - huge effect on maintaining body heat; ambient temp >24; most adults remain normothermic without requiring other measures
  • insulation - extremities and head
  • heat and moisture exchanger - artificial nose, retains moisture
  • coaxial breathing circuit - warms/humidifies inspiratory gases
72
Q

neuromuscular function standard 9

A

when NMB agents administered, monitor neuromuscular response to assess depth of blockade and degree of recovery

73
Q

peripheral nerve stimulator

A
  • monitors effect of NMB agents on NMJ - know and compare to baseline; quantify by feel
  • delivers electrical stimulation to peripheral motor nerve
  • evokes mechanical response
  • permits titration of NMBD to optimal effect
  • quantifies recovery from NMB
74
Q

S/S residual paralysis

A
  • hypoxia
  • low TV
  • stridor
  • muscle weakness
  • increased oxygen requirement
75
Q

PNS monitoring sites

A
  • ulnar nerve
  • facial nerve
  • posterior tibial nerve
  • peroneal nerve
76
Q

ulnar nerve PNS

A
  • stimulates adductor pollicis
  • thumb adduction
  • electrodes placed at wrist or elbow (negative/black placed distally; positive/red proximally)
  • most common monitoring site
  • best for recovery
  • not as good for onset because inaccurate reflection of degree of block of diaphragm or airway muscles
  • only site for quantitative
77
Q

facial nerve PNS

A
  • lies within parotid gland
  • electrodes placed in front of tragus of ear and below
  • avoid direct muscle stimulation; negative electrode placed over nerve at tragus; positive at outer campus of eye
  • be careful of facial hair intereference
  • stimulates orbicularis occuli (close eyelid or corrugator supercilli (furrows brow)
  • temporal or zygomatic branches
  • best site for onset bc mimics paralysis of diaphragm
78
Q

posterior tibial nerve PNS

A
  • place electrodes behind medial malleolus of tibia
  • stimulates flexor hallucis brevus muscle
  • causes big toe flexion
  • can also be used for recovery if no access to ulnar nerve
79
Q

peroneal nerve PNS

A
  • electrodes on lateral aspect of knee

- response - dorsiflexion of foot

80
Q

single twitch

A
  • single pulse delivered every 10 seconds
  • 0.1 or 1 Hz
  • increasing block results in diminished response
  • twitch height depressed when 75% of receptors are blocked (twitch height will remain normal until 75% of nAChR are blocked)
  • twitch height will disappear when 90-95% of receptors blocked
81
Q

train of four (TOF)

A
  • most commonly used
  • 4 repetitive stimuli (2 Hz every 0.5 second)
  • twitches progressively fade as relaxation increases
  • ratio of responses to 1st and 4th twitches are sensitive indicator of NMB
82
Q

T4/T1 ratio

A
  • assessment of number of twitches ranging from 0 to 4
  • compares the strength of the fourth twitch to that of the first
  • seen as a percentage on the screen
83
Q

loss of 4th twitch

A

75% receptors blocked

84
Q

loss of 3rd twitch

A

80% receptors blocked

85
Q

loss of 2nd twitch

A

90% receptors blocked

86
Q

loss of 1st twitch

A

90-98% receptors blocked

87
Q

what is clinical relaxation?

A

75-95% receptors blocked

88
Q

non-depolarizing NMB

A
  • fade will be seen

- ratio decreases and is inversely proportional to degree of block

89
Q

depolarizing NMB

A
  • succinylcholine
  • amplitude of all 4 twitches will decrease but TOF will remain 1 because all four twitches have the same amplitude
  • all or nothing –> no fade
90
Q

tetanic stimulation (tetany)

A
  • tetany at 50-100 Hz
  • 5 seconds at 50 Hz evoked tension approximates tension developed during a maximal voluntary effort
  • in presence of NMB fade occurs
  • sustained response occurs when TOF >70%
  • disadvantage = painful for patient
91
Q

post-tetanic count

A
  • useful when all twitches suppressed
  • apply tetanus at 50 Hz for 5 seconds
  • wait 3 seconds
  • apply single twitches (or TOF) every second up to 20
  • number of twitches inversely related to depth of block (so more twitches means less block)
92
Q

double burst suppression

A
  • less painful than tetany
  • DBS3,3 - 3 short 50 Hz impulses, 750 msec pause, followed by 3 more bursts
  • more sensitive than TOF for visual evaluation of fade
93
Q

PNS Induction

A
  • TOF

- single twitch

94
Q

PNS maintenance

A
  • TOF

- post tetanic count

95
Q

PNS emergence

A
  • TOF

- DBS

96
Q

fast onset/tracheal intubation

A
  • site = orbicularis oculi
  • twitch modality = single twitch or TOF
  • target response = 0 twitches
97
Q

profound blockade

A
  • site = adductor pollicis or orbicularis oculi
  • twitch modality = TOF or post tetanic count
  • target response = relaxant dependent
98
Q

adequacy of relaxation (abdominal surgery)

A
  • site = adductor pollicis
  • twitch modality = TOF
  • target response = 1-2 twitches present
99
Q

predicting reversible block (when no TOF response present)

A
  • site = adductor pollicis
  • twitch modality = post tetanic count
  • target response = relaxant dependent
100
Q

detecting reversible block

A
  • site = adductor pollicis
  • twitch modality = TOF
  • target response = at least 2 twitches present
101
Q

detecting adequate neuromuscular function

A
  • site = adductor pollicis
  • twitch modality = double burst suppression
  • target response = no fade present
102
Q

sensitivity of muscle groups to non-depolarizing muscle relaxant from most to least sensitive

A
  • extraocular
  • pharyngeal
  • masseter
  • adductor pollicis
  • abdominal rectus
  • orbicularis oculi
  • diaphragm
  • vocal cords
103
Q

why is diaphragm first muscle to recover from NMB?

A

it is rich in nAChR

104
Q

Which nerve do you monitor for onset?

A

facial nerve

105
Q

which nerve do you monitor for recovery?

A

ulnar nerve

106
Q

1 of 4 twitches on TOF

A

reversal may take as long as 30 min

107
Q

2-3 twitches on TOF

A

reversal may take 10-12 min following long-acting relaxants, 4-5 min after intermediate relaxants

108
Q

4 of 4 twitches on TOF

A

adequate recovery within 5 minutes of neostigmine, within 2-3 minutes of edrophonium

109
Q

unreliable clinical signs of NMB recovery

A
  • sustained eye opening
  • tongue protrusion
  • arm life to opposite shoulder
  • normal TV
  • normal or near normal vital capacity
  • max inspiratory pressure <40-50 cmH2O
110
Q

reliable clinical signs of NMB recovery

A
  • sustained head lift x 5 sec
  • sustained leg lift x 5 sec
  • sustained handgrip x 5 sec
  • max inspiratory pressure 40-50 cmH2O or greater
111
Q

quantitative nerve monitoring

A
  • device that quantifies degree of NMB
  • reliable, accurate and objective
  • post stimulation, the muscle response is objectively quantified versus baseline (MUST GET A BASELINE)
112
Q

Acceleromyography (AMG)

A

piezoelectric sensor measures muscle acceleration (voltage generated upon muscle contraction)

113
Q

Electromyography (EMG)

A

muscle action potentials recorded; electrical activity proportional to the force of contraction

114
Q

Kinemyography (KMG)

A

quantifies muscle movement with motion sensor strip containing piezoelectric sensors

115
Q

Mechanomyography (MMG)

A

detects contraction force, converts to electrical signal, signal amplitude reflects contraction strength

116
Q

Phonomyography (PMG)

A

muscle contraction produces low-frequency sounds, calculates muscle response

117
Q

Bispectral Index Score (BIS)

A
  • used to assess depth of anesthesia
  • optional, not currently part of the standard of care
  • EEG signal
118
Q

reported BIS advantages

A
  • reduced risk of awareness
  • better management of responses to surgical stimulation
  • faster wake up (controversial)
  • more cost effective use of anesthetics
119
Q

BIS numerical values

A
  • ranges from 0-100
  • 100 = awake CNS
  • > 70 = greater recall risk
  • 40-60 = general anesthesia
  • 0 = isoelectric EEG
120
Q

What affects BIS reading?

A
  • electrocautery
  • EMG
  • pacer spikes
  • EKG signal
  • patient movement
121
Q

cerebral oximetry

A
  • assesses cerebral oxygen saturation using near infrared spectrophotometry (NIRS)
  • normal = 60-80%
  • 20% reduction in cerebral NIRS has been associated with regional and global ischemia
  • noninvasive
  • detects decreases in CBF in relation to CMRO2
  • intensity difference between transmitted and received light, determines regional oxygen saturation (similar to pulse oximetry and beer-lambert)
  • light source adheres to forehead, light transmits through tissue and cranium

N928 - Basics of Anesthesia (17 decks)

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