Anesthesia monitoring Flashcards
1
Q
Why do we monitor patients?
A
standard of care
detect any early physiological abnormalities
patient safety
guides titration of therapies and medications
2
Q
What standard addresses monitoring & alarms?
A
standard 9
3
Q
What must be documented every 5 minutes at a minimum?
A
patient’s blood pressure, heart rate, and respiration
4
Q
Standard 9 requires the monitoring of
A
ventilation continuously (oxygenation SpO2/continuous EtCo2)
cardiovascular status continuously
thermoregulation continuously (MH triggers)
monitor and assess patient positioning
monitor NMBs
5
Q
CRNAs must remain vigilant until
A
care is responsibly transferred to another qualified healthcare provider
6
Q
Alarms should
A
reflect changes in patient or equipment status
have variable pitch
and threshold alarms should be on and audible
7
Q
The most important monitor is
A
the vigilant CRNA
8
Q
When inspecting, we are looking at
A
retractions, color, mucous membranes
9
Q
When listen/auscultating we are listening to
A
heart & lung sounds, wheezing, and continuous suction intraoperatively
10
Q
When we are palpating, we are feeling for
A
pulses, color, edema, crepitus, muscle tension, resistance, and compliance
11
Q
When we are smelling, we are smelling for
A
smoke/burning, volatile anesthetic
12
Q
Standard 11 is responsible for
A
transfer of care to another responsible qualified healthcare provider
13
Q
Monitors include
A
pulse oximeter, capnography, NIBP or arterial-line, EKG, temperature, oxygen analyzer, stethoscope, PA catheter, ICP, urine output, PNS, BIS, precordial doppler, TEE/TTE, SSEPs
14
Q
Oxygenation should be
A
continuously monitored via clinical observation and pulse oximetry
15
Q
The most important aspect of anesthesia is
A
the airway
16
Q
The fundamental goal of ventilation monitoring is
A
to avoid hypoxia
17
Q
Ventilation needs to be continuously monitored via
A
expired carbon dioxide during moderate sedation, deep sedation, or general anesthesia
18
Q
Oxygenation is evaluated through
A
the oxygen analyzer, pulse oximetry, skin color, color of blood, and ABG (when indicated)
19
Q
The O2 analyzer measures
A
FiO2 of the inspired gas/inspiration
low concentration alarm <30%
required for any general anesthetic
20
Q
The O2 analyzer can be used to
A
calculate PAO2 because it gives us PaO2
21
Q
The oxygen analyzer is a
A
electrochemical sensor
cathode and anode embedded in electrolyte gel
O2 reacts w/ electrodes, generates electrical signal proportional to O2 pressure (mmHg) in sample gas
22
Q
Pulse oximetry is useful for
A
provides early warning sign of hypoxemia; cyanosis= late sign
23
Q
Pulse oximetry measures
A
arterial oxygen saturation combining principles of oximetry and plethysmography
24
Q
Pulse oximetry requires a
A
pulsatile arterial bed
can be assessed at finger, toe, ear lobe, bridge of nose, palm, and foot in children
25
_____ is responsible for the mechanism of pulse oximetry
Beer-Lambert law of spectrophotometry
26
Pulse oximetry works by
absorption of red and infrared light differs in oxygenated and reduced Hgb
HbO2 absorbs more infrared (960 nm)
Reduced Hb absorbs more red (660 nm)
calculates O2 saturation by comparison of absorbances of these wavelengths
27
Factors that affect the accuracy of pulse oximetry include
high intensity light, patient movement, electrocautery, peripheral vasoconstriction, hypothermia, cardiopulmonary bypass (need pulsatile bed), presence of other hemoglobins including carbon monoxide hemoglobin (increased false reading), met hemoglobin (false decrease/increase)
28
Methylene blue gives the largest
decrease in accuracy of the pulse oximeter
29
With a hemoglobin of <5,
the pulse oximeter will not read
30
The oxyhemoglobin dissociation curve
allows us to estimate arterial O2 content
31
When PaO2 is 30
SaO2 is 60
32
When PaO2 is 60
SaO2 is 90
33
When PaO2 is 40
SaO2 is 75
34
What is ventilation?
movement of volume; inhalation/exhalation- minute volume
| elimination of CO2
35
Ventilation monitors include
continuous auscultation-stethoscope
end-tidal capnography
spirometry
chest excursion (observation)
36
The precordial stethoscope is placed at
the suprasternal notch or apex of the left lung & it is where heart/lung sounds are audible
37
The precordial stethoscope allows for
early detection of changes in breath or heart sounds & indicates
airway/circuit disconnect, endobronchial intubation, anesthetic depth/increased heart rate, contractility
38
The esophageal stethoscope is a
soft plastic catheter that is placed into intubated patients and allows for better quality heart and breath sounds
39
The esophageal stethoscope is contraindicated in patients with
esophageal varices or strictures
40
The esophageal stethoscope is placed thorugh
mouth or nose into distal 1/3rd of the esophagus
41
The respiratory gas analysis is
the gas sampling line and allows for measurement of volatile anesthetics
42
The most common respiratory gas analysis is the
non-dispersive infrared
| side=stream sampling where gas absorbs infrared energy at specific wavelength
43
Capnography confirms
ETT placement and adequate vetilation
44
The average adult produces ____ mL Co2/min.
250
45
CO2 production changes with
patient's condition, anesthetic depth, and temperature
46
Limitations of the sidestream sampling include
H2O condensation can contaminate the system and falsely increase readings
lag time between sample aspiration and reading
47
The sidestream sampling works by
aspirating airway gas and pumping it to the measuring device
| sampling flow rates of 50-250 mL/min.
48
An end tidal CO2 of 40 mmHg suggests
adequate circulation, adequate alveolar ventilation, and adequate PaCO2 production
49
The normal PACO2-PaCO2 gradient is
2-10 mmHg
50
An abnormal PACO2 to PaCO2 gradient can be from
gas sampling errors, prolonged expiratory phase, V/Q mismatch, airway obstruction, embolic states, COPD, and hypoperfusion
51
Phase 1 of the end tidal CO2 corresponds to
inspiration
| anatomic/apparatus dead space devoid of CO2 and the levels should be zero unless rebreathing
52
If there are elevated CO2 baseline levels at phase 1, it is indicative of
Bain circuit, expiratory valve is missing/incompetent, and CO2 absorbent is exhausted
53
Phase 2 of the capnograph corresponds to
early exhalation/steep upstroke
| mixing of dead space w/ alveolar gas leads to rapid rise
54
A prolonged upstroke in phase II is indicative of
mechanical obstruction (kinked ETT), slow emptying of lungs (COPD, broncospasm)
55
Phase IV is caused by
inspiration of fresh gas and a return to baseline
56
Phase III of the capnograph is a
horizontal line with mild upstroke
CO2 rich alveolar air
steepness is function of expiratory resistance (COPD, bronchospasm)
57
The mechanical ventilator senses
disconnect alarm (low airway pressure), tidal volume (integrated spirometry), and airway pressure (in-circuit pressure gauge, sustained elevated pressure, peak inspiratory pressure)
58
The electrocardiogram detects
cardiac dysrhythmmias, conduction abnormalities, electrolyte changes, myocardial ischemia/ST depression, pacemaker function/malfunction
59
The electrocardiogram is used to
display continuous heart rate with audible indicator
60
With the three electrode EKG system,
typically monitor lead II
| limited in detection of myocardial ischemia
61
With the five electrode EKG system,
better in detecting myocardial ischemia, allows better differential diagnosis of atrial and ventricular dysrhythmias, and allows recording of six standard limb leads (I, II, III, aVR, aVL, and aVF) and one precordial lead usually V5
62
Lead V5 is located at
the 5th ICS/anterior axillary line and detects anterior and lateral wall ischemia
63
Lead II yields max
P wave voltages, superior detection of atrial dysrhythmias, and detects inferior wall ischemia/ST depression
64
With the 5 lead EKG placement,
the white lead is located in the 2nd intercostal space on the right (mid-clavicular) and the black lead opposite on the left; the green lead is located in the 8th intercostal space mid clavicular and the red on the left, and the brown is located (V5) to the right of the sternal border in intercostal space 4
65
Leads V3 and V4 are used to detect
anterior MI
66
Leads V1 & V2 are used to detect
septal MI
67
Leads II, III, and aVF are used to detect
inferior MI
68
Leads I, aVL, V5, and V6 are used to detect
lateral MI
69
When auscultating the BP we are listening for
korotkoff sounds
70
The oscillometric device is
a non-invasive form of BP monitoring and the air pump inflates cuff--> microprocessor opens deflation valve--> oscillations are sampled
71
Errors with the oscillometric blood pressure can be caused by
surgeon leaning on cuff, inappropriate cuff size (large size--> low reading, small cuff--> high reading), shivering or excessive motion, atherosclerosis and HTN
72
Errors with the oscillometric BP as it relates to atherosclerosis and HTN include
systolic low and diastolic BP high compared with invasive arterial pressure
73
The cuff width should be
>20% of the mean arm diameter
74
Indications for invasive arterial BP monitoring include
any patient requiring minute to minute BP monitoring, critically ill, anticipated rapid blood loss, major procedures including cardiopulmonary bypass, aortic cross-clamping, intracranial surgery, & carotid sinus manipulation
frequent ABG
75
The radial artery is the
most common site for arterial line site selection
76
The ulnar artery for arterial line selection is
not often used and is technically more difficult/more tortuous
77
The brachial artery for arterial line selection is
predisposed to kinking/location and complications may risk limb
78
The femoral artery for arterial line selection is
prone to pseudoaneurysm and atheroma formation
79
The dorsalis pedis for arterial line selection
may have distorted waveform
80
The axillary artery for arterial line selection
has potential for plexus/nerve damage from hematoma or traumatic cannulation
81
Indications for central venous pressure monitoring include
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 veins
82
Site selection of central venous pressure includes
internal jugular (right is preferred), subclavian, external jugular, antecubital (special kit w/ long catheter)
83
Potential indications for pulmonary artery catheterization include
valvular heart disease, recent MI, ARDs, massive trauma, & major vascular surgery
84
Pulmonary artery catheters can be used to evaluate response to
fluid administration, vasopressors, vasodilators, and inotropes
85
Pulmonary artery catheters can indicate poor LV function via
EF <0.4 and CI <2L/min/m2
86
Factors that affect temperature include
ambient room temperature, scope and length of surgery (open or laprascopic approach), hypothalamic depression, intraoperative fluid replacement (warmed?), vigilance in monitoring core temperature
87
Mechanisms of heat loss include
radiation>convection>conduction>evaporation
88
Radiation is
heat radiated from the patient to the room
89
Convection is
heat loss due to air velocity
90
Conduction is
contact with OR table, blanket
91
Evaporation is
heat loss to dry inspired gases
92
Unintentional hypothermia occurs in
phase 1, most drastic heat loss within 1 hour of start time
93
Symptoms of hypothermia include
shivering, dizziness, feeling hungry, nausea, rapid breathing, problems speaking, confusion, coordination difficulties, fatigue, rapid heart rate, drowsiness, weak pulse, shallow breathing
94
Hypothermia is considered to be
temperature <36 degrees celcius
95
Mild hypothermia is
33-36 degrees Celcius and causes coagulopathy and reduced enzyme function
96
Moderate hypothermia is
=32 degrees C and causes fibrillatory threshold
97
Hypothermia can cause
delayed awakening, cause increased shivering which increases O2 consumption
98
Patients at greatest risk for hypothermia include
elderly, burn patients, neonates, and patients with spinal cord injuries
99
Shivering increases O2 consumption by
up to 400%
100
Hypothermia occurs when
heat loss outpaces metabolic heat production & anesthesia impairs normal response
body temperature may drop 1 to 4 degrees C
101
Causes of hyperthermia include
late sign of malignant hyperthermia, endogenous pyrogens, thyrotoxicosis or pheochromocytoma (increases metabolic rate), anticholinergic blockade of sweating, excessive environmental warming
102
Hyperthermia is
rarely occurring under anesthesia
103
Temperature monitoring sites include
```
esophagus (lower 1/3rd) accurately reflects body temperature
nasopharynx
rectum
bladder (integrated w/ foley catheter)
tympanic membrane (risk of perforation)
Blood (PA cath)
Skin
```
104
Active warming modalities include
forced air warmer (Bair hugger)- most effective
warming blanket- water circulating- minimally effective
radiant heat unit- no impact on mean body temp
heat liquids (IV bags or bottles on patient)- very dangerous, can cause burns
105
Bair huggers are most effective in
decreasing radiant and convective losses and decreasing postoperative shivering and PACU stay
106
Gastric lavage is
an active warming modality used to warm body core; impractical intraoperatively
107
Peritoneal irrigation is
an active warming modality that encourages use of warm irrigation during intra-abdominal procedures
108
Intravenous fluid warming is
an active warming modality that allows for warmed liquid transfer of heat (hotline) to infuse (IVF/blood/etc.)
delivers fluids at the highest temperature of any technology
109
Passive warming modalities include
insulation of the extremities and head
heat and moisture exchanger- artificial nose, retains moisture
coaxial breathing circuit ("King" circuit)- warms and humidifies inspiratory gases
ambient temperature- hugely important with greatest effect on maintaining body heat- ambient temp >24 degrees
110
The most influential passive warming modality is
ambient temperature
| ambient temperature >24 degrees C allows most adults to remain normothermic without requiring other measures
111
How many patients still have residual blockade when arriving in PACU?
up to 40%
| associated with hypoxemia, pulmonary infiltrates, ventilatory insufficiency
112
The peripheral nerve stimulator
monitors effect of neuromuscular blocking agents on NM junction- know and compare to baseline, quantify by feel
delivers electrical stimulation to a peripheral motor nerve
permits titration of drug to optimal effect
quantifies recovery from neuromuscular blockade
113
Monitoring sites for the peripheral nerve stimulator include
ulnar nerve/adductor pollicis stimulation, facial, posterior tibial nerve, peroneal nerve
place electrodes over nerves to avoid direct muscle stimulation
114
The ulnar nerve innervates the
adductor pollicis muscle & adducts thumbs
| common monitoring site with electrodes placed at wrist or elbow- negative placed distally
115
The gold standard for peripheral nerve monitoring is
the ulnar nerve
116
The facial nerve is monitored by
placing electrode in front of tragus of ear and below
| better indicator of ND blockade of diaphragm and airway than peripheral muscles
117
The facial nerve is monitoring the
contraction of orbicularis oculi (closes eyelid) or corrugator supercili (furrows brow)
118
When monitoring the posterior tibial nerve,
place electrodes behind medial malleolus of tibia
| results in plantar flexion
119
The peroneal nerve is monitoring the
dorsiflexion of the foot by placing electrodes on lateral aspect of knee
120
Patterns of stimulation include
single twitch, train of four, tetanic stimulation, post-tetanic stimulation, and double burst suppression
121
Single twitch is
```
single pulse (0.1 Hz) delivered every 10 seconds
increasing block results in diminished response
```
122
The train of four is
most commonly employed and includes 4 repetitive stimuli of 2Hz over 4 sec.
twitches progressively fade as relaxation increases
123
Describe the # of twitches as compared to how many receptors are blocked (train of four).
loss of 4th twitch= 75% receptors blocked
loss of 3rd twitch= 80% receptors blocked
loss of 2nd twitch= 90% receptors blocked
0 twitches= 90-98% of receptors blocked
124
Tetanic stimulation is
tetany at 50-100 Hz
5 seconds at 50 Hz evoked tension approximates tension developed during maximal voluntary effort
In presence of ND relaxants, fade occurs
sustained response occurs when TOF >70%
125
Double burst stimulation is
less painful than tetany
more sensitive than TOF for visual evaluation of fade
3 short 50 Hz impulses followed 750 msec by another 3 bursts
126
Post-tetanic count is
useful when all twitches are suppressed
apply tetanus @50 Hz for 5 seconds, wait 3 seconds, apply single twitches every second up to 20
# of twitches inversely related to depth of block
127
With induction, PNS used is
single twitch and train of four
128
With maintenance, PNS used is
train-of-four
| post-tetanic count
129
With emergence, PNS used is
train-of-four
| double-burst stimulation
130
Least sensitive to most sensitive muscle groups to nondepolarizing muscle relaxants is
vocal cord, diaphragm, orbicularis oculi, abdominal rectus, adductor pollicis, masseter, pharyngeal, & extraocular
131
For onset ___ should be monitored and ____ should be monitored for recovery
onset: facial nerve; recovery ulnar nerve
132
With train of four, timing of reversal is
1 of 4 twitches, reversal may take as long as 30 minutes
2-3 twitches, reversal may take 10-12 minutes following long-acting relaxants, 4-5 minutes after intermediate relaxants
4 of 4, adequate recovery within 5 minutes of neostigmine, within 2-3 minutes of edrophonium
133
Unreliable clinical signs of recovery include
sustained eye opening, tongue protrusion, arm lift to opposite shoulder, normal tidal volume, normal or near normal vital capacity, max inspiratory pressure <40-50 cm H2O
134
Most reliable clinical signs of recovery include
sustained headlift x 5 seconds, sustained leg lift x 5 seconds, sustained handgrip x 5 seconds, max inspiratory pressure 40-50 cm H2o
135
limitations of NM monitoring include
responses may appear normal despite receptor occupancy
wide variability in evoked responses--> some exhibit weakness at TOF ratio of 0.8 to 0.9
values for adequate recovery do not guarantee adequate ventilatory function or airway protection
perioperative hypothermia increases skin impedance, limiting interpretation of evoked responses
136
Quantitative nerve monitoring is a
device that quantifies the degree of NM blockade
reliable, accurate, and objective
post-stimulation, muscle response objectively quantified
137
Quantitative nerve monitoring includes
```
acceleromyography-muscle acceleration
electromyography-electrical activity proportional to the force of contraction
kinemyography
mechanomyography
phonomyography
```
138
The bispectral index score is used to
assess depth of anesthesia
| optional monitor/not currently standard of care
139
The reported advantage of BIS is
reduced risk of awareness, better management of responses to surgical stimulation, faster wake up (controversial), more cost effective use of anesthetics
140
BIS readings are affected by
electrocautery, EMG, pacer spikes, EKG signal, and patient movement
141
Levels > than _____ are associated with _____ with BIS monitoring
70; recall
142
BIS index scores
```
100= awake CNS
>70= greater recall risk
40-60= general anesthesia
0= isoelectric EEG
```
143
Cerebral oximetry is used to
assess cerebral oxygen saturation using near infrared spectrophotometry
144
Cerebral oximetry detects
decreases in CBP in relation to CMRO2
