Anesthesia Monitoring Flashcards
1
Q
Which AANA Standard is related to monitoring?
A
Standard 9: Monitoring, Alarms
2
Q
According to standard 9 which monitors do we need to document and how often do we need to document them?
A
blood pressure, heart rate, and respirations at least every 5 minutes
3
Q
National patient safety goals 2017: goal 6 refers to
A
reduce harm associated with clinical alarm systems
4
Q
Definition of vigilance
A
a state of clinical awareness whereby dangerous conditions are anticipated or recognized and promptly corrected
5
Q
Which is the most important monitor?
A
We are! :-)
vigilant CRNAs develop intuitive sense through education and experience
6
Q
Examples of things we are looking/inspecting at/for
A
retractions, color, mucous membranes, chest movement, facial expression of patient, reservoir bag
7
Q
Examples of things we are listening/auscultating for
A
heart and lung sounds, wheezing, continuous suction, the patient’s voice
8
Q
Examples of things we are feeling/palpating
A
pulses, edema, crepitus, muscle tension, resistance, compliance, temperature
9
Q
Examples of things we can smell
A
smoke, burning, volatile anesthetic
10
Q
List the various monitors we may use
A
pulse oximeter, capnography, NIBP/aline, EKG, temperature, oxygen analyzer, stethoscope, PA catheter, ICP, urine output, PNS, BIS, precordial doppler, TEE/TTE, SSEPs
11
Q
What is standard 8?
A
positioning
12
Q
What is standard 11?
A
transfer of care
13
Q
What are the subcategories under standard 9?
A
oxygenation, ventilation, cardiovascular, thermoregulation, neuromuscular function
14
Q
The most important aspect of anesthesia
A
AIRWAY
15
Q
what is the fundamental goal for anesthesia?
A
avoid hypoxia
16
Q
Alveolar gas equation
A
PAO2 = FiO2 x (Pb - 47) - PaCO2
17
Q
What does the O2 analyzer measure?
A
FiO2
18
Q
How does the pulse oximeter determine the saturation?
A
compares the absorbances of the infrared wavelength to the red wavelength
19
Q
infrared
A
960 nm
20
Q
red
A
660 nm
21
Q
Factors affecting accuracy of pulse oximeter
A
high intensity light, patient movement, electrocautery, peripheral vasoconstriction, hypothermia, cardiopulmonary bypass, presence of COHb, MetHb, IV injected dyes (methylene blue), Hb <5
22
Q
A PaO2 of 30 is a SaO2 of
A
60
23
Q
A PaO2 of 60 is a SaO2 of
A
90
24
Q
A PaO2 of 40 is a SaO2 of
A
75
25
On the oxyhemoglobin dissociation curve which is the dependent variable? independent variable?
Dependent: O2 saturation
Independent: O2 content
26
Hypoxia is when the O2 sat is ...
< 90%
27
What is ventilation?
movement of volume, inhalation and exhalation, elimination of CO2
28
What are our ventilation monitors?
continuous auscultation (stethoscope), chest excursion (observation), end tidal capnography, spirometry
29
Where do we typically place the precordial stethoscope?
at the apex of the lung or suprasternal notch or wherever you hear best
30
When would an esophageal stethoscope be contraindicated?
esophageal varices, strictures
31
Dispersive method for respiratory gas analysis
uses single optical filter (prism) to separate the component wavelengths for each of our agents
32
Nondispersive method for respiratory gas analysis
multiple narrow band, optical filters through which that infrared emission is past to determine which gas is present in the mixture; more common method
33
Modified analyzers gas sampling rate
50 - 250mL/min, can show up as a leak source
34
How much CO2/min does an average adult produce?
250mL CO2/min
35
Sidestream sampling
airway gas is aspirated and pumped to measuring device
36
Limitations of sidestream sampling
H2O condensation can contaminate the system and falsely elevate reading
Lag time between sample aspiration and reading
37
Normal PACO2 - PaCO2 gradient
2 - 10 mmHg
38
Things that cause an abnormal PACO2 - PaCO2 gradient
gas sampling errors, prolonged expiratory phase, V/Q mismatch, airway obstruction, embolic states, COPD, hypoperfusion
39
At a CO2 of 40 mmHg you have
normal CO2 production, adequate circulation, adequate alveolar ventilation
40
Beta angle on ETCO2 waveform
top right corner, actual ETCO2 reading because it is end exhalation
41
Phase 1 on ETCO2 waveform
corresponds to inhalation
anatomic and apparatus dead space
should be 0 unless rebreathing
42
what causes an elevation in the baseline on ETCO2 waveform
CO2 absorbent exhausted, expiratory valve is missing/incompetent, bain circuit
43
phase 2 on ETCO2 waveform
early exhalation, upstroke
| mixing of dead space and alveolar gas
44
things that prolong the upstroke on ETCO2 waveform
mechanical obstruction/kinked, slow emptying (COPD, bronchospasm)
45
phase 3 on ETCO2 waveform
CO2 rich alveolar air
plateau with mild upstroke at end
steepness is function of expiratory resistance
46
bare minimum urine output in the OR
0.5 mL/kg/hr
47
what do bubbles in a urine sample mean?
protein in the urine, seen in pre-eclampsia/eclampsia
48
phase 4 on ETCO2 waveform
inspiration of fresh gas, returning to baseline
49
things that decrease amplitude on ETCO2 waveform
increased BMR, leak, hyperventilation, temperature/shivering
50
how much does shivering increase o2 consumption by?
up to 400%!!
51
what factors do we look at when assessing an ETCO2 waveform?
time, frequency, slope, amplitude, baseline
52
What can curare cliffs be mistaken for on ETCO2 waveforms?
cardiac/cardiogenic oscillations which are synchronous with heart beat in thin patients or pediatrics
53
What do electrocardiograms detect?
cardiac dysrhythmias, conduction abnormalities, myocardial ischemia/ST depression, electrolyte changes, pacemaker function/malfunction
54
Which lead does a three electrode monitor?
lead II
55
Which leads can the five electrode monitor?
allows recording of 6 standard leads (I, II, III, aVR, aVL, aVF) and 1 precordial lead (V5)
56
Which lead system is better for diagnosing atrial and ventricular arrhythmias
five electrode
57
Lead II
yields max P wave voltages, best at detecting atrial dysrhythmias, detects inferior wall MI
58
V5
detects anterior and lateral wall MI
| lies at 5th intercostal space/anterior axillary line
59
Inferior MI lead detection
II, III, aVF
60
Lateral MI lead detection
I, aVL, V5, V6
61
Anterior/septal MI lead detection
V1 - V4
62
Determining BP cuff
20% > mean diameter of the extremity
63
if BP cuff is too narrow that indicates
falsely high reading
64
if BP cuff is too wide that indicates
falsely low reading
65
Things that can cause errors with BP cuff
surgeon leaning on cuff, inappropriate cuff size, shivering, excessive movement, athersclerosis, HTN
66
indications for an invasive arterial BP monitor
requiring BP measurement minute to minute, critically ill, anticipated rapid blood loss, major procedures (bypass, aortic cross clamping, intracranial surgery, carotid sinus manipulation), frequent ABGs
67
Sites used for arterial lines
radial, ulnar, brachial, femoral, dorsalis pedis, axillary
68
indications for CVP monitoring
fluid management of hypovolemia and shock, infusion of caustic agents, aspiration of air emboli, insertion of pacing leads, TPN, venous access in patients with poor peripheral veins
69
indications for pulmonary artery cath
valvular heart disease, recent MI, ARDS, massive trauma, major vascular surgery, poor LV function (EF < .4, Cl <2 L/min/m2
70
normal RA pressures
2-6 mmHg
71
normal RV pressures
20-30/0-5 mmHg
72
normal PA pressures
20-30/5-15 mmHg
73
normal PCWP pressures
4 - 12 mmHg
74
in a 70 kg patient, 1 L crystalloid at room temp will lower body temp by about
0.4 degrees C
75
in a 70 kg patient, 1 unit of PRBCs will lower temperature by about
0.2 degrees C
76
Mechanisms of heat loss
evaporation, radiation, convection, conduction
77
radiation
most common
| heat radiated from patient into room
78
convection
heat loss d/t air velocity
| KE to air molecules on skin replaced with cool molecules
79
conduction
contact with OR table, blanket
80
evaporation
heat loss to dry inspired gases
81
why can't our body compensate for hypothermia during GA?
because our anesthetics inhibit our central thermoregulation by interfering with the hypothalamus function, which normally maintains core body temp
82
How can we prevent phase 1 in unintentional hypothermia?
prewarm patients for 30 minutes prior
83
hypothermia
heat loss outpaces metabolic heat production
< 36 degrees C
mild: 33 to 36 (reduced enzyme function, coagulopathy)
moderate: < or equal to 32 (fibrillatory threshold)
84
symptoms of hypothermia
shivering, dizziness, feeling hungry, nausea, rapid breathing, problems speaking, confusion, coordination difficulties, fatigue, rapid heart rate, drowsiness, weak pulse, shallow breathing
85
patients at greatest risk for hypothermia?
elderly, burn patients, neonates, patients with spin cord injuries
86
causes of hyperthermia
MH (late sign), endogenous pyrogens, thyrotoxicosis or pheochromocytoma, anticholinergic blockade of sweating, excessive environmental warming
87
monitoring sites for temperature
esophagus (lower 1/3), nasopharynx, rectum, bladder, tympanic membrane, blood (PA cath), skin
88
which is the most effective active warming modalities?
bair hugger, it decreases radiant and convective losses and decreases postop shivering/pacu stay
89
monitoring sites for PNS
ulnar nerve/adductor pollicis, facial, posterior tibial, peroneal nerve
90
ulnar nerve PNS
innervates adductor pollicis and adducts thumb
| place negative electrode distally (black)
91
facial nerve PNS
monitor contraction of orbicularis oculi (eyelid), or corrugator supercilii (furrows brow)
92
posterior tibial PNS
behind medial malleolus of tibia and results in plantar flexion
93
peroneal nerve PNS
electrodes on lateral aspect of knee
| response = dorsiflexion of the foot
94
What do we see with depolarizing blockade in phase 1 block?
constant but diminished, no fade
95
patterns of stimulation
single twitch, TOF, tetanic stimulation, post-tetanic stimulation, double burst stimulation
96
single twitch
single pulse delivered every 10 seconds
| increasing block results in diminished response
97
train of four
4 repetitive stimuli, twitches progressively fade as relaxation increases
expressed at T4/T1 ratio
98
T4/T1 ratio for train of four
loss of 4th twitch = 75% receptors blocked
loss of 3rd twitch = 80% receptors blocked
loss of 2nd twitch = 90% receptors blocked
99
tetanic stimulation
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%
100
post tetanic count
is useful when all twitches are suppressed
apply tetanus at 50 Hz for 5 seconds, wait 3 seconds, apply single twitches every second up to 20
the number of twitches inversely related to depth of block
101
double burst stimulation
less painful, can use this because a ratio of <0.2-0.3 is difficult to detect
3 short 50 Hz impulses followed by 750 msec period of relaxation and then another 3 bursts
102
what would we use for induction in terms of PNS?
single twitch, train of four
103
what would we use for PNS during maintenance?
train of four, post tetanic count
104
what would we use for PNS during emergence?
train of four, double burst stimulation
105
what muscle is the most sensitive to nondepolarizing relaxants?
extraocular
106
what muscle group is the least sensitive to nondepolarizing relaxants?
vocal cords
107
what muscle group should we monitor PNS during onset?
facial nerve
108
what muscle group should we monitor PNS during recovery?
ulnar nerve
109
TOF 1 of 4 twitches indicates
reversal may take as long as 30 minutes
110
TOF 2-3 of 4 twitches indicates
reversal may take 10-12 minutes following long acting relaxants, 4-5 minutes after intermediate relaxants
111
TOF 4 of 4 twitches indicates
adequate recovery within 5 minutes of neostigmine, within 2-3 minutes with edrophonium
112
limitations of NM monitoring
responses may appear normal despite receptor occupancy
wide variability in evoked responses
values do not guarantee adequate ventilatory function or airway protection
perioperative hypothermia increases skin impedance which limits interpretation
113
unreliable clinical signs of recovery
sustained eye opening, tongue protrusion, arm lift to opposite shoulder, normal tidal volume, normal or near normal vital capacity, max inspiratory pressure <40-50 cmH20
114
reliable clinical signs of recovery
sustained head lift for 5 seconds, sustained leg lift for 5 seconds, sustained handgrip for 5 seconds, max inspiratory pressure 40-50 cm H2O or greater
115
4 types of quantitative assessment nerve monitoring
visual, tactile, mechanical, electrical
116
quantitative nerve monitoring
device that quantifies the degree of NM blockade
reliable, accurate, and objective
post stimulation, muscle response objectively quantified
117
acceleromyography
piezoelectric sensor measures muscle acceleration(voltage generated upon muscle contraction)
118
electromyography
muscle action potentials recorded, electrical activity proportional to the force of contraction
119
kinemyography
quantifies muscle movement with motion sensor strip containing piezoelectric sensors
120
mechanomyography
detects contraction force, converts to electrical signal, signal amplitude reflects contraction strength
121
phonomyography
muscle contraction produces low frequency sounds, calculates muscle response
122
bispectral index score
used to assess depth of anesthesia
advantages: reduced risk of awareness, better management of responses to surgical stimulation, faster wake up, more cost effective use of anesthetics
123
EEG signal index range
0-100
```
100 = awake CNS
>70 = greater recall risk
40-60 = general anesthesia
0 = isoelectric EEG
```
124
What are BIS readings affected by?
electrocautery, EMG, pacer spikes, EKG signal, patient movement
125
if SQI is ____ and EMG is ____ then BIS is ____
increased; decreased; likely more accurate
126
cerebral oximetry
assesses cerebral oxygen saturation using near infrared spectrophotometry
detects decreases in CBF in relation to CMRO2
127
conditions that can decrease cerebral oximetry reading
change in BP, partial pressure CO2 in arterial blood, regional blood volume, hemoglobin concentration
128
if >20% reduction in cerebral oximeter reading ...
regional and global ischemia
129
goal of cerebral oximetry
keep within 75% of our baseline reading
