Monitoring & Definitions Flashcards
1
Q
TOF is delivered at ….
A
2 Hz
2
Q
TOF with no NMB
vs.
completely blocked
A
no NMB = 1.0 (100%)
completely blocked = 0
3
Q
During a ___ block, the ratio decreases (fades) as the degree of block increases
A
partial nondepolarizing
Can still get fade with Suxx
No fade = Phase I
Fade = Phase II
4
Q
TOF benefits over Single Twitch
A
- does not require a baseline
- subjectively (visual, tactile) or count twitches
- consistent over a range of stimulating currents
counting is more accurate than feeling
5
Q
minimum standard for determining extubation readiness
A
TOF ratio of 0.9
6
Q
When to use single twitch, TOF, or PTC
A
- induction: Single or TOF best
- profound NMB: PTC and TOF best
7
Q
with (4) full TOF twitches – the patient still can be up to ___% blocked!!
A
75
8
Q
Which site is best for induction and reversal
A
- Induction: orbicularis oculi
- Recovery/reversal: adductor pollicis
9
Q
When will the diaphragm start moving
A
no twitches needed
95% blocked
10
Q
Abdominal muscle relaxation can be adequate at…
A
1 twitch
(90% blocked)
11
Q
Your pt has 4 twitches and their VC & Vt are normal. Whats the max possible residual blockade?
A
70-75%
12
Q
Your pt has sustained head life and hand grasp. Whats the max possible residual blockade?
A
30%
13
Q
Your etCO2 suddenly dropped to zero. There is no waveform. Whats happening?
A
- ETT malposition (pharynx, esophagus)
- sudden severe hypotension
- massive PE embolism
- cardiac arrest
- disconnected sampling line
14
Q
What would increase and decrease etCO2?
A
ETCO2 Increases:
- Hypoventilation
- Hyperthermia, MH
- Sepsis & Fever
- Rebreathing
- Bicarbonate
- Insufflation of CO2
- Shivering
- hyperthyroid
ETCO2 Decreases:
- Hyperventilation
- Hypothermia
- Low Cardiac Output
- PE, Cardiac arrest
- hypothyroid
- Circuit Disconnect
15
Q
T/F:
etCO2 is equally accurate to an ABG
A
False
ABG is more accurate
16
Q
Phases of the etCO2 waveform
A
17
Q
Where on the waveform measures the EtCO2?
A
18
Q
Gas exits the TRACHEA during 2 phases of the etCO2 waveform. What are they?
A
Phase I: Inspiration Ends (CO₂-free gas exits trachea)
Phase II: Expiration of CO2 from deadspace & Upper Alveoli (CO₂-rich gas exits trachea)
19
Q
Summary of each etCO2 phase
A
- I: Inspiration Ends (CO₂-free)
- II: Exp CO2 (deadspace & Upper Alveoli) (CO₂-rich)
- III: Exp (lower lung)
- IV: Insp. fresh gas (no CO2)
20
Q
Phase III
in detail
A
- Expiration from lower lung units
- emptying of alveoli w/ low V/Q (richest in CO₂)
- should have a slightly (+) slope
21
Q
terminal “upswing”
A
Phase IV (NOT ALWAYS PRESENT)
pregnant or obese patients due to: Decreased compliance & FRC
22
Q
it should return to zero with each new breath
A
Phase IV
etCO2
23
Q
EtCO2
A & B angle increases
A
⍺ increased: EXP outflow obstruction (COPD, bronchospasm, kinked ETT)
β increased: rebreathing CO2 from faulty INSPIRATORY valve
⍺: Phase II to Phase III
β: Phase III to Phase IV
24
Q
EtCO2
How does a faulty inspiratory vs. expiratory valve affect the waveform?
A
β angle increased = inspiratory valve
Elevated baseline = expiratory valve
BOTH will cause rebreathing of CO2
25
What should capnography read for quality CPR?
>10
26
Causes of elevated baseline CO2
* faulty expiratory valve
* inadequate inspiratory flow
* insufficient expiratory time
* CO₂ absorbent dysfunction partial rebreathing circuits
* depleted absorbent
27
Shark fin waveform
-definition
-what it means
-causes
Elevation of Phase **III** slope
obstructed airway or circuit
* inc. V/Q mismatch
* partially kinked or occluded ETT
* foreign body in airway
* obstruction in expiratory limb
* COPD
* Bronchospasm
28
What does esophageal intubation look like on etCO2?
gradual decrease
29
Carboxyhemoglobin
combination of carbon monoxide and hemoglobin
30
Carbon monoxide poisoning is usually defined as
>15% carboxyhemoglobin in the blood
31
T/F:
Methemoglobin has a 200-250x affinity than oxygen for myoglobin.
FALSE
Carbon monoxide
32
Carboxyhemoglobin
vs
Methemoglobin
effect on SpO2
CO: artificially high
Methgb: under when SPO2 > 70%
but overestimation when SPO2 < 70%.
33
The diagnosis of CO poisoning requires ____ bc...
co-oximetry
pulse oximeters cannot reliably differentiate between carboxyhemoglobin and oxyhemoglobin
34
What happens when a CO molecule combines with hemoglobin to form carboxyhemoglobin?
1. it increases the affinity of the other binding sites for oxygen, shifting the hemoglobin dissociation curve to the **left**.
1. reduced oxygen-carrying capacity
1. impaired delivery to tissues
35
Carbon monoxide dissociates slowly from hemoglobin. Half life on Room air vs 100% O2?
RA: 5h
100% O2: 72 min
36
Carboxyhemoglobin levels greater than 20% to 40% are associated with....
## Footnote
CO poisoning: >15% carboxyhemoglobin
* Cherry red lips
* neurological impairment
* Nausea
* Fatigue
* Disorientation
* Shock
37
Low levels of CO can cause symptoms bc...
it also binds cytochrome c and
myoglobin
38
How does the body compensate for the decreased O2 delivery in CO poisoning?
increased cardiac output & peripheral vasodilation
39
Methemoglobin
* hemoglobin in the form of metalloprotein
* iron in the heme group is the Fe 3+
* (ferric) state, not the Fe 2+ (ferrous)
40
Methemoglobin
light absorption
absorbs red and infrared wavelengths of light in a 1:1 ratio corresponding to a SPO2 of ~85%
## Footnote
Therefore, increases in MetHb produce an underestimation when SPO2 > 70%
and an overestimation when SPO2 < 70%.
41
Methemoglobin
causes
* LA: prilocaine, benzocaine, lidocaine, Cetacaine
* SNTP Metabolism
## Footnote
Metabolism of nitroprusside
○ Can lead to cyanide toxicity – cyanide binds w hgb to form methemoglobinemia
42
T/F:
CO poisoning/carboxyhemoglobin is treated with methylene blue.
FALSE
treats Methgb
its an oxidizing agent that converts methgb (3+) back to hgb (2+)
43
Benefit of fetal hgb having higher O2 affinity than mom's
easier to transfer O2 to the baby
44
HbF vs HbA
P50
Fetal P50: 18-20 mmHg
Maternal P50: 26-27 mmHg
## Footnote
lower P50 = greater affinity
P50: partial pressure of O2 which Hgb is 50% saturated
45
How do Fetal and Maternal Hgb O2 affinity affect the curve?
fetal hgb: shifts it LEFT
1. 2,3 DPG - facilitates→release of O2 by decreasing affinity of O2 for Hgb
1. binds best to beta chains - but fetal Hgb has no beta chains (2 alpha, 2 gamma)
1. when pregnant, get significant increase in 2,3 DPG - shifts the curve to the right
1. for pregnant women - makes mom offload O2 to the fetus
1. this is decreased with a left shift, Hgb holds onto O2, baby holds on to O2
46
When does baby achieve normal adult hemoglobin percentages
6-12 mon
47
Fractional hemoglobin
% of Hgb molecules
bound to oxygen
48
T/F:
Desaturation is an early sign of apnea or respiratory insufficiency.
False
LATE!
49
T/F:
EtCO2 is a poor indicator of adequate ventilation.
False
Pulse ox is a poor indicator of ventilation
50
The curve
when can we rely on it to tell us respiratory status?
* On the steep part of the curve, a predictable correlation exists between SaO2 & PaO2
* In this range, SaO2 reflects hypoxemia and arterial oxygenation
* If PaO2 > 75 mmHg, the SaO2 reaches a plateau and no longer reflects changes in PaO2.
51
🔷
What shifts the curve L or R?
R (lower O2 affinity): hyperCO2, acidosis, hyperT
L (higher O2 affinity): CO poison, fetal hgb??
| "Left Loves O2"
52
Pulse oximetry is based on these 3 premises
1. The color of blood is a function of oxygen saturation
1. The change in color results from the optical properties of hemoglobin and its interaction with oxygen.
1. The ratio of oxyhemoglobin (HbO2) and hemoglobin (Hb) can be determined by absorption spectrophotometry.
53
These two wavelengths of light are required to distinguish HbO2 from Hb
* Red light: 660 nm (unoxygenated Hgb)
* Infrared light: 940 nm (oxygenated Hgb)
The percentage of HbO2 is determined by measuring the ratio of infrared and red light sensed by a photodetector
54
T/F:
SpO2 is the same as SaO2.
False
pulse oximetry is not the same as the arterial saturation (SaO2) measured by a laboratory co-oximeter
55
56
Pulse oximetry measures the “____” saturation. Whats the equation?
functional
57
The absence of a pulsatile waveform can limit the ability of a pulse oximeter to calculate the SPO2. When can this happen?
during extreme hypothermia or hypoperfusion
58
Oxygen saturation is determined by
Spectrophotometry
measures light absorbance Which is based on the Lambert-Beer Law
59
3 assumptions made for programming all pulse ox devices
1. only 2 light absorbers in body: oxyhemoglobin & reduced Hgb
1. pulsations are caused by pulsatile arterial blood flow
1. empirical experimental oxygen dissociation calibration curve for all humans
60
Pulse Ox
Common Problems / Limitations
* Shows oxygen being transported by Hgb
* DOES NOT guarantee tissue delivery or utilization
* Poor indicator of adequate ventilation during supplemental O2
61
T/F:
Patients who have been breathing supplemental oxygen may be apneic for several minutes before desaturation is detected by the pulse oximeter.
True
don't trust these hoes
62
These factors affect the accuracy and
reliability of pulse oximetry
63
64
range of temperatures over which the body senses temperature as normal
Awake patients: +/- 0.2 deg C
Anesthetized patients: +/- 2-4 deg C
65
These methods of anesthesia will inhibit afferent AND efferent control of thermoregulation
general & regional
66
ANS responses to
heat vs cold
heat:
* sweating and active cutaneous vasodilation
* sweating = postganglionic cholinergic nerves
cold:
* Cutaneous vasoconstriction (alpha-1r)
* Synergistically augmented by hypothermia-induced alpha-1 & 2
67
🔷
Decreases thermoreg.
* age
* inhalationals EXCEPT N2O
* IV anesthetics
* spinal
68
How does age affect thermoregulation?
* decreased efficacy
* decreased response threshold by 1C
* shivering is not as profund
69
Three-phase process of thermoreg.
1. Afferent thermal sensing
1. Central regulation or control
1. Efferent responses
70
How does hypothermia increase infection risk?
1. shunt blood to the core
1. less blood and O2 to wound
1. Decreases superoxide production
1. infection risk
71
How does Skin temp change correlate with core temp?
skin temp changes by 1 = core temp change by 0.2
72
Spinal with sympathectomy causes temp to drop by ___℃ before vasoconstriction or shivering response occurs
up to 4
73
General Anesthesia Temp decrease
(3 phases)
1. initial rapid decrease over 30 min (0.5-1.5 ℃)- heat core → peripheral
1. Slow linear reduction: 0.3 ℃ / hr (heat loss > production)
1. Plateau: thermo-regulatory vasoconstriction
74
Volatile and IV anesthetics, EXCLUDING ___ all impair thermoregulatory control
N2O
75
AANA Standards require temp monitoring how often
Q 15
oops lol
76
Nonshivering Thermogenesis
(infant-2Y)
* metabolizing brown fat generates heat by uncoupling ox. phosphorylation (mitochondria)
* rapid heat production by bypassing ATP synthesis
* can **double** heat production
77
Nonshivering thermogen. is the most effectuve thermal response to cold, but it can be inhibited by
B-Blkrs
78
T/F:
Cold alcohol drying on skin shows heat loss by evaporation.
FALSE
convection
79
Hypothermia by definition
core temp < 36 within 1 hr of case start
80
the most well studied complication of hypothermia
coagulopathy
81
How does blood tranfusion affect our temp?
How does temp affect EBL?
drops 1 deg every 1-2 units of cold blood
If temp falls from 37-35.5 → increase EBL by 500 mL
82
A temp decrease of this gravity will increase infection risk by 2-3x
37 to 35
83
If intraop temp drop to ___, hospital stay may increase by 2.5 days
35
84
Indigo Carmine
SEs
* hypertension (increased PVR + increased HR)
* Increased BP with reflex decrease in HR
* rare: HypoTN, arrest and cerebral ischemia
85
Which dye must be used carefully with SSRI/SNRI?
methylene blue
86
Methylene Blue
* Potent MAOI
* Blocks breakdown of serotonin in CNS
* wait 24 hr before restartng SSI/SSRI/SNRI
* potentially fatal serotonin syndrome
87
T/F:
The drop in SpO2 from methylene blue is a a false negative.
True
temporarily causes SpO2 drop (not a true decrease; only shows on pulse ox)
88
T/F:
CVP allows us to treat VAE using a catheter inside the heart.
False
can treat VAE but is it not in the heart
89
When should CVP be measured?
NR?
end-exp
1-10
90
CVP is a fxn of:
* Intravascular volume
* Venous tone
* RV compliance
91
What increases & decreases CVP?
92
Other than AFIB, what can cause loss of a wave on CVP?
V pacing when the underlying waveform is asystole
93
Large a wave on CVP
atrium contracts & empties against a high resistance (at the valve or noncompliant ventricle)
* Tricuspid stenosis
* Diastolic dysfunction
* MI
* Chronic lung disease leading to RV hypertrophy
* AV dissociation
* Junctional rhythm
* PVCs
94
Large v wave CVP
increased volume & pressure in the RA
* Tricuspid regurg
* Acute increase in intravascular volume
* RV papillary muscle ischemia
95
Echogenicity by tissue type
96
OR power vs equipment power
OR: UNgrounded
equipment: grounded
97
T/F:
The LIM isolates the OR from ground.
False
Isolation transformer isolates the OR power from ground
the LIM monitors the integrity of an isolated power
system
98
When OR becomes grounded, line isolation monitor will alarm. Usually at this range...
2-5 mA
99
The LIM is alarming and its reading high. Wyd?
don't panic, this is not the current flow. this is what would flow if a second fault happened. this means you are now not grounded.
1. If >5 mA likely faulty equipment
1. unplug each starting with most recent until alarm stops
1. If needed for life support, then it can be safely used but NO NEW EQUIPMENT
100
Aldrete scoring is for ___ discharge. PADSS is for ___ discharge.
Aldrete: dc from phase 1 (9/10)
PADSS: gtfo (9/10)
101
The Aldrete vs PADSS criteria
102
PDNV scale
1. Female
1. PONV hx
1. <50Y
1. PACU opioids
1. PACU nausea
## Footnote
0: 10%
1: ~20%
2: 30%
3: 50%
4: 60%
5: 80%
103
BIS monitoring
Composite EEG monitoring **only 1 side** of frontal lobe
104
BIS values
100: awake
65-85: sedation
40-65: general anesthesia
<40: burst suppression
Absence of recall was associated with BIS values below 80.
105
BIS limitations
* Variable Indexes per agent
* Age – brain maturation affects EEG
* Hypothermia
* Neurological Impairment (unreliable)
* Interference from medical device
106
Trauma
Along with early surgical control of hemorrhage, initial strategies to limit ongoing blood loss include...
SBP ~90 mmHg (or ≤110 in older adults)
and/or MAP at 50-65
Upon hemostasis, higher BP SBP ≥90 mmHg and/or MAP ≥65 mmHg
107
HypoTN for Ortho Sx
* decrease blood loss by 40-50%
* MAP: 50-65 (60 or above)
* SBP: 80-90
## Footnote
ex: shoulder arthroplasty to improve visibility of the operative site or total hip arthroplasty ‒ can't use a tourniquet
108
# Ortho Sx
do not apply deliberate hypotension for these pts
co-existing diseases and ASA >2
109
Brain, heart, liver, and kidneys have the ability to auto regulate flow by intrinsic elasticity of the vascular smooth muscles – regulated by
baroreceptors and chemoreceptors
110
risks of deliberate hypoTN
cerebral perfusion, stroke, heart attack
Mortality and consequent ischemic organ failure is about 0.02-0.06%
111
