Exam 1 Clinical Monitoring Part 2 [6/10/24] Flashcards
1
Q
What are the two sampling sites depicted by the two arrows?
A
- Elbow
- Y-piece
S47
2
Q
What are the two types of gas sampling systems?
A
- Side-stream/ diverting analyzer
- Mainstream/ non-diverting analyzer
S48
3
Q
Which gas sampling system will have more lag time (transit time)?
A
- Side-stream/ diverting analyzer
S48
4
Q
What is rise time in terms of the gas sampling system?
A
- The time taken by the analyzer to react to the change in gas concentration
The mainstream analyzer will have a faster rise time.
S48
5
Q
Side-stream response time is dependent on what factors?
A
- Sampling tubing inner diameter
- Length of tubing
- Gas sampling rate (50 - 250 mL/min)
S48
6
Q
What are gas sampling challenges with mainstream analyzers?
A
- Water vapor (can block IR waveforms)
- Secretions
- Blood
- More interfaces for disconnections
S49
7
Q
What are gas sampling challenges with side-stream analyzers?
A
- Kinking of sampling tubing (can’t break over time)
- Water vapor (can block IR waveforms)
- Failure of sampling pump
- Leaks in the line
- Slow response time
S49
8
Q
The total pressure exerted by a mixture of gases is equal to the sum of the partial pressures exerted by each gas in the mixture. What law is this?
A
- Dalton’s Law
S50
9
Q
At sea level, what is the total pressure of all anesthetic gases in the system?
A
- 760 mmHg
S50
10
Q
Calculate the partial pressure of O2 at room air
A
- 159.6 mmHg
760 mmHg x 21% = 159.6 mmHg
S50
11
Q
Calculate the partial pressure of inspired O2 at room air.
A
- 149.7 mmHg
PIO2 = FIO2 (PB -PH2O)
21% (760 - 47) = 149.7 mmHg
S50
12
Q
____ is an instrument that allows the identification and quantification, on a breath-by-breath basis, of up to eight of the gases commonly encountered during administering an inhalational anesthetic.
A
- Mass Spectrometry
S51
13
Q
Mass Spectrometry:
* How is the concentration determined?
* Abundance of ions at specific mass/charge ratio is determined and related to what?
* How many gasses can it calculate?
A
- Concentration is determined according to mass/charge ratio
- Abundance of ions at specific mass/charge ratio is determined and r/t to the fractional composition of gas mixture
- Can calculate up to 8 different gasses.
S51
14
Q
This tool uses a high-powered argon laser to produce photons that collide with gas molecules in a gas sample. The scattered photons are measured in a spectrum that identifies each gas and concentration.
A
- Raman Spectrometry (Raman Scattering)
No longer in use
S51
15
Q
- What is Infrared [IR] analysis?
- What does it measure?
A
- IR analysis measures energy absorbed from a narrow band of wavelengths of IR radiation as it passes through a gas sample
- It measures the concentration of gasses.
- Assymetric, polyatomic molecules of various gasses absorb IR light at specific wavelengths.
S52
similiar to how different wavelength of lights read the pulse ox.
16
Q
What is the most common IR gas analyzer?
A
- Non-dispersive IR analyzer
S52
17
Q
What gases are measured using Infrared analysis?
A
- CO2
- Nitrous Oxide
- Water
- Volatile Anesthetic Gases
O2 does not absorb IR radiation
S52
18
Q
How does Infrared Analysis (IR Analyzer) work?
A
- Gas will enter the sample chamber
- Each gas has a unique IR transmission spectrum absorption band
- Strong absorption of IR light occurs at specific wavelengths
- IR light is transmitted through the gas sample and filtered via narrow-band pass filter.
- The amount of IR light that reaches the detector is inversely related to the concentration of the gas being measured
- Less light = high concentration of gas
S53
19
Q
Do side-stream analyzers take into account of water vapors?
A
- No
- Side-stream analyzers report ambient temperature and pressure dry values (ATPD).
S54
20
Q
What is the recommendation on how gas analyzers should report results?
A
- Analyzers should report results at body temperature and pressure saturated [BTPS] values.
S54
21
Q
What are the two types of oxygen analyzers?
A
- Fuel or Galvanic Cell O2 Analyzer
- Paramagnetic O2 Analyzer
S55
22
Q
How does the fuel or galvanic cell operate?
A
- It has an oxygen battery that measures the current produced when oxygen diffuses across a membrane
- The current is proportional to the partial pressure of the oxygen in the fuel cell
S55.
23
Q
What are the drawbacks of a Fuel/ Galvanic Cell O2 Analyzer?
A
- Short life span (months) depending on the length of O2 exposure
- Slow response time of approximately 30 seconds
- best to measure O2 in the inspiratory limb
S55
24
Q
How does the paramagnetic O2 analyzer operate?
A
- Oxygen is a highly paramagnetic gas d/t the magnetic energy of unpaired electrons in their outer shell orbits
- Detects the change in sample line pressure resulting from the attraction of oxygen by switched magnetic fields
- Signal changes during switching correlates withO2 concentration
S55
25
What oxygen analyzer is used in most side-stream sampling multi-gas analyzers?
What is the benefit of this analyzer?
* Paramagnetic O2 Analyzer
* Benefit: Rapid response, breath-by-breath monitoring
| S55
26
Purpose of gas sampling inside the inspiratory limb.
* Ensures oxygen delivery
* Analyzes hypoxic mixtures
| S56
27
This is arguably the most important of all monitors. It Must be calibrated for high and low concentrations
Oxygen monitoring
| S56
28
Purpose of gas sampling inside the expiratory limb.
* Ensure complete pre-oxygenation/ “denitrogenation”
* ET O2 above 90% adequate
| S56
29
Can we have oxygen monitoring at auxillary sites?
No oxygen monitoring at auxiliary sites
| S56
30
What can trigger a low O2 alarm?
* Pipeline crossover
* Incorrectly filled tanks
* Failure of a proportioning system
| S56
31
What patient population must we be wary of for high O2 alarms?
* Premature infants (high O2 can cause blindness)
* Patients on chemotherapeutic drugs (ex: **bleomycin**)
**Bleomycin has been associated with pulmonary toxicity, which can cause lung damage. Supplemental oxygen may exacerbate this toxicity.**
| S56
32
This is a key component in measuring ventilation. Its noninvasive. It assess mechnical or spotaneous ventilation.
Airway pressure monitoring.
| S58
33
What can airway pressure monitoring detect?
* Fresh gas hose kink or disconnection
* High and low scavenging system pressures
* Sustained high-circuit pressure
* Circuit disconnections
* Circuit leaks
* ETT occlusions
* Kinking in the inspiratory limb
| S58
## Footnote
Starting from the pipes then vent then the pt [out to in]
34
What are the two types of pressure gauges used in airway pressure monitoring?
* Mechanical Pressure Gauges
* Electronic Pressure Gauges
| S 58
35
What are the characteristics of mechanical pressure gauges?
* Requires no power, always on, and have high reliability
* No recording of data
* No alarm system
* Must be continually scanned
| S58
36
What are the characteristics of electrical pressure gauges?
* Built within ventilator or anesthesia machine
* Alarm system integrated
* Sensitive to small changes
| S58
37
List the types of different airway pressure alarms
* Breathing circut low pressure alarm
* Sub atmospherrc pressure alarm
* High pressure alarm
* Continuing pressure alarm
| S59-61
38
What is the purpose of the breathing circuit low-pressure alarms?
* Identification of circuit disconnection or leaks
* Does not detect some partial disconnections
* May not detect misconnections or obstructions
* Monitors airway or circuit pressure and compares it with a preset low-pressure alarm limit.
* Low-pressure limit should be set just below the normal peak airway pressure
| S59
39
Where do most of the circuit disconnections occur at?
* 70% of disconnections occur at the y-piece.
| S59
40
What is the normal peak airway pressure?
* 18-20 cmH20
*Low-pressure limit should be set just below this.*
| S59
41
What does the sub-atmospheric pressure alarm measure?
* Measure and alerts negative circuit pressure and potential for the reverse flow of gas
| S60
42
What can negative pressure cause the patient to have?
* Pulmonary Edema
* Atelectasis
* Hypoxia
| S60
43
What can cause subatmopsheric pressure alarm on the anesthesia machine?
* Active (suction) scavenging system malfunctions
* Pt inspiratory effort against a blocked circuit
* Inadequate fresh gas flow
* Suction to misplaced NGT/OGT
* Moisture in CO2 absorbent
SIM-PA
| S60
44
When is high pressure alarm activated?
Who is it valuble in?
* Activated if the pressure exceeds a certain limit
* User-adjustable or automated
* Valuable in pediatrics
| S61
45
What are the causes of high-pressure alarms?
* Obstruction
* Reduced compliance
* Cough/straining
* Kinked ETT
* Endobronchial intubation
CORKE causes high pressure
| S61
46
When are continuing pressure alarms triggered?
* Continuing pressure alarms are triggered when circuit pressure exceeds 10 cm H2O for more than 15 seconds
* Fresh gas can enter the circuit but can't leave
| S61
47
What are causes of continuing pressure alarms?
* Malfunctioning adjustable pressure relief valve
* Scavenging system occlusion
* Activation of oxygen flush system
* Malfunctioning PEEP
| S61
## Footnote
MAMS [your pressure is alarming]
48
* What are the types of peripheral nerve monitoring?
* Which one is most commonly used?
* Electrical and magnetic
* Electrical nerve stimulation most commonly used
| S63
49
Why is magnetic peripheral nerve monitoring not used even though its less painful and requires no physical contact?
* Bulky and heavy
* No TOF stimulation
* Difficult to achieve supramaximal stimulation
| S63
50
define supramaximal stimulation
Reaction of single muscle fiber to a stimulus follows an all-or-none pattern
| S63
51
The response of the whole muscle depends on what?
how many muscle fibers are activated
| S63
52
When picking a site for nerve stimulation, we want what 3 things?
* Easily accessible
* Allow quantitative monitoring
* Avoid direct muscle stimulation.
| S64
53
What is the gold standard for the site of nerve stimulation? Why?
* Ulnar Nerve
* The ulnar nerve innervates the adductor pollicis muscle and has the lowest risk of direct muscle stimulation.
| S64
54
What skeletal muscle is the most resistant to depolarizing and nondepolarizing NMBDs?
* Our favorite, the diaphragm
* Diaphragm has a shorter onset than adductor pollicis and recovers quicker than peripheral muscles.
55
If the arms are unavalible, what muscle can be used to assess nerve stimulation?
* Facial nerve orbicularis oculi
* Facial nerve corrugator supercili
| S64
56
What muscle will reflect the extent of the neuromuscular block of the laryngeal adductor and abdominal muscles the best?
* Corrugator Supercilii > Adductor pollicis.
| S64
57
Define a single twitch stimulation.
What must be obtained prior to NMBD?
Does this require a monitoring device?
* Single stimuli applied from 1.0 Hz (every second) to 0.1 Hz (every 10 seconds); earliest and simpliest
* **Reference value** mandatory prior to NMBD.
* Yes, needs a monitoring device.
| S65
## Footnote
Not used in clinicals more for research lab to establish ED95
58
What stimulation will provide reliable information throughout all phases of neuromuscular blockade w/o a monitoring device?
* Train of Four
| S66
59
* What stimulus is delivered for TOF?
* How do you calculate TOF Ratio?
* TOF is a reliable assessment of what?
* 4 supramaximal stimuli every 0.5 seconds - evaluate TOF count or fade in the muscle resposne.
* TOF ratio = 4th Response/1st Response
* Reliable assessment of onset and moderate block.
| S66
## Footnote
For deep blocks, TOF if hard to assess in patient.
60
Compare TOF Ratio for partial nondepolarizing block and partial depolarizing block.
* **Non-depolarizing block**: TOF ratio decreases (fade) and is inversely proportional to the degree of block
* **Depolarizing block**: No fade. The ratio is 1.0. (If fade, phase II block has developed)
| S66
61
This stimulation is composed of 2 short bursts of 50 Hz tetanic stimulation separated by 750 ms w/ 0.2 ms duration of each square wave impulse in the burst.
* Double Burst Stimulation
*Not used as much in clinical practice*
| S67
62
# Double burst stimulation
* What is DBS3,3 mode?
* What is DBS3,2 mode?
* **DBS3,3 mode** – 3 impulses in each of the 2 bursts
* **DBS3,2 mode**– 1st burst has 3 impulses and 2nd has 2 impulses
| S67
63
With double burst stimulation where are we comparing the fade to?
Two short muscle contractions with fade in the 2nd burst, 1st is the comparison
| S67
64
Describe tetanic stimulation.
* Tetanic stimulation given at 50 Hz for 5 seconds
* limited value for assessing recovery, very painful.
* not used as frequently.
| S68
65
Compare tetanic stimulation between non-depolarizer and depolarizer.
* **Non-depolarizers** - one strong sustained muscle contraction with fade after stimulation
* **Depolarizer** – strong sustained muscle contraction w/o fade.
* With phase II block, fade occurs.
| S68
66
* What stimulation is used for a deep/surgical blockade?
* How often is this performed
* Post-tetanic stimulation
* Performed every 6 minutes
67
with post tetanic stimulation, what is the response dependent on?
* Degree of blockade
* Frequency and duration of tetanic stimulation
* Length of time between the end of tetanic stimulation and first post-tetanic stimulus
* Frequency of the single-twitch stimulation
* Duration of single-twitch stimulation before tetanic stimulation
| S69
68
describe post tetanic stimulation
Composite stimulation pattern – tetanic stimulation (50 Hz for 5 sec) followed by 10 to 15 single twitches (1 Hz after 3 sec post tetanic stimulation)
| S69
69
* Definition of **Intense** non-depolarizing blockade.
* How do you reverse?
* Period of no response for about 3-6 min after intubating dose of non-depolarizing NMBD
* Neostigmine reversal is impossible
* high dose os sugammadex for reversal (16mg/kg)
| slide 70
70
* Definition of **Deep** Non-depolarizing blockade
* How do you reverse?
* Absence of TOF but presence of at least one response to post-tetanic count stimulation
* Neostigmine reversal usually impossible
* dose of sugammadex (4 mg/kg) for reversal
| slide 70
71
* Definition of **Moderate** Non-depolarizing blockade
* How do you reverse?
* gradual return of the 4 responses to TOF stimulation appears
* Neostigmine reversal after 4/4 TOF
* Sugammadex 2 mg/kg for reversal
| slide 70
72
What does Phase I in a Depolarizing blockade suggest?
* All 4 responses are reduced, yet equal and then all disappear simultaneously in TOF (ratio is 1.0)
* No fade or tetanic stimulation; no post-tetanic facilitation occurs
* Normal plasma cholinesterase activity
| slide 71
73
What does Phase II in a Depolarizing block suggest?
* Fade present in response to TOF and tetanic stimulation; occurrence of post-tetanic facilitation
* Response is similar to non-depolarizing blockade
* Abnormal plasma cholinesterase activity
| slide 71
74
# USE IN CLINICAL PRACTICE
For patients recieving NMBD, what should the CRNA keep in mind?
* Keep pt warm to prevent delaying nerve conduction
* Attach electrodes prior to induction, turn on after pt is unconscious
* Moderate level of blockade is sufficient for surgery with 1 or 2 responses to TOF
* Reverse when all 4 responses present to TOF
* Check for neuromuscular recovery prior to extubation post-reversal
Add Warm Mittens Right Now
| slide 72
75
Reliable clinical signs for reversal
* Sustained head lift for 5 sec
* Sustained leg lift for 5 sec
* Sustained handgrip for 5 sec
* Sustained ‘tongue depressor test’
* Maximum inspiratory pressure
| slide 72
76
What is an EEG?
How are the electrodes placed?
How many channels does it use to gather information?
* Summation of excitatory and inhibitory post-synaptic potentials in the cerebral cortex
* Electrodes placed so that surface anatomy relates to cortical regions
* Uses at least 16 channels of information
| Slide 74
77
EEG identifies:
* Consciousness
* unconsciousness
* seizure activity
* stages of sleep
* coma
* Inadequate oxygen delivery to the brain (hypoxemia or ischemia)
I-CCUSS
| Slide 74
78
# EEG Signal description
* What is amplitude?
* What is frequency?
* What is time?
* **Amplitude** – size or voltage of recorded signal
* **Frequency** – number of times per second the signal oscillates or crosses the 0-voltage line
* **Time** – duration of the sampling of the signal
| slide 74
79
Peri-op uses for EEG
* Identifies inadequate blood flow to cerebral cortex
* Guides an anesthetic-induced reduction of cerebral metabolism
* Used to predict neurologic outcome after a brain insult
* Gauges the depth of the hypnotic state of patients under GA
| Slide 75
80
What are the Hz and pt LOC of the following EEG signals:
* Beta
* Alpha
* Theta
* Delta
* **Beta** (> 13 Hz): Awake -Alert attentive brain
* **Alpha** (8 - 13 Hz): Eyes closed or Anesthetic effects
* **Theta** (4 - 7 Hz)
* **Delta** (< 4Hz): Depressed
BAT Da EEG
| slide 76
81
Processed EEG [BIS]
* Contains ____ along with desired EEG signal
* Uses ____ channels of information; ____ per hemisphere
* Necessary to display the activity of both hempspheres; delineates ____ from ____ changes (ex: Regional ischemia d/t carotid clamping (unilateral), EEG depression from anesthetic drug bolus (bilateral)
* There ____ an adequate number of studies comparing EEG vs processed EEG
* Contains **artifact** along with desired EEG signal
* Uses **< 4** channels of information; **2** per hemisphere
* Necessary to display the activity of both hempspheres; delineates **unilateral** from **bilateral** changes (ex: Regional ischemia d/t carotid clamping (unilateral), EEG depression from anesthetic drug bolus (bilateral)
* There **isn't** an adequate number of studies comparing EEG vs processed EEG
| slide 77
82
Bispectral Index (BIS):
* How does the processes EEG signal estimate anesthetic depth?
* What can the BIS help prevent.
* For cases with intraoperative awareness, what is better? the BIS or end tidal agent concentration monitoring?
* Processes EEG signal to estimate anesthetic depth **using a computer generated algorithm.**
* BIS is proposed as a method to prevent **intraop awareness**; has not been demonstrated to be superior to **end-tidal agent** concentration monitoring
* In cases with intraoperative awareness, **neither** technique was found to be completely reliable
| slide 78
83
Sensory-Evoked potentials
* most common type of evoked potential intra-op
* Electric CNS responses to electric, auditory, or visual stimuli
* Sensory system stimulus with responses recorded at various sites along the sensory pathway to the cerebral cortex
-Cortical or subcortical
| slide 79
84
* Sensory-evoked responses are described in what 2 terms?
* ____ is the time measures from the application of the stimulus to the onset/peak of the response
* ____ is the size or voltage of the recorded signal
* you need a ____ to reproduce reliable tracings
* What are 3 types of sensory evoked potentials?
* Sensory-evoked responses are described in terms of **latency** and **amplitude**
* **latency** is the time measures from the application of the stimulus to the onset/peak of the response
* **amplitude** is the size or voltage of the recorded signal
* you need a **baseline** to reproduce reliable tracings
* Include **somatosensory-evoked potentials, brainstem auditory-evoked potentials** and **visual-evoked potentials**
| slide 79
85
What do somatosensory-evoked potential do?
* Monitor the responses to stimulation of peripheral mixed nerves (contain motor and sensory nerves) to the sensorimotor cortex
* Responses consist of short-latency and long-latency waveforms
* Short-latency SSEPs are most commonly recorded intra-op; less influenced by changes in anesthetic drug levels*
* Induction, neurological disease or age, and use of different recording electrode locations may alter appearance of SSEPs
| slide 80
86
What do Brainstem Auditory-Evoked Potentials do?
Monitors the responses to click stimuli that are delivered via foam ear inserts along the auditory pathway from the ear to the auditory cortex
| slide 81
87
What do Visual-Evoked Potentials do?
* Monitors the responses to flash stimulation of the retina using light-emitting diodes embedded in soft plastic goggles through closed eyelids or contact lenses
* Least commonly used monitoring technique intra-op
| slide 81
88
What do Motor-Evoked Potentials do?
* Monitoring the integrity of the motor tracts along the spinal column, peripheral nerves, and innervated muscle
| slide 82
89
* Most common MEP?
* what does it monitor?
* **Transcranial motor-evoked potentials**
* Monitors stimuli along the motor tract via transcranial electrical stimulation overlying the motor cortex
| slide 82
90
Electromyography is a type of motor evoked potential, what does it do?
* Monitors the responses generated by cranial and peripheral motor nerves to allow early detection of surgically induced nerve damage and assessment of the level of nerve function intra-op
* Assesses the integrity of cranial or peripheral nerves at risk during surgery
| Slide 82
91
what are the 2 types of motor evoked potentials?
* Transcranial motor-evoked potential
* Electromyography
| S82
92
Temperature control:
* Primary thermoregulatory control center is the ____
* ____ fibers are the heat/warmth receptors
* ____ fibers are the cold receptors
* Primary thermoregulatory control center is the **hypothalamus**
* **unmyelinated C** fibers are the heat/warmth receptors
* **A-delta** fibers are the cold receptors
| slide 84
93
Thermoregulatory response is characterized by?
* Threshold
* Gain
* Response
94
* ____ is the temperature at which the response will occur
* ____ is the intensity of the response
* ____: sweating, vasodilation, vasoconstriction and shivering
* Threshold – temperature at which a response will occur
* Gain – the intensity of the response
* Response – sweating, vasodilation, vasoconstriction, and shivering
| slide 84
95
Why does core temperature drop with anesthesia?
anesthesia vasodialates which diverts blood away from the core, decreasing temperature
| slide 85
96
Hypothermia in GA goes through 3 phases. List the phases.
1. Initial
2. Sow linear reduction
3. plateau phase
| S85
97
What happens during the initial stage of hypothemia during GA?
* Initially: rapid decrease of approx. 0.5 to 1.5°C
* Anesthesia-induced vasodilation
* Increases heat loss d/t redistribution of body heat
* Over 30 mins
| S85
98
What happens during the slow linear reduction phase of hypothermina in GA?
* Slow linear reduction: approx. 0.3°C per hour
* GA decreases metabolic rate by 20-30%
* **Heat loss exceeds production**
* Occurs 1-2 hours after anesthesia
| S85
99
What happens during the plateau phase of hypothermina in GA?
* Thermal steady state
* **Heat loss equals heat production**
* Occurs 3-4 hours after anesthesia
* Vasoconstriction prevents loss of heat from core, but peripheral heat continues to be lost
| slide 85
100
Temperature control can vary due to which factors?
* Anesthesia
* Age
* Menstral Cycle
* Drugs
* Alchohol
* Circardiam Rhythm.
| S84
101
Hypothermia in Neuraxial anesthesia causes the autonomic thermoregulatory defenses ito be impaired. What are the 4 defences?
* vasodialation
* sweating
* vasoconstriction
* shivering
| slide 86
102
Does hypothermia cause thermal discomfort in neruaxial anesthesia?
Hypothermia **doesn't** cause much thermal discomfort. Pts do not complain of feeling cold.
| slide 86
103
Central thrmoregulatory control is inhibited by neuraxial anesthesia, what does this cause?
Decreases the thresholds that trigger peripheral vasoconstriction and shivering
| slide 86
104
* With hypothermia in neuraxial anesthesia an inital decrease in core temp is caused by?
* there may not be a plateau phase d/t?
* what threshold is centrally altered?
* neuraxial blockade-induced vasodilation
* inhibition of peripheral vasoconstriction
* vasoconstriction threshold
| slide 86
105
What are the 4 methods of heat transfer?
* Radiation
* Convection
* Evaporation
* Conduction
| S87
106
* How much heat is lost through radiation?
* ____ is exposed to environemnt?
* why are infants more vulnerable?
* heat loss to the environment, approx. 40% of heat loss in pt
* Body surface area [BSA] exposed to environment
* Infants: high BSA/body mass ratio makes them vulnerable
| slide 87
107
* How is heat loss through convection?
* what can decrease heat loss?
* Where is heat loss greater?
* loss of heat to air immediately surrounding the body, approx. 30%
* Clothing or drapes decrease heat loss
* Greater in rooms with laminar air flow
| slide 87
108
* How is heat loss through evaporation?
* what is the main pathway?
* latent heat of vaporization of water from open body cavities and respiratory tract, approx. 8-10%
* Sweating is main pathway
| slide 87
109
How is heat lost through conduction?
What are examples?
* heat loss due to direct contact of body tissues or fluids with a colder material, negligible
* Ex: contact between skin and OR table; intravascular compartment and an infusion of cold fluid
| slide 87
110
What are the 7 hypothermia complications mentioned in class?
* **Coagulopathy**: Impairs platelet aggregation enzymes involved in coagulation cascade
* **Increases need for transfusion** by 22%; blood loss by 16%
* **Decreases oxygen delivery to tissues**
* Increases risk of wound infection, decreases tissue healing
* **3x the incidence of morbid cardiac outcomes**
* Increased BP, HR, and plasma catecholamine levels
* **Shivering**
* Increases oxygen demand
* **Decreased drug metabolism**
* Increased duration of NMB
* **Post-op thermal discomfort**
| slide 88
111
What are the benefits of hypothermia?
* Protective against cerebral ischemia
* Reduces metabolism 8% per degree C
* Improved outcome during recovery from cardiac arrest
* Neurosurgery when brain tissue ischemia is expected
* More difficult to trigger MH
| slide 89
112
What are some methods to heat patient peri-op?
* Airway heating and humidification – infants and children > adults
* Warm IV fluid and blood
* Cutaneous warming:
* Forced air warming:
| slide 90
113
When using cutaneous warming what are 3 different methods you can use?
* Increased room temperature
* [Ex: liver transplants, major trauma, pediatrics]
* Insulation -
* Single blanket reduces loss by 30%.
* **Doesn’t increase body temperature**
* Hot water mattresses:
* More effective and safer placed on top of pts
| Slide 90
114
What is the most common method to prevent heat loss from radiation?
Forced air warming
*it uses convection to transfer heat to pt*
| slide 90
115
* What are 4 temperature monitoring sites?
* What are the risk/benefits with these sites?
* Pulmonary artery (gold standard)
* Tympanic membrane: approximates temp at hypothalamus (careful about preforation)
* Nasopharyngeal: reflects brain temp, but more prone to error and epistaxis
* Esophagus: safe, easy, no artifact, accurate **place in distal esophagus lower 1/3 to 1/4**
| slide 91
116
What is the OR temp (C) when the room is 70F or 65F?
70 degrees F = 21 degrees C [usally for PEDS cases]
65 degrees F = 18 degrees C [usually for adult cases]
| slide 92
