Exam 1- Clinical Monitoring (6/12/23) Flashcards
1
Q
What are the two sampling sites depicted by the two arrows?
A
- Elbow
- Y-piece
2
Q
What are the two types of gas sampling systems?
A
- Side-stream/ diverting analyzer
- Mainstream/ non-diverting analyzer
3
Q
Which gas sampling system will have more lag time (transit time)?
A
- Side-stream/ diverting analyzer
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.
5
Q
Side-stream responses is dependent on what factors?
A
- Sampling tubing inner diameter
- Length of tubing
- Gas sampling rate (50 - 250 mL/min)
6
Q
What are gas sampling challenges with mainstream analyzers?
A
- Water vapor (can block IR waveforms)
- Secretions
- Blood
- More interfaces for disconnections
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
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
9
Q
At sea level, what is the total pressure of all anesthetic gases in the system?
A
- 760 mmHg
10
Q
Calculate the partial pressure of O2 at room air
A
- 159.6 mmHg
760 mmHg x 21% = 159.6 mmHg
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
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
13
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
14
Q
What is typically used in anesthesia machines to determine the concentration of gas?
A
- IR Analysis
15
Q
What is the most common gas analyzer?
A
- Non-dispersive IR analyzer
IR analysis measures energy absorbed from a narrow band of wavelengths of IR radiation as it passes through a gas sample
16
Q
What gases are measured using a non-dispersive IR analyzer?
A
- CO2
- Nitrous Oxide
- Water
- Volatile Anesthetic Gases
O2 does not absorb IR radiation
17
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
- 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
18
Q
Do side-stream analyzers take into account of water vapors?
A
- No
- Side-stream analyzers report ambient temperature and pressure dry values (ATPD).
19
Q
What are the two types of oxygen analyzers?
A
- Fuel or Galvanic Cell O2 Analyzer
- Paramagnetic O2 Analyzer
20
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 (best to measure O2 in the inspiratory limb)
21
Q
What oxygen analyzer is used in most side-stream sampling multi-gas analyzers?
What is the benefit of this analyzer?
A
- Paramagnetic O2 Analyzer
- Benefit: Rapid response, breath-by-breath monitoring
22
Q
Purpose of gas sampling inside the inspiratory limb.
A
- Ensures oxygen delivery
- Analyzes hypoxic mixtures
23
Q
Purpose of gas sampling inside the expiratory limb.
A
- Ensure complete pre-oxygenation/ “denitrogenation”
- ET O2 above 90% adequate
24
Q
What can trigger a low O2 alarm?
A
- Pipeline crossover
- Incorrectly filled tanks
- Failure of a proportioning system
25
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.**
26
What can airway pressure monitoring detect?
* Circuit disconnections
* ETT occlusions
* Kinking in the inspiratory limb
* Fresh gas hose kink or disconnection
* Circuit leaks
* Sustained high-circuit pressure
* High and low scavenging system pressures
27
What are the two types of pressure gauges used in airway pressure monitoring?
* Mechanical Pressure Gauges
* Electronic Pressure Gauges
28
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
29
What are the characteristics of electrical pressure gauges?
* Built within ventilator or anesthesia machine
* Alarm system integrated
* Sensitive to small changes
30
What is the purpose of the breathing circuit low-pressure alarms?
* Identification of circuit disconnection or leaks
* Monitors airway or circuit pressure and compares it with a preset low-pressure alarm limit.
31
Where do most of the circuit disconnections occur at?
* 70% of disconnections occur at the y-piece.
32
What is the normal peak airway pressure?
* 18-20 cmH20
*Low-pressure limit should be set just below this.*
33
What does the sub-atmospheric pressure alarm measure?
* Measure and alerts negative circuit pressure and potential for the reverse flow of gas
34
What can negative pressure cause the patient to have?
* Pulmonary Edema
* Atelectasis
* Hypoxia
35
What can cause negative pressure 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
36
What are the causes of high-pressure alarms?
* Obstruction
* Reduced compliance
* Cough/straining
* Kinked ETT
* Endobronchial intubation
37
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
38
What are causes of continuing pressure alarms?
* Malfunctioning adjustable pressure relief valve
* Scavenging system occlusion
* Activation of oxygen flush system
* Malfunctioning PEEP
39
What is the gold standard for the site of nerve stimulation?
* Ulnar Nerve
*The ulnar nerve innervates the adductor pollicis muscle and has the lowest risk of direct muscle stimulation.*
40
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.*
41
What muscle will reflect the extent of the neuromuscular block of the laryngeal adductor and abdominal muscles the best?
* Corrugator Supercilii
42
Define a single twitch stimulation.
* Single stimuli applied from 1.0 Hz (every second) to 0.1 Hz (every 10 seconds)
43
What stimulation will Provide reliable information throughout all phases of neuromuscular blockade w/o a monitoring device?
* Train of Four
44
How do you calculate TOF Ratio?
* 4th Response:1st Response
45
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)
46
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*
47
Describe tetanic stimulation.
* Tetanic stimulation given at 50 Hz for 5 seconds
48
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
49
What stimulation is used for a deep/surgical blockade?
* Post-tetanic stimulation
*Performed every 6 minutes*
50
What kind of blocks are in columns A, B, and C?
What kind of nerve stimulation is performed in rows 1 through 4?
51
Describe an intense non-depolarizing block.
When does this occur?
Reversal?
* Period of no response 3 – 6 minutes after an intubating dose of non-depolarizing NMBD
* Reversal with high dose of Sugammadex (16 mg/kg)
* Neostigmine reversal impossible
52
Describe a deep non-depolarizing block.
Reversal?
* Absence of TOF but the presence of at least one response to post-tetanic count stimulation.
* Dose of sugammadex (4 mg/kg) for reversal
53
Describe a moderate non-depolarizing block.
Reversal?
* Gradual return of the 4 responses to TOF stimulation appears
* Neostigmine reversal after 4/4 TOF
* Dose of sugammadex (2 mg/kg) for reversal
54
Describe a phase 1 depolarizing blockade.
* No fade or tetanic stimulation; no post-tetanic facilitation occurs
* All 4 responses are reduced, yet equal and then all disappear simultaneously in TOF (ratio is 1.0)
* Normal plasma cholinesterase activity
55
Describe a phase 2 depolarizing blockade.
* Fade present in response to TOF and tetanic stimulation; occurrence of post-tetanic facilitation
* Response is similar to a non-depolarizing blockade
* Abnormal plasma cholinesterase activity
56
What are reliable clinical signs for ETT extubation?
* Sustained head lift for 5 sec
* Sustained leg lift for 5 sec
* Sustained handgrip for 5 sec
* Sustained ‘tongue depressor test’
* Maximum inspiratory pressure
57
What will EEG help identify?
* Identify consciousness/ unconsciousness
* **Seizure activity**
* Stages of sleep
* Coma
* Identify inadequate oxygen delivery to the brain (hypoxemia or ischemia)
58
Describe the following EEG factors:
-Amplitude
-Frequency
-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
59
What kind of waves are present in alert, attentive patients?
* Beta waves (>13 Hz)
* Higher frequency
60
What kind of waves are present when resting and eyes are closed?
* Alpha waves (8-13 Hz)
* Present during the beginning of induction (anesthetic effects)
61
What kind of waves are present during depressed, deep anesthesia?
* Theta waves (4-7 Hz)
* Delta waves (<4 Hz)
* Slower frequency
62
How many channels are used in processed EEG compared to the gold standard EEG?
* 4 channels vs 16 channels
63
How does a BIS monitor estimate anesthetic depth?
* Computer-generated algorithm/weighting system
*Note: BIS monitoring has not demonstrated to be superior to end-tidal agent concentration monitoring*
64
What is the BIS range for general anesthesia?
* 40-60
65
What is the most common type of evoked potential monitored intra-op?
* Sensory evoked potential
66
What is sensory-evoked potential?
* Electric CNS response to electric, auditory, or visual stimuli
67
How are sensory-evoked potentials described?
* Latency: time measured from the application of stimulus to the onset or peak of response
* Amplitude: size or voltage of recorded signal
68
What are the three types of sensory-evoked potentials?
* Somatosensory-evoked potential (SSEP)
* Brainstem auditory-evoked potential (BAEP)
* Visual-evoked potential (VEP)
69
What monitors the responses to stimulation of peripheral mixed nerves (containing motor and sensory nerves) to the sensorimotor cortex?
* Somatosensory-Evoked Potential (SSEP)
70
Monitors the responses to click stimuli that are delivered via foam ear inserts along the auditory pathway from the ear to the auditory cortex
* Brainstem Auditory-Evoked Potential (BAEP)
71
What type of latency SSEPs are most commonly recorded intra-op, less influenced by changes in anesthetic drug levels?
* Short-latency
72
Monitors the responses to flash stimulation of the retina using light-emitting diodes embedded in soft plastic goggles through closed eyelids or contact lenses
* Visual-Evoked Potential (VEP)
73
Monitoring the integrity of the motor tracts along the spinal column, peripheral nerves, and innervated muscle
* Motor-Evoked Potentials (MEP)
74
What is the most common MEP?
* Transcranial motor-evoked potentials
*Monitors stimuli along the motor tract via transcranial electrical stimulation overlying the motor cortex*
75
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
* Electromyography
*Assesses the integrity of cranial or peripheral nerves at risk during surgery*
76
Where is the primary thermoregulatory control center?
* Hypothalamus
77
What fibers are heat and warmth receptors?
* Unmyelinated C-fibers
78
What fibers are cold receptors?
* A-delta fibers
79
The thermoregulatory response is characterized by what three factors?
* Threshold – temperature at which a response will occur
* Gain – the intensity of the response
* Response – sweating, vasodilation, vasoconstriction, and shivering
80
What affects the thermoregulatory response?
* Anesthesia type
* Age
* Menstrual cycle
* Drugs/EtOH
* Circadian rhythm
81
What is the initial decrease in body temperature with hypothermia in general anesthesia?
* Rapid decrease of approximately 0.5-1.5 °C over 30 mins
* Caused by anesthesia-induced vasodilation
* Increases heat loss d/t redistribution of body heat
82
How much heat is lost during the slow linear reduction phase with hypothermia in general anesthesia?
* 0.3 °C per hour
* Caused by the decrease of the metabolic rate of 20-30%
* Heat loss exceeds production
* This occurs 1-2 hours after anesthesia has started
*Use Bair Hugger to combat heat loss*
83
Describe the plateau phase of hypothermia in general anesthesia.
* Thermal steady state
* Heat loss = heat production
* Occurs 3-4 hours after anesthesia has started
* Vasoconstriction prevents loss of heat from the core, but peripheral heat continues to be lost
84
How is central thermoregulatory control inhibited by neuraxial anesthesia?
* Neuraxial anesthesia decreases the thresholds that trigger peripheral vasoconstriction and shivering
85
Why might there not be a temperature plateau with neuraxial anesthesia?
* Neuraxial anesthesia centrally alters the vasoconstriction threshold
* Vasoconstriction of the lower extremity will be inhibited by the nerve block
86
What are the types of heat transfer?
* Radiation
* Convection
* Evaporation
* Conduction
87
Describe Radiation.
Which patient population is vulnerable to this type of heat transfer?
* Heat loss to the environment, body surface area (BSA) is exposed to the environment
* Approx. 40% of heat loss in pt
* Infants have a high BSA/body mass ratio makes them vulnerable
88
Describe Convection.
* Loss of heat to air immediately surrounding the body, approx. 30%
* Clothing or drapes decrease heat loss
* Greater in rooms with laminar airflow
89
Describe Evaporation
* Latent heat of vaporization of water from open body cavities and respiratory tract. Accounts for approx. 8-10% of heat loss
* Sweating is the main pathway
90
Describe Conduction
* Heat loss due to direct contact of body tissues or fluids with a colder material, negligible
* Contact between skin and OR table; intravascular compartment and an infusion of cold fluid
91
List complications related to hypothermia
* Coagulopathy
* Increase the need for transfusion by 22%
* Blood loss by 16%
* ↓O2 delivery to tissues
* 3x the incidence of morbid cardiac outcomes
* Shivering
* Decrease drug metabolism
* Post-op thermal discomfort
92
Benefits of hypothermia
* Protective against cerebral ischemia
* Reduces metabolism… 8% per degree Celsius
* Improved outcome during recovery from cardiac arrest
* More difficult to trigger MH
93
Peri-Op Temperature Management
* Prioritize airway/heating in pediatrics
* Warm IV fluid and blood
* Cutaneous warming
* Forced air warming (convection method)
94
How can you perform cutaneous warming?
* ↑ Room Temperature (Liver transplant, trauma)
* Insulation (blankets reduce heat loss by 30%)
* Hot water mattress (safer/effective if placed on top of pt)
95
What is the gold standard monitoring site for temperature?
* Pulmonary Artery
96
What are other monitoring sites for temperature?
* Tympanic membrane (ear) - perforation risk
* Nasopharyngeal - prone to error, nose bleeds
* Esophagus - place in the distal esophagus, lower third to lower quarter of the esophagus (best site to monitor)
97
OR Temperature
* 65 degree (18°C) to 70 degrees (21°C)
