Resp/Neuro monitoring Flashcards
1
Q
What is the difference between ETCO2 and PACO2?
A
Approximately 5 torr, up to 10 torr
2
Q
Define capnometry.
A
Encompasses all means of measuring carbon dioxide
3
Q
Define capnography..
A
Recording of the measurement of carbon dioxide
4
Q
Define capnogram.
A
Uses infrared analysis, A continuous display of carbon dioxide
5
Q
What are the two forms of capnogram?
A
Nondiverting and diverting
6
Q
Define nondiverting/mainstream monitor.
A
Measures gas directly within the breathing system
7
Q
What are the advantages of nondiverting/mainstream monitoring?
A
Minimal time delays, no scavenging necessary
8
Q
What are the disadvantages of nondiverting/mainstream monitoring?
A
Cannot measure gases other than carbon dioxide and nitrous oxide, increased deadspace
9
Q
Define diverting/sidestream monitor.
A
Extracts gas from sample tubing near the patient end of the circuit and pushes it into monitor
10
Q
What are the advantages of diverting/sidestream monitoring?
A
Minimal increase in deadspace, versatile gas analysis
11
Q
What are the disadvantages of diverting/sidestream monitoring?
A
Need for scavenging, risk of contamination from secretions
12
Q
Id the A-B portion of the waveform. What does this mean?
A
Baseline (anatomic deadspace)
13
Q
Id the B-C portion of the waveform. What does this mean?
A
Expiratory upstroke (deadspace and alveolar gas)
14
Q
Id the C-D portion of the waveform. What does this mean?
A
Expiratory plateau (alveolar gas)
15
Q
Id the D portion of the waveform. What does this mean?
A
End-tidal concentration
16
Q
Id the D-E portion of the waveform. What does this mean?
A
Descent to original baseline (inspiration)
17
Q
Capnogram – What is occurring?
A
- Rebreathing – Waveform fails to return to baseline
- Caused by inadequate fresh gas flow or depleted absorber
18
Q
Capnogram – What is occurring?
A
- Prolonged expiration
- Caused by obstruction of expired gas flow or ventilation-perfusion mismatch
19
Q
What respiratory commorbities could cause this? (3)
A
Asthma, bronchospasm, COPD, etc.
20
Q
Capnogram – What is occurring?
A
Curare Clefts
- Spontaneous respiratory effort in an anesthetized patient who is mechanically ventilated and/or paralyzed
21
Q
Be able to differentiate hyperventilation from hypoventilation.
A
Slide 90
22
Q
Capnogram – What is occurring?
A
- Loss of end tidal waveform – Dislodged ETT or ETT disconnected
- Sudden loss of circulation, e.g. PE
23
Q
What can increase ETCO2?
A
- Increased carbon dioxide delivery or production
- Hypoventilation
- Equipment problems
24
Q
What can decrease ETCO2?
A
- Decreased carbon dioxide delivery or production
- Hyperventilation
- Equipment problems
25
What are spirometry loops (pressure volume Loops)?
Assess changes in lung compliance and resistance
26
What relationship do spirometry loops (pressure volume Loops)demonstrate?
Relationship between (pressure and volume) or flow and volume
* Flow on vertical axis
* Volume on horizontal axis
27
Understand pressure loops picture.
Slide 94-97
28
Describe the relationship of flow volume loops and obstructive diease.
Reduced peak flow rate and sloping of expiratory limb occurs as small airways close during expiration, reducing the flow rate during expiration; can’t get the air out (COPD, asthma)
29
Describe the relationship of flow volume loops and restrictive diease.
Normal or heightened peak expiratory flows with a very narrow loop reflecting reduced vital capacity
30
What are some characteristics of restrictive disease?
Can’t get the air in- scarring of the lungs, interstitial dz: sarcoidosis); neuromuscular disorders; obesity
31
Identify the difference between spontaneously breathing patients flow volume loops and mechanically ventilated patients.
Slide 98
32
What does pulse oximetry measure?
heart rate and percent of oxygen saturation (SaO2) of hemoglobin continuously and non-invasively
33
What is true about oxgenated verus unoxygenated hemoglobin?
Oxygenated hgb absorbs light at a different wavelength than unoxygenated hgb
34
What type of light absorbs deoxygenated light more?
At a red wavelength between 650 and 750nm reduced oxygen hgb absorbs more light than oxyhemoglobin
35
What type of light absorbs oxygenated HGB more?
In infrared wavelengths of 900-1000nm oxyhemoglobin absorbs more light than reduced oxygen hgb
36
What is the algorithm that determines light absorption?
The algorithm used to determine the SaO2 based on light absorption is derived from the Beer-Lambert law
37
How does pulse oximetry differentiate pulsatile flow?
Uses plethysmography to differentiate pulsatile flow
38
Pulse oximetry: Shown to be accurate within 2% when oxygen saturation is between \_\_\_\_\_\_\_-\_\_\_\_\_\_\_%
80-100%
39
Pulse oximetry: Shown to be accurate within 5% when saturation falls below \_\_\_\_%
below 80%
40
What are some other locations for pulse oximetry?
Forehead, ear or nose probes shown to have comparable accuracy and reliability
41
What are some causes of abnormal hemoglobin that could result in false pulse oximetry readings?
Methemoglobin, carboxyhemoglobin, sickle cell anemia, injectable dyes (methylene blue or indigo carmine)
42
Review the oxyhemoglobin curve.
Slide 101-102.
43
Why are ORs kept at a low temperatures? (3)
* Cool to decrease bacterial growth
* Surgeon comfort
* Slows the solidification of bone cement
44
What are complications of the hypothermic patient? (5)
* Delayed wound healing
* Impaired coagulation
* Unstable cardiac cycle
* Vasoconstriction (esp. CAD pts)
* Shivering
45
How can shivering effect oxygen requirements?
Shivering (increased oxygen requirements 400%)
46
What are the types of temperature monitoring?
* Bladder
* Pulmonary artery
* Esophageal
* Nasopharynx
* Tympanic
* Axillary
47
What is true about axillary temperature monitoring?
48
What are the different types of heat loss?
Radiation, Convection, Conduction & Evaporation
49
Define radiation.
Transfer of heat energy to environment
50
Define convection.
Loss of heat via air currents
51
Define conduction.
Transfer of heat by physically touching less warm objects
52
Define evaporation.
Loss of energy when liquid is converted to a gas
53
What is the most significant form of heat loss under anesthesia?
radiation
54
What is the second most significant form of heat loss under anesthesia?
convection
55
What are the components of neurological monitoring (4)?
* Frequency
* Amplitude
* Morphology
* Four common EEG waves
56
Define frequency.
Rate of impulses or duration between impulses
57
Define amplitude.
Peak to peak measurements in the vertical plane
58
Define morphology.
shape
59
What are the most common EEG waves (4)?
alpha, beta, delta and theta
60
Define alpha brain waves.
Occurs with eyes closed during deep relaxation
61
Define beta brain waves.
Normal awake consciousness, alertness, logic and critical thinking
62
Define delta brain waves.
High amplitude; Associated with deep sleep
63
Define theta brain waves.
Light sleep
64
What effect does etomidate and propofol have on EEG?
Induction doses of etomidate and propofol increase EEG frequency and decrease amplitude of beta waves
65
What effect does ketamine have on EEG waves?
abolition of alpha waves and dominance of theta
66
What is possible on EEG with high doses of etomidate and propofol?
Burst suppression
67
Variable effects on EEG _________ depending on class of medications
frequency
68
Variable effects on EEG ______ depending on class of medications
amplitude
69
What is burst suppression?
An electroencephalogram pattern observed in states of severely reduced brain activity, such as general anesthesia, hypothermia and anoxic brain injuries
70
What is the EEG pattern associated with burst supression?
EEG pattern associated with alternating high voltage, mixed frequency, slow wave activity, along with periods of electrical suppression that last several seconds
71
What effect does burst suppression have with anesthetic agents?
results in a large reduction in the cerebral metabolic rate of oxygen (CMRO2)
72
When would burst suppression be advantageous?
Advantageous during manipulation of brain tissues for neuroprotection
73
What is cerebral oximeter?
* Monitors adequacy of oxygenation specific to the brain
* Uses near infrared spectroscopy
74
What does cerebral oximeter proveide?
measurements of oxygen supply versus demand within a region
75
What does cerebral oximeter measure?
Measure the ratio of oxygenated hgb to total hgb within a region
76
Nonquantitative cerebral oximeters use wavelengths of \_\_\_\_\_-\_\_\_\_\_\_nm
730-810nm
77
Quantitative cerebral oximeters utilize wavelengths of \_\_\_\_\_, \_\_\_\_\_,\_\_\_\_\_\_ and _____ nm
775, 825,850 and 904nm
78
What is the goal of cerebral oximeter?
Goal to maintain value at a minimum of 75% of baseline reading
79
What is transcranial doppler ultrasonography?
Non-invasive measure of blood flow velocity within the large arteries of the brain
80
What is transcranial doppler ultrasonography detect?
Detects instances of hypo and hyperperfusion
81
What is transcranial doppler ultrasonography usually measure?
middle cerebral artery flow
82
What is Jugular Bulb Oxygen Venous Saturation?
* Measurement of mixed venous blood from the jugular bulb
* Estimates degree of global oxygen extraction by the brain
83
Where does the jugular blood receive drainage?
from both left and right cerebral hemispheres
84
Jugular bulb drainage: \_\_\_\_\_\_\_\_b% from ipsilateral hemisphere and \_\_\_\_\_\_\_% from contralateral hemisphere
70% from ipsilateral hemisphere and 30% from contralateral hemisphere
85
What are the two optical fibers of the jugular bulb catheter?
One emits light and one absorbs light and transmits it to a photosensor
86
What does jugular bulb reading indicate?
Jugular bulb reading between 55-75% indicative of more positive outcomes in TBI if ICP remains normal
87
What are the different evoked potentials?
* SSEPs – Somatosensory evoked potentials
* MEPs – Motor evoked potentials
* BAEPs – Brainstem auditory evoked potentials
* VEPs – Visual evoked potentials
88
What are evoke poentials used for?
Used to guide surgical strategy and warn of neurologic deficits to prevent irreversible damage
89
What three components of waveforms are monitored for evoke potentials?
General appearance, Amplitude & Latency
90
Define amplitude.
Intensity of the evoked response
91
Define latency.
Indicative of the time necessary for the evoked response to be measured in the brain
92
What changes in evoke potentials are associated with cerebral ischemia?
50% decrease in amplitude or a 10% increase in latency
93
What is the relationship between evoke potentials and inhalational agents?
Inhalational agents (generally) have greater depressant effect on evoked potentials compared with IV anesthetic agents
94
What are somatosensory evoked potentials (SSEPs)?
Monitor the integrity of neural structures along the peripheral and central somatosensory pathways of the brain and spinal cord
95
What is SSEPS induced by?
Induced by stimulating peripheral nerves electrically, which contain both motor and sensory components
96
What is the anesthetic plan with SSEPs?
* Narcotic based anesthetics, TIVA, or 0.5 or less MAC
* No nitrous oxide
* Administration of neuromuscular blocking agents acceptable if motor responses not required
97
Review graph.
Slide 115.
98
What is Motor evoked potentials (MEPs)?
* Monitor the functional integrity of motor tracts, particularly in the corticospinal tract
* Gold standard for monitoring motor pathways
99
What is the stimuli for MEPS?
electrical or magnetic
100
What is electomyography (EMG)?
can be both passive and active to allow for awareness of what nerves are being stimulated with surgical manipulation
101
MEPS: What is needed for thyroidectomy or head and neck surgery?
Nerve integrity monitoring ETT for recurrent laryngeal nerve monitoring
102
MEPS: What should be avoided?
Avoid use of neuromuscular blocking agents
103
What is Brainstem auditory evoked potentials (BAEPs)?
Monitor the entire auditory pathway from the distal auditory nerve to the midbrain
104
What does Brainstem auditory evoked potentials (BAEPs) used?
Uses a repeating click via an earphone placed in the auditory canal
105
What is the anesthetic plan for Brainstem auditory evoked potentials (BAEPs)?
* Avoid lidocaine infusion
* Inhalational agents have proportional dose dependent effect
* Avoid even mild hypothermia
* Avoid hyperventilation
106
What are Visual evoked potentials (VEPS)?
Monitor the function of the visual pathway, which comprises the retina to the occipital cortex
107
What does VEPS use?
Uses a series of visual stimuli
* Pattern stimulus used in awake patients
* Flash stimulus used in anesthetized/sedated patients
108
What is BIS?
Analysis and processing of EEG electrical signals resulting in a numeric value between 0 and 100 which represents the patient’s level of consciousness
109
BIS Values: 100 equals \_\_\_\_\_\_
Awake
110
BIS Values: 80-100 equals \_\_\_\_\_\_
Responds to verbal stimuli
111
BIS Values: 60-80 equals \_\_\_\_\_\_
Responds to loud verbal/physical stimuli
112
BIS Values: 40-60 equals \_\_\_\_\_\_
adequate general anesthesia
113
BIS Values: \<40 equals \_\_\_\_\_\_
Deep hypnotic state
114
What is a BIS \<40 associated with?
lasting for greater than 5 minutes may be associated with increased postoperative mortality
