Exam 1 - Clinical Monitoring (airway/neuro/temp) Flashcards
What are the two types of gas sampling systems?
- Side-stream/ diverting analyzer
- Mainstream/ non-diverting analyzer
Which gas sampling system will have more lag time (transit time)?
A. sidestream
B. non-diverting
C. mainstream
A. Side-stream/ diverting analyzer
The time taken by the analyzer to react to the change in gas concentration is called:
A. sidestream response
B. transit time
C. rise time
D. mainstream response
C. rise time
The mainstream analyzer will have a faster rise time
Side-stream responses are dependent on what sampling tubing factors? select 3.
A. thickness
B. length
C. corrugation
D. inner diameter
E. material
F. gas sampling rate
B. Length of tubing
D. Sampling tubing inner diameter
F. Gas sampling rate (50 - 250 mL/min)
Gas sampling challenges with mainstream analyzers include: select 2
A. slower response time
B. leaks in the line
C. secretions or blood in tubing
D. more interfaces for disconnections
C. Secretions, Blood
D. More interfaces for disconnections
Water vapor (can block IR waveforms) - a challenge for both mainstream and sidestream
Gas sampling challenges with side-stream analyzers include: select 2.
A. failure of sampling pump or kinked sampling tubing
B. slower response time
C. secretions or blood
D. more interfaces for disconnection
A. Kinking of sampling tubing or Failure of sampling pump
B. Slow response time
… could also be leaks in the line
Water vapor (can block IR waveforms) - a challenge for both mainstream and sidestream
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?
- Dalton’s Law
At sea level, what is the total pressure of all anesthetic gases in the system?
- 760 mmHg
____ is a measure of concentration determined by mass/charge ratio of up to eight different gases administered during inhalational anesthesia.
A. raman spectroscopy
B. infrared analysis
C. mass spectrometry
D. water vapor streaming
C. Mass Spectrometry
A high-powered argon laser produces photons that collide with gas molecules in a gas sample. The scattered photons are measured in a spectrum that identifies each gas and concentration. This is called:
A. raman spectroscopy
B. infrared analysis
C. water vapor analysis
D. mass spectrometry
A. Raman Spectrometry (Raman Scattering)
No longer in use
What is most commonly used in anesthesia machines to determine the concentration of gas?
A. dispersive infrared analyzers
B. raman scattering
C. mass spectrometry
D. non-dispersive infrared analyzers
D. non-dispersive infrared analyzers
measures energy absorbed from narrow band of wavelengths of IR radiation as it passes thru a gas sample!
What gas is NOT measured when using a non-dispersive IR analyzer?
A. CO2
B. nitrous
C. O2
D. volatiles
E. water
C. O2; does not absorb IR radiation!
Long story short: How does Infrared Analysis determine concentration of a gases?
A. less light = high concentration
B. less light = lower concentration
C. more light = high concentration
- 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
A. Less light = high concentration of gas
T/F: Side-stream analyzers do not account for water vapor.
True: Side-stream analyzers report ambient temperature and pressure dry values (ATPD).
only if she asks to remove water vapor in the question then account for it (47 mmHg)
What are the two types of oxygen analyzers?
- Fuel or Galvanic Cell O2 Analyzer (mainstream)
- Paramagnetic O2 Analyzer (sidestream)
What are the drawbacks of a Fuel/ Galvanic Cell O2 Analyzer? select 2.
A. current is not proportional to PP of O2
B. slow response time
C. more agitation
D. short life span
B. Slow response time (30 secs, best to measure O2 in the inspiratory limb)
D. Short life span (months) depending on the length of O2 exposure
current IS proportional to PP of O2 in fuel cell
A paramagnetic O2 analyzer is used in most side-stream sampling multi-gas analyzers. What is the main benefit of this analyzer?
A. less agitation of signal
B. breath-by-breath monitoring which gives rapid response
C. measures current of O2 diffusing
D. longer life span
B. Rapid response; breath-by-breath monitoring
Purpose of gas sampling inside the inspiratory limb is to: select 2
A. ensure o2 delivery
B. analyze nitrous delivery
C. analyze hypoxic mixtures
D. ensure CO2 removal
A. Ensures oxygen delivery
C. Analyzes hypoxic mixtures
Purpose of gas sampling inside the expiratory limb is:
A. analyze complete deoxygenation
B. ensure CO2 delivery
C. ensure complete denitrogenation
D. ETCO2 above 90%
C. Ensure complete pre-oxygenation/ “denitrogenation”
so ET O2 above 90% (aka 0.90) = adequate!
What can trigger a low O2 alarm?
- Pipeline crossover
- Incorrectly filled tanks
- Failure of a proportioning system
What patient population must we be wary of for high O2 alarms? select 2.
A. premature infants
B. COPD patients
C. pts on chemo drugs (specifically bleomycin)
D. asthmatics
A. Premature infants (high O2 can cause blindness!)
C. Patients on chemotherapeutic drugs (bleomycin)
Bleomycin has been associated with pulmonary toxicity, which can cause lung damage. Supplemental oxygen may exacerbate this toxicity.
Mechanical pressure gauges require no power, are always on, and have high reliability. What is a downside of these pressure gauges?
A. don’t ever turn off
B. must be continually scanned
C. loud alarm system
D. only record low data
B. Must be continually scanned b/c no alarm system and no recording of data!
Electrical pressure gauges are built within anesthesia machine and the alarm system is integrated. Why is this important?
A. sensitive to small changes
B. must be continually scanned
C. only pick up huge changes
D. no recording of data
A. Sensitive to small changes
The low-pressure alarms on the breathing circuit identifies:
A. kinking of tubing
B. airway obstructions
C. disconnections or leaks
D. coughing
C. Identification of circuit disconnection or leaks
* Monitors airway or circuit pressure and compares it with a preset low-pressure alarm limit.
Where do most of the circuit disconnections occur at?
A. common gas outlet
B. proximal ETT tube
C. Y-piece
D. inspiratory limb
C. 70% of disconnections occur at the y-piece.
What is normal peak airway pressure?
A. 10-12 cmH2O
B. 15-17 cmH2O
C. 18-20 cmH2O
D. 20-23 cmH2O
C. 18-20 cmH2O
Low-pressure limit should be set just below this.
The sub-atmospheric pressure alarm measures/alerts: select 2.
A. coughing
B. negative circuit pressure
C. kinking of breathing tubing
D. high peak pressures
E. potential reverse flow of gas
B. negative circuit pressure and
E. potential for the reverse flow of gas
Deep Breath against a blocked circuit and having high negative inspiratory pressures can cause:
A. cardiac tamponade
B. hypercapnia
C. pulmonary edema
D. pleural effusion
C. Pulmonary Edema
Also could cause Atelectasis, and/or Hypoxia
What can cause negative (sub-atmospheric) pressure alarms? select 3.
A. high FGF
B. inadequate FGF
C. intubating the esophagus
D. moisture in CO2 absorbent
E. active scavenging system malfunctions
F. expiratory effort against a blocked circuit
B. Inadequate fresh gas flow
D. Moisture in CO2 absorbent
E. Active (suction) scavenging system malfunctions
also:
* Suction to misplaced NGT/OGT
* Pt inspiratory effort against a blocked circuit
What are the causes of high-pressure alarms?
- Obstruction
- Reduced compliance
- Cough/straining
- Kinked ETT
- Endobronchial intubation
When are continuing pressure alarms triggered?
A. while patient is coughing
B. if fresh gas can enter circuit but can’t leave
C. during a bronchospasm
D. while suctioning
B. Fresh gas can enter the circuit but can’t leave
* Continuing pressure alarms are triggered when circuit pressure exceeds 10 cm H2O for more than 15 seconds
Causes of continuing pressure alarms include: select 2.
A. activation of O2 flush
B. reduced compliance
C. malfunctioning APL or PEEP
D. suction on NGT/OGT
A. Activation of oxygen flush system
C. Malfunctioning APL valve or PEEP
also: a Scavenging system occlusion
What is the gold standard for the site of nerve stimulation?
Ulnar Nerve - innervates the adductor pollicis muscle and has the lowest risk of direct muscle stimulation.
What skeletal muscle is the most resistant to depolarizing and nondepolarizing NMBDs?
the diaphragm
Diaphragm has a shorter onset than adductor pollicis and recovers quicker than peripheral muscles.
What muscle reflects the extent of neuromuscular block of the laryngeal adductor and abdominal muscles the BEST?
A. adductor policis
B. corrugator supercilii
C. obicularis oculi
D. vastus medialis
B. Corrugator Supercilii (eyebrow muscle)
Define a single twitch stimulation.
- Single stimuli applied from 1.0 Hz (every second) to 0.1 Hz (every 10 seconds)
What stimulation will Provide reliable information throughout all phases of neuromuscular blockade w/o a monitoring device?
- Train of Four
How do you calculate TOF Ratio?
4th Response:1st Response
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)
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
Describe tetanic stimulation.
- stimulation given at 50 Hz and for 5 seconds
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
What stimulation is used for a deep/surgical blockade?
A. TOF
B. double-burst
C. tetanic
D. post-tetanic
D. Post-tetanic stimulation
Performed every 6 minutes
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
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
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
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
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 (pregnancy, low renal/hepatic fxn, genetics..)
What are the 5 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
What will EEG help identify?
- Identify consciousness/ unconsciousness
- Seizure activity
- Stages of sleep
- Coma
- Identify inadequate oxygen delivery to the brain (hypoxemia or ischemia)
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
What kind of waves are present in alert, attentive patients?
- Beta waves (>13 Hz)
- Higher frequency
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)
What kind of waves are present during depressed, deep anesthesia?
- Theta waves (4-7 Hz)
- Delta waves (<4 Hz)
- Slower frequency
What is the BIS range for general anesthesia?
- 40-60
What is the most common type of evoked potential monitored intra-op?
- Sensory evoked potential
What is sensory-evoked potential?
- Electric CNS response to electric, auditory, or visual stimuli
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
What are the three types of sensory-evoked potentials?
- Somatosensory-evoked potential (SSEP) - stimulate peripheral nerves
- Brainstem auditory-evoked potential (BAEP) - stimulate auditory cortex by clicking sounds
- Visual-evoked potential (VEP) - stimulate visual cortex by flashing lights
___ (short vs long) latency SSEPs are most commonly recorded intra-op, and are less influenced by changes in anesthetic drug levels.
- Short-latency
Monitoring the integrity of the motor tracts along the spinal column, peripheral nerves, and innervated muscle are called:
A. VEPs
B. MEPs
C. BAEPs
D. SSEPs
B. Motor-Evoked Potentials (MEP)
What is the most common MEP?
- Transcranial motor-evoked potentials
Monitors stimuli along the motor tract via transcranial electrical stimulation overlying the motor cortex
What 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?
A. Electroenchephalography
B. SSEPs
C. electromyography
D. TOF
C. Electromyography
Assesses the integrity of cranial or peripheral nerves at risk during surgery
The primary thermoregulatory control center is:
A. neurohypophysis
B. anterior pituitary gland
C. adrenal gland
D. hypothalamus
D. Hypothalamus
What fibers are heat/warmth receptors?
- Unmyelinated “slow pain” C-fibers
feeling hot is uncomfortable but not as painful as being cold..
What fibers are cold receptors?
- A-delta “fast pain” fibers
“feel cold much faster than you feel hot”
The thermoregulatory response is characterized by what three factors?
A. latency
B. threshold
C. gain
D. amplitude
E. frequency
F. response
B. Threshold – temperature at which a response will occur
C. Gain – intensity of the response
F. Response – sweating, vasodilation, vasoconstriction, and shivering
What affects the thermoregulatory response?
- Anesthesia type
- Age
- Menstrual cycle
- Drugs/EtOH
- Circadian rhythm
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
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!
The plateau phase (thermal steady state) of hypothermia in GA occurs ____ hours after anesthesia has started.
Occurs 3-4 hours after anesthesia has started
* Vasoconstriction prevents loss of heat from the core, but peripheral heat continues to be lost
Heat loss = heat production in this phase
How does neuraxial anesthesia affect our central thermoregulatory control?
A. does not allow shivering to occur at all
B. increases the threshold that triggers shivering
C. causes shivering sooner
D. decreases threshold that trigger peripheral vasoconstriction and shivering
D. Neuraxial anesthesia decreases the thresholds that trigger peripheral vasoconstriction and shivering
so temp will need to drop way lower than normal for patient to begin to shiver or vasoconstrict
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
What are the 4 types of heat transfer?
- Radiation (40%) - so most of the heat loss is thru radiation!
- Convection (30%)
- Evaporation (10%)
- Conduction (negligible)
Radiation is heat loss because body surface area (BSA) is exposed to the environment. Which patient population is vulnerable to this type of heat transfer?
A. elderly
B. obese
C. infants
D. paraplegics
D. Infants have a high BSA/body mass ratio makes them vulnerable
Approx. 40% of heat loss in pt
Convection is loss of heat to:
A. environment from BSA exposure
B. air immediately surrounding the body
C. evaporation of bodily fluids
D. direct contact of body tissues to colder material
B. Loss of heat to air immediately surrounding the body, approx. 30%
* Clothing or drapes decrease heat loss
* Greater in rooms with laminar airflow!!!
Evaporation is slow/latent heat of vaporization of water from open body cavities and respiratory tract. What is the main pathway of evaporation?
A. crying
B. breathing
C. sweating
D. bowel procedures
C. sweating!
evaporation accounts for approx. 8-10% of heat loss
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
Complications related to hypothermia include: select 3.
A. decreases O2 delivery
B. shivering which increases O2 demand
C. anticoagulation effect
D. decreased drug metabolism
E. decreased BP
F. cerebral infarction
A. ↓O2 delivery to tissues
B. Shivering
D. Decrease drug metabolism
also:
* Coagulopathy - can increase Blood loss by 16% and increase the need for transfusion by 22%
* 3x the incidence of morbid cardiac outcomes (b/c increased BP, HR, and plasma catecholamines)
* Post-op thermal discomfort
Benefits of hypothermia include: select 2.
A. protective against cerebral ischemia
B. protective against incidence of myocardial events
C. reduces metabolism
D. increases drug metabolism
A. Protective against cerebral ischemia
C. Reduces metabolism… 8% per degree Celsius
And:
* Improved outcome during recovery from cardiac arrest
* More difficult to trigger MH
Peri-Op Temperature Management
- Prioritize airway/heating in pediatrics
- Warm IV fluid and blood
- Cutaneous warming
- Forced air warming (convection method = bair hugger!)
How can you perform cutaneous warming?
- ↑ Room Temperature (especially for Liver transplant, trauma)
- Insulation (blankets reduce heat loss by 30%)
- Hot water mattress (safer/effective if placed on top of pt)
What is the gold standard monitoring site for temperature?
A. tympanic membrane
B. nasopharyngeal
C. pulmonary artery
D. esopagus
C. Pulmonary Artery - correlates well w/ tympanic membrane, distal esophageal and nasopharyngeal temperatures
but esophageal is the best/safest!
Apart from the pulmonary artery, what are other temperature monitoring sites?
- 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)
OR Temperature
- 65 degrees F (18°C) to 70 degrees F (21°C)
