Noninvasive Monitoring Flashcards
How do we place a modified V5 Lead?
Modified V5 lead (MCL): used to detect anterior and lateral wall ischemia if only using 3 lead electrodes
- Place right arm lead in right midclavicular line
- Left arm lead in 5th intercostal space next to left nipple
- Left leg lead on left iliac crest
- Monitor in Lead 1
other sites of pulse oximetry
penis.
What can measuring Nitrogen tell us?
Highest amount of Nitrogen is in room air
if you have a high Nitrogen amount in a patient it is indicative of
Pulmonary Embolus
Best site to monitor for extubation?
ADDUCTOR POLLICIS
What does a Curare cleft signify?
The patient is starting to breathe again.
When do you have fade?
When don’t you have fade?
You have fade on non-depolarizing
You DO NOT HAVE FADE IN SUX
What two leads do you monitor in the OR?
LEADS II AND V5
What can cause this?
Rebreathing CO2
- Faulty expiratory valve - DR. MASSIES CHOICE
- Inadequate inspiratory flow
- Insufficient expiratory time
- Malfunction of CO2 absorber system
Best site to monitor for intubation?
FACIAL
Tetanus: stimulus delivered at _____ Hz
for ___ seconds
Tetanus: stimulus delivered at 50-100 Hz
for 5 seconds
we want to see sustained 5 seconds
What muscle is resistant to sux? what muscles are sensitive to it?
Diaphragm - resistant
Laryngeal muscles -sensitive
What effect would Methemoglobin have on pulse oximetry?
the same absorption at both the red and infrared wavelengths, creating a 1:1 ratio
- The resulting 1:1 ratio corresponds to a saturation reading of 85% (algorithmically)
- So methemoglobinemia c_auses a falsely low SpO2 when saturation is actually greater than 85% and a falsely high SpO2 when saturation is actually lower than 85%_
The only quantitative monitoring technique we use (neuromuscular)
can much residual NMB can this detect?
Acceleromyography (AMG): monitor measures muscle acceleration via piezoelectric sensor; piezoelectric crystal generates voltage when put into motion due to muscle contraction
- can detect 97% of residual NMB
What can cause this waveform?
- Baseline elevated
- Abnormal descending limb of capnogram
- Allows patient to rebreathe exhaled gas
the gold standard of endotracheal tube placement and verification
CAPNOGRAPHY
- CONTINUOUS MONITORING OF ALVEOLAR VENTILATION –
Patterns of electrical stimulation
A single twitch delivers how many Hz? how long will it last?
how many seconds?
how many pulses?
- Single twitch: single pulse delivered every second to every 10 seconds at 0.1- 1.0 Hz, lasting 0.1-0.2 seconds
What does the line from C to D represent on the capnography waveform?
- end airways that are releasing the last bits of carbon dioxide.
What happens in Phase I?
Phase 1: inspiration from points E to A, during which CO2 level remains zero
With nondepolarizing muscle relaxants:
- Loss of 4th twitch represents ___% block
- Loss of 3rd twitch = ___% block
- Loss of 2nd twitch = ___% block
- Loss of 1st twitch = ___% block
Loss of fourth twitch = 75 % block
Loss of 3rd twitch = 80% block
Loss of 2nd twitch = 90% block
Loss of 1st twitch = 100% block
Shows the best approximation of alveolar CO2 (end of expiration beginning of inspiration)
POINT D
What is the wavelength of Oxyhemoglobin (HbO2)
940-990 nm
wavelength
What light does Deoxyhemoglobin absorb?
what is the wavelength?
Deoxyhemoglobin absorbs more red light at 660 nm
wavelength
What is the formula for functional saturation?
What does Lead II recognize and detect?
Lead II recognizes P waves easily and detects
dysrhythmias
What is this waveform?
SUDDEN DROP IN EtCO2
–you are in the goose–
–gradual drop is usually obstruction–
limits the degree of desaturation that can be tolerated
Oxyhemoglobin dissociation curve: limits the degree of desaturation that can be tolerated
- Between 90-100% saturation, PaO2 will be >60
torr
- Below 90% saturation, curve becomes steeper and
small drops in saturation correspond to large drops in PaO2
Narrow range of safety
What is a restrictive disease?
Neuromuscular diseases
[inspiration]
longer [I] time
Pulmonary Fibrosis
Obesity
Pregnancy
Mandatory AANA/ASA standard monitor to aid in detecting hypoxemia
Pulse Oximetry
Possible causes of Irregular plateau or baseline
- displacement of the tracheal tube into the upper airway or larynx or lower pharynx with intermittent ventilation of the stomach and lungs or from pressure on the chest which causes small volumes of gas to move in and out of the lungs.
Inadequate Seal Around ET tube
- leaky or deflated endotracheal or tracheostomy cuff
- Artificial airway is too small for the patient
How many twitches does TOF show, how many second interval at how much Hz?
- Train of four (TOF): four twitch stimuli in 2 seconds at 0.5 second intervals at 2 Hz
–>>>> Twitches progressively fade when relaxation occurs
and vice versa
How many ETCO2 waveforms do you need to see to verify that you are in the trachea?
3 good ETCO2 waveform
A point in time [DURING CASE] when we are looking at our anesthetic EtCO2 when we realize that we have to get it higher.
EMERGENCE
-end of the case-
(45-50 –> resp. drive kick in)
What is this?
Where is the first place you’ll check or what will you think?
Classic progressive obstruction on patients with
COPD, ASTHMA, EMPHYSEMA
- Think about patient history (reactive airway?)
always go back to differential diagnosis.
Reactive airway disease –> listen to the patient to see if the patient is wheezing [flip off the vent]
- Patient might be biting? (IA, Propofol, Muscle relaxant –> if the case is longer]
What is the basis of pulse oximetry?
The change in light absorption during arterial pulsation is the basis of pulse oximetry
What does lead V5 view? what does it detect?
Lead V5 views the anterior and lateral portions of the left ventricle and detects myocardial ischemia
is this a normal waveform?
Yes.
A classic pic of some room air being entrained because you have a leak in that tubing.
What else could cause a decrease in the EtCO2 reading from normal to a sudden low value?
PE
What is the formula for MAP?
what does it signify?
What effect would Carboxyhemoglobin (COHb) have?
What is the patient population that may have this?
COHb has an absorption spectrum similar to oxyhemoglobin (940 nm) so most pulse oximeters will overread the SpO2 in smoke inhalation patients –> falsely high readings
Toxicity: cherry-redappearance(latesign!)
What is an indicator of a good EtCO2 reading?
GOOD ALVEOLAR PLATEAU
This is used to determine the adequacy of neuromuscular blockade intraoperatively and adequacy of relaxant reversal postoperatively
Peripheral Nerve Stimulation (PNS)
Neuromuscular monitoring
What type of patient would you change your high CO2 alarm?
COPD –> baseline is higher CO2
Chronic Sleep Apnea
- patient safety, normalization of deviants -
ON PHASE II : What does points B to C represent?
capnography
B to C
That’s when we’re beginning to see the patients beginning to empty from all their connecting airways, going through their bronchi.
And it’s getting all the way down to the Alveolar
On BIS numerical display when do we know general anethesia?
General anesthesia is within 40 -60
What is the characteristic of a normal capnogram
- Rapid increase from B to C
- Nearly horizontal plateau between C and D
- Rapid decrease from D to E to zero
- Zerobaseline(E to A and Ato B)
Full onset NMB is faster among these muscles?
Full onset of NMB is faster in the:
Masseter muscle
Adductor pollicis
Muscles of the foot
Centrally located muscles (diaphragm, facial, rectus abdominis, laryngeal adductors, and orbicularis oculi)
Does pulse oximetry need recalibration?
LED’s provide monochromatic light; this means they emit a constant wavelength throughout life, so once calibrated, they never need recalibration
What is the correct size of cuff/bladder size?
why is this important?
What will be the blood pressure reading if the cuff is too small for an obese patient?
◦ As the site becomes more peripheral, the SBP increases and DBP decreases
- Cuff/bladder size influences the pressure measured
◦ Cuff should be 40-50% of the circumference of the limb with a length that is 80-100% of the circumference will provide accurate readings
◦ Too small cuff will reflect falsely higher pressure and too large cuff falsely lower pressure
- Obese patients: if the cuff is too small, the pressures will be falsely elevated
