Lecture 6: Anesthesia Monitoring Equipment (Exam 1) Flashcards
What ASA PS have a increased risk of death & severe hypothermia in dogs, cats, rabbits, & pigs
PS that is greater than or equal to a 3
What percent of anesthesia deaths occur post op
47-64%
When does anesthesia related death occur
- Up to seven days in horses
- W/in 48 H (small animals)
What is the general anesthesia related global morality rate of equine
- 1.4%
- 0.96% rate for non colic cases
List the 6 ACVAA monitoring guideline
- Ensure adequate BF (circulation)
- Ensure adequate arterial blood oxygenation
- Ensure ventilation is adequately maintained
- Ensure body temp doesn’t seriously deviate from norm
- Maintain legal record of significant events & enhance recognition of trends in monitored parameters
- Ensure responsible person is aware of px status @ all times during anesthesia & recovery & is prepared to intervene when needed or to alert the vet in change abt/ the changes in status
What are some basics to monitor
- Anesthetic depth signs
- HR, rhythm, & pulse quality
- RR & effort
- Noninvasive BP
- Temp
- MM color & CRT
- Pulse oximetry (SpO2)
- End tidal carbone dioxide (ETCO2) = capnography
What signs are used to determine anesthetic depth
- Eye position
- Muscle relaxation
- RR & pattern
- Response to stimulation
- Jaw tone & anal tone
What can be used to get the HR & rhythm of the px
- Palpate pulses or feel the heart beating
- Esophageal stethoscope (on small animal px)
- Ultrasonic doppler device to detect the sound of BF in the artery using the doppler shift priniciple
- ECG
- SpO2
What is pulse quality
- Subjective measurement of Cardiac output & tissue perfusion
- The diff in systolic & diastolic pressure
What are the site to get pulse quality on SA & LAs
- SA: femoral, dorsal pedal, radial, & lingual a.
- LA: Facial, transverse facial, metatarsal, digital, auricular, femoral, coccygeal a
What is an ECG
Summation of all the AP following the activation of the SA node & the heart
What does each part of the ECG represent
- P wave: atrial depolarization
- PR interval: AV node depolarization
- QRS: Ventricular depolarization
- ST segment: Time btw/ ventricular depol & ventricular repol
- T wave: Ventricular repolarization
What are the clinical uses for ECG besides HR & rhythm
- Morphology of wave to locate disease
- Cardiac oxygenation & adequate perfusion
- Electrolyte abnorms
How reliable is the ECG
- Pulseless electrical activity (PEA)
- Double counting
- Electrical interference
How do you place leads on a SA (lead II) for an ECG
- White lead -> Right elbow
- Black lead -> Left elbow
- Red lead -> Left stifle of abdomen
How do you place leads on a LA (lead 1 or base apex) for an ECG
- White lead -> Right jugular furrow
- Black lead -> left axilla region
- Red lead -> Any site remote from the heart
Describe base apex or lead 1
- Large neg R wave - electrical activity points away from + electrode
- Variable P wave morphology in horses
What is the reason for using this lead in LA
Accentuates the P wave so easier to identify changes in morphology
How can the RR & effort be obtained
- Observing the px thorax or the movement of the reservoir bag
- Esophageal stethoscope (passed to the level of the heart
- Various breathing freq monitors can be employed -> give off an audible “beep”
- Respirometer can be used to determine tidal vol (TV) & min volume
- Capnograph may also display RR
- Effectiveness of respiration assed by SpO2
What are the two main indirect methods to get an noninvasive BP
- Doble
- Oscillometric
- Photoplethysmography
Describe using a doppler
Use an inflatable cuff to occlude BF in an artery as the pressure in the cuff is released the doppler detects the return of blood flow by reflection of sound waves from moving RBC
What should the doppler reading be kept @ to ensure the px is not hypotensive
> 90 mmHg
How & where is the cuff/Doppler placed
- Cuff is proximal to where the doppler is place
- In line with the right atrium
What method best predicts the SAP in cats
- Oscillometric
- Doppler & OP provide accurate prediction of direct MAP
How is an oscilometric BP taken
Blood flow through the arteries causes vibration in the arterial wall -> translated to air in the BP cuff -> detected & transduced into electrical signals to produce a reading
What are the advantages & disadvantages of Doppler
- A: audible pulse rate & rhythm, able to quickly obtain SAP (1st sound heard)
- D: Some tech skills req to place, Doesn’t give you MAP or DAP, Not as accurate as direct BP (esp as px becomes hypotensive), & accuracy affected by selecting the correct cuff size
What are the advantages & disadvantages of oscillometric
- A: easy to place on limb, some can be set to run automatically, determines HR, SAP, MAP, & DAP
- D: Actual pressure reading takes longer than doppler & not as accurate as doppler (esp in hypotensive px, small px, px movement, arrhythmias, & vasoconstriction)
How can temp be monitored
- Rectal thermometer or temp probe positioned in esophagus, intranasally, or rectally
- Axillary is not considered accurate
Why is hypothermia common in SA
B/c of increased BSA compared to their body mass
What does MM color & CRT assess
Px perfusion
What MM color is norm
Pale pink or pink
What MM colors are abnorm
- Pale to white/gray
- Cyanotic
- Brick red
- Brown
- Yellow
- Petechiation
What is the norm CRT
1 to 2 sec
Describe SpO2
- Indirectly estimates % oxygen saturation of Hb
- Displays the pulse rate (plethysmograph)
- Device is applied over non-haired skin with pulsatile BF
- The probe can be placed on the tongue, prepuce, ears, & lips
- Red & infrared light are absorbed diff by oxygenated & reduced (deoxygenated) Hb. This diff is calculated & the % Hb saturation is displayed numerically
- Monitor contains emitter & photodector
- Two types of probes: Transmission & reflectance
What SpO2 shows sever hypoxemia
Spo2 of 90% = PaO2 of 60 mmHg
What is the ideal SpO2
> or equal to 95% = PaO2 of 80 mmHg (mild hypoxemia)
What effects the accuracy of SpO2
- Poor circulation due to vasoconstriction, hypotension, hypothermia
- Movement artifact
- Pigmentation
- Tissue thickness
- Anemia
- Carbon monoxide & cyanide poisoning (falsely high reading)
- Methemoglobinemia (reads in mid 80s)
- Ambient light
What is ETCO2
- Inspired & expired CO2 concentration measured by capnography
- Place sample adapter @ the end of the ETT where it connects to Y piece (side or mainstream)
- Slightly lower than PaCO2 (from ABG)
Increased ETCO2 = ?
- Hypoventilation
- Malignant hyperthermia
Decreased ETCO2 = ?
- Hyperventilation
- Decreased CO
- Disconnection
- Hypothermia
- Airway obstruction
How does ETCO2 work
- CO2 produced in cells from metabolism -> carried to the lungs -> exhales
- Relies on absorption of infrared light by CO2 molecules
- Concentration of CO2 determined by comparing measured absorbance w/ a known standard
Why is capnography is a useful tool
- RR & estimation of PaCO2
- Dx disconnection or leak, V/Q mismatch, alveolar dead space, bronchoconstriction, airway obstruction, decreased CO, return of spont circulation during CPR, Rebreathing of CO2, & determine if px is correctly intibated
How should monitoring be done in recovery
- Cont monitoring vital signs but not required to record on record unless adverse event or abnorm warrant documents
- Routine cases - just visual monitoring along w/ auscultation w/ a stethoscope & rectal temp are utilized
- Unstable cases or those @ risk of complications need cont monitoring in an ICU setting
- Remote vital sign monitoring systems are ava that can project px parameters to a larger screen visible to staff
Fill in the chart of the normal limit under gen anesthesia:
What are some advanced monitoring techs
- Invasive BP
- Blood gases & lactate
- Blood glucose levels
- Nerve stim
- Gas analyzer
- Pleth variability index
- Cardiac output
- Central venous pressure
- Urine 9ooutput
- Electroencephalogram (EEG) & Bispectral index (BIS)
- Co-oximety
