Monitoring During Anesthetic Flashcards
Induction
a systematic process of observing, tracking, and recording data
How often should you monitor?
every 5 minutes
What are the three stages of anesthesia?
Pre-operative
Intra-operative
Post-operative
What are the common methods of monitoring circulation?
Mucus membranes CRT Palpation of pulse Auscultation of heart beat ECG Systemic arterial blood pressure
ECG
recording of the heart electrical activity from the surface of the body
Electromechanical dissociation
When electrical activity is happening but not contracting
P wave
atrial depolarization
QRS complex
ventricular depolarization
T wave
ventricular repolarization
Mammalian A type
Purkinje fibers excite the endocardium only and excitement spreads via muscle fibers
Generating base to apex current flow
Seen in humans and small animals
Mammalian B Type
Purkinje fibers penetrate the myocardium and most of the myocardium is excited simultaneously
Generating apex to base current flow
Seen in horses, ruminants, pigs
Where do you place the white electrode on large animals?
Jugular furrow or withers
Where do you place the black electrode on large animals?
Cardiac apex
Where do you place the Red electrode on large animals?
anywhere else
What are the common arrhythmias under anesthesia?
Sinus bradycardia
tachycardia
AV blocks (1st and 2nd degree)
1st degree AV Block
Slow conduction through the AV node
2nd degree AV Block
intermittent conduction through the AV node
3rd degree AV Block
No conduction through the Av node
What is the first line of treatment for ventricular arrhythmias?
Lidocaine IV
Systolic pressure
highest point of the BP curve; represents afterload for the left ventricle
Mean Pressure
average BP over a full cycle; determinant of tissue perfusion
Diastolic Pressure
lowest point of the BP curve; determinant of myocardial perfusion
What is the definition of hypotension in small animals?
Mean: less than 60mmHg
Systolic: less than 80mmHg
What is the definition of hypotension in large animals?
Mean: less than 70mmHg
Systolic: Less than 90mmHg
What are the three treatments of hypotension?
Decrease anesthetic administration
Give Fluid bolus
Give Drugs
What is the equation for BP?
BP = (HR x SV) x SVR
SV (Stroke Volume)
depends on preload and contractility
What is the equation for Cardiac Output?
HR x SV
What are the crucial elements of CV function?
Heart Rate and Rhythm
Contractility
Circulating volume
Vasoconstriction
Invasive BP
continuously via arterial catheter
Non-invasive BP
intermittently using a pressure cuff
What are the most common types of non-invasive BP?
Oscillometric
Doppler
Where do you position the transducer in equine?
the level of the base of the heart
Oscillometric
arterial blood flowing under an inflated cuff generates pressure fluctuations in the cuff that is detected by the monitor
Doppler
An inflated cuff placed over an artery. Blood flow is detected distally from the cuff using a Doppler flow probe. After complete occlusion of flow, cuff pressure is gradually decreased. The pressure where the blood flow appears is systolic BP.
Where should the cuff be placed?
at the level of the base of the heart
What are the advantages of oscillometry?
Provides systolic, mean, diastolic BP
Easy to place
Less labor intensive
Commonly integrated in complex monitors
Disadvantages of oscillometry?
May be inaccurate outside of normal BP range Below 10 kg BW Weak pulse During movement or arrhythmias
Advantages of using Doppler
Can measure BP on smaller animals too
Less sensitive for artifacts resulting from movement, arrhythmias and vasoconstriction
excellent pulse monitor
Disadvantages of using Doppler
Does not measure MAP
Noisy
Sometimes difficult to place
more labor intensive
How do you measure oxygenation?
Pulse oximeter
blood gas
Hypoxemia
Reduction of oxygenation of arterial blood
PaO2
When do you use a pulse oximeter?
patient is breathing room air
this is a V/Q mismatch
there is respiratory disease
Normal PaO2
35-45mmHg
PaCO2 greater than 45mmHg
Hypercapnia
Hypoventilation
PaCO2 at 35-45mmHg
normocapnia
normoventilation
PaCO2 less than 35mmHg
Hypocapnia
hyperventilation
Capnometry
Measurement of CO2 partial pressure in the airways
Capnometer
only measures the ET CO2
Capnograph
continuously displays ET CO2 vs. time on a graph
What factors influence ET CO2 values?
CO2 production
Circulation
Alveolar ventilation
Measurement error
What are the phases of a capnograph?
I. Baseline
II. Expiratory upstroke
III. Alveolar plateau
IV. Inspiration begins
Where do you place the Doppler sensor in a Small Ruminant?
Median Artery
Where do you place the Doppler sensor in the Donkey?
Tail