Patient monitoring Flashcards
Why is it key to monitor the cardiovascular system during anaethesia?
Ensuring tissue oxygen delivery
A palpatable pulse is indicative of what?
Tactile arterial pressure
Mucous membrane colour represents what?
Blood oxygenation and tissue perfusion (vasoconstriction)
Capillary refill time indicates what?
Peripheral perfusion, indicator of dehydration
Arterial blood pressure can be calculated how?
ABP = SV X HR X SVR
SVR
Systemic vascular resistance
What is the normal value of blood pressure? (SAP, DAP, MAP)
SAP - 120, DAP - 60-70, Mean - 80-90 mmHg
What are the possible side effects associated with hypo and hypertension?
Hypo - reduced organ perfusion, Hyper - organ damage. (Brain, kidney, liver, eyes)
How can a patients effective breathing be assessed?
Assessing: rate, rhythm, depth (TV), mucous membrane colour
What may cyanotic MMs indicate?
Poor tissue oxygen delivery
What may brick red MMs indicate?
Hypercapnia, endotoxaemia
What is dead space air?
Volume of inspired air which does not participate in gas exchange (within the URT, trachea and ET tube)
A high PaCO2 value indicates what?
Indicate hypercapnia which in turn suggests hypoventilation. visa versa for low PaCO2
Ventilatory failure is defined as…
The clinical state produced when PaCO2 rises quickly enough to produce an immediate life-threatening situation. PaCO2 > 60mmHg (HYPOVENTILATION)
Oxygenation failure is defined as…
Acute respiratory distress resulting in PaO2 less than 60mmHg breathing room air (21% O2) (HYPOXEMIA)
V
Perfused but not ventilated (atelectasis/oedema)
V>Q
Ventilated but not perfused (pulmonary embolism)
Pulse oximeters measure what?
Measures the saturation of Hb with oxygen
Doppler and oscillometric methods of blood pressure are examples of invasive or non-invasive?
Non-invasive
Dopplers are able to measure which measure of blood pressure?
Systolic arterial pressure ONLY
Oscillometric methods of measuring blood pressure allow measurement of which blood pressures?
SAP, DAP, MAP and HR
How does direct arterial blood pressure measurement work?
Cannulation of a peripheral artery (dorsal metatarsal/ facial), connected to a pressure transducer which converts pressure signal to an electrical signal, attached to monitor.
How can anaesthesia induced hypotension be treated?
Reduce anaesthetic depth, fluids, positive inotropes, vasoconstrictors (also reduced perfusion), ventilation
What does central venous pressure measure?
A measure of hydrostatic pressure within the thoracic vena cava (indicates volaemia)
When measuring central venous pressure where is the catheter inserted into?
Through the jugular vein the catheter is inserted into the right atrium
What measure of respiratory efficiency is the best for measuring gaseous exchange in the lungs?
Arterial blood gas tension (PaCO2). Can be measured using capnometry/capnograph.
What is the difference between readings of capnometers and capnographs?
Capnometers only give a value for ETCO2 whereas capnographs also give a continuous plot of CO2 against time.
Describe the four phases which can be seen on a capnograph trace.
1 - inspiratory baseline (should be 0), 2 - expiration, 3 - expiratory plateu (peak CO2 at end), 4 - inspiration
If the inspiratory baseline of a capnograph is not at zero what would this indicate?
The animal is rebreathing CO2 - check soda lime, increase free gas flow, check the pressure limiting valve
What does an increasing ETCO2 on a capnograph indicate?
Hypoventilation - decrease anaesthetic depth, start IPPV, endobronchial intubation
Sudden zero ETCO2 on the capnograph may indicate what?
Apnoea/ disconnection
Oscillations during the inspiration phase of a capnograph trace may indicate what?
Cardiogenic oscillations - NORMAL
Describe pulse oximetry.
Utilises Lambert-beer law. OxyHb absorbs more infrared light, DeoxyHb absorbs more red light.
What SpO2 value is aimed for during anaesthesia?
> > 90% (98%), should be 100% when oxygen is supplemented
