Support and Monitoring (keeping alive and still) Flashcards
Describe a monitoring record
Legal document Fill in details before you start (saves time) Record exact mg of drugs given Assess risk for patient Record as many parameters as possible Note events occurring Assess recovery and analgesia
Describe three ways in which pulmonary activity can be monitored during anaesthesia
Spirometry is reliable and shows whether ventilation is within acceptable limits (uncommonly used) Minute volume 100-300ml/kg/min Tidal volume 7-10ml/kg
Blood gas analysis (tells us about the partial press of gasses in the blood) capnography (tells us about the vol. of CO2 that is being respired) are superior
Respiratory flow & airway pressure can be measured and airway compliance (advanced monitors – pressure volume loops)
Describe delivery of oxygen
Delivery of oxygen = how much oxygen is being carried to the tissues by how much blood pressure
What are the limitations of pulse oximetry
low heart rates
probe design
How does a pulse oximeter work?
Probe (transmitter and receiver of IR and red light transilluminates a pulsatile arteriolar bed) different absorbtion levels between haemoglobin and oxyhaemoglobin
Computer software analyses absorption of light
Oxyhaemoglobin & reduced haemoglobin absorb more IR and red light respectively
A ratio is calculated corresponding to % haemoglobin saturated with oxygen
Describe doppler blood pressure monitoring
Set up takes a few minutes
Piezoelectric crystal placed over artery (clip fur off, use gel)
Locate artery with distinct noise of arterial pulse
Cuff placed proximal to probe
Cuff size must be accurate
Audible signal v useful
Systolic pressure only
Describe non invasive blood pressure monitoring
Cuff size must be accurate Unreliable in cats & small dogs Quite expensive More accurate methods available High definition oscillometric devices– the future?, fast can cope with high HR & poor perfusion but clinically poor
Describe invasive blood pressure monitoring
Invasive blood pressure monitoring
Artery cannulation
Auricular, dorsal pedal, facial arteries most commonly used
Must label catheter, line & flush regularly (hep saline)
Never inject any other drugs
Tubing must be narrow bore and non compliant to amplify signal
Describe the process for monitoring Central venous pressure
Long jugular catheter
Indicates filling pressure of the heart
Affected by contractility and circulating blood volume
Useful for fluid therapy
Must have several readings to discern trend
What do the results of Central Venous Pressure monitoring tell us?
↑ CVP = failing heart or volume overload
↓ CVP = haemorrhage, blood pooling or inadequate fluid therapy
Describe how a capnometer and capnograph works and what it monitors
Capnometer measures concentration of CO2 in the breath
Capnograph plots conc. CO2 with time
Carbon dioxide measured by
infrared, Raman scatter, mass spectroscopy
main stream, side stream sampling
What assumption does capnography make?
Assumption - alveolar CO2 approximates arterial CO2
What may an increased CO2 reading on a capnograph tell us?
rebreathing fresh gas flow rates exhaustion of soda lime changes in dead space depth of anaesthesia hypoventilation pyrexia
What may a decreased CO2 reading on a capnograph tell us?
Disconnection (check circuit) Mis-intubation ?? Circulatory failure Hypotension Cardiac arrest Hyperventilation
Why is it important to measure temperature of an anaethetised patient?
Anaesthetised and critical patients unable to regulate temperature: Reduced shivering Vasodilation Reset thermoneutral point Behavioural modification Open body cavity Cold gases Dry gases in the form of ventilation Wetting and prep
