Week 2- Monitoring In Veterinary Anaesthesia Flashcards
What is the main aim of monitoring in veterinary anaesthesia?
- Maintain an adequate anaesthesia depth
- Assess the adequacy of analgesia
- Maintain the function of different body systems
- Identify changes/ issues
- Evaluate treatment response
How often should you record vital signs on the anaesthetic record?
at least once every 5 minutes
It is used as a source of info for future anaesthetics
How would you monitor the central nervous system during anaesthetic?
- Eye position and Movement
- Jaw tone
- Vagal tone
- Anal tone
- Pedal reflex
- Righting reflex
What is the purpose of monitoring the central nervous system?
To ensure an adequate anaesthetic level
What plane are you aiming for during anaesthesia?
Stage III, plane 2
What does the light anaesthetic plane look like?
- Eyes in central position
- Palpebral reflex
- Mild/ Strong Jaw Tone
- Possible Movements
What does the surgical plane look like?
- Eyes are rotated in the ventromedial position
- Palpebral reflex to no palpebral reflex
- Relaxed jaw tone
What does the deep plane look like?
- Eyes in the Central position
- No palpebral reflex
- No jaw tone
- No Movement
- RR and HR usually decrease
What three things do you observe when monitoring the respiratory system?
- Chest Movements
- Reservoir Bag Movements
- RR on monitor
What does a change in respiratory rate and pattern usually indicate?
Change in the depth of anaesthesia
What is Capnometry?
- Breath by Breath analysis of expired Co2
- Respiratory Rate
- FiCo2
What is FiCo2?
The Inspired Co2 Levels
should be zero
What is capnography?
Graphical representation of Capnometry through the respiratory cycle
What are the normal mercury levels in capnography?
35-45mmHg
What is Hypocapnia?
Mercury levels below 35mmHg
What is hypercapnia?
Mercury levels above 45mmHg
What are the benefits of Capnography?
- Non-Invasive, Continuous
- Early issue detection
What does capnography estimate?
- Arterial Co2
- Ventilation/ Perfusion missmatch
What does the alveolar dead space in capnography show?
Alveoli that are poorly perfused, this is larger in large animals
shows that there is more Co2 in the airways
What three things does capnometry give us information on?
- Metabolism
- Cardiac Output
- Alveolar Ventilation
- Anaesthetic Equipment
- Respiratory Rhythm
What is sidestream Capnography?
- Continuous gas aspiration
- Sample is carried away and analysed
What is mainstream capnography?
Directly connected, has no delay
Heavy
Can burning
Not usually used
What is the function of pulse-oximetry?
- Measures the degree of saturation of haemoglobin
- Calculates the amount of Oxy-Hb as a % of a total Hb
What is the normal range of haemoglobin in Pulse-Oximetry?
Normal range is 98%- 100%
What are the benefits of Pulse-Oximetry?
- Easy to use
- Non-Invasive
- Continuous measurements
- Detects hypoxaemia earlier than the human eye
Where can Pulse-Oximetry be positioned?
tongue, ears, prepuce, vulva, lips, toe web, skin flap…
How does Pulse-Oximetry Work?
- PULSE PLETHYSMOGRAPHY to detect pulse waveform
- INFRARED SPECTROSCOPY to detect absorption of light (red & infrared) by tissue under probe
What does a plethysmograph give additional information on?
Additional info on: * Vascular tone
* Perfusion
* Fluid responsiveness * Pulse deficits/variation during arrhythmias
What three leads do you use in an ECG?
Both arms and left leg
* Paws, axilla, inguinal region, ears
What is the most common ECG lead for monitoring?
Lead II (Right Shoulder to left leg)
What is the equation for blood pressure?
Force of blood flow/ Area (of the arterial wall)
Name three reasons why we care about Mean Arterial Pressure?
- Indirect indicator of Tissue perfusion
- Anaesthetic drugs depress autoregulatory mechanisms
- Start treatment if MAP< 70 mmHg & SAP <90 mmHg
How do you measure arterial blood pressure (non-invasive)
- Oscillometric devices
- HDO device
- Doppler
How do you measure arterial blood pressure (invasive)
gold standard
- Arterial Cannula placement
- Different locations in different species
- Accurate, reliable, beat to beat monitoring
- Can be challenging
- Signs of asepsis
Where should a BP cuff be placed?
distal limb or tail, cuff as close as possible to the level of the right atrium
What should the width of the BP cuff be?
30-40% of the circumference of anatomical location where the cuff is applied
What is the effect of making the BP cuff too big?
underestimation
What is the effect of making the BP cuff too small?
Over estimation
What are some technical errors that may cause a decrease in the CO2 on capnography?
- Disconnection
- Sampling leaks or blockage
- ET tube obstruction
What are some technical errors that may cause an increase in CO2 on capnography?
- Exhausted CO2 absorber
- Inadequate fresh gas flow
- Faulty valves
- Hypoventilation
What is einthovens triangle?
arrangement of the three electrodes used to record an ECG
