Perioperative Monitoring of Patients Flashcards
Why do we have to monitor patients?
As the anaesthesic drugs compromise homeostasis.
Allows evaluation of physiological feedback to maintain desired level
Allows better and more precise anaesthesia to maintain amnesia, analgesia and immobilisation
What are the general physiological effects of anaesthesic drugs?
Hypotension Bradycardia Arrhythmia Myocardial depression Vasodilation or constriction Hypoventilation Hypoxaemia
Types of pulmonary patterns?
Tachypnoea
Cheyne-Strokes
Apneuistic
What does tachypnoea during GA indicate?
Too light or too deep anaesthesia Hypoxaemia Hypercapnia Hyperthermia Hypotension Atelectasis
What is Cheyne-Strokes?
Initially shallow and infrequent breathing, then deep and rapid before fading away for 5-30 seconds.
Normal in horses.
Sign of congestive heart failure and other cardiac/brain disorders
What is apneuistic?
Inspiratory hold.
Seen in healthy cats and dogs
Seen in most species anaesthetised with ketamine
Normal tidal volume?
10-20 ml/kg/respiration
Normal total minute ventilation?
150-250ml/kg/min
How are tidal volume and total minute ventilation estimated?
By reservoir bag inflation, ventilator and ventilometer
How is PaCO2 measured?
Arterial blood can be taken and measured with blood-gas analyser
Estimated by measuring end tidal CO2
How is end tidal CO2 measured?
Sample taken from breathing circuit at end of exhalation
Normal PaCO2 levels?
35-45mmHg
What causes PaCO2 to be low?
Hypocapnia
Hyperventilation
What causes PaCO2 to be high?
Hypercapnia Intercranial disease Airway obstruction Thoracic/abdominal restrictive disease Lung parenchymal disease Hyperthermia Wrong ventilator settings
Describe end tidal CO2 values?
Lower than PaCO2
If over 30-40mmHg - the animal will breathe on own
Should be kept at 25-30mmHg
Weaned off ventilator by gradually increasing to 30mmHg
What is PO2?
Measured oxygenating efficiency of the lungs
Oxygen dissolved in blood
Related to Hb saturation
Normal PO2 levels?
80-110mmHg
HR of anaesthetised cats and dogs?
Cat - 100bpm
Dog - 60 bpm
Depends on many factors!
Life threatening cardiovascular situations?
Tachycardia- 160-180bpm Bradycardia - <60-70bpm Arrhythmia - sinus, premature ventricular contraction Heart block Filbrillation
What is the central venous pressure?
Luminal pressure in the intrathoracic vena cava
How to measure blood pressure?
Indirectly, e.g. sphygometry, doppler, oscillometric
Directly - cannula attached to manometer
When should the endotracheal tube be removed?
When the swallowing reflex returns
When are the palpabral and corneal reflexes lost?
Stage 3 (plane 4)
Which reflexes are useful during anaesthesia?
Palpebral Swallowing Pedal Ear flick (cats) Corneal Laryngeal
