Notes on sedation and general anaesthesia

39 Notes on sedation and general anaesthesia

General Considerations

Successful management of the emergency patient frequently requires the use of sedative and anaesthetic drugs. However, it is in the emergency setting that the inherent risks and adverse effects of these drugs on patient physiology assume an increased significance and this should never be underestimated.

Potential risks of sedation and anaesthesia

See Tables 39.1 and 39.2.

Table 39.1 Potential adverse effects of anaesthesia on body systems

Body system Adverse effects



Renal Reduced renal perfusion
Hepatic Reduced hepatic perfusion
Gastrointestinal Increased risk of regurgitation and subsequent aspiration
Temperature Hypothermia

Table 39.2 Potential effects of patient condition on the course of anaesthesia

Patient condition Effect on anaesthesia
Cardiovascular compromise (e.g. hypovolaemia)

Respiratory compromise Reduced ventilation results in slower onset of inhalation anaesthesia and a slowed response to altered inhalation anaesthetic concentration
Central nervous system disease Reduced level of consciousness increases sensitivity to all sedatives and anaesthetic agents
Renal disease Reduced renal elimination of drugs, prolonging duration of effect
Hepatic disease Reduced hepatic metabolism of anaesthetic drugs, prolonging duration of effect
Hypoalbuminaemia Increases nonprotein-bound, active concentration of many drugs, increasing sensitivity to these drugs

Maximizing patient safety during general anaesthesia

13 Use a balanced anaesthetic technique for the maintenance of anaesthesia: use nitrous oxide in the gas mixture if it is safe to do so, timely opioid analgesia bolus or constant rate infusion (local anaesthetic techniques, muscle relaxants if familiar with their use). Minimize anaesthetic concentrations at all times.

Table 39.3 Being prepared for anaesthesia of critical patients

Anaesthetic aspect Equipment

Complications of intubation

Oxygen administration and ventilation Appropriate breathing circuit: if continuous IPPV anticipated, use T-piece for <10 kg, use Bain or Circle for >10 kg
Monitoring Pulse oximeter, ECG, blood pressure monitor, capnograph, thermometer or temperature probe, glucometer
Intravenous fluids

Temperature control

Emergency drugs Atropine, adrenaline (epinephrine), lidocaine (only indicated if there is continuous ECG monitoring to characterize nature of cardiac dysrhythmia)

ECG, electrocardiograph; ET, endotracheal; IPPV, intermittent positive pressure ventilation.

Sep 3, 2016 | Posted by in SMALL ANIMAL | Comments Off on Notes on sedation and general anaesthesia
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