How is a patient prepared for anaesthesia?
Initial Assessment
The anaesthetist makes an initial assessment by checking the following:
- Cardiovascular System
- Obesity - associated with a higher risk of complications during the operation
- Respiratory System
- Airway is checked for ease of intubation.
- Kidney Function
- Past Medical History
- Liver Disease
- Hepatitis Status
- HIV Status (if relevant)
The ASA Status (American Society of Anaesthetists scoring system I-IV) is then used to rate the patient's general health.
Premedication
Most commonly no medication is used, but medication can be given in the following circumstances:
- Benzodiazepines for the anxious patient
- H2 receptor antagonists for the prevention of aspiration pneumonitis. The medication is given both the night before and the morning of the operation.
- Topical local anaesthetic can be used at sites of venous cannulation for children and adults with needle phobias.
- Anti-cholinergic agents to dry secretions or to prevent bradycardia.
- Analgesics for pain relief.
- Oral drugs for effect in the postoperative period.
Pre-operative Factors
- Most patients are starved for at least four hours before their operation. The aim of this is to decrease the volume of secretions to reduce the risk of aspiration.
- It is important to monitor the fluid status of children as they are at greater risk of dehydration (they are more susceptible to fluid and heat loss).
- It is important to correct any electrolyte disturbances.
- Smoking before the operation is associated with several peri-operative problems such as excessive sputum production, bronchospasm, coughing and increased carbon monoxide in the blood.
- Obesity is associated with an increase in morbidity and makes every technical procedure more difficult.