Check the patient's anaesthetic history and:

• Note details of previous anaesthetics and any problems encountered
• Examine previous anaesthetic charts if available because problems such as difficult airway should have been documented
• Note last exposure to halothane anaesthesia because repeat exposure within a 3-month period should be avoided unless specifically indicated

In the patient's family history there are a number of important hereditary conditions to look out for, such as:

• Malignant hyperthermia
• Suxamethonium apnoea
• Porphyria
• Haemoglobinopathies