Among the many roles that the anaesthetist has, risk assessment and risk modification are perhaps the most important. In order to manage peri-operative risk, the anaesthetist must have an understanding of the impact of co-existing medical conditions and concomitant drug therapy on normal physiology, and an appreciation of their likely interactions with both anaesthesia and surgery. When conducted effectively, pre-operative assessment decreases the risk of cancellations on the day of surgery and has the potential to reduce peri-operative morbidity and mortality.
Taking a detailed medical history and performing a competent physical examination remain the most efficient and effective ways of predicting and detecting significant co-morbid conditions. Pre-operative investigations should therefore be considered an adjunct to, rather than a substitute for, basic medical vigilance. Many pre-operative clinical investigations are justifiable on the grounds that they aid diagnosis (e.g. CT scan), assist in surgical planning (e.g. coronary angiography), permit more accurate risk stratification (e.g. exercise testing), guide risk-modification strategies or provide a ‘baseline’ before major surgery. A significant number of tests, however, are ordered ‘routinely’ without any clinical indication or justification.