Continuous pulse measurement and frequent arterial pressure assessment are important. An ECG is useful to detect ischaemia and dysrhythmias. For major surgery, central venous pressure monitoring and measurement of urine output may be useful. The aim is to ensure circulatory stability during surgery. All antihypertensive drugs should be taken preoperatively to assist in blood pressure control during surgery and recovery.
Many drugs used in the treatment of hypertension are vasodilators or cardiac depressants.
Since anaesthetic agents also have these actions, the effects on the circulation may be more noticeable. Care should be taken not to cause a precipitous fall in arterial pressure at induction. The use of opioids, such as morphine or fentanyl, will reduce the amount of induction agent required. Thiopentone may be used provided it is given slowly, and titrated against response. Ketamine, which raises the arterial pressure and heart rate, is best avoided.