Angiotensin-converting enzyme inhibition and blood pressure response during total intravenous anaesthesia for minor surgery

Background: This study investigates whether long-term treatment with an angiotensin-converting enzyme inhibitor (ACEI) impairs the haemodynamic regulation during total intravenous anaesthesia (TIVA) for minor surgery. Methods: In a prospective, two-armed observational study, 36 patients undergoing TIVA for minor surgery were studied. Seventeen were taking ACEIs regularly but no other antihypertensive medication (ACEI group); 19 patients without any cardiovascular medication served as controls (non-ACEI group). Haemodynamic variables were measured every minute during induction and every 5 min during surgery. The plasma levels of renin, angiotensin II, vasopressin and catecholamines were measured before and 18 min after the induction of anaesthesia. Results: The mean arterial pressure decreased to the same extent in both the groups during the induction of TIVA. There were also no differences between the groups regarding the heart rate, systolic and diastolic arterial pressure, as well as the use of vasoconstrictors, and fluids during induction and throughout surgery. In the ACEI group, the plasma renin concentration was higher at baseline and after the induction of anaesthesia presumably due to the interruption of the negative renin–angiotensin feedback loop (P