ACUTE BLOOD PRESSURE RESPONSE TO ANTIHYPERTENSIVES DURING ANESTHESIA IN AN EXPERIMENTAL MODEL OF PREECLAMPSIA

Introduction Increased blood pressure (BP), especially sudden, unexpected and severe rises in women with preeclampsia considerably increases the risk of peripartum complications. These risks are even more acute in the context of general anaesthesia. Objectives To assess the effects of antihypertensive drugs on short and long term blood pressure variability when used concurrently with propofol and ketamine anaesthesia. Methods Blood Pressure was measured during anaesthesia in six, pregnant Papio hamadryas (baboons) with experimental preeclampsia (EPE). Animals were given antihypertensives commonly used to manage preeclampsia (labetalol, methyldopa and hydralazine) at equipotent doses equivalent to mild starting dose rates commonly used in women with preeclampsia. Results When anaesthetised with ketamine (most commonly used anaesthetic agent in EPE), systolic BP increased significantly by 4.9 mmHg when animals were on labetalol ( n  = 3, p n  = 3, NS) and decreased by 4.9mmHg when animals were on hydralazine ( n  = 2, NS) as compared to systolic BP under ketamine anaesthesia prior to receiving any medication. With propofol anaesthesia (commonly used when anaesthesia required in women with preeclampsia), systolic BP decreased by 1.4 mmHg when animals were on labetalol ( n  = 3, NS), decreased by 7.2 mmHg when animals were on methyldopa ( n  = 2, NS) and increased by 2.8 mmHg when animals were on hydralazine ( n  = 3, NS) as compared to systolic BP during propofol anaesthesia prior to receiving any medication. Conclusion These results show that in the two anaesthetic agents studied so far the greatest reduction in BP was achieved with hydralazine during ketamine anaesthesia and methyldopa during propofol anaesthesia. It is likely that antihypertensive treatment affects blood pressure during anaesthesia, and that the interaction between antihypertensive and anaesthetic agent is of clinical importance in managing sudden, unexpected and severe rises in BP in women with preeclampsia.