Effects of angiotensin converting enzyme inhibition on systemic vascular resistance and vasoconstrictor requirements during hypothermic cardiopulmonary bypass.
OBJECTIVE
We proposed that angiotensin converting enzyme (ACE) inhibitor therapy would alter systemic vascular resistance (SVR) during rewarming and increase the requirement for vasoactive drugs in the immediate post-bypass period.


METHODS
Sixty-five sequential adult patients undergoing cardiac surgical procedures requiring hypothermic (28 degrees C) cardiopulmonary bypass (CPB) were recruited. Sixty-two fitted the inclusion criteria of which 21 were receiving ACE inhibitors prior to surgery. SVR was calculated at 1 min intervals during the rewarming phase of hypothermic CPB. The use of vasoactive drugs during and immediately after termination of CPB was recorded. The doctor administering these drugs was unaware of the nature of the study.


RESULTS
Mean SVR in the ACE group was 978 dyne/s per cm5 and in the control group was 1194 dyne/s per cm5 (P = 0.006). Mean arterial pressure was 48.8 mmHg in the ACE group and 56.3 mmHg in the control group (P = 0.004). There was a significant difference in vasoactive drug requirements between the groups (P < 0.01). There was no statistically significant difference in age, weight, body mass index, body surface area, theatre temperature, core temperature at which rewarming started, rate and time of rewarming, haematocrit on bypass or preoperative left ventricular function.


CONCLUSIONS
Preoperative ACE inhibitor therapy decreases SVR during the rewarming phase of CPB and increases post-bypass vasoactive drug requirements.
Deakin
C D
CD
Department of Anaesthetics, Southampton General Hospital, UK. cdeakin@compuserve.com
Dalrymple-Hay
M J
MJ
Jones
P
P
Monro
J L
JL
D000368:Aged; D000806:Angiotensin-Converting Enzyme Inhibitors / Q000494:pharmacology* / Q000627:therapeutic use; D002315:Cardiopulmonary Bypass; D001026:Coronary Artery Bypass; D019918:Heart Valve Prosthesis Implantation; D006801:Humans; D007036:Hypothermia, Induced; D008875:Middle Aged; D010865:Pilot Projects; D017694:Rewarming; D014655:Vascular Resistance / Q000187:drug effects*; D014662:Vasoconstrictor Agents / Q000627:therapeutic use*
D000806:Angiotensin-Converting Enzyme Inhibitors; D014662:Vasoconstrictor Agents