Catecholamine and renin-angiotensin response during controlled hypotension induced by prostaglandin E 1 combined with hemodilution during isoflurane anesthesia

Abstract

Study Objective: To evaluate the catecholamine and renin-angiotensin response during controlled hypotension combined with hemodilution in the clinical setting. Design: Randomized, prospective study. Setting: Inpatient surgery at Nagasaki Rosai Hospital. Patients: 30 ASA physical status I and II female patients scheduled for total hip arthroplasty. Interventions: Patients were randomly divided into three groups. Group A (N = 10) received hemodilution alone. Group B (N = 10) received controlled hypotension alone. Group C (N = 10) received hemodilution plus controlled hypotension. Hemodilution was carried out after induction of anesthesia, in which drawn blood was replaced with 6 % hydroxyethyl starch, and the final hematocrit value was approximately 22%. Controlled hypotension was induced with prostaglandin E 1 (PGE 1) to maintain mean arterial blood pressure at 55 mmHg for 80 minutes. Measurements and Main Results: Measurements included plasma renin activity (RA) and plasma concentrations of angiotensin-II (AG-II), aldosterone (AS), norepinephrine (NE), and epinephrine (EP). These indices were measured before hemodilution, after hemodilution, 80 minutes after starting hypotension, and 60 minutes after recovery from hypotension. Hemodilution alone caused no significant change in the values throughout the time course. Controlled hypotension alone caused significant increases in plasma concentrations of NE (+295%) and EP (+203%) at 80 minutes after starting hypotension, whereas it caused no change in plasma RA and plasma concentrations of AG-II and AS. Hemodilution plus controlled hypotension caused significant increases in plasma RA(+271%) and plasma concentrations of AG-II (+188%), AS (+199%), NE (+279%), and EP (+184%) at 80 minutes after starting hypotension. Conclusion: The combination of hemodilution and PGE 1 induced controlled hypotension causes significant responses, especially in a renin-angiotensin-aldosterone system under isoflurane anesthesia.