[Angiotensin converting enzyme inhibitors in controlled hypotension during spinal surgery]

Controlled hypotension is an advantage during spondylosurgical operations: the objective is to achieve a mean arteriae pressure of 8 kPa (60 mm Hg). The most frequently used 0.01% solution of sodium nitroprusside must be increased in some patients to amounts which involve the risk of intoxication. This applies to patients with an increased sympathoadrenal activity and ready mobilization of the renin-angiotensin system. The objective of the present investigation was to test the inhibitor of the angiotensin converting enzyme in hypotension controlled by nitroprusside.

To twenty patients before a spondylosurgical operation as premedication angiotensin converting enzyme inhibitor (ACE)--captopril--was administered, 25 mg by the oral route. The control group was formed by 20 patients with spondylosurgery under controlled hypotension with nitroprusside administration. The effect of captopril was manifested by a reduced amount of nitroprusside needed to maintain the median pressure of 8 kPa; in the captopril group 1.073 +/- 0.52 microgram.kg-1.min-1 was used, as compared with 1.786 +/- 1.04 micrograms.min-1 in the control group (p < 0.01). Concurrently monitored values of plasma renin activity were higher in the patients given captopril: 7.352 +/- 5.75 nmol.l-1, as compared with 5.583 +/- 3.73 nmol.l-1 (p < 0.05).

Premedication with ACE inhibitor (captopril), even when administered in small doses via p. o., reduced the sodium nitroprusside consumption by as much as 60%. The elevated plasma renin values were objective evidence of the effect of captopril.