Plasma renin-angiotensin activity [PRA] and cardiovascular responses during deliberate hypotention

ABSTRACT

A safe hypotensive technique should be easy to control, doesn't alter vital organ blood flow and can suppress or prevent increase in plasma renin angiotensin [PRA] and its untowards effects, The aim of this work is to demonstrate if PRA level differ according to the hypotensive agent used in two comparable groups using either sodium nitroprusside-trimetaphan mixture 110 [TNP] G I or isoflurane 0.75-4% G II as a method for deliberate hypotension and to demonstrate which of them is the more acceptable technique. 60 adult patients ASA class I or II were included in the study. The study showed that TNP mixture was effective as isoflurane in inducing rapid and smooth hypotension it was more rapid same for the recovery time. The mean arterial blood pressure were maintained with insignificant increase in heart rate for both groups all over the hypotensive period. No significant changes observed in ECG, blood gases [PaO2, PaCO2, SaO2], acid base [pH, BE, HCO3], or heamatological parameters [HB%, bleeding time, platelet count, clot retraction, prothrombin concentration]. Plasma renin activity [PRA] showing a significant rise in both groups [group I] 77.6%, [group II] 88% rising more for the isoflurane group denoting less control. So PRA level can be used as a reflection of resistance mechanism for induced hypotension and may aid a bit how to manipulate the used dose of the hypotensive agent. TNP mixture have been shown to produce lower levels of PRA increase, with no signs of resistance, or tachyphelaxis seen with isoflurane [two cases], with a cheaper price