ABSTRACT
The purpose of this study was to investigate the efficacy and safety of controlled hypotension versus ANH as blood conservation methods during major orthopedic surgery. Forty patients, assigned to receive either ANH [HT= 30%] or controlled hypotension. General anesthesia was induced by fentanyl 2micro gm/kg intravenously, thiopental Na 5mg/kg intravenously and atracurim 0.5mg/kg. After induction of anesthesia but before surgery, the patients were classified into two groups according to the technique of blood conservation used: group I [20 patients] acute normovolemic hemodilution. The volume of blood withdrawn has been replaced simultaneously by infusion of identical volume of hydroxyethyl starch 6% in order to maintain normovolemia. Group II [20patients]: controlled hypotensive anesthesia. A mean of 1000 ml blood was predonated [20% of the total blood volume] in hemodilutio group. Blood loss was, significantly higher in ANH group. The total loss was 1500mL [ANH] vs. 1200 mL [in hypotensive group], [p < 0.05]. The average amount of blood transfusion was 262.5 ml [ANH group] vs. 187.5 ml [hypotensive group]. 50% went through surgery without receiving blood [ANH] vs. 60% [hypotensive group]. No renal, neurological or cardiopulmonary complications were registered. Also there was slight but significant metabolic acidosis. The acidosis was metabolic in origin because PaCO2 was kept constant and [Bic] and [BE] decreased significantly and it was not lactic acidosis as serum lactate remains within normal limit. It is considered as hyperchloermic metabolic acidosis as serum chloride significantly increased. Both ANH and hypotensive anesthesia can be used safely in patients undergo major orthopedic surgery however, Deliberate hypotension was the most effective means of reducing intraoperative bleeding and the time for this procedure was shorter than for normovolaemic haemodilution combined with autotransfusion. Also there was slight but significant metabolic acidosis