Acute normovolemic hemodilution versus controlled hypotensive anesthesia in major orthopedic surgery

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 The volume of blood withdrawn has been replaced simultaneously by infusion of identical volume of hydroxyethyl starch 6% in order to maintain normovolemia.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

Preoperative beta blocker induced controlled, hypotension for nasal surgery

The purpose of this study was to compare surgical conditions for nasal surgery under general anesthesia during controlled hypotension, using either preoperative oral beta blocker atenolol [50mg twice before surgery] or intraoperative infusion of sodium nitroprusside [SNP] or esmolol. Thirty patients, assigned to receive either of the drugs as the primary hypotensive agent, were studied. The same surgeon, blinded to the hypotensive agents used and the haemodynamic variables, performed all the operations. The surgeon used a category scale [0-5] to assess surgical conditions - a value of 2-3 being ideal. Patients were positioned in 15° reverse Trendelenburg position and the mean arterial blood pressure [MABP] was reduced in steps of 5 mmHg. The anesthetist prompted category scale estimations by the surgeon following a change in any of the haemodynamic variables. Average category scale [ACS] values were compared between the three groups. At mild sodium nitroprusside [SNP] induced hypotensive anesthesia surgical conditions were poor [ACS 3.8 +/- 0.53 mean +/- SEM], while in the atenolol and esmolol groups, ideal surgical conditions [ACS 2.7 +/- 0.74 and 2.8 +/- 0.63] were recorded at MABP > 60 mmHg. The combined effects of increased venous drainage due to the reverse Trendelenburg position, hypotension as well as capillary vasoconstriction due to unopposed alpha-adrenergic effect on the mucous membrane vasculature in the atenolol and esmolol groups [as opposed to vasodilatation in the SNP group] probably caused the superior surgical conditions. Preoperative oral Beta blocker was effective in reducing surgical bleeding during nasal surgery, provide good quality of surgical field, reduce operative time, simple in use, not need complex technique for infusion, more convenient for patients and save method for induce mild hypotensive anesthesia during nasal surgery