Induced hypotension for surgical repair of congenital dislocation of the hip in children.

The surgical repair of congenital dislocation of the hip was performed under normotensive anaesthesia (23 children) and hypotensive anaesthesia (52 children). Hypotension was induced with infusion of hypotensive agents such as trimetaphan or nitroglycerin during inhalation or neurolept-anaesthesia under careful monitoring of blood pressure, haematocrit and electrocardiogram. Blood replacement was done to keep hematocrit value above 30%. Blood loss was significantly less in hypotensive group (2.53 ml/kg/h) than that in normotensive group (4.53 ml/kg/h). Twenty one percent of patients in hypotensive group required blood transfusion with the rate of 3.3 ml/kg/h compared with 43% of cases in normotensive group with the rate of 4.4 ml/kg/h. Depending upon anaesthesia technique blood loss was greater in neuroleptanaesthesia (5.5 ml/kg/h) than inhalation (2.3 ml/kg/h) or epidural (2.1 ml/kg/h) anaesthesia. Urine output and laboratory data for liver and kidney functions were not different between normotensive and hypotensive group. The dose of hypotensive agents required to produce moderate hypotension for paediatric patients was much higher than that for adult. We consider that moderate hypotension is safe procedure if employed by well experienced anaesthetist with careful monitoring of blood pressure, Hct and ECG. Blood loss and requirement of blood replacement are significantly reduced with this technique.