[Risk and hemodynamic instability in spinal anesthesia].
We investigated 131 consecutive patients who were submitted to orthopaedic surgical interventions under spinal anaesthesia during a period of 12 months. Prior to operation, all of the patients were classified according to the Boston Cardiac Risk Index. Immediately before operation, approximately 500 ml sodium chloride solution was infused. Patients were registered as haemodynamically unstable when a peroperative fall in the mean arterial pressure of more than 30% occurred or when the systolic blood pressure fell to less than 80 mmHg. In 40 patients, haemodynamically unstable conditions developed peroperatively while 91 were haemodynamically stable. In Boston group III, 67% of the patients were haemodynamically unstable peroperatively which was significantly more than in the Boston group I (25%) and the Boston group II (32%) (p less than 0.005). The postoperative mortality was significantly higher (13%) among the total number of peroperatively haemodynamically unstable patients than among the peroperatively stable patients (3%) (p less than 0.05). In Boston group III, the postoperative mortality was 42% as compared with 1% and 7% in the Boston groups I and II, respectively (p less than 0.05). It is concluded that the risk of fall in blood pressure during spinal anaesthesia may be predicted by the Boston Cardiac Risk Index and that patients who develop haemodynamic instability during spinal anaesthesia have an increased risk of developing complications. These patients should be offered maximal postoperative observation and care.