Changes in cardiac index and blood pressure on positioning children prone for scoliosis surgery

In this prospective observational study we investigated the changes in cardiac index and mean arterial pressure in children when positioned prone for scoliosis correction surgery. Thirty children (ASA 1-2, aged 13-18 years) undergoing primary, idiopathic scoliosis repair were recruited. The cardiac index and mean arterial blood pressure (median (IQR [range])) were 2.7 (2.3-3.1 [1.4-3.7]) l.min(-1).m(-2) and 73 (66-80 [54-91]) mmHg, respectively, at baseline; 2.9 (2.5-3.2 [1.7-4.4]) l.min(-1).m(-2) and 73 (63-81 [51-96]) mmHg following a 5-ml.kg(-1) fluid bolus; and 2.5 (2.2-2.7 [1.4-4.8]) l.min(-1).m(-2) and 69 (62-73 [46-85]) mmHg immediately after turning prone. Turning prone resulted in a median reduction in cardiac index of 0.5 l.min(-1).m(-2) (95% CI 0.3-0.7 l.min(-1).m(-2), p=0.001), or 18.5%, with a large degree of inter-subject variability (+10.3% to -40.9%). The changes in mean arterial blood pressure were not significant. Strategies to predict, prevent and treat decreases in cardiac index need to be developed.