Abstract

BISHOP, D G; CAIRNS, C; GROBBELAAR, M  and  RODSETH, R N. Obstetric spinal hypotension: Preoperative risk factors and the development of a preliminary risk score - the PRAM score. SAMJ, S. Afr. med. j. [online]. 2017, vol.107, n.12, pp.1127-1131. ISSN 2078-5135.  http://dx.doi.org/10.7196/samj.2017.v107i12.12390.

BACKGROUND. Obstetric spinal hypotension is a common and important problem during caesarean delivery. Identifying patients at risk for hypotension may guide clinical decision-making and allow timeous referral. OBJECTIVE. Using preoperative risk factors, to develop a simple scoring system to predict systolic hypotension. METHODS. This prospective, single-centre, observational study of patients undergoing elective or urgent caesarean delivery assessed body mass index, baseline heart rate, baseline mean arterial pressure (MAP), maternal age, urgency of surgery (elective v. non-elective) and preoperative haemoglobin concentration as predictors of spinal hypotension (systolic blood pressure <90 mmHg). We used empirical cut-point estimations in a logistic regression model to develop a scoring system for prediction of hypotension. RESULTS. From 504 eligible patients, preoperative heart rate (odds ratio (OR) 1.02, 95% confidence interval (CI) 1.00 - 1.03; p=0.012), preoperative MAP (OR 0.97, 95% CI 0.95 - 0.98; p<0.001) and maternal age (OR 1.05, 95% CI 1.02 - 1.08; p=0.002) were found to be predictors of hypotension. We derived a preliminary scoring system (pulse rate >90 bpm, age >25 years, MAP <90 mmHg - the PRAM score) for the prediction of systolic hypotension following obstetric spinal anaesthesia. Patients with three factors had a 53% chance of developing hypotension, compared with the overall incidence of 30%. The PRAM score showed good discrimination, with a c-statistic of 0.626 (95% CI 0.576 - 0.676) and good calibration. CONCLUSIONS. Preoperative heart rate, preoperative MAP and maternal age were predictive of hypotension in elective and emergency caesarean delivery. The PRAM score shows promise as a simple, practical means to identify these patients preoperatively, but requires prospective validation.

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