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Obstetric spinal hypotension: Preoperative risk factors and the development of a preliminary risk score – the PRAM score

D G Bishop, C Cairns, M Grobbelaar, R N Rodseth

Abstract


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.

 


Authors' affiliations

D G Bishop, Metropolitan Department of Anaesthetics, Critical Care and Pain Management, School of Clinical Medicine, Nelson R Mandela School of Medicine, College of Health Sciences, University of KwaZulu-Natal, Pietermaritzburg, South Africa

C Cairns, Metropolitan Department of Anaesthetics, Critical Care and Pain Management, School of Clinical Medicine, Nelson R Mandela School of Medicine, College of Health Sciences, University of KwaZulu-Natal, Pietermaritzburg, South Africa

M Grobbelaar, Metropolitan Department of Anaesthetics, Critical Care and Pain Management, School of Clinical Medicine, Nelson R Mandela School of Medicine, College of Health Sciences, University of KwaZulu-Natal, Pietermaritzburg, South Africa

R N Rodseth, Metropolitan Department of Anaesthetics, Critical Care and Pain Management, School of Clinical Medicine, Nelson R Mandela School of Medicine, College of Health Sciences, University of KwaZulu-Natal, Pietermaritzburg, South Africa; Outcomes Research Consortium, Cleveland Clinic, Ohio, USA

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Keywords

Anesthesiology; Obstetric; Spinal hypotension; Prediction; Caesarean section; Scoring system

Cite this article

South African Medical Journal 2017;107(12):1127-1131. DOI:10.7196/SAMJ.2017.v107i12.12390

Article History

Date submitted: 2017-11-27
Date published: 2017-11-27

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