Predictors of post-spinal hypotension in elderly patients; a prospective observational study in the Durban Metropole

Aims and objective: To evaluate the pre-spinal risk factors for hypotension associated with spinal anaesthesia in elderly surgical patients. Summary of background data: Hypotension is associated with morbidity and mortality following noncardiac surgery. Reducing the incidence of hypotension associated with spinal anaesthesia may be associated with improved postoperative outcomes. Methods: This was a prospective, observational study, using convenience sampling. All patients over 55 years of age scheduled to receive spinal anaesthesia for lower limb surgery were eligible. Exclusion criteria included the need for resuscitation and/or the need for vasopressors prior to anaesthesia and surgery, and patients who declined spinal anaesthesia. The dosage of spinal anaesthesia and the use of intraoperative sedation were left to the attending anaesthesiologist. The primary outcome was hypotension, which was defined as a decrease in the systolic blood pressure by 25% from the baseline, or a systolic blood pressure below 100 mmHg. The following pre-spinal risk factors were assessed in a multivariable logistic regression for their association with spinal hypotension: age, American Society of Anaesthesiologists-Physical September 2019 Status, sex, dose of local anaesthetic, isobaric bupivacaine or bupivacaine with dextrose, baseline blood pressure, baseline heart rate and fluid preloading prior to spinal anaesthesia. Results: Three hundred and eighty-nine patients were recruited. The primary outcome of spinal hypotension was independently associated with female sex (odds ratio [OR] 1.97, 95% confidence interval [CI] 1.19–3.28), increasing dosage of bupivacaine (OR 1.14, CI 1.01–1.29), and the use of isobaric bupivacaine (OR 1.50, CI 0.95–2.36). Conclusion: Spinal hypotension was associated with female sex, increasing dosage of bupivacaine, and the use of isobaric bupivacaine.