Avoiding bladder catheterisation in total knee arthroplasty: Patient selection criteria and low-dose spinal anaesthesia

Background: Bladder catheterisation may be inconvenient for patients, delay mobilisation and risk complications. We hypothesised that by excluding pre-operatively patients at high risk of post-operative urinary retention, the majority of patients could avoid perioperative catheterisation during low-dose spinal anaesthesia. Methods: Patients undergoing total knee arthroplasty were assigned if fit for spinal anaesthesia and without severe symptoms of lower urinary tract obstruction, gross incontinence, mobilisation difficulties hindering micturition and > 200 ml residual urine volume. Bladder volume was monitored by ultrasound and temporary catheterisation advised if > 400 ml. Results: Fifty-two patients (men 54%, age 65 ± 9 years, body mass index 31 ± 5, 30% with history of urinary tract problems) were included. Intrathecal hyperbaric bupivacaine given was 7.8 ± 1.08 mg and always 7.5 mg sufentanil providing sufficient anaesthesia in all cases. Crystalloid given during surgery was 8.5 ± 4.0 ml/kg. Voluntary micturition was reached by 46 patients (88%, confidence interval (CI) 79-97%), but six (12%, CI 3-21%) needed temporary catheterisation once (four men/two women). Larger bladder volumes were found in those catheterised than those with voluntary micturition on the pre-operative (131 ± 76 ml vs. 68 ± 57 ml, P = 0.03) and first post-operative bladder scan (445 ± 169 ml vs. 271 ± 129 ml, P = 0.004). All but two patients (96%) could be mobilised the same day. No patient suffered bladder dysfunction. Conclusion: Low-dose spinal anaesthesia combined with simple selection criteria allowed for early mobilisation (96%) and avoidance of bladder catheterisation in the vast majority (88%) of patients undergoing total knee arthroplasty, and the rest (12%) only needed a single temporary catheterisation.