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

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. 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. 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 μg 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. 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.