Low-dose spinal bupivacaine for total knee arthroplasty facilitates recovery room discharge: a randomized controlled trial

Purpose Regional anesthesia is the preferred technique for total knee arthroplasty to provide a bridge for early postoperative analgesia, reduce opioid consumption, and improve mobility and rehabilitation. Multiple patient and process factors must be weighed when choosing the appropriate technique to reduce morbidity and facilitate discharge. We hypothesized that a low-dose of intrathecal bupivicaine combined with regional block would facilitate discharge from the postanesthesia care unit (PACU) and reduce postoperative morbidity. Methods Patients undergoing total knee arthroplasty under spinal anesthesia received either 5 mg (low-dose group) or 10 mg (standard-dose group) isobaric bupivacaine in a double-blind randomized controlled trial. The primary outcome measure was time to achieve eligibility for PACU discharge. Secondary outcome measures included time to recovery of S2 dermatome sensation, time to voiding, rate of bladder catheterization, and time required for nursing intervention in the PACU and after discharge to the surgical ward. Results Forty-five of the 49 recruited patients completed the study. Patients receiving low-dose spinal anesthesia were eligible for PACU discharge earlier than those receiving the standard dose ( P = 0.0036). Patients receiving the standard dose had significantly delayed recovery of S2 dermatome sensation ( P = 0.0035). There was no difference between groups in the amount of time required for nursing intervention in the PACU, but patients receiving low-dose spinal anesthesia required more time for nursing intervention within the first four hours of their arrival on the ward ( P = 0.009). None of the patients required intraoperative analgesic supplementation. Conclusions In patients undergoing total knee arthroplasty, low-dose intrathecal bupivacaine (5 mg) combined with regional block is associated with a reduced time to achieve eligibility for discharge from the PACU.