P031: LIPOSOMAL BUPIVACAINE, AN OVERDOSE?
Gabrielle C Castella, Dr1; Hassan Iqbal, Dr1; Andres Missair, Dr2; Joshua Livingstone, Dr2; 1Jackson Memorial Hospital- University of Miami; 2Bruce W. Carter VA Medical Center
Introduction: There has been a growing effort by anesthesiologists to provide opioid reducing multimodal pain control regimens. We present management of a liposomal bupivacaine overdose in a post-operative patient following bilateral subpectoral interfacial plane (SIP) nerve blocks in a large tertiary care center.
Case Description: 59-year-old male with a past medical history of coronary artery disease, hypertension, human immunodeficiency virus, and obesity admitted to the surgical ICU post-operatively following three-vessel coronary artery bypass. On post-operative day one (POD#1) Acute Pain Service (APS) was consulted for placement of bilateral SIP nerve blocks for post-operative pain control. Upon completion of the block, it was noted the patient received a non-diluted preparation of liposomal bupivacaine 1.3% 20 mL per side: 520 mg total dose in place of 260 mg. Following administration patient remained at baseline vital signs and normal sinus rhythm during and after the procedure. A serum bupivacaine level was ordered at 0, 24, and 48 hours. Despite the lack of patient reported symptoms or observable signs of local anesthetic systemic toxicity (LAST), the decision was made to prophylactically administer 100mL bolus of Intralipid 20%. The patient was then started on Intralipid 20% infusion of 0.25 mL/kg/hr for 48 hours. Peak serum bupivacaine levels have been shown to be between 12-36 hours after injection (Bramlett et al). Following block the patient reported well controlled analgesia. Throughout the post-operative period, no symptoms of LAST, cardiac dysrhythmias or cardiotoxicity related adverse events were reported. Patient remained under ICU care for 96 hours and followed a normal hospital course and was discharged from the hospital.
Plasma Bupivacaine Level:
0 Hours post block: undetectable
24 Hours post block: 0.2 ug/mL (200 ng/mL)
48 Hours post block: 0.5 ug/mL (500 ng/mL)
Discussion: Given the proximity of the block to significant cardiovascular structures and the potential development of systemic LAST we used a low dose intralipid infusion to pretreat hypothetical spikes in bupivacaine plasma concentrations. The peak serum bupivacaine concentration remained below the toxicity threshold (2.5 ug/mL or 2500 ng/mL) while on a low dose infusion of Intralipid 20%. However, this preemptive conservative management may have been unwarranted given the safety profile of liposomal formulations and their characteristic delayed release. Dosing studies by Naseem et al. demonstrated that liposomal bupivacaine does not reach cardiotoxic serum concentrations for doses up to 532 mg. Further examples are described by Bramlett et al. who compared various doses of liposomal bupivacaine for intra-articular injection/infiltration. Doses ranged from 133-mg to 532-mg. Patients who received a dose of 532-mg had statistically significant improved pain and satisfaction scores. Additionally, the peak plasma concentration for patients who received 532-mg was found to be 0.925 ug/mL at 36 hours. Given our patient’s peak plasma concentration was 0.5 ug/mL, compared to 0.925 ug/mL in the aforementioned study, we can infer treatment with a low dose Intralipid infusion may have decreased the peak concentration level by about half. Our report re-demonstrates the safety profile of liposomal bupivacaine for injections performed near the heart, lungs, and around vascular structures.