Postoperative Ketamine May be Associated with Venous Thromboembolism in Chronic Opioid Users After Spine Surgery

Venous thromboembolism (VTE) is a serious postoperative adverse event after spine surgery. In patients with pain refractory to typical multimodal analgesia regimens after spine surgery, whom are often chronic opioid users, perioperative ketamine is an alternative analgesic that has grown in popularity. The aim of this study is to assess the risk of VTE in chronic opioid users undergoing spine surgery.

We conducted a structured query language search to identify patients with a diagnosis of VTE after spine surgery from 2017 to 2021. structured query language identified patient demographic information and chart review was performed to confirm procedure details, including levels fused and decompressed. Opioid use was identified using the Prescription Drug Monitoring Program for each patient. Chronic opioid users were defined as having >180 days or >9 opioid prescriptions prescribed in the 12 months prior to surgery.

A total of 322 patients were identified with complete Prescription Drug Monitoring Program and postoperative ketamine data, including 29 patients with confirmed VTE after spine surgery. Length of stay (P < 0.001) and Elixhauser comorbidity index (P = 0.008) were significantly greater in the VTE group compared to the no VTE group. Analysis of only chronic opioid users also found a significant association between postoperative ketamine and VTE (P = 0.034).

Our study found no association between chronic opioid use and VTE occurrence; however, we identified a significant association between ketamine infusion and VTE after spine surgery. Further studies should be conducted to identify the risks associated with ketamine and other newly implemented alternative analgesics.