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Supplemental digital content is available in the text., Background Over the past 2 decades, the use of intravenous ketamine infusions as a treatment for chronic pain has increased dramatically, with wide variation in patient selection, dosing, and monitoring. This has led to a chorus of calls from various sources for the development of consensus guidelines. Methods In November 2016, the charge for developing consensus guidelines was approved by the boards of directors of the American Society of Regional Anesthesia and Pain Medicine and, shortly thereafter, the American Academy of Pain Medicine. In late 2017, the completed document was sent to the American Society of Anesthesiologists' Committees on Pain Medicine and Standards and Practice Parameters, after which additional modifications were made. Panel members were selected by the committee chair and both boards of directors based on their expertise in evaluating clinical trials, past research experience, and clinical experience in developing protocols and treating patients with ketamine. Questions were developed and refined by the committee, and the groups responsible for addressing each question consisted of modules composed of 3 to 5 panel members in addition to the committee chair. Once a preliminary consensus was achieved, sections were sent to the entire panel, and further revisions were made. In addition to consensus guidelines, a comprehensive narrative review was performed, which formed part of the basis for guidelines. Results Guidelines were prepared for the following areas: indications; contraindications; whether there was evidence for a dose-response relationship, or a minimum or therapeutic dose range; whether oral ketamine or another N-methyl-d-aspartate receptor antagonist was a reasonable treatment option as a follow-up to infusions; preinfusion testing requirements; settings and personnel necessary to administer and monitor treatment; the use of preemptive and rescue medications to address adverse effects; and what constitutes a positive treatment response. The group was able to reach consensus on all questions. Conclusions Evidence supports the use of ketamine for chronic pain, but the level of evidence varies by condition and dose range. Most studies evaluating the efficacy of ketamine were small and uncontrolled and were either unblinded or ineffectively blinded. Adverse effects were few and the rate of serious adverse effects was similar to placebo in most studies, with higher dosages and more frequent infusions associated with greater risks. Larger studies, evaluating a wider variety of conditions, are needed to better quantify efficacy, improve patient selection, refine the therapeutic dose range, determine the effectiveness of nonintravenous ketamine alternatives, and develop a greater understanding of the long-term risks of repeated treatments.

Background and Objectives Butamben is a non-water-soluble local anesthetic that can be prepared as an aqueous suspension for nerve blocks. This report describes the use of 5% butamben suspension for the treatment of chronic pain of cancer and noncancer origin. Methods The clinical courses of 75 consecutive patients were analyzed following 5% butamben nerve blocks (35 epidural blocks only, 33 peripheral nerve blocks only, and 7 had both epidural and peripheral nerve blocks). Epidural blocks were performed as a series of four with additional blocks offered if needed. Peripheral nerve blocks were done as a single block with repeat injections if needed. Injection volumes varied between 15 and 25 mL for epidural injections and 5 and 20 mL for peripheral nerve blocks. Successful therapy was defined as a ≥75% reduction in subjective pain assessments for ≥4 weeks or until death. Daily opioid requirements were also recorded. Results Fifty-four of the 75 patients (72%) were successfully treated. This included 48 of 67 cancer patients (71.6%) and 6 of 8 noncancer patients (75%). Median duration of pain relief was 12 weeks (range, 1-96) in the cancer patients and 10 weeks (range, 6-166) in the noncancer patients. Mean reduction in opioid requirements in successfully treated cancer patients was 74 ± 5%. Pain on epidural injection occurred in half of the patients and was the most prevalent complication of treatment. Five patients had signs of intravascular injection. There were no serious long-term sequelae. Conclusions When used as described in this report, 5% butamben suspension appears to be effective for treatment of chronic pain of both cancer and noncancer origin and has a low incidence of adverse sequelae.

Background and objectives Current guidelines from the American Society of Regional Anesthesia state that an international normalized ratio (INR) of 1.4 is the upper limit of warfarin anticoagulation for safe removal of an epidural catheter. However, these guidelines are based primarily on expert consensus, and there is controversy regarding this recommendation as being "too conservative." Methods Prospective (3211) and retrospective (1154) patients undergoing total joint replacement followed by daily warfarin thromboprophylaxis were enrolled in this observational study. All nonsteroidal anti-inflammatory drugs and anticoagulants were held before surgery, and all patients had normal coagulation test results before surgery. Patients were followed twice a day by the acute pain service, no other anticoagulants except nonsteroidal anti-inflammatory drugs were administered, and epidural analgesia was discontinued per institutional protocol. Only patients with INR greater than 1.4 at the time of removal of epidural catheter were included. Neurologic checks were performed for 24 hrs after removal. Results A total of 4365 patients were included, and 79% underwent knee replacement and 18% hip replacement. Mean age was 68 yrs, and mean weight was 81 kg. Mean (SD) duration of epidural analgesia was 2.1 (0.6) days. Mean (SD) INR at the time of epidural removal was 1.9 (0.4), ranging from 1.5 to 7.1. No spinal hematomas were observed (0% incidence with 95% confidence interval, 0%-0.069%). Conclusions Our series of 4365 patients had uncomplicated removal of epidural catheters despite INRs ranging from 1.5 to 5.9. Removal was only during initiation of warfarin therapy (up to approximately 50 hrs after warfarin intake) when several vitamin K factors are likely to still be adequate for hemostasis.