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BackgroundThe past two decades have witnessed a surge in the use of lumbar facet blocks and radiofrequency ablation (RFA) to treat low back pain (LBP), yet nearly all aspects of the procedures remain controversial.MethodsAfter approval by the Board of Directors of the American Society of Regional Anesthesia and Pain Medicine, letters were sent to a dozen pain societies, as well as representatives from the US Departments of Veterans Affairs and Defense. A steering committee was convened to select preliminary questions, which were revised by the full committee. Questions were assigned to 4–5 person modules, who worked with the Subcommittee Lead and Committee Chair on preliminary versions, which were sent to the full committee. We used a modified Delphi method, whereby the questions were sent to the committee en bloc and comments were returned in a non-blinded fashion to the Chair, who incorporated the comments and sent out revised versions until consensus was reached.Results17 questions were selected for guideline development, with 100% consensus achieved by committee members on all topics. All societies except for one approved every recommendation, with one society dissenting on two questions (number of blocks and cut-off for a positive block before RFA), but approving the document. Specific questions that were addressed included the value of history and physical examination in selecting patients for blocks, the value of imaging in patient selection, whether conservative treatment should be used before injections, whether imaging is necessary for block performance, the diagnostic and prognostic value of medial branch blocks (MBB) and intra-articular (IA) injections, the effects of sedation and injectate volume on validity, whether facet blocks have therapeutic value, what the ideal cut-off value is for a prognostic block, how many blocks should be performed before RFA, how electrodes should be oriented, the evidence for larger lesions, whether stimulation should be used before RFA, ways to mitigate complications, if different standards should be applied to clinical practice and clinical trials and the evidence for repeating RFA (see table 12 for summary).ConclusionsLumbar medial branch RFA may provide benefit to well-selected individuals, with MBB being more predictive than IA injections. More stringent selection criteria are likely to improve denervation outcomes, but at the expense of more false-negatives. Clinical trials should be tailored based on objectives, and selection criteria for some may be more stringent than what is ideal in clinical practice.

BACKGROUNDOver 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. METHODSIn 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 Anesthesiologistsʼ 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. RESULTSGuidelines were prepared for the following areasindications; 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. CONCLUSIONSEvidence 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.

Abstract Objective In recent years, there has been increased attention to pain management after surgery in the hospital setting along with financial enticement from the US government. The aim of this study is to evaluate the current efficacy of postoperative pain management. Methods In a prospective study, patients in an academic private nonprofit medical center were asked the same questions about their postoperative pain as in a previously published 2003 survey. Questionnaires on 1) pain intensity on a verbal categorical scale and 2) patient satisfaction with pain medication were completed in the patient's room before hospital discharge, and followed-up by telephone interviews at 1 and 2 weeks later. Numerical Pain Scale (NRS) pain scores were obtained at the same time points. Hospital Consumer Assessment of Healthcare Providers and Systems (HCAHPS) results for pain management were obtained at bedside interview along with standard mailed HCAHPS survey obtained by Press Ganey. Results Based on 441 surgical inpatients (Orthopedic, General, Neurosurgery, Gynecological) 12% of patients had “Severe-to-Extreme” pain and 54% had “Moderate-to-Extreme” pain at discharge. During the first 2 weeks after discharge, 13% of patients had “Severe-to-Extreme” pain and 46% had “Moderate-to-Extreme” pain. Pain scores at discharge and after discharge were negatively correlated with patient satisfaction with pain medication ( P < 0.0001), indicating that increased pain intensity was associated with decreased patient satisfaction. For the HCAHPS question “how often was your pain well controlled?,” 66% answered “Always” in the Press Ganey report versus 51% at bedside ( P < 0.0001). Conclusions The incidence of severe-to-extreme pain in patients before and after discharge following inpatient surgery is 12–13%, and this is a reduction from 10 years ago.

BackgroundApproximately 15% of patients report persistent knee pain despite surgical success following total knee arthroplasty (TKA). The purpose of this study was to determine the association of acute-postsurgical pain (APSP) with chronic postsurgical pain (CPSP) 6 months after TKA controlling for patient, surgical and psychological confounding factors.MethodsAdult patients with osteoarthritis undergoing primary elective tricompartmental TKA, with the operated knee the primary source of preoperative pain, were studied between March 2011 and February 2017. Patients received standard operative management and a perioperative multimodal analgesia regimen. The primary outcome was CPSP at 6 months. The primary variable of interest was the APSP (weighted mean pain score) for 72 hours postoperatively. Patient, surgical and psychological confounders were assessed using binary logistic regression.Results245 cases were analyzed. The incidence of CPSP was 14% (95% CI 10% to 19%). Median APSP values were 4.2 (2.2–5.0) in the CPSP group and 2.8 (1.8–3.7) without CPSP, difference 1.4 (95% CI 0.1 to 1.8, p=0.005). The unadjusted odds for CPSP with an increase of 1 in APSP was 1.46 (95% CI 1.14 to 1.87, p=0.002)). After multivariable risk adjustment, the OR for CPSP for an increase of 1 in the APSP was 1.53 (95% CI 1.12 to 2.09, p=0.008).ConclusionsAPSP is a risk factor for CPSP following TKA even after adjusting for confounding variables such as pain catastrophizing, anxiety, depression and functional status. Studies are needed to determine if APSP is a modifiable risk factor for the development of CPSP.

Background and ObjectivesThere is a paucity of large multi-institutional surveys to determine the prevalence of and risk factors for persistent pain after total hip (THR) and knee (TKR) replacements. We surveyed a variety of practices and patients and also correlated persistent pain with health-related quality-of-life outcomes.MethodsFrom October 10, 2007, to March 15, 2010, patients who had undergone primary THR or TKR with a minimum follow-up of 1 year were identified. A previously published questionnaire to identify persistent postsurgical pain that included a 36-item Short Form Health Survey was mailed to this group. Independent risk factors for persistent pain were identified with logistic regression.ResultsResponses from 1030 patients who underwent surgery at some point in time between June 13, 2006, and June 24, 2009, were analyzed (32% response rate). Forty-six percent of patients reported persistent pain (38% after THR and 53% after TKR) with a median average pain score of 3 of 10 and worst pain score of 5. Independent risk factors for persistent pain were female sex (odds ratio [OR], 1.23), younger age (OR, 0.97), prior surgery on hip or knee (OR, 1.39), knee versus hip replacement (OR, 1.65), lower-quality postsurgical pain control (OR, 0.9), and presence of pain in other areas of the body (OR, 2.09). All scores in the 36-item Short Form Health Survey were worse (8%–28% decrease) in patients with persistent postsurgical pain (P < 0.001).ConclusionsPersistent postsurgical pain is common after THR and TKR and is associated with reduced health-related quality of life, although our survey may be biased by the low response rate and retrospective recall bias. Nonmodifiable risk factors may lead to risk stratification. Severity of acute postoperative pain may be a modifiable risk factor.

Background and Objectives:Central spinal cord sensitization can occur during surgery and may lead to persistent pain after surgery. Pregabalin has been shown to decrease central sensitization in experimental pain paradigms, and so the same antihyperalgesic effect of pregabalin may occur during and immediately after surgery. Our study investigated whether a single 300-mg dose of pregabalin in patients has sufficient central nervous system bioavailability to be useful under acute conditions where brain or spinal cord excitability may lead to long-term disease, such as chronic pain.Methods:Nine patients undergoing primary total knee replacement received pregabalin 300 mg orally, 1 hr before surgery. An intrathecal catheter was inserted for anesthesia, postoperative analgesic drug administration, and cerebrospinal fluid (CSF) sampling. Blood and CSF were then simultaneously sampled at 2, 4, 6, 8, and 24 hrs after oral pregabalin administration. Pregabalin concentration in plasma and CSF was measured using a validated high-pressure liquid chromatography assay.Results:By 2 hrs after pregabalin administration, the CSF pregabalin concentration is high enough (0.115 μg/mL) to have anticonvulsant activity, and by 6 hrs after pregabalin administration, the CSF pregabalin level is high enough (0.359 μg/mL) to reduce central nervous system hypersensitivity. The median time to peak pregabalin concentration in CSF was at 8 hrs. The pregabalin CSF/plasma based on area under the curve (AUC[0-24 hrs]) was 0.098 ± 0.016, and for AUC[0-∞], the ratio was 0.176 ± 0.064.Conclusions:Sufficient central nervous system drug concentrations are reached after oral administration of pregabalin, suggesting that postoperative pain hypersensitivity can be reduced. Decreasing this acute brain or spinal cord excitability may prevent chronic pain from developing after surgery.

Background and Objectives:A concern for anesthesiologists is whether local anesthetics are more toxic to peripheral nerves in diabetic patients. A previous study in streptozotocin-induced diabetic rats showed that larger doses of lidocaine produce moderate nerve injury after nerve block in normal rats and worse injury in diabetic rats. However, it is not clear whether a smaller local anesthetic dose that produces negligible nerve fiber damage in normal rats will produce significant nerve damage in diabetic rats and if adding adjuvant drugs modulates this effect.Methods:Rats were intravenously injected with 50 mg/kg streptozotocin to induce diabetes (blood glucose levels >250 mg/dL) and diabetic neuropathy. After waiting 35 days, an injection (0.1 mL) of 1% lidocaine alone, or with 5 μg/mL epinephrine or 7.5 μg/mL clonidine added, or 0.5% ropivacaine alone was performed at the left sciatic notch in both diabetic and nondiabetic rats. The duration of sensory (pin prick) and motor (toe spreading reflex) nerve block in the hind paws was determined. For histologic controls, all rats also received saline vehicle injection into the right sciatic notch. Another group of uninjected rats was used as naive controls. Left and right nerves were removed 2 days after injection and fixed in situ with a 4% glutaraldehyde solution. Myelinated axon profiles suggestive of neuropathy (myelin figures, pale and swollen, or dark-staining axoplasm) were counted and expressed as a percentage of the total number of fibers in each rat sciatic nerve.Results:All streptozotocin-injected rats became diabetic and had pronounced tactile allodynia. All rats had sensory and motor nerve blocks lasting for at least 50 mins after injection of local anesthetic. The duration of sensory and motor nerve block was longer in diabetic rats than in nondiabetic rats for all drug groups tested. None of the sciatic nerves examined showed greater than 3% nerve fiber degeneration. Although lidocaine in diabetic rats did not produce nerve fiber damage, diabetic rats receiving lidocaine/clonidine or ropivacaine had more abnormal myelinated axon profiles than did nondiabetic rats receiving the same drug.Conclusions:The duration of sciatic nerve block with local anesthetics is longer in diabetic compared with nondiabetic rats. A small, but statistically significant, increase in nerve damage occurred in diabetic rats after nerve block with ropivacaine alone or when duration of lidocaine block was extended with clonidine. These findings may have implications for dosing of local anesthetics in diabetic patients undergoing regional analgesia with nerve blocks.

Background and ObjectivesThere is an increasing use of local infiltration analgesia (LIA) to reduce postoperative pain. Despite widespread use of LIA, wide variations in drug combinations and concomitant use of systemic analgesics have made it difficult to determine the optimal drug combinations for LIA. Using a previously validated rat laparotomy model, the optimal LIA combination of medications to reduce postoperative pain was determined.MethodsLaparotomy was performed in an adult rat model under isoflurane anesthesia. During surgery, combinations of bupivacaine, ketorolac, and dexamethasone were injected over the sutured muscle wound before skin closing, and compared to saline (placebo). The same medications were injected systemically as controls. Postoperative pain was assessed by measuring spontaneous rearing activity.ResultsA high-dose 3-drug LIA combination (50 μL of bupivacaine 0.75%, ketorolac 6.0 mg-mL, and dexamethasone 2.0 mg-mL) increased rearing (decreased pain) at 2 hours (P = 0.0032) postsurgery compared to saline. However, the same 3 drugs injected systemically had a similar analgesic effect (P = 0.0002). Bupivacaine 0.75% alone was not effective for LIA. When low-dose (9-fold reduction) 3-drug LIA combination was used, LIA increased rearing (P = 0.0034) whereas the same 3 drugs injected systemically had no effect. Low-dose LIA ketorolac-dexamethasone (2-drug combination) also increased rearing (P = 0.0393).ConclusionsOur animal study suggests that clinical trials with low-dose LIA combinations of local anesthetic, nonsteroidal anti-inflammatory drug, and corticosteroid may be useful for reducing postoperative pain after laparotomy.

The literature and clinical data support the use of intravenous (IV) infusions of ibuprofen to control pain and reduce the opioid requirements associated with surgical pain. According to current guidelines, IV ibuprofen can be administered via a slow IV infusion performed during a 30-minute period. Although recent studies indicate that more rapid infusions may yield additional benefits for patients, the safety of such an approach needs further evaluation. The main purpose of this study was to determine the safety of single and multiple doses of IV ibuprofen (800 mg) administered over 5 to 10 minutes at the induction of anesthesia and after the surgical procedure for the treatment of postoperative pain. This was a Phase IV, multicenter, open-label, clinical surveillance study. It was conducted at 21 hospitals in the United States, and 300 adult hospitalized patients undergoing surgery were enrolled. The exclusion criteria for the study were: inadequate IV access; hypersensitivity to any component of IV ibuprofen, aspirin, or related products; and any active, clinically significant bleeding. Also excluded were patients who had taken NSAIDs <6 hours before administration of IV ibuprofen; pregnant or breastfeeding female patients; and patients in the perioperative period of coronary artery bypass graft surgery. Patients received 800 mg of IV ibuprofen administered over 5 to 10 minutes preoperatively. Vital signs, adverse events, and pain scores were assessed. Approximately 22% (65 of 300) of patients reported adverse events (serious and nonserious). The most common adverse event was infusion site pain (34 of 300 [11%]). No deaths were reported. Nine subjects reported serious adverse events, 8 of which occurred during the first 6 hours. All serious events reported were judged unrelated to ibuprofen. Of the 300 total patients, 2 (0.67%) discontinued the study drug due to an adverse event (1 patient discontinued the study because of infusion site pain, and 1 patient withdrew due to a hypersensitivity reaction after drug administration). Our study found that IV ibuprofen infused over 5 to 10 minutes at induction of anesthesia is a safe administration option for surgical patients. ClinicalTrials.gov identifier: NCT01334957.