Hooten, W. Michael

This study was conducted to audit the clinical management of a continuous local anaesthetic infusion delivered by a fluoroscopically placed thoracic epidural catheter in conjunction with supplemental intravenous opioid patient controlled analgesia for postoperative pain control following bilateral lung volume reduction surgery for severe emphysema. This retrospective case series involved a random sample of 43 patients from a possible 65 patients. The mean dose of epidural bupivacaine 0.15% was 6.7 ml/h (SD 1.5), while the mean daily dose of morphine or hydromorphone was 22.5 mg/day (SD 17.9) and 4.3 mg/day (SD 3.1), respectively. Inadequate analgesia was reported by 19 (44%) patients during the first two postoperative days, but was successfully treated by individual titration of these medications. The incidence of atrial fibrillation (n=6), premature epidural catheter dislodgement (n=6) or respiratory failure (n=3) appeared to be greater among patients who had inadequate analgesia at some stage. One patient developed excessive sedation; otherwise, there were no major complications. The use of an epidural bupivacaine infusion in conjunction with intravenous opioid patient controlled analgesia proved to be a safe and effective pain medication regimen when accompanied by individual titration of these agents in response to acute exacerbations of postoperative pain.

Abstract Catechol-O-methyltransferase (COMT) regulates extracellular catecholamines. A widely studied COMT single nucleotide polymorphism (rs4680) changes the translated amino acid from valine to methionine (Val158Met); the polymorphism has been shown to influence opioid use. The aims of this study were to investigate the influence of COMT Val158Met on the likelihood and dose of opioid use in adults with chronic pain. Adults with chronic pain consecutively admitted to an outpatient pain rehabilitation program were recruited for study participation (N = 298). Individuals were genotyped for COMT Val158Met (rs4680). The polymorphism was analyzed using an additive and codominant genotype model. The distribution of genotypes was 23% (N = 70) for Val/Val, 49% (N = 146) for Val/Met, and 27% (N = 82) for Met/Met (Hardy–Weinberg, P > 0.90). No significant association was observed between opioid use and genotype under the additive model; however, a significant association was observed under the codominant model (P = 0.027). A post hoc comparison demonstrated that the Met/Met genotype was more likely to use opioids compared with the Val/Met genotype (P = 0.0089). No significant association was observed between morphine equivalent dose and genotype under the additive model; however, a significant association was observed under the codominant model (P = 0.0496). A post hoc comparison demonstrated that the Val/Met (P = 0.019) and Met/Met (P = 0.043) genotypes used greater morphine equivalent dose compared with the Val/Val genotype. This study extends key knowledge about the influence of the Met/Met genotype and Met allele on opioid use in adults with chronic pain.

Abstract Background In the past decade, opioid use in the general population of the US has increased dramatically. Concomitantly, opioid-related morbidity and mortality have also risen steeply. The causes of opioid over-prescribing are multifactorial, with pressure from medical agencies, patients, aggressive patient-directed marketing, and use of patient surveys as an evaluation tool to unduly influence medical providers' decision-making. Providers also have significant concerns regarding scrutiny from their medical board and exposure to medicolegal liability. Content To provide the basis for best practice recommendations, several aspects of modern opioid prescribing practice require review. The practicing clinician should be aware of: (a) the pervasiveness of current opioid prescribing within the US; (b) the availability and applicability of clinical tools used to assess patient risk; (c) the new guidelines designed to facilitate appropriate and safe medical use of opioids; (d) the incorporation of clinical tools and best documentation practices to reduce medicolegal exposure. Summary On completion of this review, the reader should be able to recognize the magnitude of the problem of opioid over-prescribing in the US and identify several patient risk factors for opioid misuse, abuse, and/or diversion. Specifically, better familiarity with the recently published CDC guidelines for opioid prescribing will help ensure the adoption of best-use practices that maximize therapeutic efficacy while attenuating the possibility of harm to patients. A thorough review of the legal principles and risk-mitigation strategies relevant to opioid prescribing will also lessen the clinician's exposure to medicolegal liability.

Background. Cervical interlaminar epidural steroid injections (ESIs) are commonly performed procedures to treat painful cervical radiculopathy, but little is known about the systemic absorption and serum levels of steroids following injection. The primary objective of this study was to investigate the pharmacokinetics of fluoroscopy-guided cervical epidural-administered triamcinolone acetonide in a cohort of patients with cervical radicular pain seeking treatment in a pain medicine clinic.Methods. The study cohort included eight patients undergoing a fluoroscopically guided C7-T1 interlaminar ESI at a pain medicine specialty clinic. Blood was collected prior to the ESI and on days 1, 2, 4, 6, 8, 14, 21, 28, 35, and 42 following the injection. The sample extract was analyzed by tandem mass spectrometry.Results. The terminal elimination half-life of cervical epidural-administered triamcinolone in a noncompartmental analysis was 219 hours. In the noncompartmental analysis, peak triamcinolone concentrations of 5.4 ng/mL were detected within 22.1 hours after administration.Conclusions. The pharmacokinetics of cervical epidural-administered triamcinolone is consistent with our previous study of lumbar ESI, demonstrating that the elimination half-life is longer than that which has been reported following intravenous triamcinolone. The elimination half-life was shorter following cervical ESI than that which has been reported following lumbar ESI.

AbstractBackgroundFacet joint steroid injections are used to treat chronic low back pain. However, little is known about the systemic absorption and serum levels of steroids following intra‐articular facet joint injections. The primary objective of this preliminary study was to investigate the pharmacokinetics of triamcinolone acetonide following fluoroscopically guided intra‐articular lumbar facet joint injections in a cohort of patients with chronic low back pain. A secondary aim was to investigate the effects of triamcinolone on serum cortisol levels following lumbar facet joint injections.MethodsThe study cohort included 5 patients undergoing fluoroscopically guided intra‐articular lumbar facet joint injections at a pain medicine specialty clinic. Blood was collected prior to the injections and on days 1, 2, 4, 6, 8, 14, 21, 28, 35, and 42 following the injections.ResultsThe terminal elimination half‐life of triamcinolone in a noncompartmental analysis was 213 hours. The peak median triamcinolone concentration of 3.6 ng/mL was detected within 24 hours after the injections. Serum cortisol levels were < 30 ng/mL for an average of 4.4 days. The maximum effect of triamcinolone on cortisol suppression was observed with triamcinolone serum levels of > 1.9 ng/mL.ConclusionsThe peak serum concentration of triamcinolone following intra‐articular facet joint injections occurred within 24 hours. The median terminal elimination half‐life was 213 hours, but baseline cortisol levels were suppressed for an average of 4.4 days. Clinically, the prolonged half‐life and endocrine effects of triamcinolone could increase the risk for serious drug–drug interactions in patients taking medications that inhibit corticosteroid metabolism.

Abstract Objectives. Our purpose was to determine the incidence of surgical site infection (SSI) in cancer patients receiving an intrathecal drug delivery system (IDDS) and compare that rate with the incidence of SSI in the general population receiving an IDDS or spinal cord stimulator. We attempted to describe risk factors for SSIs in cancer patients treated with IDDS in terms of exposure to cancer treatments. Design. Retrospective review. Setting. Large tertiary care center. Patients. Cancer patients receiving an IDDS in 2006–2013. Methods. The incidence of SSI was determined according to the US Centers for Disease Control and Prevention definition. Medication regimens and current cancer treatment were investigated to identify immunocompromised patients during IDDS placement. Microbacteriology, treatment, and overall outcomes were investigated. Results. Sixty-four patients had an IDDS implanted in 2006–2013. SSI developed in four patients (6.2%). All four patients had received chemotherapy or radiotherapy within three months before implantation. Three of the three were receiving dexamethasone, and three of the four required explantation of the IDDS. Conclusion. The incidence of SSI was at the upper end of the published infection rates for IDDS. The risk of SSI may be increased in this population because of factors that alter the patient’s immune status, including concomitant corticosteroid use, radiotherapy near the SSI, and presence of immunomodulators. The identification and mitigation of certain risk factors for this population may prevent infection in future patients.

Background: The principle aim of this study was to investigate the associations between heat pain (HP) perception, pain catastrophizing, and pain-related anxiety in a heterogenous cohort of community-dwelling adults with chronic pain admitted to a 3-week outpatient pain rehabilitation program. Methods: All adults consecutively admitted to an outpatient pain rehabilitation program from July 2009 through January 2011 were eligible for study recruitment (n=574). Upon admission, patients completed the Pain Catastrophizing Scale (PCS), the short version of the Pain Anxiety Symptoms Scale (PASS-20), and HP perception was assessed using a standardized quantitative sensory testing (QST) method of levels. Results: Greater PCS scores were significantly correlated with lower standardized values of HP threshold (HP 0.5) (P=0.006) and tolerance (HP 5) (P=0.003). In a multiple variable model adjusted for demographic and clinical factors known to influence HP perception, every 10-point increase in the PCS was associated with a −0.124 point change in HP 0.5 (P=0.014) and a −0.142 change in HP 5 (P=0.014) indicating that participants with higher PCS scores had lower HP thresholds and tolerances, respectively. Similarly, greater PASS-20 scores significantly correlated with lower standardized values of HP 0.5 and HP 5. In a multiple variable model, every 10-point increase in the PASS-20 was associated with a −0.084 point change in HP 0.5 (P=0.005) and a −0.116 point change in HP 5 (P=0.001) indicating that participants with higher PASS-20 scores had lower HP thresholds and tolerances, respectively. Conclusions: The findings of this study extend the use of a standardized method for assessing HP in a heterogenous sample of adults with chronic pain. Although pain catastrophizing shares significant variance with pain-related anxiety, our findings suggest that either measure would be appropriate for use in future studies that incorporate the QST method of levels.