Heat pain detection threshold is associated with the area of secondary hyperalgesia following brief thermal sensitization:a study of healthy male volunteers

INTRODUCTION: The area of secondary hyperalgesia following brief thermal sensitization (BTS) of the skin and heat pain detection thresholds (HPDT) may both have predictive abilities in regards to pain sensitivity and clinical pain states. The association between HPDT and secondary hyperalgesia, however, remains unsettled, and the dissimilarities in physiologic properties suggest that they may represent 2 distinctively different pain entities. The aim of this study was to investigate the association between HPDT and BTS-induced secondary hyperalgesia. METHODS: A sample of 121 healthy male participants was included and tested on 2 separate study days with BTS (45°C, 3 minutes), HPDT, and pain during thermal stimulation (45°C, 1 minute). Areas of secondary hyperalgesia were quantified after monofilament pinprick stimulation. The pain catastrophizing scale (PCS) and hospital anxiety and depression scale (HADS) were also applied. RESULTS: A significant association between HPDT and the size of the area of secondary hyperalgesia (p<0.0001) was found. The expected change in area of secondary hyperalgesia due to a 1-degree increase in HPDT was estimated to be −27.38 cm(2), 95% confidence interval (CI) of −37.77 to −16.98 cm(2), with an R(2) of 0.19. Likewise, a significant association between HADS-depression subscore and area of secondary hyperalgesia (p=0.046) was found, with an estimated expected change in secondary hyperalgesia to a 1-point increase in HADS-depression subscore of 11 cm(2), 95% CI (0.19–21.82), and with R(2) of 0.03. We found no significant associations between secondary hyperalgesia area and PCS score or pain during thermal stimulation. CONCLUSION: HPDT and the area of secondary hyperalgesia after BTS are significantly associated; however, with an R(2) of only 19%, HPDT only offers a modest explanation of the inter-participant variation in the size of the secondary hyperalgesia area elicited by BTS

PANSAID - PAracetamol and NSAID in combination:study protocol for a randomised trial

BACKGROUND: Effective postoperative pain management is essential for the rehabilitation of the surgical patient. No ‘gold standard’ exists after total hip arthroplasty (THA) and combinations of different nonopioid medications are used with virtually no evidence for additional analgesic efficacy compared to monotherapy. The objective of this trial is to investigate the analgesic effects and safety of paracetamol and ibuprofen alone and in combination in different dosages after THA. METHODS: PANSAID is a placebo-controlled, parallel four-group, multicentre trial with centralised computer-generated allocation sequence and allocation concealment and with varying block size and stratification by site. Blinding of assessor, investigator, caregivers, patients and statisticians. Patients are randomised to four groups: (A) paracetamol 1 g × 4 and ibuprofen 400 mg × 4, (B) paracetamol 1 g × 4 and placebo, (C) placebo and ibuprofen 400 mg × 4 and (D) paracetamol 0.5 g × 4 and ibuprofen 200 mg. The two co-primary outcomes are 24-h consumption of morphine and number of patients with one or more serious adverse events within 90 days after surgery. Secondary outcomes are pain scores during mobilisation and at rest at 6 and 24 h postoperatively, and number of patients with one or more adverse events within 24 h postoperatively. Inclusion criteria are patients scheduled for unilateral, primary THA; age above 18 years; ASA status 1–3; BMI >18 and <40 kg/m(2); women must not be pregnant; and provision of informed consent. Exclusion criteria are patients who cannot cooperate with the trial; participation in another trial; patients who cannot understand/speak Danish; daily use of strong opioids; allergy against trial medication; contraindications against ibuprofen; alcohol and/or drug abuse. A total of 556 eligible patients are needed to detect a difference of 10 mg morphine i.v. the first 24 h postoperatively with a standard deviation of 20 mg and a family wise type 1 error rate of 0.025 (two-sided) and a type 2 error rate of 0.10 for the six possible comparisons of the four intervention groups. DISCUSSION: We started recruiting patients in December 2015 and expect to finish in September 2017. Data analysis will be from September 2017 to October 2017 and manuscript submission ultimo 2017. TRIAL REGISTRATION: EudraCT: 2015-002239-16 (12/8-15); ClinicalTrials.gov: NCT02571361. Registered on 7 October 2015. ELECTRONIC SUPPLEMENTARY MATERIAL: The online version of this article (doi:10.1186/s13063-016-1749-7) contains supplementary material, which is available to authorized users

The effect of preoperative dexamethasone on pain 1 year after lumbar disc surgery:a follow-up study

BACKGROUND: It has been hypothesized that dexamethasone can inhibit persistent postoperative pain, but data on humans is lacking and results from animal studies are conflicting. We explored the effect of 16 mg dexamethasone IV administered preoperatively on persistent pain 1 year after lumbar discectomy. METHODS: This is a prospective 1-year follow-up on a single-centre, randomized, and blinded trial exploring the analgesic effect of 16 mg IV dexamethasone or placebo after lumbar discectomy. One year follow-up was a written questionnaire including back and leg pain (VAS 0–100 mm), Short Form 36 survey (SF-36), EuroQol 5D (EQ-5D), OSWESTRY Low Back Pain Questionnaire, duration of sick leave, working capability, contentment with surgical result. RESULTS: Response rate was 71% (55 patients) in the dexamethasone group, 58% (44 patients) in the placebo group. Leg pain (VAS) was significantly lower in the placebo group compared to the dexamethasone group: 17 (95% CI 10–26) vs 26 (95% CI 19–33) mm, respectively (mean difference 9 mm (95% CI −1 to 0), (P = 0.03). No difference regarding back pain. The placebo group reported significantly more improvement of leg pain and were significantly more satisfied with the surgical result. Patients in the dexamethasone group reported significantly higher pain levels in EQ-5D- and Oswestry questionnaires. No difference in the SF-36 survey or daily analgesic consumption. CONCLUSIONS: We found significantly higher pain levels in the dexamethasone group compared to placebo 1 year after lumbar disc surgery. TRIAL REGISTRATION: Clinicaltrials.gov (NCT01953978). Registered 26 Sep 2013