A randomised controlled trial of peri-operative pregabalin vs. placebo for video-assisted thoracoscopic surgery.

We allocated 52 participants to oral pregabalin 300 mg and 48 participants to placebo tablets before thoracoscopic surgery and for five postoperative days. The median (IQR [range]) cumulative pain scores at rest for nine postoperative months were 184 (94-274 [51-1454]) after pregabalin and 166 (66-266 [48-1628]) after placebo, p = 0.39. The corresponding scores on deep breathing were 468 (281-655 [87-2870]) and 347 (133-561 [52-3666]), respectively, p = 0.16. After three postoperative months, 29/100 participants had persistent surgical site pain, 19/52 after pregabalin and 10/48 after placebo, p = 0.12, of whom four and five, respectively, attended a pain management clinic, p = 0.24. The median (IQR [range]) morphine equivalent consumption six days after surgery was 273 (128-619 [39-2243]) mg after pregabalin and 319 (190-663 [47-2258]) mg after placebo, p = 0.35.

A prospective cohort study comparing early opioid requirement between Chinese from Hong Kong and Caucasian Australians after major abdominal surgery.

BACKGROUND: The relationship between ethnicity and early opioid consumption is not well understood. Our prospective cohort study tested whether Chinese patients in Hong Kong require less opioid after major abdominal surgery compared with Caucasian patients in Australia. METHODS: Matched cohorts of patients from Hong Kong (n=68) and Australia (n=68) were recruited. Patient attitudes and expectations to pain management documented. After operation, all patients received i.v. morphine using a patient-controlled analgesia device. Postoperative opioid consumption, pain intensity, and incidence of opioid-related side-effects were recorded. RESULTS: The average (sd) opioid requirement (i.v. morphine equivalent) at 72 h after surgery was significantly less among Chinese patients [86.8 (62.6) mg (95% CI 71.8, 101.8)] compared with Caucasian patients [130.6 (71.9) mg, (P<0.0005) (95% CI 113.4, 147.8)]. Numeric rating scale pain score (0-10) was, however, higher in Chinese patients compared with Caucasian Australians, 5.3 (2.7) vs 4.4 (2.3) (P=0.029). The incidence of pruritus among Chinese patients was significantly higher than Caucasians at 24-48 h (P=0.001) and 48-72 h (P=0.001). Chinese patients also reported a strong preference for others to manage their pain, and their nurse carers were more likely to expect severe pain after surgery. CONCLUSIONS: Chinese patients in Hong Kong required less opioid and experienced greater pain intensity and pruritus than Caucasian patients. Clinicians should consider differences in the side-effect profile of morphine and patient expectations related to pain control when planning postoperative analgesia for patients of Chinese ethnicity.

Intraoperative nitrous oxide as a preventive analgesic.

Preventive analgesia is defined as the persistence of the analgesic effects of a drug beyond the clinical activity of the drug. The N-methyl D-aspartate receptor plays a critical role in the sensitisation of pain pathways induced by injury. Nitrous oxide inhibits excitatory N-methyl D-aspartate sensitive glutamate receptors. The objective of our study was to test the efficacy of nitrous oxide as a preventive analgesic. We conducted a retrospective analysis of data from a subset of patients (n = 100) randomly selected from a previous major multicentre randomised controlled trial on nitrous oxide (ENIGMA trial). Data analysed included postoperative analgesic requirements, pain scores and duration of patient-controlled analgesia during the first 72 postoperative hours. There was no significant difference in postoperative oral morphine equivalent usage (nitrous group 248 mg, no nitrous group 289 mg, mean difference -43 mg, 95% confidence interval 141 to 54 mg). However, patients who received nitrous oxide had a shorter duration of patient-controlled analgesia use (nitrous group 35 hours, no nitrous group 51 hours, mean difference -16 hours, 95% confidence interval -29 to -2 hours, P = 0.022). There was no difference in pain scores between the groups. The shorter patient-controlled analgesia duration in the nitrous oxide group suggests that intraoperative nitrous oxide may have a preventive analgesic effect.

Predicting the effectiveness of virtual reality relaxation on pain and anxiety when added to PCA morphine in patients having burns dressings changes.

BACKGROUND: Pain arising in burns sufferers is often severe and protracted. The prospect of a dressing change can heighten existing pain by impacting both physically and psychologically. In this trial we examined whether pre-procedural virtual reality guided relaxation added to patient controlled analgesia with morphine reduced pain severity during awake dressings changes in burns patients. METHODS: We conducted a prospective randomized clinical trial in all patients with burns necessitating admission to a tertiary burns referral centre. Eligible patients requiring awake dressings changes were randomly allocated to single use virtual reality relaxation plus intravenous morphine patient controlled analgesia (PCA) infusion or to intravenous morphine patient controlled analgesia infusion alone. Patients rated their worst pain intensity during the dressing change using a visual analogue scale. The primary outcome measure was presence of 30% or greater difference in pain intensity ratings between the groups in estimation of worst pain during the dressing change. FINDINGS: Of 88 eligible and consenting patients having awake dressings changes, 43 were assigned to virtual reality relaxation plus intravenous morphine PCA infusion and 43 to morphine PCA infusion alone. The group receiving virtual reality relaxation plus morphine PCA infusion reported significantly higher pain intensities during the dressing change (mean=7.3) compared with patients receiving morphine PCA alone (mean=5.3) (p=0.003) (95% CI 0.6-2.8). INTERPRETATION: The addition of virtual reality guided relaxation to morphine PCA infusion in burns patients resulted in a significant increase in pain experienced during awake dressings changes. In the absence of a validated predictor for responsiveness to virtual reality relaxation such a therapy cannot be recommended for general use in burns patients having awake dressings changes.