Co-administration of dexamethasone with peripheral nerve block: intravenous vs perineural application: systematic review, meta-analysis, meta-regression and trial-sequential analysis.

BACKGROUND: I.V. and perineural dexamethasone have both been found to prolong loco-regional analgesia compared with controls without dexamethasone. It is unclear whether perineural administration offers advantages when compared with i.v. dexamethasone. METHODS: A systematic literature search was performed to identify randomized controlled double-blind trials that compared i.v. with perineural dexamethasone in patients undergoing surgery. Using the random effects model, risk ratio (for binary variables), weighted mean difference (for continuous variables) and 95% confidence intervals were calculated. We applied trial sequential analysis to assess the risks of type I and II error, meta-regression for the study of the doseresponsive relationship, and the Grading of Recommendations Assessment, Development, and Evaluation system. RESULTS: We identified 10 randomized controlled double-blind trials (783 patients). When using conventional meta-analysis of nine low risk of bias trials, we found a statistically significantly longer duration of analgesia, our primary outcome with perineural dexamethasone (241 min, 95%CI, 87, 394 min). When trial sequential analysis was applied, this result was confirmed. Meta-regression did not show a dose-response relationship. Despite the precision in the results, using the Grading of Recommendations Assessment, Development, and Evaluation system (GRADE), we assessed the quality of the evidence for our primary outcome as low. CONCLUSIONS: There is evidence that perineural dexamethasone prolongs the duration of analgesia compared with i.v. dexamethasone. Using GRADE, this evidence is low quality.

Paravertebral block and persistent postoperative pain after breast surgery: meta-analysis and trial sequential analysis.

We examined whether paravertebral block has an effect on the prevalence of persistent postsurgical pain after breast surgery. Seven randomised, controlled trials (559 patients) which had the outcome assessor blinded were included, comparing patients who received paravertebral blocks after breast surgery with patients who did not. The risk ratio (95% CI) was 0.75 (0.48-1.15) for the incidence of postoperative pain at 3 months (four studies, 317 patients); the risk ratio (95% CI) obtained from three studies including 301 patients reporting on pain after 6 months was 0.57 (0.29-1.72), and the risk ratio (95% CI) for pain after 12 months (three trials, 237 patients) was 0.42 (0.15-1.23). Conventional meta-analysis using the random effects model thus showed no statistically significant risk reduction for persistent postoperative pain at 3 months, 6 months or 12 months. Trial sequential analysis, used to consider the risk of type 1 and type 2 random error, showed that at 3 months, 6 months and 12 months, the number of subjects in the analyses were only 18.3%, 6.8% and 4.2% of the required information sizes at those time points, respectively. Our study is the first to evaluate data on pain 12 months postoperatively. Trial sequential analysis revealed that the current evidence is not sufficient to reach a conclusion. These findings stand in contrast to previous meta-analyses with fewer studies that had concluded that paravertebral block effectively reduces chronic pain.

Does anaesthesia with nitrous oxide affect mortality or cardiovascular morbidity? A systematic review with meta-analysis and trial sequential analysis.

BACKGROUND: The role of nitrous oxide in modern anaesthetic practice is contentious. One concern is that exposure to nitrous oxide may increase the risk of cardiovascular complications. ENIGMA II is a large randomized clinical trial currently underway which is investigating nitrous oxide and cardiovascular complications. Before the completion of this trial, we performed a systematic review and meta-analysis, using Cochrane methodology, on the outcomes that make up the composite primary outcome. METHODS: We used conventional meta-analysis and trial sequential analysis (TSA). We reviewed 8282 abstracts and selected 138 that fulfilled our criteria for study type, population, and intervention. We attempted to contact the authors of all the selected publications to check for unpublished outcome data. RESULTS: Thirteen trials had outcome data eligible for our outcomes. We assessed three of these trials as having a low risk of bias. Using conventional meta-analysis, the relative risk of short-term mortality in the nitrous oxide group was 1.38 [95% confidence interval (CI) 0.22-8.71] and the relative risk of long-term mortality in the nitrous oxide group was 0.94 (95% CI 0.80-1.10). In both cases, TSA demonstrated that the data were far too sparse to make any conclusions. There were insufficient data to perform meta-analysis for stroke, myocardial infarct, pulmonary embolus, or cardiac arrest. CONCLUSION: This systematic review demonstrated that we currently do not have robust evidence for how nitrous oxide used as part of general anaesthesia affects mortality and cardiovascular complications.

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.