I.V. and perineural dexamethasone are equivalent in increasing the analgesic duration of a single-shot interscalene block with ropivacaine for shoulder surgery: a prospective, randomized, placebo-controlled study

BACKGROUND

Interscalene brachial plexus block (ISB) provides excellent, but time-limited analgesia. Dexamethasone added to local anaesthetics prolongs the duration of a single-shot ISB. However, systemic glucocorticoids also improve postoperative analgesia. The hypothesis was tested that perineural and i.v. dexamethasone would have an equivalent effect on prolonging analgesic duration of an ISB.

METHODS

We performed a prospective, double blind, randomized, placebo-controlled study. Patients presenting for arthroscopic shoulder surgery with an ISB were randomized into three groups: ropivacaine 0.5% (R); ropivacaine 0.5% and dexamethasone 10 mg (RD); and ropivacaine 0.5% with i.v. dexamethasone 10 mg (RDiv). The primary outcome was the duration of analgesia, defined as the time between performance of the block and the first analgesic request. Standard hypothesis tests (t-test, Mann-Whitney U-test) were used to compare treatment groups. The primary outcome was analysed by Kaplan-Meier survival analysis with a log-rank test and Cox's proportional hazards regression.

RESULTS

One hundred and fifty patients were included after obtaining ethical committee approval and patient informed consent. The median time of a sensory block was equivalent for perineural and i.v. dexamethasone: 1405 min (IQR 1015-1710) and 1275 min (IQR 1095-2035) for RD and RDiv, respectively. There was a significant difference between the ropivacaine group: 757 min (IQR 635-910) and the dexamethasone groups (P<0.0001).

CONCLUSIONS

I.V. dexamethasone is equivalent to perineural dexamethasone in prolonging the analgesic duration of a single-shot ISB with ropivacaine. As dexamethasone is not licensed for perineural use, clinicians should consider i.v. administration of dexamethasone to achieve an increased duration of ISB.

Gradual withdrawal of remifentanil infusion may prevent opioid-induced hyperalgesia

BACKGROUND

The aim of this study was to examine if gradual withdrawal of remifentanil infusion prevented opioid-induced hyperalgesia (OIH) as opposed to abrupt withdrawal. OIH duration was also evaluated.

METHODS

Nineteen volunteers were enrolled in this randomized, double-blinded, placebo-controlled, crossover study. All went through three sessions: abrupt or gradual withdrawal of remifentanil infusion and placebo. Remifentanil was administered at 2.5 ng ml(-1) for 30 min before abrupt withdrawal or gradual withdrawal by 0.6 ng ml(-1) every five min. Pain was assessed at baseline, during infusion, 45-50 min and 105-110 min after end of infusions using the heat pain test (HPT) and the cold pressor test (CPT).

RESULTS

The HPT 45 min after infusion indicated OIH development in the abrupt withdrawal session with higher pain scores compared with the gradual withdrawal and placebo sessions (both P<0.01. Marginal mean scores: placebo 2.90; abrupt 3.39; gradual 2.88), but no OIH after gradual withdrawal compared with placebo (P=0.93). In the CPT 50 min after end of infusion there was OIH in both remifentanil sessions compared with placebo (gradual P=0.01, abrupt P<0.01. Marginal mean scores: placebo 4.56; abrupt 5.25; gradual 5.04). There were no differences between the three sessions 105-110 min after infusion.

CONCLUSIONS

We found no development of OIH after gradual withdrawal of remifentanil infusion in the HPT. After abrupt withdrawal OIH was present in the HPT. In the CPT there was OIH after both gradual and abrupt withdrawal of infusion. The duration of OIH was less than 105 min for both pain modalities.

CLINICAL TRIAL REGISTRATION

NCT 01702389. EudraCT number 2011-002734-39.

Analgesic efficacy of caudal dexamethasone combined with ropivacaine in children undergoing orchiopexy

BACKGROUND

Epidural administration of dexamethasone might reduce postoperative pain in adults. We evaluated whether a caudal block of 0.1 mg kg(-1) dexamethasone combined with ropivacaine improves analgesic efficacy in children undergoing day-case orchiopexy.

METHODS

This randomized, double-blind study included 80 children aged 6 months to 5 yr who underwent day-case, unilateral orchiopexy. Patients received either 1.5 ml kg(-1) of 0.15% ropivacaine (Group C) or 1.5 ml kg(-1) of 0.15% ropivacaine in which dexamethasone of 0.1 mg kg(-1) was mixed (Group D) for caudal analgesia. Postoperative pain scores, rescue analgesic consumption, and side-effects were evaluated 48 h after operation.

RESULTS

Postoperative pain scores at 6 and 24 h post-surgery were significantly lower in Group D than in Group C. Furthermore, the number of subjects who remained pain free up to 48 h after operation was significantly greater in Group D [19 of 38 (50%)] than in Group C [four of 37 (10.8%); P<0.001]. The number of subjects who received oral analgesic was significantly lower in Group D [11 of 38 (28.9%)] than in Group C [20 of 37 (54.1%); P=0.027]. Time to first oral analgesic administration after surgery was also significantly longer in Group D than in Group C (P=0.014). Adverse events after surgery including vomiting, fever, wound infection, and wound dehiscence were comparable between the two groups.

CONCLUSIONS

The addition of dexamethasone 0.1 mg kg(-1) to ropivacaine for caudal block can significantly improve analgesic efficacy in children undergoing orchiopexy. Clinical trial registration NCT01604915.

Pain management in pigs undergoing experimental surgery; a literature review (2012-4)

Failure to provide effective analgesia to animals in noxious studies contravenes the obligation to refine animal experimentation and, by increasing 'noise' in physiological data sets, may decrease the scientific validity of results. Pig models of surgical conditions are becoming increasingly important and used for translational work. This review aimed to determine the extent to which the recent biomedical literature describes pain assessment and alleviation in pigs recovering from experimental surgery. Three databases (Medline, Web of Knowledge, and Google Scholar) were searched to find relevant studies published from January 2012 to March 2014. Information on pain assessment and peri- and postoperative analgesia was extracted. The review identified 233 papers meeting selection criteria. Most articles (193/233, 83%) described use of drugs with analgesic properties, but only 87/233 (37%) described postoperative analgesia. No article provided justification for the analgesic chosen, despite the lack of guidelines for analgesia in porcine surgical models and the lack of formal studies on this subject. Postoperative pain assessment was reported in only 23/233 (10%) articles. It was found that the reporting of postoperative pain management in the studies was remarkably low, reflecting either under-reporting or under-use. Analgesic description, when given, was frequently too limited to enable reproducibility. Development of a pain-scoring system in pigs, together with the mandatory description of pain management in submitted articles, would contribute to improved laboratory pig welfare.