Induction opioids for caesarean section under general anaesthesia: a systematic review and meta-analysis of randomised controlled trials.

INTRODUCTION: The adverse effects of induction opioids on the neonate are poorly characterised. The study aim was to investigate whether induction opioids can be used in caesarean section without adversely affecting the neonate. METHODS: Six databases were systematically searched from inception until January 2019. Included studies compared induction opioids and placebo in caesarean section. Results were presented as odds ratios (95% confidence intervals) for dichotomous outcomes and weighted mean difference for continuous outcomes. An I2 statistic of >50% was significant for heterogeneity. The primary outcome was Apgar score (1 and 5 min). Secondary outcomes included neonatal adverse events, cord blood gas analyses, maternal haemodynamic parameters (systolic blood pressure (SBP), mean arterial pressure (MAP), heart rate (HR) and catecholamine concentrations. RESULTS: Seventeen studies (n=987) were included in the meta-analysis. Remifentanil 0.5-1 µg/kg or 2-3 µg/kg/h, alfentanil 7.5-10 µg/kg and fentanyl 0.5-1 µg/kg were compared to placebo. There was no significant difference in Apgar scores at 1 min (P=0.25, 0.58 and 0.89 respectively) for all three opioids or at 5 min for remifentanil and alfentanil (P=0.08 and 0.21 respectively). Fentanyl significantly reduced 5 min Apgar scores (P=0.002). There was no difference in neonatal airway interventions with remifentanil or alfentanil (P <0.05). All three induction opioids caused a significant reduction in maximum SBP (P <0.0001), MAP (P <0.00001) and HR (P <0.00001). CONCLUSION: Induction opioids are effective sympatholytic agents. Remifentanil and alfentanil appear to be safe, with no significant effect on Apgar scores or neonatal airway intervention, but a well-powered trial is required to confirm these findings.

Efficacy and adverse effects of buprenorphine in acute pain management: systematic review and meta-analysis of randomised controlled trials.

Buprenorphine appears to have a ceiling effect on respiratory depression, but not analgesia in healthy young patients. However, the efficacy and side-effects of buprenorphine in the setting of acute pain are poorly characterized. The aim of this study was to characterize the analgesic efficacy and adverse effects of buprenorphine compared with morphine in the acute pain setting. A systematic review of five databases was performed. Randomised controlled trials (RCTs) comparing buprenorphine with morphine in acute pain management were included. Studies performed outside of the hospital setting were excluded. The a priori primary outcomes included pain, respiratory depression, and sedation. Secondary outcomes included requirement for rescue analgesia, time to rescue analgesia, nausea, vomiting, dizziness, hypotension, and pruritus. Twenty-eight RCTs with 2210 patients met the inclusion criteria. There was no difference in pain [visual analogue scale weighted mean difference (WMD)=-0.29; 95% confidence interval (CI)=-0.62 to 0.03; I2=99%; P=0.07], incidence of respiratory depression [odds ratio (OR)=2.07; 95% CI=0.78-5.51; I2=30%; P=0.14], or sedation (OR=1.44; 95% CI=0.76-2.74; I2=23%; P=0.26). There was only one secondary outcome with an overall significant difference; buprenorphine use was associated with significantly less pruritus (OR=0.31; 95% CI=0.12-0.84; I2=6%; P=0.02). Whilst a theoretical ceiling effect may exist with respect to buprenorphine and respiratory depression, in a clinical setting, it can still cause significant adverse effects on respiratory function. However, given that buprenorphine is an equally efficacious analgesic agent, it is a useful alternative opioid because of its ease of administration and reduced incidence of pruritus.

Apnoeic oxygenation during intubation: a systematic review and meta-analysis.

Apnoeic oxygenation during intubation is used to prevent desaturation during intubation. The aim of this review was to assess whether apnoeic oxygenation during endotracheal intubation reduced the incidence of hypoxaemia. Five major databases were systematically searched for all relevant studies published up to May 2016. All study designs with a control group and a group receiving apnoeic oxygenation were included in this review. These studies were then assessed for level of evidence and risk of bias. The data were then analysed using a meta-analysis. Eleven studies (six high quality randomised controlled trials, four low quality level two studies and one low quality level three study) were found. In the meta-analysis there was strong evidence for benefit of apnoeic oxygenation in terms of improved SpO2 in elective surgical patients, obese patients and those undergoing emergency intubation without respiratory failure. However, no significant benefit was found in patients with respiratory failure. This is the first meta-analysis to be performed on apnoeic oxygenation during intubation. Apnoeic oxygenation provides significant benefit in terms of improving SpO2 for the majority of intubations, although there appears to be no benefit in patients whose indication for intubation is respiratory failure. Apnoeic oxygenation ought to be considered for integration into intubation protocols.

Adjuncts to local anaesthetics in tonsillectomy: a systematic review and meta-analysis.

The infiltration of local anaesthetic agents has been shown to reduce post-tonsillectomy pain. A number of recent studies have shown that the addition of agents such as clonidine and dexamethasone improve the efficacy of nerve blocks and spinal anaesthesia. The aim of this review was to determine whether additives to local anaesthetic agents improve post-tonsillectomy outcomes. Four major databases were systematically searched for all relevant studies published up to August 2016. All study designs with a control group receiving local anaesthetic infiltration and an intervention receiving the same infiltration with an added agent were included in this review. These studies were then assessed for level of evidence and risk of bias. The data were then analysed both qualitatively and where appropriate by meta-analysis. We reviewed 11 randomised controlled trial (RCTs) that included 854 patients. Due to inconsistencies in the methods used to report outcomes, both quantitative and qualitative comparisons were required to analyse the extracted data. Overall, we found that dexamethasone, magnesium, pethidine and tramadol reduce post-operative pain and analgesia use, with dexamethasone in particular significantly reducing post-operative nausea and vomiting and magnesium infiltration significantly reducing the incidence of laryngospasm. This systematic review of RCTs provides strong evidence that the use of dexamethasone and magnesium as additives to local anaesthetics reduces post-tonsillectomy pain and analgesia requirement. There is limited evidence that pethidine and tramadol have a similar effect on pain and analgesia requirement. The studies in this pooled analysis are sufficiently strong to make a level one recommendation that the addition of magnesium to local anaesthetics reduces the incidence of laryngospasm, a potentially lethal post-operative complication. Review level of evidence: 1.