Background: Although the addition of a background infusion for intravenous patient-controlled analgesia (IV-PCA) has been identified as a risk factor for the development of respiratory depression, this has not clearly been examined in a systematic fashion. The authors undertook a systematic review and meta-analysis of available randomized controlled trials (RCTs) to examine whether the addition of a background or continuous infusion to an IV-PCA regimen would be associated with an increased risk of respiratory depression.
Methods: Studies were identified by searching the National Library of Medicine's PubMed database (1966 to November 30, 2008). Inclusion criteria were a clearly defined analgesic technique of demand-only IV-PCA versus IV-PCA utilizing both a demand dose and background infusion, opioid medication used, and randomized trials. Data were abstracted and analyzed with the RevMan 4.2.7 (The Cochrane Collaboration, 2004).
Results: The search yielded 687 abstracts from which the original articles were obtained and data abstracted with a total of 14 articles analyzed. There were 402 subjects in the continuous IV-PCA with demand group versus the 394 subjects in the demand-only IV-PCA group. Addition of a background infusion to the demand dose for IV-PCA with opioids was associated with a significant increased risk for respiratory depression (odds ratio [OR] = 4.68, 95% confidence interval [CI]: 1.20-18.21). Subgroup analysis revealed that this increased risk was seen in adult but not in pediatric patients.
Conclusions: Our meta-analysis indicates that the addition of a continuous or background infusion to the demand dose for IV-PCA is associated with a higher incidence of respiratory events than demand IV-PCA alone in adult but not in pediatric patients; however, our overall results should be interpreted with caution due to the relatively small sample size and the wide range of definitions for respiratory depression in studies examined.