Are the HEAVEN criteria reliable as a predictive tool for emergency airway management? A systematic review

Background: Airway management is one of the most vital skills used by advanced airway providers. Anticipating a difficult airway is crucial for the risk-benefit analysis and may help providers to determine the optimal airway management approach. Existing difficult airway assessment tools may have limited application in emergency airway management. In addition, these do not incorporate physiological factors. More recently, Davis and Olvera proposed the HEAVEN criteria as a novel difficult airway predictive tool for emergency airway management. The objective of this study is to review HEAVEN as a novel airway prediction tool. Material and Methods: This systematic review was conducted following the Preferred Reporting Items for Systematic Reviews and Meta-Analyses (PRISMA) statement. Results of a comprehensive search in three major databases, as well as hand searching, were screened in title/abstract and full-text stages. We included the journal articles which review HEAVEN as a novel airway prediction tool with both retrospective and prospective study designs. The population included patients requiring rapid sequence intubation (RSI) or delayed sequence intubation (DSI). Two investigators independently extracted the data with an electronic table in Microsoft Word. Due to the heterogeneity in included study designs, settings, methods, study outcomes, and measurement of the studies, we did not carry out a meta-analysis. The risk of bias (RoB) was assessed using Joanna Briggs Institute checklist. Results: Out of 103 records, only four studies were included. The most cited criterion was the anatomical challenge, which was significantly associated with first-attempt success in three studies. Most studies on HEAVEN did not support physiological factors as predictors of difficult intubation. Two studies reported significant associations between individual HEAVEN criteria and first-attempt success without desaturation. Some included studies reported significant associations between anatomical HEAVEN criteria (extremes of size, anatomical challenge, vomit/blood/fluid, and neck mobility) and difficult airway view. Furthermore, a prospective study reported that hypoxemia and vomit/blood/fluid were significantly associated with intubation complications. Based on the results of the RoB analysis, there wasn’t considerable bias in a great number of included studies. Conclusion: The HEAVEN criteria may represent a development over the traditional approaches. HEAVEN assessment tool considers both physiological and anatomical factors. In addition, all HEAVEN elements can be performed in emergent situations. The HEAVEN criteria seem to be a useful tool to predict difficult airways. There was a variation among studies in the definition of the difficult airway. There is currently no consensus on the definition of a difficult airway, which may explain some of the heterogeneity of the results of this systematic review. Due to the heterogeneity in included studies, we did not carry out a meta-analysis. Therefore, we suggested that future studies should consider homogeneous patient populations, a uniform study design, a matching study setting, and a widely accepted definition of the difficult airway to provide the opportunity to perform meta-analyses. The controversial results of studies highlighted a requirement for more prospective studies with an appropriate study design and considering the possible confounding factors to reach more reliable evidence.