Humidification and Tracheostomy Care in Transit: A Systematic Review of Current Evidence and Future Directions

Spontaneously breathing tracheostomy patients face unique challenges in maintaining adequate humidification of inspired gases due to the absence of natural humidification provided by the nasal passage and pharynx. This systematic review evaluates the effectiveness of current humidification strategies to identify the best practices, aiming to better understand their potential application in low-humidity environments such as in air medical transport. In adult, spontaneously breathing tracheostomy patients, how effective are current humidification strategies-heat and moisture exchangers (HMEs), cool mist humidification (CMH), and heated humidifiers (HHs)-in maintaining adequate humidification and preventing complications?

A systematic review was conducted following the PRISMA (Preferred Reporting Items for Systematic reviews and Meta-Analyses) guidelines, with a comprehensive search of PubMed, MEDLINE, Cochrane Library, and EBSCO databases for studies published between 2013 and 2024. The inclusion criteria were studies that involved spontaneously breathing tracheostomy patients and evaluated the effectiveness of humidification strategies, whereas exclusion criteria were studies on mechanically ventilated patients and pediatric population and reviews, editorials, and non-peer-reviewed articles. Data from the selected studies were extracted and assessed using the Cochrane risk of bias tool, the Newcastle-Ottawa scale, and an adapted CONSORT (Consolidated Standards of Reporting Trials) checklist for bench studies. A narrative synthesis was performed to summarize the findings due to the heterogeneity of study designs, interventions, and outcomes.

A total of 6 studies were included in the review. These studies involved various humidification methods such as HMEs, CMH, and HHs. Results indicated that HMEs generally struggle to provide sufficient humidification, particularly when supplemental oxygen is required. CMH was generally less effective in maintaining adequate humidity levels, requiring more frequent tracheal suctioning due to inadequate humidification. HHs consistently provided the highest humidity levels and were the most effective in reducing respiratory complications and improving patient comfort, even with supplemental oxygen.

The evidence included in this review is limited by the high risk of bias in some studies and the variability in study designs and methodologies. Although none of these studies specifically evaluated the effectiveness of humidification strategies in the unique environment of air medical transports, their findings suggest that the use of HHs is the most reliable method for maintaining adequate humidity levels. This review highlights the necessity of improving humidification strategies to ensure the comfort and safety of tracheostomy patients during air transport. Future research should focus on investigating the performance of different humidification methods in low-humidity environments, such as aircraft cabins, to address these challenges and improve patient outcomes.