Effects of heated humidification on positive airway pressure side effects in patients with obstructive sleep apnoea: a meta-analysis

Purpose An earlier study found that heated humidification reduced the side effects of positive airway pressure (PAP) in patients with obstructive sleep apnoea (OSA). However, other studies disagreed with this finding. Therefore, we evaluated the relationship between heated humidification and the side effects of PAP in patients with OSA. Methods According to the Preferred Reporting Items for Systematic Reviews and Meta-Analyses guidelines, six databases were searched for relevant randomised controlled trials (RCTs) performed from January 1999 to June 2021. Results From 1012 retrieved articles, we identified 9 eligible RCTs. Compared to the control group, the heated humidification group reported improvements in dry nose (pooled standardised mean difference [SMD] = - 0.70, 95% confidence interval [CI] = -0.96 to - 0.45, I-2 = 0%, p < 0.00001), blocked nose (SMD = -0.47, 95%CI - 0.69 to - 0.25, I-2 = 36%, p < 0.0001), runny nose (SMD= -0.22, 95%CI - 0.44 to 0, I-2 = 0%, p = 0.05), dry mouth (SMD= -0.62, 95%CI - 0.87 to - 0.37, I-2 = 0%, p < 0.00001), and dry throat (SMD = - 0.61, 95%CI - 0.90 to - 0.33, I-2 = 41%, p < 0.0001), but did not enhance positive airway pressure adherence (pooled mean difference [MD] = 0.24, 95% CI - 0.10 to 0.58, I-2 = 0%, p = 0.17). Conclusions Heated humidification improved some PAP side effects in patients with OSA but did not increase PAP adherence. Additional large-scale multi-centre RCTs are needed to verify the long-term effects.