Sanjay Singhal, Salvatore Notaro, R K Singh, Anup Kumar, Shubham Singh
Compared with HMEs, HHs were associated with lower PaCO2 and higher arterial pH, without a significant difference in PaO2. However, no comparative evidence was available for the prespecified primary outcome of artificial airway obstruction, and evidence regarding patient-centered clinical outcomes remains insufficient."
BACKGROUND: In acute respiratory distress syndrome (ARDS), increased dead space with Heat and moisture exchangers (HMEs) may impair carbon dioxide elimination during lung-protective ventilation. To assess its impact, we conducted a systematic review and meta-analysis.
METHODS: After registration with the International Prospective Register of Systematic Reviews (CRD420261368917), PubMed, EMBASE, and Scopus were searched for studies of ARDS patients receiving IMV comparing HHs and HMEs. Random-effects meta-analyses of paired physiological outcomes were conducted using inverse-variance models, and standardised mean change (SMCs) with 95% confidence intervals (CIs) were calculated. Risk of bias was assessed using ROBINS-I or the NIH Before-After Quality Assessment Tool, as appropriate.
RESULTS: Ten studies were included in the systematic review; quantitative synthesis included paired physiological studies evaluating PaO2 (4 studies), PaCO2 (5 studies), pH (4 studies), and physiological dead-space fraction (2 studies). Compared with HMEs, HHs significantly reduced PaCO2 (SMC -0.76, 95% CI -1.03 to -0.49; p<0.001; I2=0) and increased arterial pH (SMC 0.66, 95% CI 0.38-0.95; p<0.001; I2=0%). No significant differences were observed for PaO2 (SMC -0.00, 95% CI -0.26 to 0.25; p=0.98; I2=0%) or physiological dead-space fraction (SMC -0.45, 95% CI -0.98 to 0.08; p=0.09; I2=43%). No eligible comparative data were available for the prespecified primary outcome of artificial airway occlusion or other patient-centered clinical outcomes.
CONCLUSIONS: Compared with HMEs, HHs were associated with lower PaCO2 and higher arterial pH, without a significant difference in PaO2. However, no comparative evidence was available for the prespecified primary outcome of artificial airway obstruction, and evidence regarding patient-centered clinical outcomes remains insufficient."