Abstract
BACKGROUND: The impact of humidification devices on ventilatory and arterial blood gases parameters during noninvasive ventilation (NIV) remains controversial. The aim of the study was to compare the short-term impact of heat and moisture exchangers (HMEs) and heated humidifiers (HHs) during NIV for either hypercapnic or hypoxemic acute respiratory failure.
METHODS: Consecutive subjects receiving NIV were successively treated with HME and HH in randomized order for 30 min each. At the end of each period, arterial blood gases were measured and ventilatory parameters were recorded.
RESULTS: Eighty-one subjects were enrolled, of whom 52 were hypercapnic (with or without acidosis) and 29 hypoxemic. Minute ventilation was greater with the HME, in comparison with the HH (15 [12–18] vs 12 [10–16] median [interquartile range], P < .001), while PaCO2 was increased when using HME, indicating a dead space effect. This effect was observed in all subjects, but was more pronounced in hypercapnic subjects (PaCO2 62 ± 17 mm Hg with HME vs 57 ± 14 with HH, P < .001). In a subgroup of 19 subjects with respiratory acidosis, alveolar hypoventilation improved only with the HH. The amplitude of the dead space impact was a function of the degree of hypercapnia.
CONCLUSIONS: Use of an HME decreased CO2 elimination during NIV, despite increased minute ventilation, especially in hypercapnic subjects.
- noninvasive ventilation
- humidification
- heated humidifiers
- heat and moisture exchangers
- dead space
- alveolar hypoventilation
- acute respiratory failure
- COPD
Footnotes
- Correspondence: François Lellouche MD PhD, Unité de Soins Intensifs de Chirurgie Cardiaque, Groupe de Recherche en Santé Respiratoire, Centre de Recherche de l'Institut Universitaire de Cardiologie et de Pneumologie de Québec, 2725 Chemin Sainte-Foy, Ville de Québec, Québec Canada G1V 4G5. E-mail: francois.lellouche{at}criucpq.ulaval.ca.
Dr Lellouche presented a version of this paper at the International Conference of the American Thoracic Society, held May 17–22, 2002, in Atlanta, Georgia.
The humidifiers for this study were supplied free of charge by Fisher & Paykel, which was not involved in the design or conduct of the study, collection, management, analysis, or interpretation of the data; or preparation, review, or approval of the manuscript.
Dr Brochard has disclosed relationships with Hudson and Fisher & Paykel.
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