Document Detail

Impact of Humidification and Nebulization during Expiratory Limb Protection: An experimental bench study.
MedLine Citation:
PMID:  23232732     Owner:  NLM     Status:  Publisher    
BACKGROUND: Different filtering devices are used during mechanical ventilation to avoid dysfunction of flow and pressure transducers or for airborne micro7organisms containment. Water condensates resulting from the use of humidifiers, but also residual nebulization particles, may have a major influence on expiratory limb resistances. OBJECTIVES: To evaluate the influence of nebulization and active humidification on the resistance of expiratory filters. METHODS: A respiratory system analog was constructed using a test lung, an ICU ventilator, heated humidifiers, and a piezoelectric nebulizer. Humidifiers were connected to different types of circuits (unheated, monoheated, biheated7new and old generation). Five filter types were evaluated (electrostatic, heat7and7moisture exchangers, standard, specific and internal heated HEPA). Differential pressure measurements were carried out after 247hrs of continuous in7vitro use for each condition, and after 24hrs of use with an old7generation biheated circuit without nebulization. Baseline characteristics were also obtained from each dry filter. RESULTS: While using unheated circuits, measures had to be interrupted before 247hrs for all filtering devices, except the internal heated HEPA. Heat7and7moisture exchangers occluded before H24 with unheated and mono7heated circuits. The circuit type, nebulization practice, or even the duration of use did not influence internal heated HEPA resistances. CONCLUSION: This bench7study confirms that expiratory limb filtration is likely to induce several major adverse events. Resistance of expiratory filters increase is mainly due to the humidification circuit type, rather than to nebulization itself. If filtration is mandatory while using unheated circuits, a dedicated filter should be used for equal or less than 247hrs, or a heated HEPA for a longer duration.
Alexandre Tonnelier; François Lellouche; Pierre Alexandre Bouchard; Erwan L'her
Publication Detail:
Type:  JOURNAL ARTICLE     Date:  2012-12-4
Journal Detail:
Title:  Respiratory care     Volume:  -     ISSN:  0020-1324     ISO Abbreviation:  Respir Care     Publication Date:  2012 Dec 
Date Detail:
Created Date:  2012-12-12     Completed Date:  -     Revised Date:  -    
Medline Journal Info:
Nlm Unique ID:  7510357     Medline TA:  Respir Care     Country:  -    
Other Details:
Languages:  ENG     Pagination:  -     Citation Subset:  -    
Réanimation Médicale et Urgences Adultes, CHRU de la Cavale Blanche, 29609 Brest, Cedex, France.
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