title: [Respiratory filters and pneumonia: many unresolved questions].
abstract: OBJECTIVE
  The use of heat and moisture exchanging filters (HMEF) instead of conventional heated humidifiers is a cost-effective method in intensive care medicine. It was the objective of this paper to investigate the evidence for HMEF from the viewpoint of prevention of pneumonia and to investigate the appropriate changing intervals as well as filter materials.
  
  
  METHODS
  Randomised controlled trials published in recent years and focusing on prevention of pneumonia as well as other prospective controlled studies were reviewed systematically.
  
  
  RESULTS
  The studies demonstrate neither a clear advantage nor disadvantage of HMEF. No final statement is possible concerning changing intervals and the most appropriate filter materials. However, the data give some evidence for a possible extension of changing intervals to 72 hours without harm to the patients and probably show very little influence of filter materials.
  
  
  CONCLUSIONS
  Because of the economic advantages of HMEF instead of an active humidification, the use of filters--with the exception of contraindications for individual patients--should be preferred.
authors.affiliation: Arbeitsbereich Krankenhaushygiene, Institut für Medizinische Mikrobiologie, Medizinische Hochschule Hannover. Gastmeier.Petra@mh-hannover.de
authors.forename: P
authors.initials: P
authors.lastname: Gastmeier
authors.forename: K D
authors.initials: KD
authors.lastname: Beck
authors.forename: H
authors.initials: H
authors.lastname: Lode
mesh_terms: D005374:Filtration / Q000295:instrumentation*; D006358:Hot Temperature; D006801:Humans; D006813:Humidity; D007362:Intensive Care Units / Q000191:economics; D016239:MEDLINE; D015201:Meta-Analysis as Topic; D011014:Pneumonia / Q000517:prevention & control*; D011446:Prospective Studies; D016032:Randomized Controlled Trials as Topic; D012307:Risk Factors; D013997:Time Factors
vernacular_title: Beatmungsfilter und Pneumonie in der Intensivmedizin: viele ungelöste Fragen.