title: Do the components of heat and moisture exchanger filters affect their humidifying efficacy and the incidence of nosocomial pneumonia?
abstract: OBJECTIVE
  To compare the efficiency of two heat and moisture exchange filters (HMEFs) of different compositions of the humidifying capacity and the rate of bronchial colonization and ventilator-associated pneumonia in patients in the intensive care unit (ICU).
  
  
  METHODS
  Prospective, randomized study.
  
  
  METHODS
  ICU of a university hospital.
  
  
  METHODS
  All patients who required mechanical ventilation for 24 hrs or more during the study period.
  
  
  METHODS
  At admission to the ICU, patients were randomly assigned to one of two groups. In one group, the patients were ventilated with Humid-Vent Filter Light HMEF. The condensation surface was made of paper impregnated with CaCl2. The filter membrane was made of polypropylene. In the other group, the patients were ventilated with the Clear ThermAl HMEF (Intersurgical, France). The condensation surface was made of plastic foam impregnated with AlCl2. The filter membrane was made of two polymer fibers (modacrylic and polypropylene). In both groups, HMEFs were changed daily.
  
  
  RESULTS
  Seventy-seven patients were ventilated for 19+/-7 days with the Humid-Vent Filter Light HMEF and 63 patients for 17+/-6 days with the Clear ThermAl HMEF. Patients ventilated with the Humid-Vent Filter Light underwent 8.7+/-3.7 tracheal aspirations and 1.2+/-2.0 instillations per day and those with the Clear ThermAl, 8.2+/-3.9 and 1.5+/-2.4 per day, respectively (NS). The abundance of tracheal secretions and the presence of blood and viscosity, as evaluated by semiquantitative scales, were similar in both groups. One episode of tracheal tube occlusion was observed with the Humid-Vent Filter Light HMEF and none with the other HMEF (NS). Tracheal colonization was observed at a rate of 91% with the Humid-Vent Filter Light and 97% with the Clear ThermAl (NS). The rate of ventilator-associated pneumonia was similar in both groups (35%). Bacteria responsible for tracheal colonization and pneumonia were similar in both groups.
  
  
  CONCLUSIONS
  Despite differences in their components, the two HMEFs that were tested achieved similar performances in terms of humidification and heating of inspired gases. Only one episode of endotracheal tube occlusion was detected, and very few patients (three in each group) had to be switched to an active heated humidifier. No difference was observed either in the rate of tracheal colonization or of ventilator-associated pneumonia. These data show that the Humid-Vent Filter Light and the Clear ThermAl HMEFs are suited for use with ICU patients.
authors.affiliation: Intensive Care Unit and Trauma Center, Hôpital Nord, Marseilles University Hospital System, Marseilles Medical School, France.
authors.forename: L
authors.initials: L
authors.lastname: Thomachot
authors.forename: R
authors.initials: R
authors.lastname: Vialet
authors.forename: S
authors.initials: S
authors.lastname: Arnaud
authors.forename: B
authors.initials: B
authors.lastname: Barberon
authors.forename: A
authors.initials: A
authors.lastname: Michel-Nguyen
authors.forename: C
authors.initials: C
authors.lastname: Martin
mesh_terms: D000328:Adult; D003428:Cross Infection / Q000209:etiology*; D004866:Equipment Contamination; D005260:Female; D005374:Filtration / Q000295:instrumentation*; D006358:Hot Temperature; D006801:Humans; D006813:Humidity; D017053:Infection Control; D008297:Male; D009330:Nebulizers and Vaporizers; D018410:Pneumonia, Bacterial / Q000209:etiology*; D011126:Polypropylenes; D011446:Prospective Studies; D012121:Respiration, Artificial / Q000009:adverse effects* / Q000295:instrumentation
chemical_list: D011126:Polypropylenes