title: The influence of a heat and moisture exchanger on tracheal climate in a cold environment.
abstract: OBJECTIVE
  The incidence of pulmonary complaints, severe tracheitis and lung function deterioration is increased during wintertime in laryngectomized individuals. We analyzed how a heat and moisture exchanger (HME) performs in cold and dry ambient circumstances, and how its efficiency in this environmental climate might be improved.
  
  
  METHODS
  Randomized crossover.
  
  
  METHODS
  Intra-tracheal temperature and humidity were measured in 10 laryngectomized patients with and without HME, in a cold (mean, 4.7 degrees C) and dry (mean, 4.5 mgH2O/L) room.
  
  
  RESULTS
  Presence of an HME causes the intra-tracheal mean humidity minima and maxima to increase with 4.2 mgH2O/L (95%CI: 3.3-5.0 mgH2O/L; p<0.001) and 2.4 mgH2O/L (95%CI: 1.7-3.1 mgH2O/L; p<0.001), respectively. The intra-tracheal mean temperature minima and maxima increased with 3.9 degrees C (95%CI: 2.7-5.1 degrees C; p<0.001) and 1.2 degrees C (95%CI: 0.8-1.2 degrees C; p<0.001), respectively. In the majority of patients, the calculated relative humidity values appear to reach well above 100% during inspiration.
  
  
  CONCLUSIONS
  In a cold environment, presence of an HME significantly increases both inspiratory and expiratory temperature and humidity values. Relative humidity calculations suggest the formation of condense droplets during inspiration. To further increase its effectiveness, improvement of the HME's thermal capacity should be aimed for.
authors.affiliation: Department of Head and Neck Oncology and Surgery, The Netherlands Cancer Institute-Antoni van Leeuwenhoek Hospital, Amsterdam, The Netherlands.
authors.forename: J Karel
authors.initials: JK
authors.lastname: Zuur
authors.forename: Sara H
authors.initials: SH
authors.lastname: Muller
authors.forename: Andrew
authors.initials: A
authors.lastname: Vincent
authors.forename: Michiel
authors.initials: M
authors.lastname: Sinaasappel
authors.forename: Frans H C
authors.initials: FH
authors.lastname: de Jongh
authors.forename: Frans J M
authors.initials: FJ
authors.lastname: Hilgers
mesh_terms: D000368:Aged; D000369:Aged, 80 and over; D003080:Cold Temperature; D018592:Cross-Over Studies; D004780:Environment, Controlled; D005260:Female; D006358:Hot Temperature; D006801:Humans; D006813:Humidity; D007825:Laryngectomy; D008297:Male; D008875:Middle Aged; D011786:Quality Control; D012121:Respiration, Artificial / Q000295:instrumentation* / Q000379:methods; D014132:Trachea / Q000502:physiology*; D014867:Water / Q000378:metabolism*
chemical_list: D014867:Water