title: A study of the effect of a resistive heat moisture exchanger (Trachinaze) on pulmonary function and blood gas tensions in patients who have undergone a laryngectomy: a randomized control trial of 50 patients studied over a 6-month period.
abstract: BACKGROUND
  Previous work from this department has shown that resistive tracheostomy filters increase the partial pressure of oxygen in capillary blood and also provide a significant amount of heat/moisture exchange. Until now it has not been shown whether there is any long-term beneficial effect and in particular whether raised tissue oxygenation is maintained using a practical filter device.
  
  
  METHODS
  We carried out a 6-month randomized control trial including 50 laryngectomees. Twenty-five patients were treated with the Liverpool Heat Moisture Exchange device incorporating an airway resistor (Trachinaze). Another 25 patients were treated with a placebo device. Relevant subjective and objective data were collected before and at the end of the study. The objective measurements were capillary oxygen tension (which parallels blood arterial tension), carbon dioxide tension, FEV(1), FVC, and PIF. Patients were reviewed at intervals throughout the study. Data were analyzed using the Mann-Whitney U test and the paired t test to test the difference between the active device and placebo at 6 months.
  
  
  RESULTS
  Subjective lower airway parameters, including cough, number of chest infections, mucus production, and shortness of breath at rest, were significantly improved in the active group compared with the placebo group. The objective parameters FEV(1), FVC, and PIF were not significantly different. Capillary oxygen tension, however, was highly significantly raised in the active group at 6 months.
  
  
  CONCLUSIONS
  Trachinaze is highly superior to placebo at improving subjective pulmonary parameters, including shortness of breath. It is also superior in its ability to maintain an increased peripheral tissue oxygen tension over a 6-month period.
authors.affiliation: Department Medicine, Head and Neck Group, University of Liverpool, Clinical Sciences Center, University Hospital Aintree, Long Lane, Liverpool L9 7AL, United Kingdom. profasjones@beestoncastle.fsnet.co.uk
authors.forename: Andrew Simpson
authors.initials: AS
authors.lastname: Jones
authors.forename: Pamela Elizabeth
authors.initials: PE
authors.lastname: Young
authors.forename: Zul Bin
authors.initials: ZB
authors.lastname: Hanafi
authors.forename: Zorustra George Grange
authors.initials: ZG
authors.lastname: Makura
authors.forename: John Elian
authors.initials: JE
authors.lastname: Fenton
authors.forename: Joseph Peter
authors.initials: JP
authors.lastname: Hughes
mesh_terms: D000403:Airway Resistance; D002245:Carbon Dioxide / Q000097:blood*; D005260:Female; D005374:Filtration / Q000295:instrumentation*; D005541:Forced Expiratory Volume; D006358:Hot Temperature; D006801:Humans; D006813:Humidity; D007320:Inspiratory Capacity; D007825:Laryngectomy / Q000534:rehabilitation*; D008297:Male; D008875:Middle Aged; D010100:Oxygen / Q000097:blood*; D015656:Respiratory Mechanics; D014139:Tracheostomy / Q000295:instrumentation*; D014797:Vital Capacity
chemical_list: D002245:Carbon Dioxide; D010100:Oxygen