title: Comparison of the effects of heat and moisture exchangers and heated humidifiers on ventilation and gas exchange during non-invasive ventilation.
abstract: OBJECTIVE
  To compare the short-term effects of a heat and moisture exchanger (HME) and a heated humidifier (HH) during non-invasive ventilation (NIV).
  
  
  METHODS
  Prospective, clinical investigation.
  
  
  METHODS
  Intensive care unit of a university hospital.
  
  
  METHODS
  Twenty-four patients with acute respiratory failure (ARF).
  
  
  METHODS
  Each patient was studied with a HME and a HH in a random order during two consecutive 20min periods of NIV.
  
  
  RESULTS
  Respiratory rate (RR), expiratory tidal volume (VTe) and expiratory minute ventilation (VE) were measured during the last 5 min of each period and blood gases were measured. Mean pressure support and positive end-expiratory pressure levels were, respectively, 15+/-4 and 6+/-2 cmH(2)O. VE was significantly greater with HME than with HH (14.8+/-4.8 vs 13.2+/-4.3 l/min; p<0.001). This increase in VE was the result of a greater RR for HME than for HH (26.5+/-10.6 vs 24.1+/-9.8 breaths/min; p=0.002), whereas the VT for HME was similar to that for HH (674+/-156 vs 643+/-148 ml; p=0.09). Arterial partial pressure of carbon dioxide (PaCO(2)) was significantly higher with a HME than with a HH (43.4+/-8.9 vs 40.8+/-8.2 mmHg; p<0.005), without significantly changing oxygenation.
  
  
  CONCLUSIONS
  During NIV the increased dead space of a HME can negatively affect ventilatory function and gas exchange. The effect of HME dead space may decrease efficiency of NIV in patients with ARF.
authors.affiliation: Unité de Réanimation et de Transplantation-Département d'Anesthésie-Réanimation B, CHU de Montpellier Hôpital Saint Eloi, 80 avenue Augustin Fliche, 34295 Montpellier Cedex, France. jaber@creteil.inserm.fr
authors.forename: Samir
authors.initials: S
authors.lastname: Jaber
authors.forename: Gérald
authors.initials: G
authors.lastname: Chanques
authors.forename: Stefan
authors.initials: S
authors.lastname: Matecki
authors.forename: Michèle
authors.initials: M
authors.lastname: Ramonatxo
authors.forename: Bruno
authors.initials: B
authors.lastname: Souche
authors.forename: Pierre-François
authors.initials: PF
authors.lastname: Perrigault
authors.forename: Jean-Jacques
authors.initials: JJ
authors.lastname: Eledjam
mesh_terms: D000208:Acute Disease; D000328:Adult; D000368:Aged; D000369:Aged, 80 and over; D006358:Hot Temperature; D006801:Humans; D006813:Humidity; D007362:Intensive Care Units; D008875:Middle Aged; D011446:Prospective Studies; D011659:Pulmonary Gas Exchange; D012123:Pulmonary Ventilation; D012044:Regression Analysis; D012121:Respiration, Artificial / Q000379:methods*; D012126:Respiratory Dead Space; D012131:Respiratory Insufficiency / Q000503:physiopathology / Q000628:therapy*; D018709:Statistics, Nonparametric