Comparison of the effects of heat and moisture exchangers and heated humidifiers on ventilation and gas exchange during non-invasive ventilation.
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.
Jaber
Samir
S
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
Chanques
Gérald
G
Matecki
Stefan
S
Ramonatxo
Michèle
M
Souche
Bruno
B
Perrigault
Pierre-François
PF
Eledjam
Jean-Jacques
JJ
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