Chest
-
Randomized Controlled Trial Comparative Study Clinical Trial
Comparison of the effects of heat and moisture exchangers and heated humidifiers on ventilation and gas exchange during weaning trials from mechanical ventilation.
Heat and moisture exchangers (HME) are increasingly used to warm and humidify inspired gases in intubated ventilated patients. But these devices add dead space that may alter the alveolar ventilation. This could impair the efficiency of spontaneous ventilation (SV) during weaning trials from mechanical ventilation. ⋯ The higher PaCO2 with HME than with HH (44 +/- 2 mm Hg vs 42 +/- 2 mm Hg; p < 0.005) revealed an insufficient alveolar ventilation response to the increase in dead space. Arterial Po2 rose with the HME, but not significantly above the HH values (103 +/- 6 mm Hg vs 97 +/- 6 mm Hg; p = 0.055), possibly because of a positive end-expiratory pressure effect of the HME. The need to increase VE in SV when an HME is used should be taken into account during difficult weaning from mechanical ventilation.