Humidification and secretion volume in mechanically ventilated patients
OBJECTIVE:To determine potential effects of humidification on the volume of airway secretions in mechanically ventilated patients. METHODS:Water vapor delivery from devices providing non-heated-wire humidification, heated-wire humidification, and heat and moisture exchanger (HME) were quantified on the bench. Then, patients requiring 24-hour mechanical ventilation were exposed sequentially to each of these humidification devices, and secretions were removed and measured by suctioning every hour during the last 4 hours of the 24-hour study period. RESULTS:In vitro water vapor delivery was greater using non-heated-wire humidification, compared to heated-wire humidification and HME. In vivo, a total of 9 patients were studied. Secretion volume following humidification by non-heated-wire humidification was significantly greater than for heated-wire humidification and HME (P=.004). CONCLUSIONS:The volume of secretions appeared to be linked to humidification, as greater water vapor delivery measured in vitro was associated with greater secretion volume in vivo.