A model for the relationship between airway mucosal dysfunction and the combination of the humidity of inspired gas and the duration over which the airway mucosa is exposed to that humidity is proposed. This model suggests that there is an optimal temperature and humidity above which, and below which, there is impaired mucosal function. This optimal level of temperature and humidity is core temperature and 100% relative humidity. However, existing data are only sufficient to test this model for gas conditions below core temperature and 100% relative humidity. These data concur with the model in that region. No studies have yet looked at this relationship beyond 24 hrs. Longer exposure times to any given level of inspired humidity and inspired gas temperatures and humidities above core temperature and 100% relative humidity need to be studied to fully verify the proposed model.

Objective: To test whether a reduction in air temperature within the clinical range [37 C to 30, 100% relative humidity (RH)] altered mucus transport velocity (MTV) and ciliary beat frequency (CBF) in an in vitro ovine tracheal model. Design: Controlled laboratory study. Setting: University research laboratory. Subjects: Farm-reared sheep. Interventions: Tracheae were mounted flat in an organ bath. Krebs Henseleit bathed the serosal surface and air at 100% (RH) was passed over the mucosal surface at 4 l/min.

Background: It is unknown whether fluid resuscitation with colloid or crystalloid in patients with severe sepsis or septic shock is associated with an improvement in clinical outcome. This randomized controlled trial determined the feasibility of conducting a large trial testing resuscitation with pentastarch vs normal saline in early septic shock, powered for a difference in mortality.

Inspired gas at body temperature and saturated is thermodynamically neutral to the intubated airway, and thus may be considered the optimal condition for ventilation lasting more than a few hours.