Relationship between the humidity and temperature of inspired gas and the function of the airway mucosa

Abstract

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.

High-flow nasal oxygen therapy and noninvasive ventilation in the management of acute hypoxemic respiratory failure

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A Preliminary Randomized Controlled Trial to Assess Effectiveness of Nasal High-Flow Oxygen in Intensive Care Patients

“…The system conditions the inspired gas to 37°C and 44 mg H 2 O/L, which is considered thermodynamically neutral to the airway, 3 preserving the function of the ciliated mucosa. 4 Recent work described complications associated with unhumidified high-flow face mask (HFFM) oxygen therapy, which include discomfort and airway drying. 5 …”

Nasal high flow therapy: a novel treatment rather than a more expensive oxygen device

“…By this mechanism, mucociliary function and secretion clearance is improved [15], as shown in patients with idiopathic bronchiectasis from the reduced percentage of retention of an inhaled tracer before and after receiving warm and humidified air through NHF [16]. Furthermore, the required metabolic cost of warming and increasing the relative humidity of inspired gas is reduced, especially in patients with increased minute ventilation [17].…”