Heat and water respiratory exchanges: comparison between mouth and nose breathing in humans

Abstract

The temperatures (TI, TE) of inspired and expired gas and the mass of expired water (MEH2O) have been measured in four subjects at rest during mouth and nose breathing of dry air at room temperature. TI and TE were measured by copper-constantan thermocouples, MEH2O by freezing and ventilatory parameters by total body plethysmography. During mouth breathing, temperatures are significantly higher (TI = 28.1 degrees C, TE = 31.5 degrees C) and the amount of expired water larger (MEH2O = 27.8 mg dm-3 BTPS) than during nose breathing (TI = 24.8 degrees C; TE = 29.6 degrees C; MEH2O = 26.6 mg dm-3 BTPS). From these experimental data the appropriate computations show clearly that in humans, while either nose or mouth breathing, the expired air is not water saturated; the latent heat exchanges represent the larger part of the respiratory heat exchanges; the counter current expiratory heat recovery is imperfect; in terms of heat and water respiratory exchanges, no large difference exists between the oral and nasal routes. This last point is confirmed by the calculation of a difference less than 10% in the total respiratory heat losses between mouth and nose breathing.

Dependence of human respiratory thermal washout on extrathoracic airway conditions

“…HANSON [21] showed that tc alters pulmonary heat exchange and expired air temperatures but could not separate these effects from temperature-dependent increases in V 'E. Lowering tc might produce a similar confounding effect in the present study, with heat exchange altered by both lower blood temperatures and reduced V'E.…”

“…This work also raises the question of whether the nasal passage exchanges heat more efficiently than the oral cavity. VARENE et al [21] found that tpn and tpo did not significantly differ in subjects breathing room (21°C) air. Sensible heat losses were calculated to be far less than latent heat losses and they concluded that oral and nasal heat exchange efficiency was roughly equivalent [21].…”

“…VARENE et al [21] found that tpn and tpo did not significantly differ in subjects breathing room (21°C) air. Sensible heat losses were calculated to be far less than latent heat losses and they concluded that oral and nasal heat exchange efficiency was roughly equivalent [21]. However, mean tpn and tpo were approximately 4.5 and 3.5°C lower, respectively, than comparable temperatures found by HOPPE [15] or in the present study.…”

Micro-shear bond strength of adhesive resins to enamel at different relative humidity conditions

“…While considering the source of the humidity in oral environment, air that is exhaled through the mouth, had always been overlooked. The amount of water saturated in the exhaled air is reported to be about 27 mg/dm 3 and its possible effects on dental practice requires careful evaluation 9) . Although rubber dam can be used in routine in order to isolate the adhesive surface from the oral environment, its use could be restricted during luting laminate veneers and crowns with subgingival margins, operating in Class V lesions, bonding brackets in the posterior area or in many other chair-side conservative applications.…”

CFD heat transfer simulation of the human upper respiratory tract for oronasal breathing condition

“…Reynolds number. Varene et al (1986), have conducted a study concluding that the temperature during inspiration (T I ) and during expiration (T E ) differs for the oral and nasal cavities (the oral cavity having the higher temperature rate than the nasal cavity). But it was concluded by that no large differences exist from an energetic point of view between the nasal and oral cavities.…”