14 Moreover, the airway cooling during exercise followed by rapid re-warming of the airways after exercise could add an additional stress (ie, a thermal stress).
It is conceivable that cough receptors may respond to thermal stimuli or to mediators that are produced or released as a consequence of airway cooling.
Theoretically, HHFNC should prevent airway water loss, airway cooling, thickened secretions, and nasal irritation [ 10, 13].
Military wintertime training is associated with significant cold exposure and heavy physical exercise which could result in aggravated airway cooling and functional changes of the airway epithelia favouring influenza virulence and other respiratory tract infections [ 15].
Cold weather induces functional changes in the airways through cooling of the skin or the simultaneous cooling and drying of the nasal and airway mucosa while inhaling cold air (Eccles 2002).
In fact, exercise-induced bronchospasm is caused by cooling and drying in the airways, which occurs with obligate mouth breathing during vigorous activity.
The normal physiological mechanisms of brain cooling are heat loss from the upper airways and through the skull, and these can produce selective brain cooling.
Its cooling sensation when topically applied to the skin or mucous membranes of the airways (Eccles 1994) is a well-liked effect, which is used in many oral health care products, cosmetics food products, and tobacco.
It has been suggested that even cooling of the body surface could elicit a reflex vasoconstriction in the nose and upper airways and inhibit the respiratory defence and convert an asymptomatic subclinical viral infection into a symptomatic clinical infection [ 14].
Following a cooling and maintenance period, to assess the impact of nasal cooling on the upper respiratory airway, three pigs underwent an MRI scan using a 3-T MR scanner (Biograph PET/MR scanner, Siemens Medical Systems, Erlangen, Germany) equipped with eight-channel head array coils.
Cooling was obtained by endovascular cooling device or surface cooling.
