★Viewpoint article of Dr. Katagiri and Associate professor Fujii was published in the Experimental Physiology
In humans, ventilation is tightly regulated in accordance with oxygen uptake and carbon dioxide production to maintain arterial blood gas homeostasis. However, when humans are passively heated, hyperventilation occurs as core temperature rises, even at rest where metabolism remains almost constant. This response leads to hypocapnia, which is accompanied by blood and cerebral intra- and extracellular alkalosis, thereby disturbing acid–base homeostasis. Notably, this response appears distinct from the tachypnoeic panting observed in some acutely heat-stressed animals, such as dogs, in which respiratory frequency markedly increases while tidal volume decreases, resulting in minimal change in alveolar ventilation. This breathing pattern enhances evaporative and conductive heat dissipation from the airways but does not induce blood alkalosis. Accordingly, the physiological significance of the breathing response during heat stress appears to differ between panting animals and humans. Nevertheless, it remains unclear whether hyperthermia-induced hyperventilation in humans represents an adaptive physiological response for regulating acid–base balance.
In this perspective article, the authors discuss the following points: (1) hyperthermia-induced hyperventilation in humans is unlikely to be an adaptive response for maintaining acid–base homeostasis; (2) from a thermal homeostasis, this response may even be disadvantageous; and (3) potential strategies to mitigate or prevent the exacerbation of this response.
A. Katagiri and N. Fujii, “Should we breathe more like dogs when overheated? A perspective from acid–base balance,” Experimental Physiology, DOI: 10.1113/EP093499.
Full text available at Experimental Physiology
