ORIGINAL ARTICLES   

Minerva Pneumologica 2008 September;47(3):121-5

Copyright © 2008 EDIZIONI MINERVA MEDICA

language: English

Does mechanical work of breathing imply a substantial thermogenetic effect on human body? A theoretical calculation

Rubini A. ¹, Del Monte D. ², Catena V. ³

¹ Section of Physiology Department of Human Anatomy and Physiology University of Padua, Italy 2 Intensive Care Unit, ASL 15 Camposampiero Hospital, Padua, Italy 3 Intensive Care Unit, ASL 3 Bassano del Grappa Hospital, Vicenza, Italy

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Aim. The mechanical work of breathing implies an heat production resulting in a thermogenetic effect on human body, which is very difficult to measure directly and for this reason has never been previously estimated or quantified.
Methods. From previously published data concerning oxygen consumption in breathing and mechanical ventilator work authors calculated the thermogenic effect of the mechanical work of breathing, both at different values of pulmonary ventilation during spontaneous breathing in normal subjects, and during mechanical ventilation in normal subjects and in the presence of lung diseases such as Adult Respiratory Distress Syndrome or Chronic Obstructive Pulmonary Disease. The calculations were carried out on the theoretical basis that all breathing transforms energy in heat at the end of the respiratory cycle, due to the lack of potential energy storing.
Results. Calculations show that breathing dependent heat production is estimable but it is too low to affect significantly body heat balance, in any considered condition, both during spontaneous and artificial breathing.
Conclusion. The thermogenic effect produced by breathing may be easily quantified. The correlated heat production results usually very low with respect to the total body heat production, so that it may be disregarded as a possible source of hyperthermya, even during mechanical ventilation of diseased patients.