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Work of breathing (WOB) is the energy expended to inhale and exhale a breathing gas. It is usually expressed as work per unit volume, for example, joules/litre, or as a work rate (power), such as joules/min or equivalent units, as it is not particularly useful without a reference to volume or time. It can be calculated in terms of the pulmonary pressure multiplied by the change in pulmonary volume, or in terms of the oxygen consumption attributable to breathing.〔Medical Dictionary for the Health Professions and Nursing. S.v. "work of breathing." Retrieved September 8, 2015 from http://medical-dictionary.thefreedictionary.com/work+of+breathing〕〔Medical Dictionary. S.v. "work of breathing." Retrieved September 8, 2015 from http://medical-dictionary.thefreedictionary.com/work+of+breathing〕 In a normal resting state the work of breathing constitutes about 5% of the total body oxygen consumption. It can increase considerably due to illness〔Mosby's Medical Dictionary, 8th edition. S.v. "work of breathing." Retrieved September 8, 2015 from http://medical-dictionary.thefreedictionary.com/work+of+breathing〕 or constraints on gas flow imposed by breathing apparatus, ambient pressure, or breathing gas composition. ==Mechanism of breathing== The normal relaxed state of the lung and chest is partially empty. Further exhalation requires muscular work. Inhalation is an active process requiring work. Some of this work is to overcome frictional resistance to flow, and part is used to deform elastic tissues, and is stored as potential energy, which is recovered during the passive process of exhalation, Tidal breathing does not require active muscle contraction during exhalation. The required energy is provided by the stored elastic energy. When there is increased gas flow resistance, the optimal respiratory rate decreases. 抄文引用元・出典: フリー百科事典『 ウィキペディア（Wikipedia）』 ■ウィキペディアで「Work of breathing」の詳細全文を読む スポンサード リンク
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