However, differences in the exact way of measuring this space result in clinically significant different results and, therefore, debate remains about the true value of this measured parameter.Ĭopyright © 2023, StatPearls Publishing LLC. Indeed, it may serve as a prognostic factor in patients with acute repository distress syndrome (ARDS) who require ventilation. This phenomenon has clinical significance because, both in healthy and impaired lungs, properly calculating and accounting for this non-physiological space is important for the proper respiratory care of ventilated patients. This is therefore termed anatomical dead space as it serves no respiratory function. Using Fowlers single breath nitrogen analyzing technique, atropine was found to increase dead space by 19.2 per cent at one hour, declining to 11.02 per cent at four hours. In the single-breath nitrogen washout technique, also called the Fowler method, a subject has a nitrogen meter attached to a mouthpiece to monitor N 2 fraction in the inspired or expired air. Anatomic dead space is an important phenomenon in respiratory physiology whereby, owing to the fact that upper airways do not function as locations for gas exchange, and because of the tidal nature of ventilation, there is always a fraction of the inspired air that does not perform a physiologic function of exchanging carbon dioxide for oxygen. The anatomical dead space can be measured using plaster cast techniques in cadavers or by a single-breath nitrogen washout technique (figure).
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