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Respir Care. 2013 Apr;58(4):633-8. doi: 10.4187/respcare.01916.

Optoelectronic vital capacity measurement for restrictive diseases.

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Services de Physiologie-Explorations Fonctionnelles, Plateforme d'Analyse du Mouvement, et Centre d'Innovations Technologiques, Unité Mixte de Recherche 805, Hôpital Raymond Poincaré, Assistance Publique Hôpitaux de Paris, Garches, France.



To determine whether optoelectronic plethysmography accurately evaluated vital capacity (VC) in patients with respiratory muscle dysfunction of variable severity, including those with paradoxical abdominal movements.


In 20 subjects, VC was measured in the supine position using both spirometry and optoelectronic plethysmography (6 optoelectronic cameras and 52 reflective markers on the anterior chest wall).


Spirometry VC (VC-Spiro) correlated positively with optoelectronic VC (VC-Opto) (r(2) = 0.99, P < .001), and the regression line was very close to the identity line (VC-Opto [mL] = -1.202 + 1.007 × VC-Spiro [mL]). A Bland-Altman plot showed that the mean difference was -20 mL (95% CI -63 mL to 24 mL) and the limits of agreement were 163 mL (95% CI 106 mL to 231 mL) and -203 mL (95% CI -271 mL to -146 mL). The difference between the 2 values expressed as the percentage of the mean value was < 15% in all 20 subjects, < 10% in 17 (85%) subjects, and < 5% in 11 (55%) subjects. The difference, expressed as the percentage of the mean value, was unrelated to the contribution of abdominal motion to VC (r = 0.02 and P = .94), but was significantly related to body mass index (r = 0.53, P = .02).


Optoelectronic plethysmography is accurate and suitable for VC measurement in patients with various degrees of respiratory failure, including those with paradoxical abdominal movements. This noninvasive method may be an attractive alternative for accurately measuring VC in the event of air leakage (through the mouth or tracheostomy) or when patients are unable to breathe with the dead space added by the spirometer.


neuromuscular; optoelectronic plethysmography; pulmonary function; respiratory failure; spirometry; vital capacity

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