Utility of the dead space fraction (Vd/Vt) as a predictor of extubation success

• Published in: Medicina intensiva Vol. 35; no. 9; p. 529
• Main Authors: González-Castro, A, Suárez-Lopez, V, Gómez-Marcos, V, González-Fernandez, C, Iglesias-Posadilla, D, Burón-Mediavilla, J, Rodríguez-Borregan, J C, Miñambres, E, Llorca, J
• Format: Journal Article
• Language: Spanish
• Published: Spain 01.12.2011
• Subjects: Aged; Airway Extubation; APACHE; Cardiovascular Diseases - therapy; Continuous Positive Airway Pressure; Female; Humans; Male; Middle Aged; Prospective Studies; Pulmonary Disease, Chronic Obstructive - therapy; Respiratory Dead Space; Ventilator Weaning - methods
• ISSN: 1578-6749
• DOI: 10.1016/j.medin.2011.05.016

To determine the value of Vd/Vt as a predictor of extubation failure in patients with mechanical ventilation admitted to the intensive care units. A prospective, observational cohort study conducted from 1 September 2010 to 1 March 2011. General intensive care unit (G-ICU) of a third level university hospital. The study included patients on mechanical ventilation (MV) for over 12 hours, and who in the process of weaning were subjected to low-level pressure support. Exclusion criteria were age under 18 years, ventilation via tracheotomy and patients failing to cooperate for different reasons. During the study, 392 patients were admitted to the G-ICU; of these, 214 required MV. The weaning process was started in 154 cases. Fifty-four patients were excluded from the study, and 24 were not extubated from MV. A total of 76 patients were finally extubated and analyzed. Vd/Vt was calculated as the ratio (PaCO(2)-Pє CO(2))/PaCO(2), with the recorded parameters. Logistic regression analysis showed a significant association between the Vd/Vt and extubation failure, with OR=1.52 (95%CI 1.11 to 2.09, p=0.008). The area under the ROC curve with respect to the prediction of extubation failure according to the Vd/Vt value was 0.94 (95%CI 0.86 to 0.98, p<0.0001). Vd/Vt is a powerful predictor of extubation failure in patients on MV.