Utility of Arterial to End-tidal Carbon Dioxide Difference [P(a – ET)CO2] as a Weaning Index

Todur, Prathibha and Johnson, Saumy and Shenoy, Anitha (2013) Utility of Arterial to End-tidal Carbon Dioxide Difference [P(a – ET)CO2] as a Weaning Index. Indian Journal of Respiratory Care, 2 (1). pp. 227-232.

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Introduction: Quantification of physiological dead space (VDphys) provides important insight into the efficiency of ventilation and its relation to pulmonary perfusion. Arterial to end-tidal carbon dioxide difference [P(a-ET)CO2] may provide a valuable surrogate measure of VDphys and may be useful as an index of weaning success. Aim: To evaluate the utility of [P(a-ET)CO2] as a weaning index. Methods: This prospective study enrolled 52 invasively mechanically ventilated adult patients treated in Medical Intensive Care Unit (MICU) between December 2010 and December 2011. The end-tidal carbon dioxide concentration was measured using a side stream capnograph at each attempt at decreasing ventilatory support and when they were ready to be weaned. A receiver operating characteristic (ROC) curve was constructed for weaning success, progressive weaning and extubation success. A cut-off point was obtained from these curves from which the sensitivity, specificity, positive and negative predictive values were obtained. Results: The ability of [P(a-ET)CO2] as a predictor of progressive reduction in ventilator support (n = 118), predictor of weaning from mechanical ventilation (n = 40) and for extubation success (n = 39) was evaluated. The area under the curve (AUC) for progressive weaning, spontaneous breathing trial and extubation success were 0.852, 0.905 and 0.702 and a threshold of 10.5 mm Hg, 9.4 mm Hg and 9.5 mm Hg respectively were obtained. Conclusion: P(a-ET)CO2 of ≤ 10 mm Hg may be used as an index of weaning during progressive weaning from mechanical ventilation, spontaneous breathing trial and to predict success of extubation.

Item Type: Article
Uncontrolled Keywords: Weaning index; Arterial to end-tidal carbon dioxide gradient; Dead space
Subjects: Allied Health > MCOAHS Manipal > Respiratory Therapy
Depositing User: KMC Manipal
Date Deposited: 13 Feb 2014 04:13
Last Modified: 13 Feb 2014 04:13
URI: http://eprints.manipal.edu/id/eprint/138801

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