Session/Time	Pulmonary I/Thu, 9:45 - 12 00 PM
Title	Real Time Lung Carbon Dioxide Elimination Rate (LC02): A Good Predictor of Alveolar Deadspace Volume (Vdalv) in Pediatric Patients Receiving Ventilatory Support
Author	OF Soremi, MD; MJ Banner, PhD; SR Goodwin, MD
Affiliation	Departments of Anesthesiology, Pediatrics, and Physiology, University of Florida College of Medicine, Gainesville, Florida
Introduction	Although recognized as a potentially useful parameter for assessing alveolar ventilation-to-perfusion matching, Vdalv , is not routinely measured because of the time required and difficulty in obtainin-CP accurate measurements. Recently, simple to operate, computerized equipment became available allowing accurate measurements Of Vdalv , and LC02-1 An arterial blood gas (PaCO2) is required for calculating Vdalv ,.LCO2, the area displayed in real time under the exhaled. C02 and volume curve, is easier to.'measure, and does not require an arterial blood cas. Because LCO is a reflection of pulmonary capillary blood flow, our objective was to determine if LCO2 is a predictor of Vdalv  in critically ill children receiving ventilatory support.
Method	After Institutional Review Board approval, 12 children (2 wk to 17 yr, 19.51 ± 19.62 kg) diaposed with respiratory failure and receiving ventilatory support were studied. Flow and capnometer sensors positioned between the "Y" piece of the breathing circuit and the endotracheal tube were directed to a conunercially available respiratory monitor (Novametrix), which calculated Vdalv and LCO2 usinc, the single breath C02 elimination technique.' Arterial blood cas samples were obtained from a previously inserted arterial catheter.Data ,Yere analyzed using regression analysis; alpha was set at 0.05 for statistical significance
Result	LCO2 correlated inversely with (r = -.89), and was a good predictor Of Vdalv (r 2 = 0.8) (Fig). When LC02 was low, Vdalv   was high and vice-versa.
Conclusion	LCO, is Sillipler to measure than Vdalv arid may provide us--,irul clinical information. It appears that real time LCO, data may be used to assess Vdalv and thus, the appropriateness of ventilatory support. For example, an acute decrease in LCO, could be the result of increased mean airway pressure, decreased cardiac output, and/or pulmonary emboli, all of which predispose to increased Vdalv. Reference (1) Crit Care Med 1996: 24:96-102.

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