End-inspiratory rebreathing reduces the end-tidal to arterial PCO gradient in mechanically ventilated pigs.

Autor: Fierstra, Jorn, Machina, Matthew, Battisti-Charbonney, Anne, Duffin, James, Fisher, Joseph Arnold, Minkovich, Leonid
Předmět:
Zdroj: Intensive Care Medicine; Sep2011, Vol. 37 Issue 9, p1543-1550, 8p, 1 Color Photograph, 1 Diagram, 2 Charts, 3 Graphs
Abstrakt: Purpose: Noninvasive monitoring of the arterial partial pressures of CO (PaCO) of critically ill patients by measuring their end-tidal partial pressures of CO (P etCO) would be of great clinical value. However, the gradient between P etCO and PaCO (P et-aCO) in such patients typically varies over a wide range. A reduction of the P et-aCO gradient can be achieved in spontaneously breathing healthy humans using an end-inspiratory rebreathing technique. We investigated whether this method would be effective in reducing the P et-aCO gradient in a ventilated animal model. Methods: Six anesthetized pigs were ventilated mechanically. End-tidal gases were systematically adjusted over a wide range of P etCO (30-55 mmHg) and P etO (35-500 mmHg) while employing the end-inspiratory rebreathing technique and measuring the P et-aCO gradient. Duplicate arterial blood samples were taken for blood gas analysis at each set of gas tensions. Results: P etCO and PaCO remained equal within the error of measurement at all gas tension combinations. The mean ± SD P et-aCO gradient (0.13 ± 0.12 mmHg, 95% CI −0.36, 0.10) was the same ( p = 0.66) as that between duplicate PaCO measurements at all P etCO and P etO combinations (0.19 ± 0.06, 95% CI −0.32, −0.06). Conclusions: The end-inspiratory rebreathing technique is capable of reducing the P et-aCO gradient sufficiently to make the noninvasive measurement of P etCO a useful clinical surrogate for PaCO over a wide range of P etCO and P etO combinations in mechanically ventilated pigs. Further studies in the presence of severe ventilation-perfusion (V/Q) mismatching will be required to identify the limitations of the method. [ABSTRACT FROM AUTHOR]
Databáze: Complementary Index
Externí odkaz: