Ventilation-Perfusion Distribution Related to Different Inspiratory Flow Patterns in Experimental Lung Injury

In acute lung injury (ALI), controlled mechanical ventilation with decelerating inspiratory flow (V̇dec) has been suggested to improve oxygenation when compared with constant flow (V̇con) by improving the distribution of ventilation and perfusion (V̇A/Q̇). We performed the present study to test this...

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Veröffentlicht in:Anesthesia and analgesia 2004-01, Vol.98 (1), p.211-219
Hauptverfasser: Dembinski, Rolf, Henzler, Dietrich, Bensberg, Ralf, Prüsse, Berit, Rossaint, Rolf, Kuhlen, Ralf
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Sprache:eng
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Zusammenfassung:In acute lung injury (ALI), controlled mechanical ventilation with decelerating inspiratory flow (V̇dec) has been suggested to improve oxygenation when compared with constant flow (V̇con) by improving the distribution of ventilation and perfusion (V̇A/Q̇). We performed the present study to test this hypothesis in an animal model of ALI. Furthermore, the effects of combined decelerating and constant flow (V̇deco) were evaluated. Thus, 18 pigs with experimental ALI were randomized to receive mechanical ventilation with either V̇con, V̇dec or a fixed combination of both flow wave forms (V̇deco) at the same tidal volume and positive end-expiratory pressure level for 6 h. Hemodynamics, gas exchange, and V̇A/Q̇ distribution were determined. The results revealed an improvement of oxygenation resulting from a decrease of pulmonary shunt within each group (P < 0.05). However, blood flow to lung areas with a normal V̇A/Q̇ distribution increased only during ventilation with V̇con (P < 0.05). Accordingly, Pao2 was higher with V̇con than with V̇dec and V̇deco (P < 0.05). We conclude that contrary to the hypothesis, V̇con provides a more favorable V̇A/Q̇ distribution, and hence better oxygenation, when compared with V̇dec and V̇deco in this model of ALI.
ISSN:0003-2999
1526-7598
DOI:10.1213/01.ANE.0000090319.21491.91