Effects of a combination of prone positioning and high-frequency oscillatory ventilation on blood gas exchange in an experimental pig model of acute respiratory distress syndrome

Abstract

This animal study was conducted in order to verify the effects of combining high-frequency oscillatory ventilation and prone positioning and the order of application of both methods on blood gas exchange in an experimental model of acute respiratory distress syndrome.Forty domestic pigs were used for the study. Saline solution washout was produced by bilateral lung lavage. The lavage process was repeated until adequate impairment of gas exchange (defi ned as PaO2 < 100 mmHg) 60 min following the last lavage was achieved. Subsequently, lung injury was established and each model was randomized to one of fi ve groups, with differences in the type of mechanical ventilation used (conventional mechanical ventilation in accordance with the principles of protective lung ventilation or high-frequency oscillatory ventilation) and also in the positioning of the experimental model (supine position or mode changing prone and supine positions in a ratio 18:6 hours).The best oxygenation was achieved in the group prone position + high-frequency oscillatory ventilation. The most favorable combination in terms of carbon dioxide elimination is the high-frequency oscillatory ventilation + prone position. The best results in terms of oxygenation index value were obtained in the combination of a prone position with the high-frequency oscillatory ventilation and in the prone position.In conclusion, by using combinations of prone positioning and high-frequency oscillatory ventilation, one can achieve better blood gas parameters during acute respiratory distress syndrome.

Ispitivanje je sprovedeno sa ciljem utvrđivanja efekata kombinacije oscilatorne ventilacije visoke frekvencije i ležećeg položaja, na razmenu gasova u krvi u eksperimentalnom modelu sindroma akutnog respiratornog šoka, kod 40 svinja. Urađena je bilateralna lavaža pluća fi ziloškim rastvorom. Postupak lavaže je ponovljan dok nije postignut adekvatan poremećaj razmene gasova (defi nisano kao PaO2<100 mmHg) 60 minuta posle poslednje lavaže. Posle toga, uočena je ozleda pluća i svaki model je nasumično raspoređen u jednu od pet grupa sa različitim tipom mehaničke ventilacije kao i prema poziciji eksperimentalnog modela (leđni položaj ili izmena stomačnog i leđnog položaja). Najbolja oksigenacija je postignuta u grupi sa stomačnim položajem + oscilatorna ventilacija visoke frekvencije. Najbolja kombinacija u odnosu na eliminaciju ugljen dioksida je bila oscilatorna ventilacija visoke frekvencije + stomačni položaj. Najbolji rezultati u odnosu na indeks oksigenacije dobijeni su primenom kombinacije stomačnog položaja + oscilatorna ventilacija visoke frekvencije kao i samo stomačni položaj. Može da se zaključi da se primenom kombinacije stomačnog položaja i oscilatorne ventilacije visoke frekvencije dobijaju bolje vrednosti gasova u krvi tokom sindroma akutnog respiratornog šoka.