[Effects of different levels of positive end expiratory pressure on lung recruitment and hemodynamics after sustained inflation in acute respiratory distress syndrome in sheep].
OBJECTIVE
To study the effects of different levels of positive end expiratory pressure (PEEP) on recruitment and hemodynamics after sustained inflation in acute respiratory distress syndrome (ARDS) in sheep.


METHODS
Twelve adult sheep were anaesthetized and ARDS was induced by lung lavage with warm normal saline. Pressure-volume (P-V) curves were traced using the low flow technique and the upper inflection point (UIP) was determined. Sustained inflation was exercised at the pressure of 5 cm H(2)O (1 cm H(2)O=0.098 kPa) below UIP, and the sheep were divided into groups according to different PEEP levels (PEEP5, PEEP10, PEEP15, PEEP20). Hemodynamics and lung mechanics values were recorded during the 2 hours of recruitment, and biopsy was performed at the end of the trial.


RESULTS
There was no effect on hemodynamics and recruitment in 2 hours in PEEP5 and PEEP10 groups, but oxygenation was found to be decreased in PEEP5 group, and focal alveolar collapse was found in pathological examination. When the PEEP level reached 15 cm H(2)O, there was significant elevation in central venous pressure (CVP), and cardiac index (CI) fell remarkably, but oxygenation index and lung mechanics were improved and stable in 2 hours.


CONCLUSIONS
Our study demonstrates that it can obviously improve oxygenation when PEEP is set at 10-20 cm H(2)O, oxygenation can be obviously improved, with little disturbance to hemodynamics in case cardiac function is normal.
Xu
Lei
L
Intensive Care Unit, Tianjin Third Central Hospital, Tianjin 300170, China.
Wang
Shu-peng
SP
Zhang
Na-xin
NX
Qin
Ying-zhi
YZ
D000818:Animals; D004195:Disease Models, Animal; D005260:Female; D006439:Hemodynamics; D008168:Lung / Q000473:pathology / Q000503:physiopathology; D008297:Male; D011175:Positive-Pressure Respiration / Q000379:methods*; D011897:Random Allocation; D012128:Respiratory Distress Syndrome / Q000503:physiopathology* / Q000628:therapy; D012756:Sheep