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Updated: Oct 24, 2026

Normothermic Negative Pressure Ventilation Ex Situ Lung Perfusion: Evaluation of Lung Function and Metabolism
Published on: February 14, 2022
Immediate application of positive-end expiratory pressure is more effective than delayed positive-end expiratory
M Ruiz-Bailén1, E Fernández-Mondéjar, B Hurtado-Ruiz
1Department of Intensive Medicine, Virgen de las Nieves Hospital, Granada, Spain.
Objective:
To determine by the measurement of extravascular lung water (EVLW) whether the timing of positive-end expiratory pressure (PEEP) application influences the intensity of lung injury.
Design:
Animal experimental study.
Setting:
Animal experimental laboratory.
Subjects:
Mixed-breed pigs (n = 18), aged 4 to 5 mos, weighing 25 to 30 kg.
Interventions:
The animals were anesthetized and tracheotomized, after which a permeability pulmonary edema was instigated by infusing oleic acid (0.1/kg) into the central vein. All animals were then randomly divided into three groups. In group 1 (n = 5), 10 cm H2O of PEEP was applied immediately after the oleic acid infusion and maintained throughout the 6 hrs of the experiment. Group 2 (n = 7) received the same level of PEEP 120 mins after the insult for 4 hrs. Group 3 (n = 6), the control group, was ventilated without PEEP for the six hrs of the experiment.
Measurements And Main Results:
At the end of the experiment, EVLW was calculated by gravimetric method. EVLW in group 1 (11.46+/-2.00 mL/kg) was significantly less than in group 2 (19.12+/-2.62 mL/kg) and group 3 (25.81+/-1.57 mL/kg), (p<.0001). Oxygenation also showed important differences by the end of the experiment when the Pao2/Fio2 ratio was significantly better in group 1 (467+/-73) than in group 2 (180+/-82) and group 3 (39+/-9), (p<.0001).
Conclusions:
The application of 10 cm H2O of PEEP reduces EVLW in a time-dependent manner and maximum protective effect is achieved if it is applied immediately after lung injury production.
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