Effects of lung protective ventilation in prone or supine position on inhibiting adrenomedullin release in acute respiratory distress syndrome caused by pulmonary and extra-pulmonary insults in dog

Objective: To investigate the changes in adrenomedullin release in bronchial alveolar lavage fluid (BALF) from different lung areas in acute respiratory distress syndrome (ARDS) of produced dogs, by pulmonary and extra-pulmonary causes, with low tidal volume and positive end expiratory pressure (PEEP) treatment under supine and prone position.

Methods: Twenty-four male mongrel dogs were randomly divided into ARDSp (ARDS caused by pulmonary causes) supine group, ARDSp prone group, ARDSexp (ARDS caused by extra-pulmonary causes) supine group, and ARDSexp prone group. A detergent to cause lung injury in ARDSp dogs, and intravenous oleic acid was given in ARDSexp dogs. The results of adrenomedullin in different areas of dog's lung (upper lobe, middle lobe, and lower lobe) and arterial blood gas under lung protective ventilation treatment were measured.

Results: After lung injury, the arterial oxygenation index was lowered, and the levels of adrenomedullin in the upper lobe and middle lobe of ARDSp dogs were higher than that of ARDSexp dogs. After receiving low tidal volume and PEEP ventilation, the conditions of all the dogs were gradually getting ameliorated, and prone position ventilation gave better effects on lung injury dogs by inhibiting adrenomedullin release.

Conclusions: There are statistical differences in adrenomedullin release in different lung areas between ARDSp dogs and ARDSexp dogs, and in both ARDSexp dogs and ARDSp dogs low tidal volume and PEEP treatment under prone position ventilation give better results compared to supine position.