Lung and 'end organ' injury due to mechanical ventilation in animals: comparison between the prone and supine positions.

INTRODUCTION: Use of the prone position in patients with acute lung injury improves their oxygenation. Most of these patients die from multisystem organ failure and not from hypoxia, however. Moreover, there is some evidence that the organ failure is caused by increased cell apoptosis. In the present study we therefore examined whether the position of the patients affects histological changes and apoptosis in the lung and 'end organs', including the brain, heart, diaphragm, liver, kidneys and small intestine. METHODS: Ten mechanically ventilated sheep with a tidal volume of 15 ml/kg body weight were studied for 90 minutes. Five sheep were placed in the supine position and five sheep were placed in the prone position during the experiment. Lung changes were analyzed histologically using a semiquantitative scoring system and the extent of apoptosis was investigated with the TUNEL method. RESULTS: In the supine position intra-alveolar hemorrhage appeared predominantly in the dorsal areas, while the other histopathologic lesions were homogeneously distributed throughout the lungs. In the prone position, all histological changes were homogeneously distributed. A significantly higher score of lung injury was found in the supine position than in the prone position (4.63 +/- 0.58 and 2.17 +/- 0.19, respectively) (P < 0.0001). The histopathologic changes were accompanied by increased apoptosis (TUNEL method). In the supine position, the apoptotic index in the lung and in most of the 'end organs' was significantly higher compared with the prone position (all P < 0.005). Interestingly, the apoptotic index was higher in dorsal areas compared with ventral areas in both the prone and supine positions (P < 0.003 and P < 0.02, respectively). CONCLUSION: Our results suggest that the prone position appears to reduce the severity and the extent of lung injury, and is associated with decreased apoptosis in the lung and 'end organs'.

Sudden death from contusion of the right atrium after blunt chest trauma: case report and review of the literature.

Occult cardiac injury following blunt trauma is more common than generally suspected. Myocardial lesions range from myocardial contusion to cardiac rupture. Myocardial contusion is not uncommon, it is usually a benign disorder which often remains undiagnosed. We report the case of a previously healthy 29-year-old man who was involved in a fight and suffered from blunt heart injury leading to contusion of the right atrium. The patient died soon after the injury and before admission to the Hospital. The diagnosis was made at autopsy. The present case is of special interest because of the unusual eliciting event and the rarity of the contusion site (right atrium). It is reported in order to raise the index of suspicion in physicians treating patients involved in a fight and aid in prompt diagnosis of myocardial contusion.