The difference of compression of lungs by the heart in the supine and prone position:a CT study

Objective:To study the potential mechanism of the prone position improving gas exchange of the lungs.Methods:Seven healthy adults were performed high resolution CT scanning in both the supine and the prone position.The four axial tomographic sections between the carina and the diaphragm were selected to measure the relative volume of lung located directly under the heart in the supine and prone position,respectively.Results:When supine,the total volume of left and right lung located under the heart was 8.2% to 44.7% and 5.5% to 10.8%,respectively;When prone,the total volume of the left and right lung located under the heart was 0.1% to 1.9% and 0.8% to 4.2%,respectively.The relative volume of lung is significantly less in prone position than in supine position ( P 0.01).Conclusion:The prone position improves obviously gas exchange of the lung in human.