"It appears that pulmonary mechanics is evolutionary designed and optimised for prone position, which is the normal posture in quadrupeds" Prone position is used in operation rooms for a long time for surgical procedures on dorsal aspect of body. It has been acknowledged that respiratory and hemodynamic instability may result because of compression of chest and abdomen in prone position, which may be relieved by supporting upper chest and pelvis with padding, to facilitate free movement of anterior abdominal wall. Beneficial effect of prone position in respiratory mechanics was first proposed by Bryan in 1974. Bryan studied the effect of sedation and paralysis on diaphragm, and suggested that prone position improve dorsal lung expansion and oxygenation 1 . Few years later Piehl and Douglas separately reported that prone position dramatically improved oxygenation in ARDS patients 2,3 . But, it had to take one more decade, to understand the mechan...