In obese people, the presence of adipose tissue around the rib cage and abdomen and in the visceral cavity loads the chest wall and reduces functional residual capacity
The other three measures shown are functional residual capacity
(FRC, the amount of air left in the lungs after a normal expiration), residual volume (RV, the amount of air left in the lungs after a maximal expiration), and total lung capacity (TLC, VC plus RV)-.
Studies of post-surgical patients have found improvement in pulmonary function, including oxygen saturation, (24) oxygen consumption and carbon dioxide production, (25) and functional residual capacity
(26) in the sitting compared with the supine position (24-26) and further improvement in oxygen saturation in the standing position.
increasing the functional residual capacity
, and improves gas exchange (3,4).
The lung has a basic inherent capacity to maintain lung volume or functional residual capacity
. This is suboptimal or weak in a newborn especially a preterm baby whose lungs have a tendency to collapse in expiration.