<br /> <b>Warning</b>: Undefined array key "mm" in <b>/www/wwwroot/www.ai-bt.com/si.php</b> on line <b>10</b><br /> <br /> <b>Deprecated</b>: trim(): Passing null to parameter #1 ($string) of type string is deprecated in <b>/www/wwwroot/www.ai-bt.com/si.php</b> on line <b>10</b><br /> The physiology of intermittent positive-pressure breathing (IPPB). A discussion of lung mechanics as applied to I.P.P.B. and an analysis of the physiological characteristics of some respirators.