<prompt> What is the physiological dead space when aerial PCO2 PaCO2 is 48mmHg, expired PCO2 PECO2 is 25mmHg and tidal volume of 500ml?260ml240ml220ml200ml  <response>: Bohrs equation PCO2 x VT PCO2 x VT - PDS25 x 500 48 500 - PDS1250048500 - PDS260 500-PDSPDS 240ml 