Effects of alveolar dead-space, shunt and V˙/Q˙distribution on respiratory dead-space measurements

Our studies show that increased pulmonary shunt causes an apparent increase in Vdphys, and that abnormal V˙/Q˙distributions affect the calculated Vdphys and Vdalv, but not Fowler dead-space. Dead-space and PACO2 calculated by the Koulouris method do not represent true Bohr dead-space and PACO2 respectively, but the shunt-corrected equation performs well.