Question

Indicate whether each statement is correct or incorrect regarding the following values from this 5 foot 9 inch male. VE = 8 L/m f = 16/min PaCO2 = 35 mm Hg PECO2 = 25 mm Hg Vt = 500 ccs VD is lower than normal? VD/VT is lower than normal? the subject has significant shunting?

Answer 1

Answer

* Formula for calculating Vd / Vt is,

                 VD / VT = PaCO2 - PeCO2 / PaCO2

              Here

                      PaCO2 = 35 mmHg.

                      PECO2 = 25 mmHg.

                           Vt     = 500 ccs

   Based on above formula,

                     VD /VT = 35 -25 /35

                                 = 0.28     ( Normal value approximately between 0.28 to 0.33 )

Here VD is,

                       VD =( PaCO2 - PECO2 / PaCO2) * VT

                             = 0.28 * 500

                             = 140   (Normal level approximately 150 ccs)

* Both VD and VD/VT are approximately normal so no significant problems in this patient.