![]() ![]() VA measures VE without the inclusion of airway dead space, or the volume of air you breathe without active gas exchange in the lungs. Shunt and anatomical deadspace caused some inaccuracy, although they are unlikely to prevent the clinical usefulness of this formula. Alveolar ventilation (VA) is another important measurement related to tidal volume. Thus, assuming a normal tidal volume of 500 ml, about 30 of this air is wasted in the sense that it does not participate in gas exchange. ![]() The relationship between (Pa-E'CO2)/PaCO2 and VDalv/VTalv (best fit: VDalv VTalv = 1.135 x (Pa-E'CO2)/PaCO2-0.005) during normal physiological conditions was approximately linear and less influenced by physiological variation. The relationship between Pa-E'CO2 and VDalv/VTalv was non-linear and was affected significantly by all the factors except anatomical deadspace. The relationships were observed while pulmonary shunt, anatomical deadspace, ventilatory minute volume and metabolic rate were varied. The aim of the study was to examine the relationship between the arterial to end-tidal PCO2 gradient (Pa-E'CO2) and VDalv/VTalv and between (Pa-E'CO2)/PaCO2 and VDalv/VTalv using the Nottingham Physiology Simulator, an original, validated physiology simulation. The alveolar deadspace as a fraction of alveolar ventilation (VDalv/VTalv), while technically difficult to measure, is an objective monitor of pulmonary disease progression and a predictor of successful weaning from mechanical ventilation. ![]()
0 Comments
Leave a Reply. |
AuthorWrite something about yourself. No need to be fancy, just an overview. ArchivesCategories |