<prompt> All the following are false regarding physiological dead space exceptIn healthy adults, 20-50ml more than anatomical dead spaceDetected by Bohrs method10-15 of tidal volumeIncreased by endotracheal intubation  <response>: Ans: b Detected by Bohrs method Ref.Gonong 22ndPhysiological dead space is calculated by Bohrs method.In normal healthy adult, physiological dead space anatomical dead space.Anatomical dead space in a healthy 70kg adult is 150 ml, which is 30 of tidal volume.Total dead space physiological dead space Anatomical dead space alveolar dead space.Anatomical dead space The part of the respiratory system that is not available for gas exchange with pulmonary capillary blood. It is 150 ml.Alveolar dead space Those alveoli that are non functioning and not receiving adequate blood flow.The total dead space can be calculated from the PCO2 of expired air, the PCO2 of arterial blood, and the tidal volume. The tidal volume VT times the PCO2 of the expired gas PECO2 equals the arterial PCO2 PaCO2 times the difference between the tidal volume and the dead space VD plus the PCO2 of inspired air PICO2 times VD Bohrs equation:PFCO2 x VT PaCO2 x VT - VD PICO2 x VDThe term PICO2 x VD is so small that it can be ignored and the equation solved for VD. 