Value of measurement of alveolo-arterial gradient of PCO2 compared to pulmonary scan in diagnosis of thromboembolic pulmonary disease

Volumetric or time‐based capnography for excluding pulmonary embolism in outpatients?

“…In 1996, Stein et al [9] popularized the insufficient discriminatory value of arterial CO 2 partial pressure (P a CO 2 ) in more than 700 patients from the PIOPED study. Earlier in the 1960s and 1970s, authors focused on the potential diagnostic strength of the difference between P a CO 2 and expired end-tidal CO 2 (EtCO 2 ), expressing alveolar deadspace from well-ventilated but unperfused alveoli, but pitfalls and sources of errors caused this test to be abandoned [10][11][12][13][14]. The interest in CO 2 re-emerged in the late 1990s, when authors studied the combination of D-dimer measurement and volumetric capnography (VCap) for the exclusion of PE [15][16][17][18][19].…”

Neural Network Analysis of the Volumetric Capnogram to Detect Pulmonary Embolism

“…However, the scientific basis for the use of volumetric capnography to screen for PE has been recognized for Ն 30 years. 19,31,32 PE causes several physiologic alterations, which may be manifested in the respiratory variables measured by the volumetric capnograph. One such physiologic alteration with PE is the development of alveolar dead space.…”

Diagnosis of pulmonary embolism by measurement of alveolar dead space

“…A number of different approaches to measurement of gas exchange abnormalities, such as the physiological dead space fraction [2,3,8,9], the arterial-end tidal CO 2 gradient [2,3,8,10,11] and the alveolararterial oxygen gradient [12][13][14] have been evaluated as possible means of diagnosing PE. These efforts have generally met with limited success, mainly because of the overlap between patients with PE and patients with airways disease.…”