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Clinical application of the pO 2 –pCO 2 diagram
Author(s) -
Paulev P.E.,
SiggaardAndersen O.
Publication year - 2004
Publication title -
acta anaesthesiologica scandinavica
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.738
H-Index - 107
eISSN - 1399-6576
pISSN - 0001-5172
DOI - 10.1111/j.1399-6576.2004.00487.x
Subject(s) - hypercapnia , medicine , hypoxemia , oxygen , arterial blood , logarithm , diagram , partial pressure , venous blood , breathing , anesthesia , oxygen tension , breathing gas , carbon dioxide , cardiology , respiratory system , mathematics , statistics , physics , mathematical analysis , chemistry , organic chemistry , quantum mechanics
Based on the classic, linear blood gas diagram a logarithmic blood gas map was constructed. The scales were extended by the use of logarithmic axes in order to allow for high patient values. Patients with lung disorders often have high arterial carbon dioxide tensions, and patients on supplementary oxygen typically respond with high oxygen tensions off the scale of the classic diagram. Two case histories illustrate the clinical application of the logarithmic blood gas map. Variables from the two patients were measured by the use of blood gas analysis equipment. Measured and calculated values are tabulated. The calculations were performed using the oxygen status algorithm . When interpreting the graph for a given patient it is recommended first to observe the location of the marker for the partial pressure of oxygen in inspired, humidified air (I) to see whether the patient is breathing atmospheric air or air with supplementary oxygen. Then observe the location of the arterial point (a) to see whether hypoxemia or hypercapnia appears to be the primary disturbance. Finally observe the alveolo‐arterial oxygen tension difference to estimate the degree of veno‐arterial shunting . If the mixed venous point (v) is available, then observe the value of the mixed venous oxygen tension. This is the most important indicator of global tissue hypoxia .