Tips on Blood-Gas Analysis

and Richard A. Jaffe2



(1)
David Geffen School of Medicine at UCLA, Los Angeles, California, USA

(2)
Stanford University School of Medicine, Stanford, California, USA

 



Keywords
Blood-gasArterialVenous


During cardiopulmonary resuscitation of a patient who sustained a cardiac arrest, the anesthesia provider asks a colleague to insert an arterial catheter and draw blood for blood-gas analysis. Shortly thereafter, the results are obtained, and the oxygen tension value is reported as 51 mmHg. The anesthesia provider says to the assistant “You must have drawn a venous sample.” The assistant asserts with confidence that it was an arterial sample. He is right but how can he be so certain? The answer lies in the following analysis.

Consider the blood-gas values in a normal , healthy patient breathing room air, assuming a total partial pressure of one atmosphere or 760 mmHg (Table 18.1).


Table 18.1
Partial pressure of gases in arterial and venous blood in a patient breathing room air at one atmosphere






























Arterial blood

Venous blood

PaO2

100 mmHg

PvO2

40 mmHg

PaCO2

40 mmHg

PvCO2

46 mmHg

P water vapor

47 mmHg

P water vapor

47 mmHg

P nitrogen

573 mmHg

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Jul 14, 2017 | Posted by in Uncategorized | Comments Off on Tips on Blood-Gas Analysis

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