I am grateful to Drs. Cowley & Owen, Prof. Bion and the Editors of the BMJ for printing the useful paper: Interpreting Arterial Blood Gas Results. BMJ 2013;346:f16.
Assessing acid-base balance is not simple at first sight.
A difficulty with acid-base balance is that three variables are concomitantly involved (paCO2, pH and HCO3-) whereas we usually deal with one or two variables at a time.
In interpreting acid-base physiology and disorders I find graphs which include all three variables on an x-y graph with a superimposed third variable quite useful. The result of a blood gas sample is a point on such graphs, i.e. values for paCO2, pH and HCO3-.
The position of this point on the graph corresponds to normality or to a disorder: acidosis, alkalosis, acute, chronic, respiratory, metabolic or mixed.
As a result acid-base disorders are assessed at a glance on these graphs (there exist various such graphs).
An acid-base graph (nomogram) is shown below.(1)
I recommend assessing acid-base disorders on such graphs, aware that our body (lungs, kidneys, blood buffers) strives to normalize blood pH (compensation).
Reference
1. Levinsky NG. Acidosis and Alkalosis, p. 231. In: Petersdorf RG, Adams RD, Braunwald E, Isselbacher KJ, Martin JB, Wilson JD, (eds). Harrison's Principles of Internal Medicine. Mc Graw-Hill Book Company, New York, 1983. The graph is from: G.S. Arbus. An in vivo acid-base nomogram for clinical use. Can Med Assoc J 1973; 109:291-93.
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Re: Interpreting arterial blood gas results
I am grateful to Drs. Cowley & Owen, Prof. Bion and the Editors of the BMJ for printing the useful paper: Interpreting Arterial Blood Gas Results. BMJ 2013;346:f16.
Assessing acid-base balance is not simple at first sight.
A difficulty with acid-base balance is that three variables are concomitantly involved (paCO2, pH and HCO3-) whereas we usually deal with one or two variables at a time.
In interpreting acid-base physiology and disorders I find graphs which include all three variables on an x-y graph with a superimposed third variable quite useful. The result of a blood gas sample is a point on such graphs, i.e. values for paCO2, pH and HCO3-.
The position of this point on the graph corresponds to normality or to a disorder: acidosis, alkalosis, acute, chronic, respiratory, metabolic or mixed.
As a result acid-base disorders are assessed at a glance on these graphs (there exist various such graphs).
An acid-base graph (nomogram) is shown below.(1)
I recommend assessing acid-base disorders on such graphs, aware that our body (lungs, kidneys, blood buffers) strives to normalize blood pH (compensation).
Reference
1. Levinsky NG. Acidosis and Alkalosis, p. 231. In: Petersdorf RG, Adams RD, Braunwald E, Isselbacher KJ, Martin JB, Wilson JD, (eds). Harrison's Principles of Internal Medicine. Mc Graw-Hill Book Company, New York, 1983. The graph is from: G.S. Arbus. An in vivo acid-base nomogram for clinical use. Can Med Assoc J 1973; 109:291-93.
Competing interests: No competing interests