The range of plasma pH in health and disease

The pH values of arterial plasma measured for all the individuals in a crowd of normal healthy people would fall mostly in the range 7.35 to 7.45, with an average of 7.4 (Robinson, 1962, p. 3). The plasma pH values measured on patients admitted to the metabolic ward of a hospital and suffering from untreated disorders of acid-base physiology would probably range between 7.1 and 7.7, this being the range compatible with life. For short periods of time, it is possible for the pH to go even further from normal particularly on the acid side, but these are useful limits to remember and are shown in Table 2.1. 

Range in disorders of acid-base physiology compatible with life  

For potassium, the relevant limits compatible with life are 2 and 8mM these values are also shown in Table 2.1. This similarity of numbers may act as a useful aide-memoire. 

Bicarbonate and carbon dioxide are two chemicals of great importance in acid-base physiology and they too can deviate in concentration widely from normal before the change becomes life-threatening. 

VARIATIONS IN IONIC COMPOSITION OF THE EXTRACELLULAR FLUID COMPATIBLE WITH LIFE 

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