Articles on Medical Diseases and Conditions

In addition to its use in the Henderson-Hasselbalch equation, PCO2 provides information on pulmonary alveolar gas exchange (ventilation). If PCO2 is high, there is not a sufficient degree of alveolar ventilation. This may be due to primary lung disease (inability of the lungs to ventilate properly) or to some other reason. If PCO2 is low, […]

To summarize plasma pH problems, in metabolic acidosis there is eventual HCO–3 deficit, leading to decreased plasma pH and decreased CO2 content (or CO2 combining power). In respiratory acidosis there is primary H2CO3 excess, which causes decreased plasma pH, but the CO2 content is increased due to renal attempts at compensation. In metabolic alkalosis there […]

The other major subdivision of alkalosis is respiratory alkalosis, which occurs when the respiratory mechanism blows off more CO2 than it normally would due to respiratory center stimulation from some cause. The main conditions in which this happens are the hyperventilation syndrome caused by hysteria or anxiety, high fever, and direct stimulation of the respiratory […]

Alkalosis may also be divided into metabolic and respiratory types. In metabolic alkalosis, three relatively common situations should be discussed. Alkali administration. Alkali administration most commonly occurs when sodium bicarbonate is taken in large quantities for the treatment of peptic ulcer symptoms. If this happens, excess HCO–3 is absorbed above the amount needed to neutralize […]

The second major category of acidosis is that called respiratory acidosis. This may be due to any condition that causes pulmonary CO2 retention. These conditions include the respiratory muscle paralysis of poliomyelitis, the respiratory brain center depression sometimes seen in encephalitis or with large doses of such drugs as morphine, primary lung disease (e.g., pulmonary […]

This type of acidosis has at least three main causes. Acid-gaining acidosis. Hydrogen ions not included in the CO2 system are added to the blood. The common situations are: 1. Direct administration, such as treatment with ammonium chloride, or the late effects of salicylate poisoning. Ammonium chloride (NH4Cl) releases H+ ions and Cl– ions as […]

With this background, one may proceed to the various clinical disturbances of pH. These have been clinically termed “acidosis,” when the pH is decreased toward the acid side of normal and alkalosis, when the pH is elevated toward the alkaline side of normal. Acidosis, in turn, is usually subdivided into metabolic and respiratory etiology, and […]

In the early days, acid-base studies were performed on venous blood. Venous specimens are nearly as accurate as arterial blood for pH and HCO3 (or PCO2) measurements if blood is obtained anaerobically from a motionless hand or arm before the tourniquet is released. Nevertheless, arterial specimens have mostly replaced venous ones because venous blood provides […]

This section describes the laboratory tests used in pH abnormalities, which, incidentally, are often called “acid-base problems” because of the importance of the bicarbonate and carbonic acid changes involved. Carbon dioxide combining power. Venous blood is drawn aerobically with an ordinary syringe and the serum is then equilibrated to normal alveolar levels of 40 mm […]

The term pH comes from the French puissance hydrogen, meaning the strength or power of hydrogen. The hydrogen ion concentration of blood expressed in gram molecular weights of hydrogen per liter (moles/L) is so much less than 1 (e.g., 0.0000001) that it is easier to communicate this information in terms of logarithms; thus, 0.0000001 becomes […]