Acid-base data interpretation has always been one of the more difficult areas of laboratory medicine. In most uncomplicated untreated cases the diagnosis can be achieved with reasonable ease. There are several ways of approaching an acid-base problem. One way is to examine first the arterial PCO2 value. Since primary respiratory disorders result from hypoventilation or [...]
Compensation refers to the degree of PCO2 change when there is, or has been, an abnormality in pH. An uncompensated disorder is a primary metabolic or respiratory condition that has not been altered by any significant degree of correction. In the case of a primary metabolic condition the respiratory counterbalance (change in ventilation which is [...]
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 [...]
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 [...]
Fluid and electrolyte problems are common in hospitalized patients. Most of these problems are secondary to other diseases or are undesirable side effects of therapy. There are a few diseases regularly associated with certain pH or electrolyte alterations that can help suggest the diagnosis and can be used to monitor therapy. Fluid and electrolytes in [...]
