Arterial blood gases in the coronary care unit. Part I

Blood gas analyses are frequently helpful and at times vital in the management of patients who develop complications during an acute myocardial infarction. This vignette discusses the arterial blood gases when congestive heart failure complicates an acute myocardial infarction. Blood gas measurements are generally obtained for two principle reasons: (1) to determine if the patient is well oxygenated--Po2 and O2 arterial gas measurements, and (2) to determine the patient's acid base status (a) using respiratory component of acid base status--PCO2 measurement, (b) using metabolic component of acid base status--HCO-3 measurement, and (c) using both a and b. Arterial blood gases are preferred over venous blood gases. Venous blood gives information relative to the extremity it drains and may be misleading if the extremity is cold, clammy, or underperfused.