Arterial blood gases and other “acute care” biochemical blood tests are frequently ordered during recovery from cardiac arrest. Cardiac arrest, sudden loss of blood flow consequent on cessation of heart activity, is the ultimate medical emergency, frequently exploited for the dramatic nature of its presentation...

The gold standard sample for blood gas analysis is arterial blood, whereas venous blood is the standard sample for all other biochemical and hematological tests. By comparison with venipuncture, the procedure used to sample venous blood, collection of an arterial blood sample is technically more difficult, as well as...

Hemoglobin is the oxygen-carrying protein contained in red blood cells that ensures delivery of inspired oxygen from lungs to all tissue cells. This process depends on oxygen forming a reversible ionic link with ferrous iron (Fe⁺⁺) contained within the hemoglobin molecule. Methemoglobin (MetHb) is a dysfunctional form ...

Transfusion of donated (allogenic) red blood cells is of undoubted life-saving benefit to those suffering rapid and massive blood loss (hemorrhage) due to major trauma, or complications during surgery and childbirth. However, the procedure is not without risk, and accumulated evidence over the past 2 decades has...

In health, blood pH is maintained within a narrow reference range, 7.35-7.45.  Medical texts discussing general aspects of acid-base disturbance frequently include the observation that pH <6.8 is inevitably fatal. However, there are individual case reports of survival despite this degree of extreme acidosis. One such...

Calculation-based approaches to determining oxygen saturation, as used in some point-of-care tests, increasingly deviate from values measured directly by CO-oximetry as the partial pressure of oxygen in the blood decreases. Oxygen saturation should be measured by CO-oximetry when inaccuracies in calculations may...

Blood gas analysis involves determination of three parameters (pH, bicarbonate and partial pressure of carbon dioxide, pCO₂) necessary for assessment of patient acid-base status and identification of those whose acid-base is disturbed. There are four classes of acid-base disturbance: metabolic acidosis, metabolic...

As the authors of this recently published review article acknowledge, sepsis is an increasingly common and serious illness that takes the lives of close to a third of those affected. Optimal care of patients with sepsis is delivered in an intensive care unit but rapid early diagnosis, vital for survival, occurs...

Plasma sodium concentration is normally maintained within the approximate reference range of 135-145 mmol/L. Raised plasma sodium (hypernatremia) is less common than reduced plasma sodium (hyponatremia), and severe hypernatremia (usually defined as plasma sodium >160 mmol/L) is rare but associated with potential for...

As the site of production of the hormones: renin, erythropoietin and calcitriol that regulate, respectively, blood pressure, erythrocyte (red blood cell) production and absorption of dietary calcium, the kidneys have significant and disparate endocrine function. Additionally, of course, the kidneys have an excretory...