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...

This article explores the potential benefits of point-of-care testing in the ED. Price and St. John provide a detailed description on how to approach four common aspects of point-of-care testing (POCT) in the ED, specifically, the challenges of adopting POCT, the impact of POCT on clinical decisions, the impact of...

Almost all (99 %) of the approximate 1 kg of calcium in the adult human body is contained in bone, but a small fraction (approximately 350 mg) circulates in blood plasma at a concentration of around 2.5 mmol/L. This circulating calcium comprises three fractions: around half (50 %) is free ionized calcium; the rest is...

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...

The process of laboratory/point-of-care testing of patient samples comprises three distinct phases: the preanalytical phase, which includes sample collection and transport to the site of testing; the analytical phase; and the postanalytical phase, which includes communication and interpretation of the test result as...

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...

Summary The reference interval for a biochemical analyte is usually an interval of values bounded by the reference limit values at certain designated percentiles [1].  As always when choosing a cut-off, the value will determine the trade-off between clinical sensitivity and specificity. When a low cut-off is chosen,...

Intravenous (iv) catheters are routinely employed for speedy delivery of fluids and drugs to the critically ill; they also provide the means for sampling blood for testing. This iv catheterization occurs in a range of settings including prehospital emergency care, hospital emergency rooms and intensive/critical care...

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...

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...