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...

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...

As a blood marker of tissue hypoxia, lactate is routinely measured to assess and monitor critically ill patients. Hypoperfusion and resulting tissue hypoxia with evolving lactic acidosis is a common feature of many conditions that render patients critically ill. Tissue hypoxia is by no means the only cause of lactic...

Discussion of acid-base physiology usually focuses mainly on the role of lungs and kidneys, and it is a disease that affects the function of these two organs that are usually invoked when considering, in general terms, acid-base disorders. As the authors of this review article make clear, the liver also plays an...

The gold standard sample for blood gas analysis is arterial blood. Compared with collection of venous or capillary blood, collection of arterial blood by arterial puncture is a painful procedure that can induce feelings of anxiety. The notion that this pain and anxiety could be a source of preanalytical error in blood ...

As the authors of this review article acknowledge, chronic kidney disease (CKD) is a growing public health burden around the world. Recent study, cited by the authors, suggests an estimated 14 % of the US population are now diagnosed with CKD, and 0.2 % have end-stage renal disease (ESRD), the most severe presentation ...

Monitoring patient acid-base status is one of three principal clinical utilities of blood gas analysis (the other two are monitoring patient oxygen and ventilation status). Three parameters generated during blood gas analysis (pH, pCO₂ and bicarbonate) allow this acid-base assessment and classification of all...