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...

Reduced plasma/serum sodium (hyponatremia), widely defined as plasma/serum sodium Mild hyponatremia, i.e. plasma/serum sodium in the approximate range of 130 to 136 mmol/L, is usually not associated with symptoms, but most patients whose plasma/serum is Explanation of these effects of hyponatremia is contained in...

Because measurements of GFR are tedious, estimated GFRs based on creatinine or cystatin C are widely used for assessing kidney function. Both measured GFRs and the Staging System for CKD based on GFR have analytical and clinical shortcomings. The advantages of serum creatinine and cystatin C, and eGFR will be...

The diagnosis of pulmonary embolism is challenging due to the non-specificity of signs and symptoms and the very busy Emergency Departments to which the overall majority of patients with suspected PE present. While several well-validated diagnostic algorithms exist and are readily available, it is known that in many...

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...

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...