The process of patient sample testing, whether performed in the clinical laboratory or at the point of care, is the sum of three distinct phases. The first is the preanalytical phase, which includes test selection as well as sample collection and handling.  The second is the analytical or measuring phase that...

ROC curves are frequently used to show in a graphical way the connection/trade-off between clinical sensitivity and specificity for every possible cut-off for a test or a combination of tests. In addition the area under the ROC curve gives an idea about the benefit of using the test(s) in question.  ROC curves are...

As healthcare seeks to provide better care with fewer resources, Point-of-Care Testing steps in to move key diagnostic or screening tests to the patient’s bedside. The results can have a significant impact on a patient outcome and operational costs.

Mechanical ventilation is necessary for survival of patients with acute respiratory distress syndrome (ARDS). It was once supposed that ventilation should be adjusted to maintain pCO₂(a) within the normal range but this degree of mechanical ventilation can result in further damage to the lungs. Less aggressive (low...

Pulse oximetry provides the means for continuous non-invasive monitoring of blood oxygenation by measuring % oxygen saturation (SpO₂). This safe, easy and convenient method of monitoring oxygenation status is ubiquitous in clinical medicine and is now a routine part of the overall assessment and monitoring of all...

Increasing obesity is associated with worsening arterial blood gases (pO₂(a) and pCO₂(a)). That is the headline finding of a recent cross-sectional study of morbidly obese individuals with apparently normal lung function and no respiratory disease.  The study population comprised 114 women and 35 men with a mean (SD) ...

Hypokalemia, one of the most common electrolyte disturbances, is diagnosed if plasma potassium concentration is less than 3.5 mmol/L. Mild hypokalemia (plasma potassium 3.0-3.5 mmol/L) is usually asymptomatic, but greater degree of hypokalemia can result in signs and symptoms that reflect the fundamental role of...

Most babies born prematurely have respiratory problems and require assisted ventilation and oxygen therapy to ensure adequate tissue oxygenation. Supplemental oxygen is a double-edged sword for these babies because although of life-preserving benefit, oxygen in excess is toxic.  The principal (but not the only)...

In the intensive care unit blood is frequently sampled for arterial blood gases via an indwelling arterial catheter. Around a third of critically ill patients have such catheters inserted; they allow not only easy access for blood sampling but also continuous monitoring of blood pressure. In a short editorial the...

If the results of a recent New Zealand study are representative, there is room for improvement in the quality of blood gas test result interpretation among emergency-room medical staff. A total of 80 emergency-room doctors (37 consultants and 43 emergency-medicine trainees) voluntarily submitted themselves for a...