As a global marker of tissue oxygenation serum lactate measurement has proven its usefulness in monitoring the critically ill. It has also proved useful as a screening tool for sepsis in the emergency room.  However, lactate measurement is not always readily available. Increased lactate is a common cause of raised...

Pleural effusion, defined as excess fluid in the pleural space, can complicate the course of a large and pathologically diverse range of pulmonary and non-pulmonary diseases. Laboratory analysis of pleural fluid provides much useful information for the clinician whose diagnostic challenge is the patient presenting...

The anion gap (AG) is a calculated parameter derived from measured serum/plasma electrolyte concentrations. The clinical value of this calculated parameter is the main focus of this article. Both increased and reduced anion gap have clinical significance, but the deviation from normal that has most clinical...

The field of point-of-care testing (POCT) is entering a period of rapid expansion. This expansion is being driven by new evidence for clinical effectiveness of POCT, and new technologies that allow consolidation of testing onto smaller platforms. Technological improvements will also lead to increased accuracy for...

The lowest ever recorded arterial oxygen tension (pO₂) was just one result of a series of remarkable physiological investigations conducted on Mount Everest that included arterial blood gas analysis at an altitude of 8,400 m (27,599 ft) above sea level, just 484 m short of the summit.  At this high altitude the...

The notion that increased oxygen delivery limits ischemic damage to the myocardium during myocardial infarction seems, on the face of it, highly plausible. Perhaps not surprising, then, that for the best part of a century administration of oxygen has been a routine component of medical care for many patients suffering ...

 Of all tests performed on patient blood samples, arterial blood gases (ABGs) are conceptually probably the most complex. An understanding of the clinical significance of the measured and derived parameters generated by blood gas machines depends on a basic knowledge of so many topics, including acid-base theory,...

Premature neonates frequently have inadequate respiratory function and require oxygen therapy during the weeks after birth. Since they are also exquisitely vulnerable to oxygen toxicity, careful monitoring of oxygen status is an essential component of neonatal intensive care.  Measuring % oxygen saturation by pulse...

Hemolysis, the breakdown of erythrocyte (red-cell) membranes, can occur in vivo as a result of disease, or more commonly in vitro when it is most usually a consequence of poor blood collection or sample handling technique.  Hemolysis is of significance for laboratory staff because it results in the release of...

As point-of-care applications of lab testing demand more rapid and clinically integrated order entry and results-reporting processes, it becomes paramount for the laboratory to investigate entire clinical processes. Direct observation and process mapping of these clinical applications – end to end - are "lean" tools...