In health, serum potassium concentration is maintained within the approximate range of 3.5-5.2 mmol/L. Disturbance of potassium homeostasis is a common electrolyte disorder that is clinically manifest through its adverse effect on both skeletal and cardiac muscle cell function.  Although often asymptomatic, both...

Arterial blood gas analysis is used to assess and monitor patient acid-base status. Disturbance of acid-base balance is classified to one of four main types depending on the pH, pCO₂(a) and bicarbonate results generated during blood gas analysis; the four types are respiratory acidosis, respiratory alkalosis,...

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) ...

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...

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...

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...

Many drugs, when taken in overdose, can deleteriously affect acid-base balance, leading to abnormal arterial blood gas (ABG) results. Aspirin is one such, and perhaps because of its easy availability, one of the most common of all drugs to be taken in overdose. Salicylate (aspirin) poisoning thus represents the most...

Metformin, a blood-glucose-lowering drug widely used for treatment of type 2 diabetes, is associated with risk of potentially fatal metabolic (lactic) acidosis. This can occur not only following overdose but also at therapeutic dose in patients with pre-existing renal or liver disease. Results of arterial blood gas...

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...

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)...