[The usefulness of a computer program Oxygen Status Algorithm (OSA) with particular consideration of oxygen...

The traditional parameters such as the oxygen tension (pO2) and the haemoglobin oxygen saturation (sO2) obtained from arterial blood samples are not always sufficient in clinical practice. The purpose of the study is to present the examples where pO2 and sO2 even in combination may provide misleading information. We examined patients with bronchial asthma, respiratory insufficiency and with extrinsic allergic alveolitis who had been admitted to the Chest Disease Department. We used the Oxygen Status Algorithm (OSA) to calculate the new oxygen parameters. These new parameters are: 1) oxygen extraction tension px defined as the tension required to extract 2.3 mmol of oxygen per liter of blood, 2) the concentration of extractable oxygen cx defined as the concentration of oxygen extracted per liter of blood at a tension of 5.0 kPa, 3) the oxygen compensation factor (Qx), derived as 2.3 mmol/l/cx. This data defines the blood oxygen availability. Additional parameters such as effective hemoglobin concentration ceHb (equivalent of oxygen capacity) and the hemoglobin oxygen affinity (p50) inform us of the oxygen supply to the tissue. The results show that the new oxygen parameters are helpful in undertaking decisions of starting therapy and its duration.