[Preclinical blood gas analysis. Technical description--initial experiences--indications]

A new portable device for blood gas analyses (BGA) has been examined for prehospital application.

After a 1 h introduction to the procedure, two physicians used the blood gas analyzer in the emergency medical system in Graz, Austria, for 7 months. The indications for prehospital BGA were prolonged cardiopulmonary resuscitation, mechanical ventilation, hyperventilation for reducing increased intracranial pressure, respiratory failure and metabolic disorders. All patients tested were also checked with pulse oximetry and capnography. TECHNICAL SPECIFICATION: The device measures pO2, pCO2 and pH using the fluorescence method. The innovation of a single-use cassette system makes it unnecessary to do any calibrations or transport any test substances. The storage battery measures eight samples without recharge. The time spent on one measurement is 3-6 min.

We took 49 samples from 24 patients and found 16 indications for therapeutical intervention, such as buffering metabolic acidosis and adjusting mechanical ventilation by means of BGA. In all cases the analyzer worked reliably.

One advantage of BGA over the non-invasive methods pulse oximetry and capnography is that it does not interfere with factors like peripheral vasoconstriction or inequality of the pulmonary ventilation/ perfusion ratio. Moreover, it is the only method for controlled buffering of acid-base disturbances. This means more security in diagnostics and therapeutical interventions for the patient in danger of dying. The device has proved to be a useful addition to the monitoring methods for prehospital application.