OBI Medical

v-TAC™ precision

The accuracy of v-TAC™ has been validated in several clinical studies in which venous blood gas and SpO2 measurements converted to arterial values by v-TAC™ were compared to simultaneous arterial blood gas measurements.

How is v-TAC™ precision measured?

The study population includes a broad range of patients from emergency departments, pulmonary departments and intensive care units with various diagnoses, including COPD, sepsis, asthma, pneumonia and lung cancer. Thus, v-TAC™ has been validated on both spontaneously breathing patients and on mechanically ventilated patients, including patients on non-invasive ventilation. The patient cohort included both haemodynamically stable and unstable patients. Ideally the pair of samples should be collected simultaneously. In the studies, the arterial blood gas samples were drawn shortly before the venous blood gas samples were drawn. The time between drawing of the arterial blood gas and the v-TAC™ samples was typically between 2 and 5 minutes.

The accuracy of both arterial blood gas and venous blood gas is affected by pre-analytical errors in the time span from the blood sample is drawn and until it is analysed and by analytical errors. In addition, both arterial blood gas and venous blood gas are affected by biological fluctuations. When comparing two subsequent measurements on human specimen, the biological change will have an impact on the result. This becomes evident when comparing v-TAC™ to the repeatability of arterial blood gas vs. arterial blood gas and capillary blood gas vs. arterial blood gas.

The table below shows the statistical variation (95% confidence interval) of the v-TAC™ calculated arterial blood gas vs. the reference arterial blood gas measurement and statistical variation of measured arterial blood gas vs. measured arterial blood gas repeatability.

The accuracy includes the contribution from all error sources, including variation from SpO2.