OBI Medical

Validation of v-TAC

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

The included subjects were adult patients (>18 years) from emergency departments, pulmonary departments, and intensive care units with various diagnoses, including COPD, sepsis, asthma, pneumonia and lung cancer.

Ideally, the pair of samples should be collected simultaneously. In the studies, the time between drawing of the arterial blood gas and the v-TAC samples was typically between 2 and 5 minutes. The figure below illustrates the technique used in the studies for collecting blood samples.

The repeatability 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. A study by Toftegaard et al. showed that the repeatability of the v-TAC calculated values vs. arterial blood gas is comparable to the repeatability of arterial blood gases for blood gas parameters, including pH, pCO2 and pO2 (up to 10 kPa / 75 mmHg).