How to convert venous blood gas values to arterial values


Arterial blood gas is the gold standard for blood gas and acid-based testing in critical care. There is a trend towards the use of venous blood, as venous punctures are less invasive for the patient and less complex for healthcare providers.

Clinical parameters differ between arterial and venous samples. Learn how Roche v-TAC software helps to overcome these limitations.

Draw a peripheral venous blood sample.

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Arterial punctures usually require specially-trained staff. Venous punctures are less complex and can be conducted by other staff groups (e.g. nurses).1

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Combining blood sampling for venous blood gas with routine blood sampling decreases the need for arterial punctures.1

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Compared to an arterial blood draw, taking blood from a vein means less anxiety and pain, and fewer potential side effects for the patient.1

Measure the patient’s arterial oxygen saturation with a pulse oximeter.

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Analyse the venous blood sample and enter the measured arterial oxygen saturation.

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The blood gas analyser transmits the venous blood values to cobas® infinity POC.

From here the results are sent to Roche v-TAC which converts venous into arterial values before sending them back to cobas® infinity POC.


Roche v-TAC can be used with Roche’s cobas b 123 POC system and cobas b 221 system in combination with cobas® infinity POC.

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cobas® infinity POC forwards the values to the Laboratory Information System or Electronic Patient Record.

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The calculated arterial blood gas values can be printed on a selected network printer (optional).

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The results can now be used by healthcare professionals to improve patient management and to enable more informed decisions.

Potential benefits of v-TAC

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Improve speed of providing blood gas values.2

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Transfer blood gas testing from physicians to other staff groups (e.g. nurses).1

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Enable workflow improvements to help improve efficiency.1

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Combine venous blood gas draws with routine blood sampling.1

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Reduce painful arterial blood draws and potential side effects.1


  1. Ekström, M, et al. Calculated arterial blood gas values from a venous sample and pulse oximetry: Clinical validation. PLoS ONE. 2019, 14(4):e0215413.
  2. Kamperidis P, et al. Optimizing acute non-invasive ventilation care in the NHS; the v-TAC approach. Thorax 2018