Webinar

Using physiology-based mathematical models to calculate arterial blood gas values from venous blood

19 Nov, 2024
headshot of Stephen Rees

Blood gas analysis is essential for diagnosing and managing respiratory and metabolic disorders.1 Traditional arterial sampling is painful, requires trained personnel, and has low first-draw success rates, which complicates workflows and increases risks.2,3 Venous blood sampling is easier, but can venous blood gases (VBG) provide reliable clinical evaluation similar to arterial blood gases (ABG)? If not, is there a better way to obtain ABG values?

In this webinar, Prof. Rees, an expert in respiratory and critical care technology at Aalborg University, explains the limitations of VBG. These relate to the poor correlation of ABG and VBG values,1 with the relationship between ABG and VBG varying substantially even in the same patient at different time points.4 Prof. Rees then introduces the venous-to-arterial blood gas conversion (v-TAC) method, which uses VBG and pulse oximetry data to calculate ABG values, eliminating the need for painful arterial sampling. This is possible as the v-TAC method accounts for differences in the aerobic metabolism at the tissues, allowing for calculation of arterial values under different conditions in the same patient.

Over the years, Prof. Rees and other researchers have conducted extensive studies on v-TAC across various clinical settings, now summarized in a meta-analysis. The results show that v-TAC can accurately calculate VBG from venous blood, with minimal bias, acceptable limits of agreement, and no difference in these across clinical groups.5 Therefore, it can potentially be used for screening in emergency medicine, monitoring chronic respiratory diseases like Chronic Obstructive Pulmonary Disease (COPD), and tracking ABG values in critical care patients without the need for arterial catheters, ultimately improving patient care.

We hope you enjoy this webinar!

Speakers

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References:

  1. Kelly AM et al. Agreement between arterial and venous pH and pCO2 in patients undergoing non-invasive ventilation in the emergency department. Emerg Med Australas. 2013 June; 25(3):203-6.
  2. Turner JS et al. Patients' recollection of intensive care unit experience. Crit Care Med.1990; 18:966-968.
  3. Davies MG et al. Comparison of mathematically arterialised venous blood gas sampling with arterial, capillary, and venous sampling in adult patients with hypercapnic respiratory failure: a single-centre longitudinal cohort study. BMJ Open Respir Res. 2023 June; 10(1):e001537.
  4. Rees SE et al. Calculating acid-base and oxygenation status during COPD exacerbation using mathematically arterialised venous blood. Clin Chem Lab Med. 2012 December; 50(12):2149-54.
  5. Shastri L et al. The use of venous blood gas in assessing arterial acid-base and oxygenation status - an analysis of aggregated data from multiple studies evaluating the venous to arterial conversion (v-TAC) method. Expert Rev Respir Med. 2024 July; 18(7):553-559.

The views and opinions expressed in this webinar are those of the speakers and do not necessarily reflect the views or positions of Roche or any other sponsors.