22 January 2019

Clinicians at Royal Papworth Hospital are aiming to find out if a new method of blood testing can simplify treatment for patients with potentially life-threatening respiratory failure.

Severe lung, muscle or neurological disorders can cause respiratory failure and the current standard test to assess patients with, or at risk of, the condition is an arterial blood gas (ABG) sample.

For some people with abnormal test results, assisted breathing via non-invasive ventilation (NIV) at home, typically during sleep only, can improve quality of life and, in an acute setting, be life-saving. 

However, ABG sampling is sometimes painful. Venous blood gas (VBG) is easier to obtain and less painful, but the results are not as accurate.

Meanwhile, the results of successive British Thoracic Society audits and the 2017 National Confidential Enquiry into Patient Outcome and Death (NCEPOD) study into acute NIV are a cause for concern. These studies have shown significant delays and omissions in patient assessment and monitoring. Blood gas measurement is a vital part of this process.

In this MATHS (Mathematical Arterialised Testing in Hypercapnic Subjects) study, the Respiratory Support and Sleep Centre (RSSC) team will investigate whether they can obtain the reliability of ABG results but with the ease of the VBG process.

Doctors will use a new software application - v-TAC™ (Venous-to-Arterial-Conversion method), which calculates arterialised acid-base and blood gas values from peripheral venous blood, combined with blood oxygen levels from a simple finger or earlobe probe. 

Dr Michael Davies, RSSC consultant physician, said: “Arterial sampling is the gold standard, but has a number of limitations. 

“In our study, we will be sampling patients referred for home NIV. We plan to test the v- TAC™ method against ABG sampling. While the real-time clinical decisions will be made on the ABG results, we will look at clinical decision-making with the help of clinicians who are blinded to the test method. 

“If we show that the v- TAC™ method and ABG samples provide comparable results and the same clinical decisions, then NIV assessment and treatment will be simplified. 

“Essentially, we hope that we can provide results that are as accurate as an arterial sample and as simple and convenient as a venous sample. Further, if we show a benefit in this patient group then the results have the potential to improve outcomes for patients treated with acute NIV.”

The v-TAC™ software is already used in European hospitals and is supported by the Danish company OBI Medical. 

The study will be conducted at Royal Papworth Hospital in collaboration with a team of scientists and researchers from Aalborg University, who originally developed the algorithm. The results are expected to be published later in 2019.