Mathematically Arterialised Testing of Hypercapnic Subjects
Research type
Research Study
Full title
Role of mathematically arterialised venous blood sampling in the assessment and management of adult subjects with respiratory failure; a prospective observational cohort study to investigate the physiological agreement between arterial sampling (the reference method) and mathematically arterialised venous blood sampling and the impact upon clinical decision-making and patient experience.
IRAS ID
240201
Contact name
Michael Davies
Contact email
Sponsor organisation
Royal Papworth Hospital NHS Foundation Trust
Duration of Study in the UK
0 years, 9 months, 1 days
Research summary
Accurate assessment of gas exchange is essential to manage patients with acute and chronic respiratory failure (too high levels of CO2 in blood). Current guidance is to use arterial blood gas (ABG) sampling. However, clinicians are looking for other approaches as ABG sampling can cause complications including pain (frequent) and injury to the artery. Existing alternative methods include capillary blood gas (CBG) samples via earlobe puncture. In comparison to ABGs, CBGs are easier to obtain and usually less painful. However, they are less accurate.
A newer method, v-TAC, is available. V-TAC combines measurements from venous blood (VBG) with oxygen saturation data collected from a pulse oximeter in a process of mathematical arterialisation. VBG sampling is easier and less painful than ABG sampling, but accuracy is limited without mathematical arterialisation. If this method is to be adopted we must ensure that the results obtained are reliable and robust enough to base clinical decisions on, especially for a population of patients with high in-hospital mortality.
To date, no studies have evaluated whether calculated arterial values (v-TAC) provide a useful substitute to directly measured values in clinical decision-making. Therefore, we will assess patients with known or suspected chronic respiratory failure. We will obtain simultaneous blood gas samples obtained via arterial, capillary, and venous methods. Any impact on clinical decision making could be assessed by comparing the agreement of ABG, v-TAC, and CBG results against pre-defined clinical treatment thresholds; including the accuracy of detection of a minimally important clinical change in carbon dioxide levels and also the ability of v-TAC to identify clinically relevant treatment thresholds. The primary measure will focus on the comparison of v-TAC to ABG, the existing gold standard. Secondary measures will assess the agreement of all other methods of blood gas sampling, including CBG and VBG.
REC name
North West - Preston Research Ethics Committee
REC reference
18/NW/0547
Date of REC Opinion
30 Jul 2018
REC opinion
Further Information Favourable Opinion