We have recently commenced a new randomised clinical trial led by Dr Milind Sovani at NUH with funding from Radiometer using a skin probe to monitor Carbon Dioxide (CO2) level of patients blood to asses if this can reduce the number of arterial blood samples needed in patients who need NIV to correct respiratory failure with a build-up of carbon dioxide and asses the safety of Transcutaneous CO2 monitoring.
Non-invasive Monitoring for non-invasive ventilation: Use of transcutaneous carbon dioxide monitoring to guide acute Non-invasive ventilation in patients with acute hypercapnic respiratory failure: A multi-centre study.
What is the purpose of the study?
a) What is the purpose of the study?
This study is to find out if using a skin probe to measure carbon dioxide levels in patients who have a chronic breathing condition and need support with their breathing using Non-Invasive Ventilation (NIV), can reduce the number of blood samples required to be taken. NIV is a way of helping people who find it difficult to breathe. A mask is placed over the mouth and the nose. Through this mask the machine (ventilator) blows air into the lungs, providing the body with oxygen, whilst helping to remove carbon dioxide gas that has built up in the blood. We measure carbon dioxide levels to help us monitor how well people are breathing / their lungs are working. Currently, carbon dioxide levels are measured by taking a small blood sample from a blood vessel called an artery, in the wrist. Our study is comparing carbon dioxide measuring using several blood samples usually taken from an artery in the wrist, to an alternative, ‘non-invasive’ approach, which uses a probe which sticks to the skin, usually on the ear lobe, to continuously measure carbon dioxide levels through the skin (called transcutaneous monitoring).
We are conducting a randomised trial. This means we are putting people into two groups. One group have their carbon dioxide levels measured using only blood samples collected from the artery in the wrist (this is what is usually done) – this is called the ABG group. The second group have their carbon dioxide level measured continuously, using the skin probe, and blood samples taken from a vein, for example in the arm or hand, every 24 hours, with blood samples collected from the artery in the wrist at any time where the doctor feels this is required – this is called the transcutaneous group. The number of times blood is taken from the artery in the wrist will then be compared between the two groups. To try and make sure the groups are the same to start with, each patient is put into a group by chance (randomly). For this trial, there is an equal chance of being randomised to the ABG, and the transcutaneous groups. The results will then be compared.
b) What is the procedure being tested?
The skin probe we are using is called a transcutaneous carbon dioxide monitor; it is currently routinely used to guide treatment in stable patients who need long-term support with their breathing.
c) What are the alternatives for treatment?
There is currently no alternative to taking repeated blood samples from a patient’s artery to accurately determine their carbon dioxide levels, in order to guide their breathing support whilst in hospital.