PARAMEDIC3 is a large research study in which we are aiming to work out the best way to give people life-saving medications if they have a cardiac arrest.

A cardiac arrest occurs when the heart suddenly stops pumping blood around the body. This can be for many different reasons, including a heart condition (such as a heart attack), an accident causing the loss of a large amount of blood, or a clot in the lungs. When someone has a cardiac arrest, immediate treatment is essential. Brain cells will start to die in only a few minutes. Individuals that have a cardiac arrest are most likely to survive if someone nearby immediately calls an ambulance, start cardiopulmonary resuscitation (pressing hard and fast on the breastbone), and uses a defibrillator (if one is available) to deliver electrical shocks to the heart.

Each year in the UK, 30,000 people have a cardiac arrest and are treated by NHS paramedics. Unfortunately, despite the best efforts of paramedics, doctors, and nurses, less than one in ten patients survive to leave hospital. Our previous research (PARAMEDIC-2) has shown that adrenaline is very effective at restarting the heart. However, in PARAMEDIC-2, we found that drug treatments were given on average 21-minutes in to the cardiac arrest. This probably reduces the effectiveness of the adrenaline. In the NHS, current guidelines recommend that paramedics first try to give drugs in to a vein (intravenous route), but it can take several critical minutes to put a drip in to a vein, ready to give drugs. An alternative approach is to give drugs into a small needle into an arm or leg bone. This may be quicker and easier, and allows drugs to be injected directly into the rich blood supply found in the bone marrow. We do not currently know whether it is better to give drugs into a vein or in to a bone. The International Liaison Committee on Resuscitation (ILCOR) has highlighted the urgent need for a randomised controlled trial to determine the most effective approach.

In a randomised controlled trial, the treatment that patients receive is decided by chance. This is the best and fairest way to work out whether one treatment is better than another. In PARAMEDIC-3, it will be decided by chance whether medications during the cardiac arrest are given by the intraosseous route or intravenous route.

Intravenous means “within the vein.” To give intravenous medication, a needle is inserted into the vein, sometimes called a drip. Many patients in hospital have a drip, so that medicines (such as antibiotics) and fluids can be given.

Intraosseous refers to being within the bone. To give drugs into the bone, a needle is inserted in to the bone marrow at the top of the arm or the top of the lower leg. The bone marrow has a very good blood supply, which means that drugs reach the blood quickly. Paramedics are trained in inserting intraosseous needles.

Patients will be enrolled in to the trial during their cardiac arrest. As the patient will be in cardiac arrest, they will be unconscious. If the person is eligible for the trial, they will be allocated to receive intraosseous or intravenous access by chance. Any drugs needed during the cardiac arrest will be given by this medication route. The treatment process being looked at in this trial is very urgent. This means that there will not be time to discuss trial participation with someone close to the patient before they are entered in the trial. This procedure has been approved by an independent NHS Research Ethics Committee, based on the authority given to them by the Mental Capacity Act 2005. If the patient survives to reach hospital, a researcher will approach them as soon as possible (normally after they are discharged from the Intensive Care Unit) to discuss their willingness to complete some follow-up questionnaires about how well they recover after their cardiac arrest. If the patient is unable to make decisions for themselves, the researcher may approach someone that can express a view on behalf of the patient.

We aim to recruit 15,000 patients to the trial.

We will enrol patients who have undergone an out-of-hospital cardiac arrest aged 18 years or over and are suitable to receive treatment using the intraosseous or intravenous medication route.

We will start enrolling patients in the trial in September 2021, with recruitment scheduled to finish in October 2023.

The study has been approved by the South Central Oxford C NHS Research Committee (21/SC/0178), the Health Research Authority Confidentiality Advisory Group (20/CAG/0092), and the Health Research Authority.

We (the University of Warwick) will need to use information from patients medical records for the study. This information will include name, date of birth, NHS number and contact details (address and telephone number). People will use this information to do the research or to check your records to make sure that the research is being done properly. People who do not need to know who you are will not be able to see your name or contact details. Your data will have a code number instead. We will keep all information about you safe and secure. Once we have finished the trial, we will keep some of the data so we can check the results. We will write our reports in a way that no-one can work out that you took part in the study.

We have carefully considered the benefits and burdens of different approaches to informing the relatives of the deceased, to inform them about the trial. The trial sought specific advice on this question from a panel of patient and public representatives, an advisory group made up of patients and families with experience of cardiac arrest. They carefully considered the pros and cons of directly informing relatives or using passive methods of communication and decided on balance the decision to use passive methods will cause the least distress to relatives during a very difficult time. Passive methods include presenting information on the trial website, using newsletters and posters displayed in hospitals, GP surgeries, registrar of births/death offices, libraries, and council websites. These methods have been widely used across previous UK emergency care research such as the PARAMEDIC 1 and PARAMEDIC 2 trials.

All details regarding how your information will be used, the data controller for the trial and how your participation will be kept confidential can be found here in the patient information sheet available to download on our website on the trial resources page - https://warwick.ac.uk/fac/sci/med/research/ctu/trials/paramedic3/trialresources/

Those that have had a cardiac arrest may struggle to return to their normal life. If you feel you need help, please talk to your own doctor or the hospital team that is looking after you (if you have a follow-up outpatient team). There are several charities and other organisations that can also provide support for you and your family, including Sudden Cardiac Arrest UK (https://www.suddencardiacarrestuk.org/), the British Heart Foundation (https://www.bhf.org.uk/informationsupport/conditions/cardiac-arrest), and SADS UK (link:https://www.sadsuk.org.uk/sudden-cardiac-arrest-survivors.html)