As part of a National team we will be investigating the use of sodium bicarbonate in a multi-centre randomised controlled trial beginning in 2021 funded through the NIHR HTA.

Around 184,000 critically ill adults are admitted to critical care units each year in the UK. Around half have a sudden worsening in kidney function that happens as part of their illness. This is called acute kidney injury (AKI). AKI prevents the kidneys from working properly, causing more acid than normal to build-up in the blood (a process known as acidosis) which can cause further harm. Once this point has been reached, more than half of patients who have acidosis and AKI will not survive their illness. One way to treat patients with acidosis is to give patients an alkali (opposite to acid) to stop the effects of the acid build-up and to bring the level of acid in the blood to normal. Sodium bicarbonate is often used and is a cheap and accessible treatment, but there is little evidence to support its use, which has resulted in variation in practice with some doctors using it, and others not. Doctors and nurses have to decide if the patient should get sodium bicarbonate or progress to more invasive kidney support (known as renal replacement therapy, RRT), which has added risks and needs specialist staff and equipment, making it very expensive. So far, only one study has looked at the benefits of sodium bicarbonate in critically ill patients with acidosis. This found that giving sodium bicarbonate to all patients who had acidosis was not an effective treatment. However, in a subgroup of patients who had acidosis and AKI, results pointed to possible benefits of sodium bicarbonate, with fewer patients dying and fewer patients needing RRT. However, to know with certainty, this needs to be tested thoroughly in a larger study (known as a randomised clinical trial) specifically designed to test this question. Our aim is to find out whether using sodium bicarbonate to treat critically ill people with acidosis and AKI improves survival and is cost-effective for the NHS. We plan to conduct a randomised clinical trial, in which we will include 2,250 patents from 60 NHS critical care units. They will be randomly assigned by a computer to receive sodium bicarbonate or no sodium bicarbonate. This helps to ensure that the two groups are as similar as possible, and only differ by whether they receive bicarbonate or not. All other medical treatment will be decided by the doctors and nurses treating the patient. We will follow-up all patients at 28-days, 90-days and 1-year following the study to see how they are after leaving the ICU. Giving sodium bicarbonate to critically ill patients with acidosis and AKI may increase the number of patients who survive their illness and may also reduce the need for patients to undergo RRT, which may mean they recover more quickly and may also have important cost implications for the NHS. We have patient and public representatives as co-investigators on this study. They have been involved in the design of the study and how the study will be conducted. They will also help to oversee the conduct and management of the study. Once the study is complete, the results will be published in widely read and well-regarded medical journals. The results will also be presented at various national and international conferences for intensive care doctors, nurses, other health professionals, managers and policy makers. We will also make the results available to the public and patients through our website.