A randomised trial of blood pressure maintenance using angiotensin II versus noradrenaline in cardiac surgery patients to determine effect on length of hospital stay

More than 20,000 heart operations are carried out each year in Australia. While most patients survive their surgery, many spend a long period of time in hospital recovering. Delayed recovery may happen as a result of the complexity of the surgery, or due to medical problems that occur after the operation such as irregular heart rhythms, stroke or kidney failure. These medical problems following surgery are known as postoperative complications. Postoperative complications can lead to long-term ill health and loss of independence, as well as prolonging hospital stay. In addition, a longer stay in hospital may expose patients to risks such as infection and predispose to physical deconditioning. Reducing length of stay in hospital is associated with improved recovery from surgery, in addition to reduced healthcare costs. Previous studies have suggested that a new drug called ‘angiotensin II’ can successfully be used to treat low blood pressure in critically unwell patients. Drugs to preserve blood pressure are also often needed in heart surgery, however there are no large studies that have assessed the effectiveness of angiotensin II in patients during and after heart surgery. We previously carried out a small study that showed that using the drug angiotensin II during and after cardiac surgery is possible (ACTRN12621000195853). This knowledge has allowed us to design a new study to compare the use of angiotensin II to the current standard drug used to treat low blood pressure after heart surgery, called noradrenaline. In our previous research, patients who were given angiotensin II had fewer postoperative complications (although this difference wasn't statistically significant) and shorter lengths of stay in hospital. However, before we can recommend that angiotensin II is better for treatment of low blood pressure during cardiac surgery, we need to confirm these findings in a much larger study to make sure that our previous study findings were not simply the result of chance. In this study we will assess whether the administration of angiotensin II reduces length of hospital stay compared to noradrenaline.