Full title: A clinical trial of continuous positive airway pressure (CPAP) to improve lung function for patients who have abdominal surgery

Aim: assess if Continuous Positive Airway Pressure (CPAP) benifits patients after abdominal surgery.

Background: Mortality and morbidity after surgery are major healthcare problems. 1-4% of the two million surgical procedures carried out in the UK every year result in death. Surgical complications are associated with reduced long-term survival. The most common of these affect the respiratory tract. This is particularly important for major abdominal procedures because of the impact of this type of surgery on respiratory function. Evidence from small trials (n<200) suggests that routine postoperative continuous positive airway pressure (CPAP) reduces pulmonary complications after abdominal surgery. However, it is not a part of routine practice because evidence of clinical effectiveness is lacking.

PRISM is a large international, multi-centre, pragmatic, randomised controlled trial with open study group allocation to determine whether early postoperative continuous positive airway pressure (CPAP) reduces the incidence of subsequent respiratory complications and improves one year survival following major intra-peritoneal surgery. We will recruit 4800 patients over the age of 50 and undergoing major elective intra-peritoneal surgery. The primary outcome measure is a composite endpoint of pneumonia, re-intubation or death within 30 days of randomisation. The secondary outcomes are: infection within 30 days of randomisation, mechanical ventilation within 30 days of randomisation, hospital re-admission within 30 days of randomisation, days in critical care, duration of hospital stay, all-cause mortality within one year of randomisation, and quality adjusted life years at one year after surgery.

The trial is based in the UK, with sites in Italy, Norway and Sweden. We would like to thank all interested parties who have registered their details through registration of interest page on this website. We are in the process of opening the final batch of centres and we are assessing our capacity to take on further new sites. Thank you for your interest and support.