Dr. Felix Ratjen's research aims to conduct clinically relevant studies that have a direct impact on patient's lives. The Cystic Fibrosis Clinical Research team is a multidisciplinary group of scientists, respiratory therapists, nurses, statisticians and research staff who work together to conduct interventional and observational studies. The Ratjen Lab's research at SickKids focuses on evaluating novel treatments, designing new ways to conduct research and investigating how we can better measure and monitor lung function in young children.


Doctor examining a child patient by stethoscope during a routine clinical visit.


Our research focuses on physiological outcomes that can better identify early lung disease and monitor patients with respiratory diseases. Currently, many of our studies focus on the Multiple Breath Washout test which measures how effectively the lungs clears a tracer gas. Our research studies aim to understand how we can interpret the results of this test to monitor patients with cystic fibrosis.

stethoscope on the cardiogram


With a strong emphasis on evidence-based research, our team conducts interventional and observational studies in children with cystic fibrosis to improve the quality and longevity of life. The research studies offers insight into patterns of disease progression, risk factors for specific outcomes and real-life effectiveness of new treatments.

Happy child with oxygen mask playing with toy during his routine clinical care visit.


The Multiple Breath Washout (MBW) test has been identified as promising outcome for evaluating the efficacy of new treatments. As the North American MBW training centre, our team provides hands-on training sessions, certification and support for new operators. We also provide quality control over-reading services as the North American MBW core facility for data collected as part of clinical trials.