The authors – from the College of William and Mary (Williamsburg, VA), the University of Virginia (Charlottesville, VA) and the University of Virginia Health System – used the algorithm to analyse around 100 baby-years of data. They found that even state-of-the-art bedside monitors missed about 14% of extreme events (apneas lasting more than 30 s) in infants. The new algorithm, on the other hand, only missed about 5%. It also halved the rate of false alarms.

The key to this improved detection ability lies in the effective filtering out of cardiac artefacts in the chest impedance signal used to measure respiration. Such artefacts, caused by the heart beating, can confuse the monitor's apnea alarm. The new algorithm changes the unit of time to the interval between heartbeats, effectively creating a new timescale. As the heart rhythm changes, so does the clock, enabling the program to recognise and filter out the heart signal, leaving just the breathing signal (see Algorithm improves apnea detection for more details).

Since publication of their award-winning paper, the researchers have been working to improve the accuracy of their apnea detection algorithm and extend its coverage, for example, to detect central apnea with neither bradycardia or desaturation. They have also used the algorithm on large databases to acquire better information about the accuracy of nursing records, the effect of blood transfusions on apnea and how apnea changes with age.

"More importantly, we have developed new methods to study cardiorespiratory coupling, and have discovered an unexpected number of cases of extreme apnea, lasting more than 60 seconds," said John Delos, Professor of Physics at the College of William and Mary. "Also, we are beginning a study of periodic apneas, which had long been thought to be benign, but which in extreme cases, appear to provide early warning of pathological conditions."

Delos emphasized that this project is very much a team effort, and that the award is being accepted on behalf of all of this team. "Hoshik Lee and I conceived and developed the algorithms for apnea detection, which were refined and validated through the hard work of the clinicians," he told medicalphysicsweb. "Part of the fun of this project has been working with a great variety of people with many different sets of skills, and all pulling together toward our goals."

"I never expected to receive this prize," added Lee (now working for the Samsung Advanced Institute of Technology in South Korea). "I was really lucky to be able to work with Dr Delos and the other co-authors. I would not have received it without their help."

The shortlist

The Martin Black award is an annual prize awarded by IOP Publishing, the publishers of PMEA, in association with the journal owners, the Institute of Physics and Engineering in Medicine (IPEM). The responsibility for deciding the winner falls to the Editorial and International Advisory boards of the journal. A shortlist was constructed using referees' comments and ratings and then the board members assessed and ranked the selected papers.

The following six articles (listed in alphabetical order) were shortlisted for the 2012 Martin Black award

More information on the shortlisted papers can be found here.

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