Mixed Blessing

Since 1981, when obstructive sleep apnea was shown to be treated successfully by an electromechanical device, there has been an increasing concentration of medical research on this disorder and its consequences. The combination of all the occurrences of sleep disordered breathing presents a potential market of 20 million Americans, growing at a rate of 20 percent per year. Yet the market remains untapped, for the most part.

Adverse consequences from OSA manifest in a variety of ways, including sleep deprivation, which causes daytime fatigue and accidents, and activation of the sympathetic nervous system, which leads to hypertension.

And, certain medical conditions can lead to OSA. Doctors believe that as many as 90 percent of morbidly obese individuals suffer from OSA. Of course they would, because, based on the physical nature of their disease, the additional weight puts pressure on their airways and diaphragms. Additionally, more than 30 percent of the 4.8 million people in the United States who suffer from congestive heart failure experience a special kind of sleep disordered breathing. Called Cheyne Stokes respiration, it is characterized by a series of deep panting breaths interspersed with central apneas.

As awareness increases about the diseases associated with OSA, the number of prescriptions being written for continuous positive airway pressure, or CPAP, devices will increase. We also will see more multidisciplinary approaches to treating these patients — treating the whole patient instead of just the one symptom of the disease.

Currently, a range of devices are made to suit patients' differing needs. ResMed's most advanced device, the AutoSet, is fully automatic. To treat OSA, from a low base pressure, it senses airflow against time for every breath. From this measurement, a computerized algorithm determines when an abnormality begins to occur. By increasing pressure, it pre-empts the formation of an impending apnea, before returning to a low pressure when airway resistance normalizes. Large-scale clinical trials are underway to confirm early findings that such treatment may reverse much of the cardiovascular damage and reduce the heart transplant queues.