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"Polysomnography is a diagnostic test, which establishes the presence orabsence of sleep disorders. But standard methods have the potential tosignificantly disturb a patient's sleep pattern, so what we see in the lab maynot be a true representation of the patient's sleep habits," said lead studyauthor Jayasimha Murthy, MD, Assistant Professor of Medicine, University ofTexas Health Science Center at Houston, TX. "However, remote infrared imagingis a noncontact method, so there is minimal interference with the patient. Infact, this system can be designed to where the patient isn't even aware thatmonitoring is taking place."
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In the first study of its kind, Dr. Murthy and his colleagues from theUniversity of Texas Health Science Center at Houston, the University ofHouston, and Memorial Hermann Sleep Disorders Center in Houston, TX, evaluatedthe efficacy of remote infrared imaging (IR-I) in 13 men and women withoutknown sleep apnea. Researchers recorded the heat signals expired frompatients' nostrils or mouth using an infrared camera during 1 hour ofpolysomnography. To minimize any bias, airflow channels were recorded andanalyzed separately. Results were then compared with those obtained throughthe conventional methods of sleep apnea diagnosis, including nasal pressure,nasal-oral thermistors, and capnography.
"The underlying principle of monitoring the relative changes in airflowbased on the changing of the infrared heat signal is similar to that of thetraditional thermistor," Dr. Murthy explained. "However, the biggestdifference is that the thermistor is placed in the subject's nostril while theinfrared camera is placed 6 to 8 feet from the patient's head. Also, thismethod allows us to have recorded data, so we can go back and extract theairflow data after the completion of the study, which we can't do withconventional sensors."
Upon completion, results showed that IR-I detected 20 sleep-disorderedbreathing events, compared with 22 events detected by the nasal-oralthermistor, and 19 events detected by nasal pressure. Given the outcome,researchers suggest that IR-I was in near-perfect agreement with conventionalmethods and that it represents a noncontact alternative to standard nasal-oralthermistors. Though Dr. Murthy acknowledges that this study represents apreliminary stage of testing, he is optimistic about the future of infraredimaging for sleep disorder diagnosis.
"The results from this study will greatly impact the development of thistechnology," he said. "While implementation of this technology for clinicalstudies is still far away, these early results are encouraging enough for usto pursue this further."
"Sleep apnea is a debilitating condition that affects millions ofAmericans and can lead to other, life-threatening illnesses," said Alvin V.Thomas, Jr., MD, FCCP, President of the American College of Chest Physicians."It is important for physicians and researchers to continue to explore newdiagnostic tools in order to detect and treat this sleep disorder at theearliest possible stage."
CHEST 2007 is the 73rd annual international scientific assembly of theAmerican College of Chest Physicians, held October 20-25 in Chicago, IL. ACCPrepresents 17,000 members who provide patien
