of asthma exacerbations. The present work addresses this notion with three separate but interrelated components. Methods: Using the electronic medical record, HR of children admitted with asthma exacerbation between 2014 and 2015 was interrogated from admission through discharge. The accuracy of a passive HR monitor, which measures HR of sleeping children from beneath the mattress, was validated by comparison with HR recording from the polysomnography laboratory. To assess feasibility, an observational study was undertaken in a 12 year old male subject with moderate persistent asthma. The HR monitor was placed under the mattress in the subject's home. Asthma Control Test (ACT) was collected at baseline and every two weeks. IRB approval and written informed consent were obtained for all relevant portions. Results: In asthmatic children, HR decreased by 30.8AE10.6 % over the hospital course. In pilot studies conducted in the polysomnography laboratory, HR measurement by passive and ECG monitoring correlated well, r2¼0.96. In the feasibility study, HR was stable for the month prior to hospitalization but demonstrated a significant increase in the 3 days immediately preceding exacerbation. HR was stable after exacerbation resolution. Conclusion: These data support the notion that increases in HR may be a sensitive and early sign of asthma exacerbation. Passive monitoring may offer an opportunity for early detection and intervention that might attenuate disease severity, hospitalization frequency and cost.

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