The CHIME study, funded by NICHD's Pregnancy and Perinatology Branch (PPB), looked at whether home monitors were effective in identifying episodes of apnea that are dangerous to an infant's health. Other objectives were to correlate physiological markers, health status, and behavior with the propensity for life-threatening events; and provide important information on the maturation of heart and respiratory function in sleeping infants.
After the CHIME study began, PPB staff, CHIME researchers, and industry members collaborated to develop new monitoring to detect and record life-threatening cardiorespiratory episodes. The monitors tracked chest and abdominal movement during breathing to measure the volume in the lungs when the muscles of respiration are relaxed. They included an electrocardiogram (ECG) to measure heart rate, a pulse oximeter to monitor oxygen in the blood, and an accelerometer to detect infant motion and position. The monitors recorded data before, during, and after an event and stored continuous RR intervals (time between heart beats) from the ECG, continuous breath-breath intervals, and 3-minute recordings of "normal," non-event sleep time collected hourly.
Between May 1994 and February 1998, 1,079 infants were enrolled, including:
- Healthy term infants
- Preterm infants weighing less than 1,750 grams at birth
- Siblings of babies who died from sudden infant death syndrome (SIDS)
- Infants who experienced an idiopathic life-threatening event
Findings from CHIME showed that cardiorespiratory events (apnea, bradycardia, etc.) that met conventional alarm thresholds were quite common, even in healthy term infants. However, more severe events were common only in preterm infants. Timing of these events suggested they were not likely to be immediate precursors to SIDS (JAMA, 2001; 285, 2199−2207).
Based on this and other research, the American Academy of Pediatrics does not recommend using home monitors to predict or prevent SIDS (Pediatrics, 2005; 116, 1245−1255).
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