The CHIME Study, funded by the NICHD’s Pregnancy and Perinatology Branch (PPB) and now complete, looked at whether home monitors are effective in identifying episodes of apnea that are dangerous to the infant's health. Other objectives were to (a) correlate physiological markers, health status, and behavior with the propensity for life-threatening events, and (b) 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 technology and to evaluate the technology for its potential 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, and also 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 apparent life-threatening event
Findings from CHIME showed that cardiorespiratory events ( apnea, bradycardia, etc.) meeting 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).
The CHIME dataset and data from another completed study, the National Infant Sleep Position (NISP) Study, are available to the scientific community for secondary analyses to ensure that these important data are used to their fullest extent. The CHIME database contains raw and analyzed physiologic waveforms from overnight polysomnogram recordings and the home monitor recordings , as well as sociodemographic and medical data about the mother and the infant at entry and from scheduled medical follow-up visits through 1 year of age weekly phone calls knowledge about the monitor and satisfaction scales periodic assessments with the Bayley II Scales of Infant Development, NCAST (Nursing Child Assessment Satellite Training), and subscales of the Parenting Stress Index and hospitalizations .