Study: Infants at risk to SIDS using Non-Invasive Monitoring Systems Chime monitor

Non-Invasive Monitoring Systems announced the results of a peer-reviewed, scientific study in which its cardiorespiratory monitor was utilized to study infants at risk to Sudden Infant Death Syndrome (SIDS). In 1993, Non-Invasive Monitoring Systems, Inc. (NIMS) was awarded a contract to design and manufacture a monitoring device (CHIME monitor) in competition with six other vendors for a National Institute of Health sponsored multicenter study of a "home monitor with extensive memory and one that also detected obstructed breaths to view the full range of respiratory abnormalities that might cause apnea."

Apnea is cessation of breathing that might play a role in SIDS. This monitor incorporated NIMS' patented respiratory monitoring technology, the respiratory inductive plethysmograph (Respitrace(R)). Results of the study were reported by Drs. Ramanathan, Lister and associates in a paper "Cardiorespiratory Events Recorded on Home Monitor: Comparison of Healthy Infants with Those at Increased Risk for SIDS" published in the May 2 issue of the Journal of American Medical Association. The study from 1994 to 1998 included 306 healthy full-term infants and 773 infants at risk to SIDS.

The NIMS' CHIME monitor was set to sound an audible alarm for apnea of at least 20 seconds. Extreme events were defined as apneas of at least 30 seconds. During approximately 720,000 hours of home monitoring, there were 7000 events exceeding 20 seconds in 445 infants (41%). Of these, 650 were extreme events in 116 infants (10%), and of those events with apnea, 70% included at least 3 obstructed breaths. The frequency of at least 1 extreme event was similar in term infants in all groups, but preterm infants were at increased risk of extreme events until 43 weeks' postconceptional age.

Drs. Ramanathan, Lister and associates noted: "the high proportion of apnea containing at least 3 obstructed breaths exemplifies the value of using RIP (Respitrace(R)), which can identify obstructed breaths. For this reason, transthoracic impedance (current apnea home monitoring technology), which detects effort during obstruction, would not detect many of these apneas, and currently available home monitors would have detected less apnea than we observed. Although detection of bradycardia (slowed heart rate) might provide an alternative opportunity to detect events, fully half of extreme events had no bradycardia, even when associated with desaturation (decreased oxygen in blood)."

The authors commented: "The observation that 20% of asymptomatic preterm infants experienced 1 extreme event highlights the need to determine clinical relevance of extreme events. Until then, however, it is not possible to refute or support the recommendations of the NIH Consensus Development Conference that monitoring or an alternative therapy is medically indicated for symptomatic but not asymptomatic preterm infants." They added "...since many conventional and extreme events caused a monitor alarm, it is possible that the duration of some events in the risk groups was shortened by either an alarm-induced auditory arousal (from NIMS' CHIME monitor) or by caretaker intervention (shaking the baby for arousal or initiating CPR)."

The authors discussed the choice of NIMS' Respitrace(R) technology over the currently utilized impedance pneumograph home apnea monitors to detect apneas and obstructed breaths. "Although our choice of RIP for breath detection limits direct comparison to data based on customary impedance monitoring, the high frequency of obstructed breaths in our subjects strongly suggests that many events would have been missed by techniques commonly used in clinical practice (impedance monitoring)."

Six infants died during the study. Not one baby was connected to the NIMS' CHIME monitor at the time of death. There was one death in the healthy full-term group and five deaths in the risk to SIDS group. Four of the five babies at risk to SIDS group had findings consistent with SIDS. Dr. Marvin Sackner, CEO of NIMS notes that the incidence of SIDS in the healthy full term group of this study was 1 of 306 or 32 deaths per 10,000 births and in the risk to SIDS group 4 of 773 or 52 deaths per 10,000 births. The annual death rate from SIDS in the United States is approximately 3,000 babies of 4 million births per year or 8 deaths per 10,000 births. Therefore, the annual incidence of deaths in the babies in the CHIME study not connected to the monitor at the time of death was far greater. On the other hand, in babies connected to NIMS' CHIME monitors in whom auditory alarms sounded from the CHIME monitor that might have aroused the baby during apnea or where the alarm brought about caretaker intervention, not one death occurred. This issue was not addressed in the study possibly because the objective was designed "To test the hypothesis that preterm infants, siblings of infants who died of SIDS, and infants who have experienced an idiopathic, apparent life-threatening event have a greater risk of cardiorespiratory events than healthy term infants."

Drs. Ramanathan, Lister and associates concluded: "In this study, conventional events are quite common, even in healthy term infants. Extreme events were common only in preterm infants, and their timing suggests that they are not likely to be immediate precursors to SIDS. The high frequency of obstructed breathing in study participants would likely preclude detection of many events by conventional techniques. These data should be important for designing future monitors and determining if an infant is likely to be at risk for a cardiorespiratory event." Dr. Sackner states that NIMS is pleased that this study verified its long held contention that Respitrace(R) technology is superior to current impedance apnea monitors as a means to detect apneas and obstructed breathing. He adds that NIMS has designed and fabricated an improved monitor based upon its CHIME monitor technology that will be initially marketed to Neonatal Intensive Care Units in hospital after regulatory approval.

Source: Non-Invasive Monitoring Systems, Inc.

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