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Increased Risk of Cardiorespiratory Events is Not Seen in Term High-Risk Infants


  • Do high risk infants have an increased risk for cardiorespiratory events on home monitor when compared to healthy infants?

Clinical Bottom Lines

  1. Term infants with ALTE (apparent life threatening event) or term siblings of SIDS victims (SIDS-SIBS) are not at increased risk for cardiorespiratory events.
  2. Preterm infants (<37 wk EGA) are at increased risk for severe apneic/bradycardic events.
  3. The clinical significance of these events is unclear given the large number of events seen in healthy term infants.
  4. Highest rate of extreme events seen in infants less than 43 week post-conceptional age (PCA), whereas the peak incidence of SIDS occurs after 49 weeks PCA.
  5. Unclear relationship remains between apneic events and sudden death.
  6. Standard transthoracic impedence monitors would miss 70% of extreme apneic events seen by respiratory inductance plethysmography.

Summary of Key Evidence

  1. Longitudinal cohort study of 1079 infants divided into seven groups according to history of ALTE, SIDS-SIB, prematurity or healthy term.
  2. Infants monitored for 6 months or until alarm free for 12 weeks. Monitoring included heart rate, pulse oximetry, tidal volume and respiratory inductance plethysmography.
  3. Over 700,000 hours of monitor data and over 21,000 recorded events evaluated.
  4. Events rated as conventional or extreme per criteria set prior to study.
  5. 43% healthy term infants had events. 20% asymptomatic preterm infants had extreme events. 70% of apneic episodes would not be recognized with conventional monitoring.
  6. Relative risk of extreme events was statistically increased for preterm groups with: symptomatic preterm 18.0 (95% CI 6.2-53), asymptomatic preterm 10.1 (95% CI 3.7-28), ALTE preterm 7.6 (95% CI 2.2-26), and SIDS-SIBS preterm 5.6 (95% CI 1.6-20)
  7. Risk of extreme event decreased to that of reference group by 44 weeks PCA.
  8. Almost all of subsequent events occurred within 6 week of the prior event.

Additional Comments

  • Currently the relationships between apnea, bradycardia, hypoxia and sudden death is unclear.
  • This larger study corroborates previous small studies showing that repeat events occur within 6 weeks of initial event.2
  • CHIME monitor more sensitive in measuring obstructive apnea than standard monitoring devices. This may have played a role in number of events recorded by healthy infants although this would not change the relative risks.3


  1. Ramanathan R, Corwin MJ, Hunt CE, et al. Cardiorespiratory events recorded on home monitors: comparison of healthy infants withthose at increased risk for SIDS. JAMA 2001;285:2199-2207.
  2. Cote A, Hum C, Brouillette RT, Themens M. Frequency and timing of recurrent events in infants using home cardiorespiratory monitors. J Pediatrics 1998; 132:783-98.
  3. Weese-Mayer DE, Corwin MJ, Peucker MR, et al, and the CHIME Study Group. Accuracy of the respiratory inductance plethysmography (RIP) Collaborative Home Infant Monitoring Evaluation monitor in identifying obstructed breaths. Am J Resp Crit Care Med 2000; 162:471-480.
  4. Michigan Association of Apnea Professionals Consensus Statement of Infantile Apnea and Home Monitoring Fourth Edition. 1998.
  5. Dr. Nancy McIntosh RN, PhD. University of Michigan. Personal communication.

CAT Author: Pamela Davis, MD

CAT Appraisers: John G. Frohna, MD, MPH

Date appraised: May 30, 2001

Last updated October 15, 2002
Department of Pediatrics and Communicable Diseases
© 1998-2002 University of Michigan Health System