Abstract
The relationship between apnea (AP) and heart rate (HR) was determined in 8 premature infants (gestational age 27-31 weeks) during their 1st 5 days of life. Inspection of 276 hours of continual recording of respiration (impedance pneumograph), mean HR and intra-aortic pressure demonstrated 286 episodes of apnea (≥ 20 seconds, preceded by 2 minutes of uninterrupted breathing). In 94% of these apneic events, a drop in HR (10-110 bpm) followed the onset of apnea, with a mean delay in onset of HR drop of 9.7 ± 4.0 seconds. The drop in HR never preceded the onset of apnea and on only 2 occasions began simultaneously with the onset of apnea. The drop in HR appears to be a secondary response rather than part of the primary phenomenon. The hypothesis that the magnitude of the drop in HR is indicative of the significance of the apnea to the infant was tested by examining 17 pairs of apnea when the 2nd apnea occurred < 2 minutes after the first. (In 10 cases, the 2nd apnea occurred < 30 seconds after the 1st.) The HR nadir of the 2nd event compared to the 1st event was the same (within 10 bpm) or higher in 16 of the 17 pairs. The data suggest that a drop in heart rate invariably occurs as a response to apnea, but that the magnitude of the drop does not reflect the physiologic significance of the apnea to the infant.
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Rowe, J., Flanagan, W., Hodson, W. et al. THE RELATIONSHIP BETWEEN APNEA AND HEART RATE IN PREMATURE INFANTS. Pediatr Res 11, 541 (1977). https://doi.org/10.1203/00006450-197704000-01029
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DOI: https://doi.org/10.1203/00006450-197704000-01029