PROSPECTIVE ANALYSIS OF HEART RATE AND BREATHING PATTERNS IN INFANTS SUCCUMBING TO SIDS AND IN CONTROLS

Abstract

In studies of babies at high risk for SIDS (near-SIDS and siblings), we have identified among some who died excess periodic breathing (PB) excess variability (var) of respiratory frequency (f) and increased oscillation of heart rate (HR), at 4-7 cycles per min., (low frequency peak-LFP). The present study was planned to test the hypothesis that in an unselected prospectively studied population, these same variables might discriminate SIDS from controls. From 6914 term infants, we selected 24 hour pneumograms performed at 6 weeks on 11 SIDS and 101 random controls. One SIDS had one near-SIDS spell. Casettes were coded for blind analysis. From data recorded between 12MN and 6AM we transcribed ECG and respiratory signals onto hard copy for visual inspection and we transferred these signals during all 5 min epochs of quiet breathing (Q) onto FM tape for spectral analysis. We inspected hard copies for PB and apnea ⩾10s. Spectral analysis identified f and var, HR and var and power at f (resp. sinus arrhythmia) and at the LFP. We rank ordered results to test hypothesis 1) that PB and 2) that abnormal spectral var were markers for SIDS. We performed cluster analysis on each data set The code was then broken; neither hypothesis was correct. These results neither support nor negate the apnea hypothesis of SIDS.