AUTONOMIC NERVOUS-SYSTEM FUNCTION IN SEVERE BREATH-HOLDING SPELLS

This study attempted to determine noninvasively whether a dysregulatio n of autonomic nervous system reflexes exists in children with severe cyanotic breath-holding spells (BHS). This was a cross-sectional study performed in the neurophysiology laboratory at a tertiary care hospit al. Patients, 18 months of age and older taken from a referral populat ion of children with severe cyanotic BHS and normal controls, were stu died. Fourteen children with cyanotic BHS and 12 controls were evaluat ed. Several noninvasive measures of parasympathetic and sympathetic re flex functions were assessed and statistically analyzed using analysis of variance and covariance, and Fisher's exact tests. The cyanotic BH S group had a significantly greater increase in pulse rate at 15 s of standing after rising from the supine position (P < .06), with a trend toward a concomitant higher mean arterial pressure (P < .09). After a djusting for age, sex, and mean supine systolic and diastolic blood pr essures, breath-holders had a greater decrease in diastolic blood pres sure (P < .02) without an increase in systolic blood pressure after st anding from the supine position. Breath-holders also had significantly abnormal 30:15 R-R interval ratios compared with controls (P < .002). These results support the hypothesis that children with cyanotic BHS have underlying autonomic nervous system dysregulation. This dysregula tion may contribute to the pathophysiology of severe BHS in these chil dren.