1745 THE HYPERCARBIC VENTILATORY RESPONSE TEST: NEAR-MISS SIDS SIBLINGS OF SIDS, AND SUBSEQUENT APNEA

Abstract

Hypercarbic ventilatory response (HVR) tests were administered to 65 near-miss SIDS victims, 78 siblings of SIDS victims, and 31 controls. HVR values were compared, then correlated with the incidence of subsequent apnea. HVR tests used a steady-state, breath-by-breath technique. HVR results were expressed as changes in exhaled minute volume per change in PACO2 (ml/min/kg/ mmHg PACO2). Twenty-three near-miss SIDS victims (35%) had subsequent apnea; one died of SIDS. Seven siblings of SIDS victims (9%) eventually developed apnea; two died of SIDS. HVR values were similar in the three patient groups. HVR values were not different from controls in either those infants with previous apnea or those who developed subsequent apnea. Surprisingly, resting PACO2 values were lower in the mear-tniss group (P <.05). When all infants who developed subsequent apnea (both near-miss and siblings) were compared to all those who did not, those with subsequent apnea also had lower PACO2 values (P <0.001) along with higher HVR values (P <.05). Conclusions: 1) HVR values were not depressed in near-miss SIDS or siblings of SIDS victims; 2) Resting PACO2 values were lower in near-miss SIDS victims; 3) Infants who developed subsequent apnea had higher HVR values and lower PACO2 values than those who did not.