Post Discharge Cardiorespiratory Events in Preterm Infants

Background: Home monitors designed to identify cardiorespiratory events are frequently used for premature infants who suffer from persistent apneic and/ or bradycardic events after they are otherwise ready for discharge home. Objective: We have hypothesized that using event recording monitor will characterize the events during home monitoring and identifies at what postconceptional age (PCA) the infants are event free. Materials and Methods: 12 hours bedside four channel pneumogram was performed on 452 preterm infants born at ≤34 weeks of gestational age before hospital discharge. 108 infants had at least one episode of apnea≥20 second and/ or one episode of bradycardia< 80 beats per minute (BPM) for ≥5 second and they were considered symptomatic and discharged on event recording monitor. The monitor documented transthoracic impedance, electrocardiogram and heart rate. The monitor was downloaded at least once a month. An event was considered to be significant when an apnea lasted ≥20 seconds or when the heart rate was <80 BPM for ≥5 seconds for PCA <44 weeks and <60 BPM for PCA ≥44 weeks. Each infant was monitored for at least one month after the last event. Infants who were monitored for <50% of available days or <8 hours per day were excluded from the study. Results: Duration of post discharge monitoring ranged from 4-30 weeks (median 7 weeks). When the patients were events free PCA ranged from 34-55 weeks (Median 39 weeks). Compliance for the usage of monitor for available days was 50-100% (median 100%). For daily use the time range was 8-12 hours (median 19 hours). During 152,664 hours of home monitoring 1,240 events were recorded. Of these events only 184 were apnea more than 20 seconds 47% of infants did not have apnea ≥20 seconds after discharge. 80% of infants with apneic episode had ≤5 episodes during home monitoring. Bradycardia without apnea of at least 20 seconds represented 32% of the events. 75% of bradycardiac episode were associated with short apnea (10±4 seconds). Conclusions: Preterm infants discharged home on event recording monitor had low incidence of apnea ≥20 seconds. Using event record monitor will characterize the events during home monitoring and is helpful in determining the appropriate time of discontinue monitoring.