Darnall R A, Kattwinkel J, Nattie C, Robinson M
Department of Pediatrics,Dartmouth Medical School, Dartmouth-Hitchcock Medical Center, Lebanon, New Hampshire 03756, USA.
Pediatrics. 1997 Nov;100(5):795-801. doi: 10.1542/peds.100.5.795.
Most neonatologists include an apnea-free period in the criteria for the discharge of preterm infants. However, the length of time one should wait after the cessation of apnea before sending an infant home without a monitor is debated. We undertook this study in an attempt to define a minimal and safe observation period between the time of the last apnea episode and discharge.
We reasoned that in infants with idiopathic apnea of prematurity, the intervals between days on which apnea occurs gradually increase until some point at which clinically significant apnea ceases. Therefore, knowledge about the intervals between days on which apnea occurred just before the last apnea would provide a reasonable estimate of the minimal safe observation interval between the last apnea and discharge. We reviewed the charts of 266 infants born in 1993 and 1994 at </=32 weeks' gestational age or weighing </=1500 g at birth from two institutions to determine the intervals between the day on which the last apnea occurred and the previous two days on which apnea occurred. One hundred seventy-five infants were excluded because they never experienced apnea, or data about the last apnea was missing, or they were on xanthines during the period encompassing the last 3 apnea days, or they weighed <1500 g or were <34 weeks' postmenstrual age at the time of the last apnea. Of the 91 remaining infants, gestational age at birth, birth weight, 1- and 5-minute Apgar scores, and discharge weight were not different between the two institutions. For each infant we determined the longest of the intervals between the 2 days on which apnea occurred previous to the day of the last apnea (MAXINT for maximum interval). The infants were then ordered by MAXINT and, starting at the longest MAXINT, the medical records of each infant were carefully examined for other conditions known to be associated with apnea (eg, recovering from anesthesia, sepsis, chronic lung disease, and so forth). The minimal safe observation period was then defined as the longest MAXINT in which there was at least 1 infant with no other explanation for the apnea other than prematurity.
The median duration of the intervals between the 2 days on which apnea occurred previous to the day on which the last apnea occurred were 3. 0 and 2.0 days and the median duration of the MAXINT was 4.0 days. On careful examination of the charts, it was determined that each of 13 infants with a MAXINT preceding the day on which the last apnea occurred of greater than 8 days had some other condition that might result in apnea, including residual lung disease, sepsis, surgery, and so forth. In contrast, among the group of infants with a MAXINT of </=8 days, at least 1 infant at each MAXINT (eg, 1 to 8) had significant apnea with no other explanation other than prematurity.
We conclude that otherwise healthy preterm infants continue to have apneas separated by as many as 8 days before the last apnea before discharge. Conversely, infants with longer apnea intervals often have identifiable risk factors other than apnea of prematurity.
大多数新生儿科医生将无呼吸期纳入早产儿出院标准。然而，在停止呼吸后，在不使用监测仪就送婴儿回家之前应等待多长时间存在争议。我们开展这项研究，试图确定最后一次呼吸暂停发作至出院之间的最短安全观察期。
我们推断，在患有特发性早产呼吸暂停的婴儿中，呼吸暂停发作的间隔天数会逐渐增加，直到临床上显著的呼吸暂停停止。因此，了解最后一次呼吸暂停前呼吸暂停发作的间隔天数，将为最后一次呼吸暂停至出院之间的最短安全观察间隔提供合理估计。我们回顾了1993年和1994年在两家机构出生的266例胎龄≤32周或出生体重≤1500克的婴儿的病历，以确定最后一次呼吸暂停发作日与前两次呼吸暂停发作日之间的间隔。175例婴儿被排除，原因包括从未经历过呼吸暂停、最后一次呼吸暂停的数据缺失、在最后3次呼吸暂停发作期间使用了黄嘌呤、最后一次呼吸暂停时体重<1500克或孕龄<34周。在剩下的91例婴儿中，两家机构的出生胎龄、出生体重、1分钟和5分钟阿氏评分以及出院体重无差异。对于每个婴儿，我们确定最后一次呼吸暂停发作日前两次呼吸暂停发作日之间最长的间隔（最大间隔的最大整数，即MAXINT）。然后按MAXINT对婴儿进行排序，从最长的MAXINT开始，仔细检查每个婴儿的病历，查找已知与呼吸暂停相关的其他情况（如从麻醉中恢复、败血症、慢性肺病等）。然后将最短安全观察期定义为最长的MAXINT，在此期间至少有1例婴儿除早产外无其他呼吸暂停原因。
最后一次呼吸暂停发作日前两次呼吸暂停发作日之间间隔的中位数为3.0天和2.0天，MAXINT的中位数为4.0天。仔细检查病历后发现，最后一次呼吸暂停发作日前MAXINT大于8天的13例婴儿中，每例都有其他可能导致呼吸暂停的情况，包括残留肺病、败血症、手术等。相比之下，在MAXINT≤8天的婴儿组中，每个MAXINT（如1至8）至少有1例婴儿有明显呼吸暂停，除早产外无其他原因。
我们得出结论，在出院前，其他方面健康的早产儿在最后一次呼吸暂停前仍会出现间隔长达8天的呼吸暂停。相反，呼吸暂停间隔较长的婴儿除早产呼吸暂停外，通常有可识别的风险因素。
