The Natural History of the Appearance of Apnea of Prematurity

Abstract

ABSTRACT. Twenty healthy preterm infants of less than 34 wk gestation were studied with continuous recordings, commencing within 8 h of birth, for up to 1 wk of age to determine the usual time course of the appearance of apnea and to classify apnea types. Airway occlusion studies were also performed on a regular basis to determine whether apneic spells were preceded or followed by a reduction in central respiratory drive. Apneic spells of greater than 15 s duration accompanied by hypoxia or bradycardia occurred in all infants before 24 h of age. The frequency of apneic spells was highest in the first 24 h after birth with a mean frequency of 0.9/h and gradually reduced thereafter, falling to 0.2/h by 5 d of age ( p < 0.01). Apneic spells were more likely to be obstructive in the first 2 d of life than thereafter ( p < 0.05). Central apnea was proportionately significantly less frequent during this time period. Reduced respiratory drive, as demonstrated by airway occlusion pressures, was associated with more frequent apnea and was evident at the first occlusion study, which frequently preceded the first significant apnea. (Pediatr Res 29: 372-375,1991) Abbreviations SpOz, pulse oximeter-derived saturation Po.,, airway pressure 0.1 s after initiation of first occluded breath ANOVA, analysis of variance It is commonly stated that idiopathic apnea of prematurity develous after the first 24 to 72 h of life and amea that is noted early requires vigorous investigation (1). The factual basis of this statement is uncertain. Henderson-Smart (2) previously demonstrated that apnea (more than three spells of greater than 20 s duration) developed on the 1st or 2nd postnatal d in 77% of preterm infants. He appears to have used impedance monitoring only and it is uncertain whether any recordings were made for independent confirmation of apnea (3). Carlo et al. (4), utilizing 60-min recordings, showed that apneic spells of greater than 5 s duration occurred on d 1 in eight of 10 preterm infants without lung disease.There appears to be no published information regarding the usual frequency and nature of significant apneic spells in an unselected population of healthy newborn preterm infants who have undergone prolonged recordings.Our main objective was to ascertain the usual age of the appearance of apneic spells and the relative frequency of obstructive, mixed, and central apnea during the 1 st wk of life in preterm infants without respiratory disease. Our secondary objective was to describe the development of respiratory drive, by determining the postnatal progression of occlusion pressures, in infants with and without apnea. SUBJECTS AND METHODSTwenty infants of less than 34 wk gestation with birth weights above the 5th percentile for gestational age were studied. Infants were all born in the Royal Alexandra Hospitals and were entered into the study as soon after birth as possible. We entered consecutive infants who were clinically determined to be free of acute medical problems; in particular, they were without significan...

Tripartite Purinergic Modulation of Central Respiratory Networks during Perinatal Development: The Influence of ATP, Ectonucleotidases, and ATP Metabolites

“…Indeed, the greater sensitivity of fetal preparations to ADO (Herlenius et al, 2002) is a hypothesized factor in the greater sensitivity of premature mammals to hypoxic ventilatory depression. It also has implications for apnea of prematurity in which a premature, ADO-sensitive respiratory network is a hypothesized contributor to respiratory instability (Barrington and Finer, 1991). In fact, despite ongoing debate as to whether the beneficial effects of caffeine are attributable to A 1 receptor antagonism, caffeine administration is a primary therapy for apnea of prematurity (Hascoet et al, 2000;Bhatt-Mehta and Schumacher, 2003;Schmidt, 2005;Schmidt et al, 2006).…”

Effects of caffeine on renal and pulmonary function in preterm newborn lambs

“…Apnea of prematurity is one of the most common problems encountered in the clinical management of preterm infants, occurring in 85% of infants born at <34 wk gestation (2). Apnea of prematurity (usually defined as a cessation of breathing >15 s) is often associated with bradycardia and arterial desaturation (3) and is common in preterm infants because they have immature respiratory control mechanisms.…”

Summary Proceedings From the Apnea-of-Prematurity Group

“…AOP is found in Ͼ50% of premature infants and is almost universal in infants who are Ͻ1000 g at birth. [1][2][3] The literature defines clinically significant apnea in infants as breathing pauses that last for Ͼ20 seconds or for Ͼ10 seconds if associated with bradycardia (eg, Ͻ80 beats per minute) or oxygen desaturation (eg, O 2 saturation of Ͻ80 -85%). 4,5 This definition may vary depending on geographic location or the infant's symptomatology.…”