Cardiorespiratory Events with Bolus versus Continuous Enteral Feeding in Healthy Preterm Infants Luigi Corvaglia, MD, Silvia Martini, MD, Arianna Aceti, MD, Maria Grazia Capretti, PhD, Silvia Galletti, MD, and Giacomo Faldella, MD, PhD We evaluated the effects of bolus vs continuous tube feeding on cardiorespiratory events, detected by polysomnographic monitoring, in healthy preterm infants. Continuous tube feeding resulted in a significant increase of apneas and apneas-related hypoxic episodes compared with bolus feeding. (J Pediatr 2014;165:1255-7).
T
ube feeding routinely is used for prolonged periods to provide adequate enteral nutrition in very preterm infants as the result of their inability to coordinate sucking, swallowing, and breathing. The slower infusion rate of continuous feeding is preferable in cases with delayed gastric emptying; however, the presence of the intragastric tube for the feeding period might affect breathing patterns1 and predispose the infant to gastroesophageal reflux (GER).2 Intermittent bolus feeding will cause greater gastric distension, which can increase airflow and respiratory instability.3 Furthermore, the insertion of the feeding tube for bolus administration represents a trigger for a vagal reflex,4 which is characterized by bradycardia and a transitory reduction in cardiac output. Prolonged apneas are often followed by bradycardia and hypoxic episodes, which temporarily impair tissue perfusion and oxygen delivery to vital organs. Furthermore, the subsequent recovery from hypoxia may cause oxidative stress and proinflammatory responses.5 A greater incidence of severe retinopathy of prematurity6 and unfavorable neurodevelopmental outcomes7 was observed in preterm infants with recurrent intermittent hypoxic episodes; in addition, a possible linkage between intermittent hypoxic episodes and later sleep-disordered breathing has been hypothesized.7 To date, the effect of bolus and continuous tube feeding on apnea, bradycardia, and hypoxic episodes in preterm infants is uncertain.1,8-10 The impact of the 2 feeding techniques on cardiorespiratory events has not been evaluated as a primary outcome. Thus, we investigated the effect of bolus and continuous tube feeding on cardiorespiratory events in healthy tube-fed preterm infants.
Methods Infants admitted to the Neonatal Intensive Care Unit of Sant’Orsola-Malpighi Hospital, Bologna, Italy, were eligible for the study if they fulfilled the following criteria: gestational age 30% below the baseline or 20 seconds and not associated with bradycardic and/or hypoxic events (Table II). Furthermore, continuous feeding resulted in more mild (oxygen saturation measured by pulse oximetry 81%-85%) and short (#10 seconds) hypoxic episodes concomitant with cardiorespiratory events. A slightly greater number of bradycardias was documented after the administration of a bolus; the difference between the 2 feeding techniques was not significant.
Discussion We evaluated the effect of continuous and bolus tube feeding on cardiorespiratory events in a healthy preterm population. Continuous feeding was associated with a greater number of prolonged apneas and apnea-related hypoxic episodes. Our findings are consistent with those of Dollberg et al.10 The present study, however, analyzed a larger population of exclusively healthy preterm infants to avoid possible interfering factors such as feeding intolerance, necrotizing enterocolitis, intraventricular hemorrhage, sepsis, and respiratory distress, which can lead to an increased frequency of cardiorespiratory events. Akintorin et al8 reported greater rates of apnea in relation to bolus feeding in preterms infants. In their study, the feeding tube was not removed after the administration of the bolus, thus removing possible effects as the result of tube insertion or to its permanence through the gastroesophageal junction.
Table I. Main characteristics of the study population (n = 33) Characteristics Gestational age, wk, median (IQR) Birth weight, g, median (IQR) Postnatal age at examination, d, median (IQR) Weight at examination, g median (IQR) Methylxanthine treatment during hospital stay, n (%) Methylxanthine treatment at time of examination, n (%) Need for supplemental O2 at time of examination, n (%) Type of feeding, n (%) Fortified human milk Standard preterm formula Mixed feeding 1256
31 (28-32) 1356 (1160-1545) 16 (12-33) 1575 (1468-1742) 23 (70%) 12 (36%) 0 (0%) 12 (36%) 7 (21%) 14 (43%)
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Table II. Number of cardiorespiratory events recorded after bolus administration and during continuous feeding of 33 infants
Apneas Total Type CA OA MA Duration, s >20 #20 Related to bradycardia/hypoxic episodes Yes No Hypoxic episodes Total SpO2 values 81%-85% #80% Duration, s >10 #10 Related to apnea/bradycardia Yes No Bradycardia Total
T
ube feeding routinely is used for prolonged periods to provide adequate enteral nutrition in very preterm infants as the result of their inability to coordinate sucking, swallowing, and breathing. The slower infusion rate of continuous feeding is preferable in cases with delayed gastric emptying; however, the presence of the intragastric tube for the feeding period might affect breathing patterns1 and predispose the infant to gastroesophageal reflux (GER).2 Intermittent bolus feeding will cause greater gastric distension, which can increase airflow and respiratory instability.3 Furthermore, the insertion of the feeding tube for bolus administration represents a trigger for a vagal reflex,4 which is characterized by bradycardia and a transitory reduction in cardiac output. Prolonged apneas are often followed by bradycardia and hypoxic episodes, which temporarily impair tissue perfusion and oxygen delivery to vital organs. Furthermore, the subsequent recovery from hypoxia may cause oxidative stress and proinflammatory responses.5 A greater incidence of severe retinopathy of prematurity6 and unfavorable neurodevelopmental outcomes7 was observed in preterm infants with recurrent intermittent hypoxic episodes; in addition, a possible linkage between intermittent hypoxic episodes and later sleep-disordered breathing has been hypothesized.7 To date, the effect of bolus and continuous tube feeding on apnea, bradycardia, and hypoxic episodes in preterm infants is uncertain.1,8-10 The impact of the 2 feeding techniques on cardiorespiratory events has not been evaluated as a primary outcome. Thus, we investigated the effect of bolus and continuous tube feeding on cardiorespiratory events in healthy tube-fed preterm infants.
Methods Infants admitted to the Neonatal Intensive Care Unit of Sant’Orsola-Malpighi Hospital, Bologna, Italy, were eligible for the study if they fulfilled the following criteria: gestational age 30% below the baseline or 20 seconds and not associated with bradycardic and/or hypoxic events (Table II). Furthermore, continuous feeding resulted in more mild (oxygen saturation measured by pulse oximetry 81%-85%) and short (#10 seconds) hypoxic episodes concomitant with cardiorespiratory events. A slightly greater number of bradycardias was documented after the administration of a bolus; the difference between the 2 feeding techniques was not significant.
Discussion We evaluated the effect of continuous and bolus tube feeding on cardiorespiratory events in a healthy preterm population. Continuous feeding was associated with a greater number of prolonged apneas and apnea-related hypoxic episodes. Our findings are consistent with those of Dollberg et al.10 The present study, however, analyzed a larger population of exclusively healthy preterm infants to avoid possible interfering factors such as feeding intolerance, necrotizing enterocolitis, intraventricular hemorrhage, sepsis, and respiratory distress, which can lead to an increased frequency of cardiorespiratory events. Akintorin et al8 reported greater rates of apnea in relation to bolus feeding in preterms infants. In their study, the feeding tube was not removed after the administration of the bolus, thus removing possible effects as the result of tube insertion or to its permanence through the gastroesophageal junction.
Table I. Main characteristics of the study population (n = 33) Characteristics Gestational age, wk, median (IQR) Birth weight, g, median (IQR) Postnatal age at examination, d, median (IQR) Weight at examination, g median (IQR) Methylxanthine treatment during hospital stay, n (%) Methylxanthine treatment at time of examination, n (%) Need for supplemental O2 at time of examination, n (%) Type of feeding, n (%) Fortified human milk Standard preterm formula Mixed feeding 1256
31 (28-32) 1356 (1160-1545) 16 (12-33) 1575 (1468-1742) 23 (70%) 12 (36%) 0 (0%) 12 (36%) 7 (21%) 14 (43%)
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Table II. Number of cardiorespiratory events recorded after bolus administration and during continuous feeding of 33 infants
Apneas Total Type CA OA MA Duration, s >20 #20 Related to bradycardia/hypoxic episodes Yes No Hypoxic episodes Total SpO2 values 81%-85% #80% Duration, s >10 #10 Related to apnea/bradycardia Yes No Bradycardia Total
