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Methods of enteral feeding in preterm infants
Early Human Development 88S2 (2012) S31–S33
Contents lists available at ScienceDirect
Early Human Development j o u r n a l h o m e p a g e : w w w. e l s ev i e r. c o m / l o c a t e / e a r l h u m d ev
Methods of enteral feeding in preterm infants L. Maggio*, S. Costa, C. Zecca, L. Giordano Division of Neonatology, Department of Paediatrics, Catholic University Sacred Heart, Rome, Italy
article info
summary
Keywords: Newborn Enteral nutrition methods Feeding tolerance
Whenever possible, oral feeding is the preferred method in neonatal feeding. However, many premature infants are unable to suck and swallow effectively; in these cases alternative methods of nutrient delivery must be used. We briefly review the different feeding methods used in neonatal units, with particular attention to their theoretical advantages, disadvantages and to the current best evidence available. © 2012 Elsevier Ireland Ltd. All rights reserved.
1. Why tube feeding? Preterm infants commonly gain the coordinated sucking ability between the 32th and 34th week of post-menstrual age but some infants, especially those with lower gestational age and those with a high neonatal morbidity rating, require a variable period of tube feeding before they reach this developmental competence [1]. While objective stages of oral feeding have been accurately characterised, the timescale for progression through these stages is still unclear [2]. The decision that an infant is ready for oral feeding trials depends upon several infant characteristics, including post-menstrual age, feeding tolerance, respiratory status, and upon the nurse’s assessment of the quality of non-nutritive sucking. In the meantime the preterm infants acquire the ability to coordinate sucking, swallowing and breathing, the neonatologist should choose the best tube feeding method to ensure adequate feeding tolerance. 2. Intermittent bolus or continuous feeding? Intermittent bolus feeding consists of administering a prescribed volume of milk over a short period of time, usually over 10 to 20 minutes every 2 or 3 hours, by gravity through a feeding tube. This feeding method seems to be more physiologic because it promotes the cyclical surges of gastrointestinal hormones, normally seen in healthy term infants [3]. Continuous feeding consists of administering a prescribed volume of milk continuously through a tube, using an infusion pump. This technique is associated to the theoretical advantage of avoiding the risk of feeding intolerance that the delayed gastric emptying, related to gestational age, could increase. * Corresponding author. Dr. Luca Maggio, MD. Division of Neonatology – Department of Paediatrics, Catholic University Sacred Heart, Largo A. Gemelli 8, 00168 Rome, Italy. Tel.: +39 6 30154169; fax: +39 6 3055301. E-mail address: [email protected] (L. Maggio). 0378-3782/$ – see front matter © 2012 Elsevier Ireland Ltd. All rights reserved.
The question of whether the two feeding strategies have an effect on gastrointestinal tolerance, growth and morbidity has been raised by several authors, but the results are still limited and conflicting. Continuous feeding decreases energy expenditure [4], enhances duodenal motor function [5], and is not associated with adverse effects on pulmonary function [6]. However, bolus feeding promotes the cyclical pattern of release of gastrointestinal tract hormones such as gastrin, gastric inhibitory peptide, and enteroglucagon which might affect the gastrointestinal tract development and function, metabolic homeostasis, and growth [7]; furthermore, bolus feeding could reduce the risks associated to the lower oesophageal sphincter kept open by an indwelling tube. Recently, a systematic review analysed 7 trials, involving 511 very low birth weight (VLBW) infants randomised to bolus or continuous feeding and found no differences in time to achieve full enteral feeds between the two feeding methods (weighted mean difference 2 days; 95% CI −0.3, 3.9) [8]. In subgroup analysis based on weight groups, infants less than 1000 g and 1000–1250 g birth weight gained weight faster when fed by the continuous feeding method compared to intermittent feeding method (mean difference [MD] 2.0 g/day; 95% CI 0.5, 3.5; and MD 2.0 g/day; 95% CI 0.2, 3.8, respectively). A trend toward earlier discharge was described for infants less than 1000 g birth weight fed by the continuous tube feeding method compared to intermittent tube feeding (MD −11 days; 95% CI −21.8, −0.2). However, small sample sizes, methodologic limitations, discrepancies in many variables that may affect outcomes, and conflicting results of the studies make it really difficult to suggest strong recommendations regarding the best tube feeding method for this population. 3. Orogastric or nasogastric tube feeding? Preterm infants should be fed through a tube placed either up their nose and into the stomach (nasogastric feeding) or
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L. Maggio et al. / Early Human Development 88S2 (2012) S31–S33
through their mouth and into the stomach (orogastric feeding). Current practice with regard to the route used for placement of enteral feeding tubes varies among neonatal units. Enteral feeding tubes passed via the nose may be easier to secure to the face than orally placed tubes. However, neonates are obligate nose breathers and nasogastric tubes can cause partial nasal obstruction, increased airway resistance, and increased work of breathing [9]. On the other hand, frequent movement of the orally placed tube may result in mucosal trauma and may increase the incidence of apnoea and bradycardia due to vagal stimulation. To date, only two small randomised trials comparing the use of the nasal versus oral route for placing enteral feeding tubes in preterm infants have been published and their cumulative data do not provide sufficient evidence on which of the two routes should be preferable in the clinical setting [10]. 4. Which is the correct feeding tube position? Accurate tube placement, in the body of the stomach, is important to ensure safe and effective enteral feeding. In fact, malposition of feeding tubes may be associated to gastric bleeding, aspiration, or gastro-oesophageal reflux problems. The usual procedure to anticipate the insertion length and depth of the tubes is measuring the distance from the nose to the earlobe to the termination of the xiphoid process, even though there is no strong evidence to validate this method [11]. Possible alternative reference marks are the distance from the nose to the earlobe and then to a point midway between the termination of the xiphoid process and the umbilicus, or measurements using a formula including regression on height, as in children. There are several ways to assess feeding tube placement, such as the appearance of feeding-tube aspirates, auscultation of insufflated air or pH measurement, but they all have limited reliability [12]. Even though neonatal standards are still lacking, radiographs seem to be the gold standard to define the exact position of feeding tubes [13]. Sonography could be an alternative method to identify the right position of the tip of feeding tubes, but its reliability and practicability must be determined. In a recent paper, only 41% of the tube placements in neonates reached the correct position; in the remaining cases the tube tips were located too deep in the stomach, bending along, touching lightly, or going through the greater curvature of the stomach [13]. These data confirm the urgent need for both better rules to measure the distance between nose or lips and the body of the stomach and improved methods to identify optimal tube position in neonates.
systematic review [14]: no effect on short- and long-term growth rates was found but transpyloric feeding was associated with a greater incidence of gastrointestinal disturbance (relative risk [RR] 1.45, 95% CI 1.05, 2.09) and there was some evidence that feeding via the transpyloric route increased mortality (RR 2.46, 95% CI 1.36, 4.46). 5.2. Cup feeding Cup feeding has been suggested as an alternative to tube feeding because it only requires the infant to lap the milk and then coordinate swallowing and breathing. Cup feeding could also have benefits in enhancing the newborn’s ability to develop a suckling action for breastfeeding and facilitating the newborn’s ability to self-regulate feeds and demand feeds [15]. However, there are potential risks, such as aspiration pneumonia when the improper technique is used, physiological instability, poor weight gain, and potential “cup addiction”. A systematic review including 4 studies did not show any significant positive effect of cup feeding and demonstrated a lower number of not fully breastfeeding infants at hospital discharge associated to cup feeding (RR 0.75, 95% CI 0.61, 0.92). In the only study that assessed it, there was a significantly increased length of hospital stay in the cup-fed infants [MD 10.1 days (95% CI 3.9, 16.3). Based on the best available evidence cup feeding cannot be recommended, even though control intervention was bottle feeding in all 4 studies included in the review [16]. 6. Transition to bottle and breast feeding Once preterm infants are able to coordinate sucking, swallowing and breathing, oral feeds are increased gradually as the infant demands or he/she is assessed to be ready to progress. As the number of sucking feeds increases, the number of tube feeds decreases until sucking feeds alone provide sufficient intake for growth. When the mother is unavailable to breast-feed or when the their own mother’s milk is unavailable, preterm infants are fed by bottle. When their own mother’s milk is available, the dilemma concerns the opportunity to breast-feed the premature infants. Since there are no studies that identify the right time to begin breast-feeding, clinicians commonly use empiric criteria, such as infant weight, gestational age, and ability to suck, as indicators of readiness to breast-feed. Instead, several studies showed that preterm infants who were breast-fed, compared to those bottle-fed, had improved physiologic responses, in terms of higher oxygen saturation, higher body temperature, fewer desaturation events, and a significantly lower energy expenditure [17,18].
5. Other feeding methods? 5.1. Transpiloric tube feeding
Conflict of interest statement
Placement of the enteral feeding tube in the duodenum or jejunum (transpyloric route) means delivery of enteral feeds to the main sites of nutrient absorption, and has the theoretical advantage of decreasing the potential for oesophageal reflux and aspiration of milk into the lungs. On the other hand, the gastric phase of the digestion is bypassed and secretion of upper intestinal hormones and growth factors may be impaired; there is also a risk that potentially pathogenic organisms, which would have been removed in the acidic environment of the stomach, may be delivered to the upper small bowel. Additionally, transpyloric feeding tubes are difficult to position and, unlike gastric tubes, the position of the transpyloric catheter must be confirmed with imaging. Data from 9 trials were analysed in a
The authors disclose any financial and personal relationships with other people or organisations that could inappropriately influence their work. References 1. Dodrill P, Donovan T, Cleghorn G, McMahon S, Davies PS. Attainment of early feeding milestones in preterm neonates. J Perinatol 2008;28:549–55. 2. Lau C, Alagugurusamy R, Schanler RJ, Smith EO, Shulman RJ. Characterization of the developmental stages of sucking in preterm infants during bottle feeding. Acta Paediatr 2000;89:846–52. 3. Aynsley-Green A, Adrian TE, Bloom SR. Feeding and the development of enteroinsular hormone secretion in the preterm infant: Effects of continuous gastric infusions of human milk compared with intermittent boluses. Acta Paediatr Scand 1982;71:379–83.
L. Maggio et al. / Early Human Development 88S2 (2012) S31–S33
4. Grant J, Denne SC. Effect of intermittent versus continuous enteral feeding on energy expenditure in premature infants. J Pediatr 1991;118:928–32. 5. de Ville K, Knapp E, Al-Tawil Y, Berseth CL. Slow infusion feedings enhance duodenal motor responses and gastric emptying in preterm infants. Am J Clin Nutr 1998;68:103–8. 6. Blondheim O, Abbasi S, Fox WW, Bhutani VK. Effect of enteral gavage feeding rate on pulmonary functions of very low birth weight infants. J Pediatr 1993; 122:751–5. 7. Aynsley-Green A. New insights into the nutritional management of newborn infants derived from studies of metabolic and endocrine inter-relations during the adaptation of postnatal life. Proc Nutr Soc 1989;48:283–92. 8. Premji SS, Chessell L. Continuous nasogastric milk feeding versus intermittent bolus milk feeding for premature infants less than 1500 grams. Cochrane Database Syst Rev. 2011;(11):CD001819. 9. Greenspan JS, Wolfson MR, Holt WJ, Shaffer TH. Neonatal gastric intubation: differential respiratory effects between nasogastric and orogastric tubes. Pediatr Pulmonol 1990;8:254–8. 10. Hawes J, McEwan P, McGuire W. Nasal versus oral route for placing feeding tubes in preterm or low birth weight infants. Cochrane Database Syst Rev 2004;(3):CD003952.
S33
11. Ellett ML, Beckstrand J, Flueckiger J, Perkins SM, Johnson CS. Predicting the insertion distance for placing gastric tubes. Clin Nurs Res 2005;14:11–27. 12. Huffman S, Pieper P, Jarczyk KS, Bayne A, O’Brien E. Methods to confirm feeding tube placement: application of research in practice. Pediatr Nurs 2004;30:10–3. 13. Quandt D, Schraner T, Ulrich Bucher H, Arlettaz Mieth R. Malposition of feeding tubes in neonates: is it an issue? J Pediatr Gastroenterol Nutr 2009;48(5):608–11. 14. McGuire W, McEwan P. Transpyloric versus gastric tube feeding for preterm infants. Cochrane Database Syst Rev 2007;(3):CD003487. 15. Thorley V. Cup feeding. www.breastfeeding.asn.au/bfinfo/cup-feeding 16. Flint A, New K, Davies MW. Cup feeding versus other forms of supplemental enteral feeding for newborn infants unable to fully breastfeed. Cochrane Database Syst Rev 2007;(2):CD005092. 17. Chen CH, Wang TM, Chang HM, Chi CS. The effect of breast- and bottle-feeding on oxygen saturation and body temperature in preterm infants. J Hum Lact 2000;16:21–7. 18. Berger I, Weintraub V, Dollberg S, Kopolovitz R, Mandel D. Energy expenditure for breastfeeding and bottle-feeding preterm infants. Pediatrics 2009;124: 1149–52.
Contents lists available at ScienceDirect
Early Human Development j o u r n a l h o m e p a g e : w w w. e l s ev i e r. c o m / l o c a t e / e a r l h u m d ev
Methods of enteral feeding in preterm infants L. Maggio*, S. Costa, C. Zecca, L. Giordano Division of Neonatology, Department of Paediatrics, Catholic University Sacred Heart, Rome, Italy
article info
summary
Keywords: Newborn Enteral nutrition methods Feeding tolerance
Whenever possible, oral feeding is the preferred method in neonatal feeding. However, many premature infants are unable to suck and swallow effectively; in these cases alternative methods of nutrient delivery must be used. We briefly review the different feeding methods used in neonatal units, with particular attention to their theoretical advantages, disadvantages and to the current best evidence available. © 2012 Elsevier Ireland Ltd. All rights reserved.
1. Why tube feeding? Preterm infants commonly gain the coordinated sucking ability between the 32th and 34th week of post-menstrual age but some infants, especially those with lower gestational age and those with a high neonatal morbidity rating, require a variable period of tube feeding before they reach this developmental competence [1]. While objective stages of oral feeding have been accurately characterised, the timescale for progression through these stages is still unclear [2]. The decision that an infant is ready for oral feeding trials depends upon several infant characteristics, including post-menstrual age, feeding tolerance, respiratory status, and upon the nurse’s assessment of the quality of non-nutritive sucking. In the meantime the preterm infants acquire the ability to coordinate sucking, swallowing and breathing, the neonatologist should choose the best tube feeding method to ensure adequate feeding tolerance. 2. Intermittent bolus or continuous feeding? Intermittent bolus feeding consists of administering a prescribed volume of milk over a short period of time, usually over 10 to 20 minutes every 2 or 3 hours, by gravity through a feeding tube. This feeding method seems to be more physiologic because it promotes the cyclical surges of gastrointestinal hormones, normally seen in healthy term infants [3]. Continuous feeding consists of administering a prescribed volume of milk continuously through a tube, using an infusion pump. This technique is associated to the theoretical advantage of avoiding the risk of feeding intolerance that the delayed gastric emptying, related to gestational age, could increase. * Corresponding author. Dr. Luca Maggio, MD. Division of Neonatology – Department of Paediatrics, Catholic University Sacred Heart, Largo A. Gemelli 8, 00168 Rome, Italy. Tel.: +39 6 30154169; fax: +39 6 3055301. E-mail address: [email protected] (L. Maggio). 0378-3782/$ – see front matter © 2012 Elsevier Ireland Ltd. All rights reserved.
The question of whether the two feeding strategies have an effect on gastrointestinal tolerance, growth and morbidity has been raised by several authors, but the results are still limited and conflicting. Continuous feeding decreases energy expenditure [4], enhances duodenal motor function [5], and is not associated with adverse effects on pulmonary function [6]. However, bolus feeding promotes the cyclical pattern of release of gastrointestinal tract hormones such as gastrin, gastric inhibitory peptide, and enteroglucagon which might affect the gastrointestinal tract development and function, metabolic homeostasis, and growth [7]; furthermore, bolus feeding could reduce the risks associated to the lower oesophageal sphincter kept open by an indwelling tube. Recently, a systematic review analysed 7 trials, involving 511 very low birth weight (VLBW) infants randomised to bolus or continuous feeding and found no differences in time to achieve full enteral feeds between the two feeding methods (weighted mean difference 2 days; 95% CI −0.3, 3.9) [8]. In subgroup analysis based on weight groups, infants less than 1000 g and 1000–1250 g birth weight gained weight faster when fed by the continuous feeding method compared to intermittent feeding method (mean difference [MD] 2.0 g/day; 95% CI 0.5, 3.5; and MD 2.0 g/day; 95% CI 0.2, 3.8, respectively). A trend toward earlier discharge was described for infants less than 1000 g birth weight fed by the continuous tube feeding method compared to intermittent tube feeding (MD −11 days; 95% CI −21.8, −0.2). However, small sample sizes, methodologic limitations, discrepancies in many variables that may affect outcomes, and conflicting results of the studies make it really difficult to suggest strong recommendations regarding the best tube feeding method for this population. 3. Orogastric or nasogastric tube feeding? Preterm infants should be fed through a tube placed either up their nose and into the stomach (nasogastric feeding) or
S32
L. Maggio et al. / Early Human Development 88S2 (2012) S31–S33
through their mouth and into the stomach (orogastric feeding). Current practice with regard to the route used for placement of enteral feeding tubes varies among neonatal units. Enteral feeding tubes passed via the nose may be easier to secure to the face than orally placed tubes. However, neonates are obligate nose breathers and nasogastric tubes can cause partial nasal obstruction, increased airway resistance, and increased work of breathing [9]. On the other hand, frequent movement of the orally placed tube may result in mucosal trauma and may increase the incidence of apnoea and bradycardia due to vagal stimulation. To date, only two small randomised trials comparing the use of the nasal versus oral route for placing enteral feeding tubes in preterm infants have been published and their cumulative data do not provide sufficient evidence on which of the two routes should be preferable in the clinical setting [10]. 4. Which is the correct feeding tube position? Accurate tube placement, in the body of the stomach, is important to ensure safe and effective enteral feeding. In fact, malposition of feeding tubes may be associated to gastric bleeding, aspiration, or gastro-oesophageal reflux problems. The usual procedure to anticipate the insertion length and depth of the tubes is measuring the distance from the nose to the earlobe to the termination of the xiphoid process, even though there is no strong evidence to validate this method [11]. Possible alternative reference marks are the distance from the nose to the earlobe and then to a point midway between the termination of the xiphoid process and the umbilicus, or measurements using a formula including regression on height, as in children. There are several ways to assess feeding tube placement, such as the appearance of feeding-tube aspirates, auscultation of insufflated air or pH measurement, but they all have limited reliability [12]. Even though neonatal standards are still lacking, radiographs seem to be the gold standard to define the exact position of feeding tubes [13]. Sonography could be an alternative method to identify the right position of the tip of feeding tubes, but its reliability and practicability must be determined. In a recent paper, only 41% of the tube placements in neonates reached the correct position; in the remaining cases the tube tips were located too deep in the stomach, bending along, touching lightly, or going through the greater curvature of the stomach [13]. These data confirm the urgent need for both better rules to measure the distance between nose or lips and the body of the stomach and improved methods to identify optimal tube position in neonates.
systematic review [14]: no effect on short- and long-term growth rates was found but transpyloric feeding was associated with a greater incidence of gastrointestinal disturbance (relative risk [RR] 1.45, 95% CI 1.05, 2.09) and there was some evidence that feeding via the transpyloric route increased mortality (RR 2.46, 95% CI 1.36, 4.46). 5.2. Cup feeding Cup feeding has been suggested as an alternative to tube feeding because it only requires the infant to lap the milk and then coordinate swallowing and breathing. Cup feeding could also have benefits in enhancing the newborn’s ability to develop a suckling action for breastfeeding and facilitating the newborn’s ability to self-regulate feeds and demand feeds [15]. However, there are potential risks, such as aspiration pneumonia when the improper technique is used, physiological instability, poor weight gain, and potential “cup addiction”. A systematic review including 4 studies did not show any significant positive effect of cup feeding and demonstrated a lower number of not fully breastfeeding infants at hospital discharge associated to cup feeding (RR 0.75, 95% CI 0.61, 0.92). In the only study that assessed it, there was a significantly increased length of hospital stay in the cup-fed infants [MD 10.1 days (95% CI 3.9, 16.3). Based on the best available evidence cup feeding cannot be recommended, even though control intervention was bottle feeding in all 4 studies included in the review [16]. 6. Transition to bottle and breast feeding Once preterm infants are able to coordinate sucking, swallowing and breathing, oral feeds are increased gradually as the infant demands or he/she is assessed to be ready to progress. As the number of sucking feeds increases, the number of tube feeds decreases until sucking feeds alone provide sufficient intake for growth. When the mother is unavailable to breast-feed or when the their own mother’s milk is unavailable, preterm infants are fed by bottle. When their own mother’s milk is available, the dilemma concerns the opportunity to breast-feed the premature infants. Since there are no studies that identify the right time to begin breast-feeding, clinicians commonly use empiric criteria, such as infant weight, gestational age, and ability to suck, as indicators of readiness to breast-feed. Instead, several studies showed that preterm infants who were breast-fed, compared to those bottle-fed, had improved physiologic responses, in terms of higher oxygen saturation, higher body temperature, fewer desaturation events, and a significantly lower energy expenditure [17,18].
5. Other feeding methods? 5.1. Transpiloric tube feeding
Conflict of interest statement
Placement of the enteral feeding tube in the duodenum or jejunum (transpyloric route) means delivery of enteral feeds to the main sites of nutrient absorption, and has the theoretical advantage of decreasing the potential for oesophageal reflux and aspiration of milk into the lungs. On the other hand, the gastric phase of the digestion is bypassed and secretion of upper intestinal hormones and growth factors may be impaired; there is also a risk that potentially pathogenic organisms, which would have been removed in the acidic environment of the stomach, may be delivered to the upper small bowel. Additionally, transpyloric feeding tubes are difficult to position and, unlike gastric tubes, the position of the transpyloric catheter must be confirmed with imaging. Data from 9 trials were analysed in a
The authors disclose any financial and personal relationships with other people or organisations that could inappropriately influence their work. References 1. Dodrill P, Donovan T, Cleghorn G, McMahon S, Davies PS. Attainment of early feeding milestones in preterm neonates. J Perinatol 2008;28:549–55. 2. Lau C, Alagugurusamy R, Schanler RJ, Smith EO, Shulman RJ. Characterization of the developmental stages of sucking in preterm infants during bottle feeding. Acta Paediatr 2000;89:846–52. 3. Aynsley-Green A, Adrian TE, Bloom SR. Feeding and the development of enteroinsular hormone secretion in the preterm infant: Effects of continuous gastric infusions of human milk compared with intermittent boluses. Acta Paediatr Scand 1982;71:379–83.
L. Maggio et al. / Early Human Development 88S2 (2012) S31–S33
4. Grant J, Denne SC. Effect of intermittent versus continuous enteral feeding on energy expenditure in premature infants. J Pediatr 1991;118:928–32. 5. de Ville K, Knapp E, Al-Tawil Y, Berseth CL. Slow infusion feedings enhance duodenal motor responses and gastric emptying in preterm infants. Am J Clin Nutr 1998;68:103–8. 6. Blondheim O, Abbasi S, Fox WW, Bhutani VK. Effect of enteral gavage feeding rate on pulmonary functions of very low birth weight infants. J Pediatr 1993; 122:751–5. 7. Aynsley-Green A. New insights into the nutritional management of newborn infants derived from studies of metabolic and endocrine inter-relations during the adaptation of postnatal life. Proc Nutr Soc 1989;48:283–92. 8. Premji SS, Chessell L. Continuous nasogastric milk feeding versus intermittent bolus milk feeding for premature infants less than 1500 grams. Cochrane Database Syst Rev. 2011;(11):CD001819. 9. Greenspan JS, Wolfson MR, Holt WJ, Shaffer TH. Neonatal gastric intubation: differential respiratory effects between nasogastric and orogastric tubes. Pediatr Pulmonol 1990;8:254–8. 10. Hawes J, McEwan P, McGuire W. Nasal versus oral route for placing feeding tubes in preterm or low birth weight infants. Cochrane Database Syst Rev 2004;(3):CD003952.
S33
11. Ellett ML, Beckstrand J, Flueckiger J, Perkins SM, Johnson CS. Predicting the insertion distance for placing gastric tubes. Clin Nurs Res 2005;14:11–27. 12. Huffman S, Pieper P, Jarczyk KS, Bayne A, O’Brien E. Methods to confirm feeding tube placement: application of research in practice. Pediatr Nurs 2004;30:10–3. 13. Quandt D, Schraner T, Ulrich Bucher H, Arlettaz Mieth R. Malposition of feeding tubes in neonates: is it an issue? J Pediatr Gastroenterol Nutr 2009;48(5):608–11. 14. McGuire W, McEwan P. Transpyloric versus gastric tube feeding for preterm infants. Cochrane Database Syst Rev 2007;(3):CD003487. 15. Thorley V. Cup feeding. www.breastfeeding.asn.au/bfinfo/cup-feeding 16. Flint A, New K, Davies MW. Cup feeding versus other forms of supplemental enteral feeding for newborn infants unable to fully breastfeed. Cochrane Database Syst Rev 2007;(2):CD005092. 17. Chen CH, Wang TM, Chang HM, Chi CS. The effect of breast- and bottle-feeding on oxygen saturation and body temperature in preterm infants. J Hum Lact 2000;16:21–7. 18. Berger I, Weintraub V, Dollberg S, Kopolovitz R, Mandel D. Energy expenditure for breastfeeding and bottle-feeding preterm infants. Pediatrics 2009;124: 1149–52.