Preterm Infant Enteral Feeding: A Brief Review of Certain NICU Practice Issues

Jean Rhodes, PhD, CNM, IBCLC / September 2015

 

Many enteral feeding decisions impact feeding intolerance; however, consistent evidence to support one feeding strategy over another is often lacking. Conflicting practices without evidence-based answers include those related to feed volumes;1 timing of initial feeds;2 feed progression;3-14 tubing material and locus of tube placement.15-19 One of the few absolutes in the neonatal intensive care unit (NICU) is the superiority of human milk, in particular mothers’ own milk, over infant formulas in reducing related short and long-term morbidities in preterm infants.20-31 The purpose of this article is to examine research related to enteral feeding of NICU infants.

Continuous versus Bolus Feeds

In 2005 Dsilna and associates16 published a randomized controlled trial (RCT) comparing continuous to intermittent feeding in very low birth weight infants. Infants in the continuous feeding group had an average shorter time to full feeds, better feeding tolerance and improved weight gain. However, in 2011 Cochrane review1 of seven clinical trails the authors concluded there is not enough evidence to support continuous over intermittent feeds.

Type of Feeding Tube (OG or NG)

There is also little definitive information in the literature to support nasogastric (NG) over orogastric (OG) tubes. Both tube insertion sites have advantages and disadvantages: nasogastric tubes are believed to be more stable and less likely to become dislodged but they block one nostril so are not appropriate for infants with respiratory distress; orogastric tubes leave both nares open but may be associated with bradycardia during insertion and are more likely to become dislodged.18,32,33

However, in 2013 the National Association of Neonatal Nurses’ (NANN) Infant-Directed Oral Feeding for Premature and Critically Ill Hospitalized Infants: Guideline for Practice recommended “advancement of oral feeding while an infant maintains an indwelling nasogastric feeding tube….”(p.7)34 Newer enteral tubes now provide the option of leaving them safely in place for longer periods of time, in some cases up to 30 days.35-37 But before enteral feeding tubes are placed nurses need evidence-based guidance on how to measure enteral tube length for proper placement.

Enteral Tube Placement

Of the few clinical trials on enteral tube placement in newborns, many suggest approximately half of feeding tubes in neonates are misplaced. Enteral feeding tubes can be too long, causing curling in the stomach or placement of the tip into the small intestine, leading to complications such as malabsorption and poor weight gain. Conversely, feeding tubes can be too short, resulting in the tip placement in the esophagus causing risks of and aspiration and pneumonia. 38-44

Historically, practitioners have used one of two methods, the direct distance nose-ear-xiphoid method (NEX) 43,44 or the direct distance nose-ear-mid-umbilicus method (NEMU) but neither method is consistently accurate.43,44 Other methods have been proposed which factor in infant weight45 or height.38 However, consequent regression equations are not always easy to use and do not apply equally to both NG and OG tube measurements.46 Of note, Cirgin-Ellett and associates46 calculated a final regression equation for ideal NG tube length, and then translated their data into a useful table based on infant length categories, e.g., 35-35.5 cm, and 36.0-37.0 cm.

Cordero and associates40 have also developed an OG measurement model using the NEX method with a regression formula based on infant weight with results that place OG tubes in the stomach 96% of the time. Obviously there are many issues yet to be resolved regarding enteral feeding options. As infants progress from enteral feeds to full oral feeds, their path may be influenced by care respectful of their developmental and physiologic needs.

Infant Feeding Tolerance, Stress and Trauma-Informed Care

Life in the NICU is stressful for preterm infants. Beyond separation from their mothers, infants must cope with new stimuli and uncomfortable procedures. In 2012 Moore and associates47 suggested feeding intolerance in NICU infants is a symptom of stress overload. Other researchers have studied NICU stressors and infant responses. Peng et al48 positively correlated increasing environmental stressors (such as sounds, lights and interventions) with stress responses in infant behavior, heart rate, respiratory rate and O2 saturation.

Concluding Remarks

Managing enteral feedings for preterm infants involves awareness of current research, new feeding technologies, infant developmental care and coordination with the entire health care team, including parents. While many questions remain unanswered and practice guidelines are currently in flux, what will not change is the need to support infants safely as they transition to full oral feeds in a manner that is extremely sensitive to their need for comfort.

 

References:

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About the Author

Jean Rhodes has been involved in the care of women and infants for over 30 years. After completing her Bachelor's of Science in Nursing in 1979 and a Master's of Science in Nursing in 1983, Jean joined the faculty of the Nurse-Midwifery Program at the Medical University of South Carolina (MUSC). While teaching and practicing nurse-midwifery, she earned her PhD in Nursing Science in 1990 at the University of South Carolina. She has practiced full-scope nurse-midwifery in academic and private practice settings. Over the years Jean has taught-both at MUSC and Brown University School of Medicine-students from many disciplines including nursing, midwifery, and medicine as well as medical residents in obstetrics, pediatrics and family medicine.

With nurse-midwifery as the philosophical base of her practice, Jean developed a postpartum home follow-up program at the MUSC tertiary care hospital to improve the continuity of care and provide better support of new mothers and their infants. She became an IBCLC in 2001 and, since then, has focused her clinical practice on lactation support of normal and high risk mother and infants. Her areas of research and publication include a wide range of topics from the philosophy of art and aesthetics as it applies to the art of nursing practice to the more clinically-based issues of the refrigerator shelf life of human milk and the process of test weighing to accurately determine infant intake at breast.