Push versus gravity for intermittent bolus gavage tube feeding of premature and low birth weight infants
Abstract
This is a protocol for a Cochrane Review (Intervention). The objectives are as follows:
In preterm and/or low birth weight infants who require intermittent bolus tube feeding, to determine whether the use of push feeding compared with gravity feeding results in a more rapid establishment of full gavage tube feeds, without increasing adverse events.
Background
Many small, sick and premature infants are unable to suck and swallow and require gavage feeding. In these cases milk feeds are delivered through a catheter, or tube passed via the nose or mouth into the stomach. The physiological effects of gavage feeding include a transient rise in post prandial oxygen consumption (Mukhtar 1982), decrease in oxygenation (Blondheim 1993; Hammerman 1995, Wilkinson 1974; Yu 1976, Krauss 1978), increase in heart rate (Mukhtar 1982), decreased functional residual capacity (Heldt 1988) and decreased lung volumes (Pitcher‐Wilmott 1979). It is postulated that these cardiorespiratory effects are related to the volume displacement of feeds introduced into the stomach (Yu 1976). Additionally, intermittent bolus gastric tube feeding (gavage feeding) may decrease cerebral perfusion (Nelle 1997).
Gavage milk feeds may be delivered by intermittent bolus, a continuous drip, or a slow infusion over one hour, with an interval of at least one hour until the next feeding (Evans 2001). A Cochrane review has shown that small babies less than 1500 grams, fed by intermittent bolus (push or gravity) compared with continuous infusion, took a shorter time to reach full feeds with no difference in somatic growth, days to discharge, or the incidence of necrotizing enterocolitis (Premji 2002).
Intermittent bolus milk feeds may be administered using a syringe to gently push milk into the infant's stomach. Alternatively, milk can be poured into a syringe attached to the tube and allowed to drip in by gravity (Stronati 1982). In two neonatal textbooks the authors recommended that bolus gavage tube feeds should be given slowly, preferably by gravity (Wilkinson 1992; Townsend 1998). Sun et al in their discussion on tube feeding recommend against injecting fluid (milk) under pressure (Sun 1998).
The choice of intermittent bolus gavage tube feeding method (push or gravity) appears to be based on unit policy and tradition. In a survey of neonatal units in the United Kingdom, the method of bolus feeding varied, with some units declaring a preference for either push or gravity feeding (Symon 1994). Nurses who declare a preference for either method claim that with their preferred method they can more easily control the speed at which milk is delivered to the infant. As intermittent bolus gavage tube feeding is a common practice in neonatal intensive care units and special care baby nurseries it is important to evaluate the available data on push versus gravity gavage tube feeding in preterm infants.
Objectives
In preterm and/or low birth weight infants who require intermittent bolus tube feeding, to determine whether the use of push feeding compared with gravity feeding results in a more rapid establishment of full gavage tube feeds, without increasing adverse events.
Methods
Criteria for considering studies for this review
Types of studies
Randomised or quasi‐randomised controlled trials
Types of participants
Preterm infants (less than 37 weeks gestation) and/or low birth weight infants (less than 2500 grams) who require partial or complete gavage tube feeding and no congenital anomalies which might interfere with establishing enteral feeds and who are not ventilated.
Types of interventions
Push versus gravity gavage tube feeding.
Types of outcome measures
Primary outcomes:
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Time taken to establish full tube feeding (days);
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Feeding intolerance (number of episodes per day); defined as significant abdominal distension or discoloration, signs of perforation, obvious blood in stool; gastric residuals ≥ 25% to 50% of interval volume for two to three feedings; bilious gastric residual or emesis; significant apnea/bradycardia; significant cardiopulmonary instability (Kuzma‐O'Reilly 2003).
Secondary outcomes:
All to be assessed during gavage feeding:
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Apnea (frequency of episodes) ‐ defined as a cessation of breathing for more than 20 seconds or a shorter pause associated with bradycardia or cyanosis (AAP 2003);
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Bradycardia (frequency of episodes) ‐ defined as a fall in heart rate of more than 30 per cent below the baseline or less than 100 beats per minute for greater than or equal to ten seconds;
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Oxygenation ‐ defined as the continuous measurement of oxygen saturation (SpO2) during gavage feed;
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Spontaneous episodes of oxygen desaturation (frequency of episodes) ‐ defined as a spontaneous fall in SpO2 ≤85 per cent for longer than or equal to ten seconds in duration;
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Severe apnea (frequency of events) ‐ defined as a cessation of breathing and a fall in heart rate more than 30 per cent below the baseline or less than 100 beats per minute for greater than or equal to ten seconds and a concurrent fall in SpO2 ≤ 85 per cent;
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Days to full feedings (from initiation of feedings to achievement of 120 cc/kg/day);
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Days to full sucking feeds (breast or bottle) (from initiation of feedings to achievement of 120 cc/kg/day);
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Incidence of aspiration pneumonia (frequency of episodes);
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Incidence of necrotizing enterocolitis (Bell's Stage II or greater) (including suspected and confirmed) (Bell 1978);
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Weight gain (grams per day, or grams per kilogram per day);
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Length of hospital stay (days) from admission to discharge;
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Caregiver satisfaction with giving feed (nurse or parent) as reported by study authors.
If the data are available, we will undertake sub‐group analyses of:
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Infants of very low birth weight (less than 1.5 kilograms);
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Infants requiring partial (more than one gavage tube per 24 hours) or all feeds via gavage tube.
Search methods for identification of studies
See Neonatal Collaborative Review Group search strategy. The standard search strategy of the Neonatal Review Group as outlined in The Cochrane Library will be used. This will include searches of The Cochrane Central Register of Controlled Trials (CENTRAL, The Cochrane Library) MEDLINE (1966 ‐ current), EMBASE (1988‐current) and CINAHL (1982 ‐ current), using the text terms 'tube feeding', 'gavage', 'gavage feeding', 'bolus feeding', 'enteral feeding', 'gastric feeding' and MeSH terms 'infant, preterm', 'low birth weight', 'enteral nutrition', 'intensive care, neonatal'. There will be no language restriction. The title and abstract of each retrieved study will be examined to assess eligibility by two reviewers. If there is uncertainty, the full paper will be examined. Differences about study eligibility will be resolved by discussion with a third reviewer.
Data collection and analysis
The standard methods of the Neonatal Review Group will be used. The methodological quality of each trial will be reviewed independently by two reviewers. Two reviewers (JD, RS) will extract data separately. Differences will be resolved by discussion with the third reviewer (NB). Additional information will be requested from the authors of trials to clarify methodology and seek further data if necessary. Dichotomous variables will be analysed using relative risk and risk difference with 95% confidence intervals. Where statistically significant results are found the number needed to treat (NNT) and the number needed to harm (NNH) will be reported. Continuous variables will be analysed using weighted mean differences and 95% confidence intervals. Outcomes measured as count data, for example frequency of apnea, bradycardia and episodes of SpO2 desaturation, will be analysed by comparing rates of events and the rate ratio will be reported. The heterogeneity of studies will be tested using an I‐squared statistic. In the absence of heterogeneity, meta‐analysis will be conducted using a fixed effect model.
