Key messages
Necrotising enterocolitis is a serious intestinal disease in premature babies that causes damage and death of gut tissue and may result in a hole in the intestine.
• Routine monitoring of stomach aspirates to decide on feeding in premature babies probably has little or no effect on the risk of necrotising enterocolitis.
• Monitoring stomach aspirates probably increases the time taken to reach full feeds, duration of parenteral nutrition (feeding through a vein) and the risk of infections. It may increase the time taken to regain birth weight and feed interruption episodes (time frames when feeds are stopped temporarily) in premature babies. The effect of stomach aspirates monitoring on other important outcomes is uncertain.
• There is uncertainty whether using two different criteria of stomach aspirates to interrupt feeds has an effect on important outcomes in preterm infants.
Background
Monitoring of stomach aspirates is performed by withdrawing the stomach contents via the feeding tube and assessing these contents for quantity and quality at regular intervals. Monitoring of stomach aspirates to diagnose feed intolerance and necrotising enterocolitis is a common practice in premature babies who are on tube feeds. There is inadequate evidence to support routine monitoring of stomach aspirates as a guide for when to start or increase feeds in otherwise healthy premature babies. However, not monitoring stomach aspirates may take away an early warning sign for necrotising enterocolitis and thus may increase its risk in premature infants.
What did we want to find out?
We wanted to look for evidence from studies that assessed whether routine monitoring of stomach aspirates is beneficial or harmful in premature babies.
What did we do?
We searched for studies that looked at monitoring of stomach contents in premature babies. We compared and summarised the results of the studies and rated our confidence in the evidence, based on factors such as the size of the study and the methods used.
What did we find?
We included five studies (423 babies) in this review.
We found four studies on 336 premature babies that compared routine monitoring versus no monitoring of stomach aspirates in premature babies. We found one study comparing the usage of two different sets of criteria based on quantity and quality of stomach aspirates to decide on interrupting feeds while monitoring stomach aspirates.
What are the limitations of the evidence?
We are moderately confident about the evidence on the effect of monitoring stomach aspirates on outcomes such as necrotising enterocolitis, risk of infections, time taken to reach full feeds, and duration of parenteral nutrition.
How up-to-date is this evidence?
The search is up-to-date as of February 2022.
Moderate-certainty evidence suggests routine monitoring of gastric residual has little or no effect on the incidence of NEC. Moderate-certainty evidence suggests monitoring gastric residual probably increases the time to establish full enteral feeds, the number of TPN days and the risk of invasive infection. Low-certainty evidence suggests monitoring gastric residual may increase the time to regain birth weight and the number of feed interruption episodes, and may have little or no effect on all-cause mortality before hospital discharge. Further RCTs are warranted to assess the effect on long-term growth and neurodevelopmental outcomes.
Routine monitoring of gastric residual in preterm infants on gavage feeds is a common practice used to guide initiation and advancement of feeds. It is believed that an increase in or an altered gastric residual may be predictive of necrotising enterocolitis (NEC). Withholding monitoring of gastric residual may take away the early indicator and thus may increase the risk of NEC. However, routine monitoring of gastric residual as a guide, in the absence of uniform standards, may lead to unnecessary delay in initiation and advancement of feeds and hence might result in a delay in establishing full enteral feeds. This in turn may increase the duration of total parenteral nutrition (TPN) and central venous line usage, increasing the risk of associated complications. Furthermore, delays in establishing full enteral feeds increase the risk of extrauterine growth restriction and neurodevelopmental impairment.
• To assess the efficacy and safety of routine monitoring versus no monitoring of gastric residual in preterm infants
• To assess the efficacy and safety of routine monitoring of gastric residual based on two different criteria for interrupting feeds or decreasing feed volume in preterm infants
We conducted searches in Cochrane CENTRAL via CRS, Ovid MEDLINE, Embase and CINAHL in February 2022. We also searched clinical trials databases, conference proceedings, and the reference lists of retrieved articles for randomised controlled trials (RCTs), quasi- and cluster-RCTs.
We selected RCTs that compared routine monitoring versus no monitoring of gastric residual and trials that used two different criteria for gastric residual to interrupt feeds in preterm infants.
Two authors independently assessed trial eligibility, risk of bias and extracted data. We analysed treatment effects in individual trials and reported risk ratio (RR) for dichotomous data, and mean difference (MD) for continuous data, with respective 95% confidence intervals (CI). We calculated the number needed to treat for an additional beneficial/harmful outcome (NNTB/NNTH) for dichotomous outcomes with significant results. We used GRADE to assess the certainty of evidence.
We included five studies (423 infants) in this updated review.
Routine monitoring versus no routine monitoring of gastric residual in preterm infants
Four RCTs with 336 preterm infants met the inclusion criteria for this comparison. Three studies were performed in infants with birth weight of < 1500 g, while one study included infants with birth weight between 750 g and 2000 g. The trials were unmasked but were otherwise of good methodological quality.
Routine monitoring of gastric residual:
- probably has little or no effect on the risk of NEC (RR 1.08, 95% CI 0.46 to 2.57; 334 participants, 4 studies; moderate-certainty evidence);
- probably increases the time to establish full enteral feeds (MD 3.14 days, 95% CI 1.93 to 4.36; 334 participants, 4 studies; moderate-certainty evidence);
- may increase the time to regain birth weight (MD 1.70 days, 95% CI 0.01 to 3.39; 80 participants, 1 study; low-certainty evidence);
- may increase the number of infants with feed interruption episodes (RR 2.21, 95% CI 1.53 to 3.20; NNTH 3, 95% CI 2 to 5; 191 participants, 3 studies; low-certainty evidence);
- probably increases the number of TPN days (MD 2.57 days, 95% CI 1.20 to 3.95; 334 participants, 4 studies; moderate-certainty evidence);
- probably increases the risk of invasive infection (RR 1.50, 95% CI 1.02 to 2.19; NNTH 10, 95% CI 5 to 100; 334 participants, 4 studies; moderate-certainty evidence);
- may result in little or no difference in all-cause mortality before hospital discharge (RR 2.14, 95% CI 0.77 to 5.97; 273 participants, 3 studies; low-certainty evidence).
Quality and volume of gastric residual compared to quality of gastric residual alone for feed interruption in preterm infants
One trial with 87 preterm infants met the inclusion criteria for this comparison. The trial included infants with 1500 g to 2000 g birth weight.
Using two different criteria of gastric residual for feed interruption:
- may result in little or no difference in the incidence of NEC (RR 5.35, 95% CI 0.26 to 108.27; 87 participants; low-certainty evidence);
- may result in little or no difference in time to establish full enteral feeds (MD -0.10 days, 95% CI -0.91 to 0.71; 87 participants; low-certainty evidence);
- may result in little or no difference in time to regain birth weight (MD 1.00 days, 95% CI -0.37 to 2.37; 87 participants; low-certainty evidence);
- may result in little or no difference in number of TPN days (MD 0.80 days, 95% CI -0.78 to 2.38; 87 participants; low-certainty evidence);
- may result in little or no difference in the risk of invasive infection (RR 5.35, 95% CI 0.26 to 108.27; 87 participants; low-certainty evidence);
- may result in little or no difference in all-cause mortality before hospital discharge (RR 3.21, 95% CI 0.13 to 76.67; 87 participants; low-certainty evidence).
- we are uncertain about the effect of using two different criteria of gastric residual on the risk of feed interruption episodes (RR 3.21, 95% CI 0.13 to 76.67; 87 participants; very low-certainty evidence).