Nutritional management in newborn babies receiving therapeutic hypothermia: two retrospective observational studies using propensity score matching.

BACKGROUND

Therapeutic hypothermia is standard of care for babies with moderate to severe hypoxic-ischaemic encephalopathy. There is limited evidence to inform provision of nutrition during hypothermia.

OBJECTIVES

To assess the association during therapeutic hypothermia between (1) enteral feeding and outcomes, such as necrotising enterocolitis and (2) parenteral nutrition and outcomes, such as late-onset bloodstream infection.

DESIGN

A retrospective cohort study using data held in the National Neonatal Research Database and applying propensity score methodology to form matched groups for analysis.

SETTING

NHS neonatal units in England, Wales and Scotland.

PARTICIPANTS

Babies born at ≥ 36 gestational weeks between 1 January 2010 and 31 December 2017 who received therapeutic hypothermia for 72 hours or who died during treatment.

INTERVENTIONS

Enteral feeding analysis - babies who were enterally fed during therapeutic hypothermia (intervention) compared with babies who received no enteral feeds during therapeutic hypothermia (control). Parenteral nutrition analysis - babies who received parenteral nutrition during therapeutic hypothermia (intervention) compared with babies who received no parenteral nutrition during therapeutic hypothermia (control).

OUTCOME MEASURES

Primary outcomes were severe and pragmatically defined necrotising enterocolitis (enteral feeding analysis) and late-onset bloodstream infection (parenteral nutrition analysis). Secondary outcomes were survival at neonatal discharge, length of neonatal stay, breastfeeding at discharge, onset of breastfeeding, time to first maternal breast milk, hypoglycaemia, number of days with a central line in situ, duration of parenteral nutrition, time to full enteral feeds and growth.

RESULTS

A total of 6030 babies received therapeutic hypothermia. Thirty-one per cent of babies received enteral feeds and 25% received parenteral nutrition. Seven babies (0.1%) were diagnosed with severe necrotising enterocolitis, and further comparative analyses were not conducted on this outcome. A total of 3236 babies were included in the matched enteral feeding analysis. Pragmatically defined necrotising enterocolitis was rare in both groups (0.5% vs. 1.1%) and was lower in babies who were fed during hypothermia (rate difference -0.5%, 95% confidence interval -1.0% to -0.1%;

LIMITATIONS

Propensity score methodology can address imbalances in observed confounders only. Residual confounding by unmeasured or poorly recorded variables cannot be ruled out. We did not analyse by type or volume of enteral or parenteral nutrition.

CONCLUSIONS

Necrotising enterocolitis is rare in babies receiving therapeutic hypothermia, and the introduction of enteral feeding is associated with a lower risk of pragmatically defined necrotising enterocolitis and other beneficial outcomes, including rates of higher survival and breastfeeding at discharge. Receipt of parenteral nutrition during therapeutic hypothermia is associated with a higher rate of late-onset infection but lower mortality. These results support introduction of enteral feeding during therapeutic hypothermia.

FUTURE WORK

Randomised trials to assess parenteral nutrition during therapeutic hypothermia.

TRIAL REGISTRATION

Current Controlled Trials ISRCTN474042962.

FUNDING

This project was funded by the National Institute for Health Research (NIHR) Health Technology Assessment programme and will be published in full in

Every year, approximately 1200 babies in the UK suffer a lack of oxygen to the brain around birth. This is called hypoxic–ischaemic encephalopathy and can lead to brain injury or death. To treat hypoxic–ischaemic encephalopathy, babies receive cooling treatment in which their body temperature is lowered. Doctors do not know the best way to give nutrition to babies receiving cooling treatment. Babies can either be fed milk into their stomach (enteral nutrition) or be given nutrients through their veins (parenteral nutrition). We compared babies who were fed milk while they were being cooled with babies from whom milk was withheld while they were being cooled to see if there was a difference in the frequency of necrotising enterocolitis, a severe gut disease. In addition, we compared babies who received parenteral nutrition while they were being cooled with babies who did not to see if there was a difference in infections. Finally, we looked at other outcomes, including survival and breastfeeding. We used the National Neonatal Research Database, which holds de-identified (i.e. no baby can be identified) information on all babies who have received NHS neonatal care. We used a statistical approach to match babies in each group (i.e. fed babies and not fed babies) as closely as possible so that any difference in outcomes was because of different nutrition and not because of other differences. We included > 6000 babies with hypoxic–ischaemic encephalopathy. Approximately one in three babies received milk feeds and one in four babies received parenteral nutrition during cooling. Necrotising enterocolitis was very rare. More babies who were fed milk during cooling had good outcomes (e.g. being breastfed at discharge) and fewer had necrotising enterocolitis. Most of these babies received only a small amount of milk in the first 3 days. More babies given parenteral nutrition had infections, but also more survived. This suggests that it is probably safe and may be beneficial to feed babies milk during cooling. More research should look at milk feeding and parenteral nutrition during cooling.