Low phosphatemia in extremely low birth weight neonates: A risk factor for hyperglycemia?

Quality improvement project in a neonatal intensive care unit reduced the prevalence and duration of hypophosphatemia with significant and sustainable results

BACKGROUND

Hypophosphatemia is associated with prolonged mechanical ventilation and may affect growth, bone mineralization, nephrocalcinosis, and mortality in preterm infants. Optimal nutrition practices may decrease risk for hypophosphatemia and improve outcome.

METHODS

A quality improvement project was established to improve parenteral and enteral phosphorus intake with the goal to decrease prevalence and duration of hypophosphatemia in the first 14 days in infants <32 weeks' gestation.

RESULTS

Among 406 preterm infants, the prevalence of moderate hypophosphatemia decreased from 44% to 19% (P < 0.01) over 4 years. The median duration of moderate hypophosphatemia decreased from 72 h (48-128) to 24 (24-53) (P < 0.01). Daily intakes of parenteral calcium and phosphorus on the fourth day of life increased from 1.5 to 2.5 mEq/kg/day (P < 0.01) and 0.6 to 1.3 mmol/kg/day (P < 0.01), respectively. The median postnatal age of first serum phosphorus concentration assessment decreased from 53 h (41-64) to 32 (24-40) (P < 0.01).

CONCLUSION

During this quality improvement project, reduced prevalence and duration of hypophosphatemia in infants <32 weeks' gestation in the first 14 days of life was achieved through the optimization of parenteral and enteral phosphorus intake and improved response to acute hypophosphatemia.

Preterm infant nutrition: considerations for infants at risk of refeeding syndrome

Refeeding syndrome (RS) in preterm infants is a scenario of fetal malnutrition, primarily resulting from placental insufficiency, followed by a postnatal physiologic adaptation and response to an imbalance of nutrients provided parenterally. Growth restriction and small gestational age status are common findings in infants at risk of developing RS. Adverse clinical outcomes associated with RS may be severe and life-threatening. The biochemical abnormalities that occur in RS may be mitigated through careful monitoring and adaptation of the clinical management of parenteral and enteral nutrition. This perspective reviews the physiology and metabolism in infants with RS and provides suggested approaches to their clinical monitoring and nutritional management.

Thresholds of glycemia, insulin therapy, and risk for severe retinopathy in premature infants: A cohort study

BACKGROUND

Hyperglycemia in preterm infants may be associated with severe retinopathy of prematurity (ROP) and other morbidities. However, it is uncertain which concentration of blood glucose is associated with increased risk of tissue damage, with little consensus on the cutoff level to treat hyperglycemia. The objective of our study was to examine the association between hyperglycemia and severe ROP in premature infants.

METHODS AND FINDINGS

In 2 independent, monocentric cohorts of preterm infants born at <30 weeks' gestation (Nantes University Hospital, 2006-2016, primary, and Lyon-HFME University Hospital, 2009-2017, validation), we first analyzed the association between severe (stage 3 or higher) ROP and 2 markers of glucose exposure between birth and day 21-maximum value of glycemia (MaxGly1-21) and mean of daily maximum values of glycemia (MeanMaxGly1-21)-using logistic regression models. In both the primary (n = 863 infants, mean gestational age 27.5 ± 1.4 weeks, boys 52.5%; 38 with severe ROP; 54,083 glucose measurements) and the validation cohort (n = 316 infants, mean gestational age 27.4 ± 1.4 weeks, boys 51.3%), MaxGly1-21 and MeanMaxGly1-21 were significantly associated with an increased risk of severe ROP: odds ratio (OR) 1.21 (95% CI 1.14-1.27, p < 0.001) and OR 1.70 (95% CI 1.48-1.94, p < 0.001), respectively, in the primary cohort and OR 1.17 (95% CI 1.05-1.32, p = 0.008) and OR 1.53 (95% CI 1.20-1.95, p < 0.001), respectively, in the validation cohort. These associations remained significant after adjustment for confounders in both cohorts. Second, we identified optimal cutoff values of duration of exposure above each concentration of glycemia between 7 and 13 mmol/l using receiver operating characteristic curve analyses in the primary cohort. Optimal cutoff values for predicting stage 3 or higher ROP were 9, 6, 5, 3, 2, 2, and 1 days above a glycemic threshold of 7, 8, 9, 10, 11, 12, and 13 mmol/l, respectively. Severe exposure was defined as at least 1 exposure above 1 of the optimal cutoffs. Severe ROP was significantly more common in infants with severe exposure in both the primary (10.9% versus 0.6%, p < 0.001) and validation (5.2% versus 0.9%, p = 0.030) cohorts. Finally, we analyzed the association between insulin therapy and severe ROP in a national population-based prospectively recruited cohort (EPIPAGE-2, 2011, n = 1,441, mean gestational age 27.3 ± 1.4, boys 52.5%) using propensity score weighting. Insulin use was significantly associated with severe ROP in overall cohort crude analyses (OR 2.51 [95% CI 1.13-5.58], p = 0.024). Adjustment for inverse propensity score (gestational age, sex, birth weight percentile, multiple birth, spontaneous preterm birth, main pregnancy complications, surfactant therapy, duration of oxygen exposure between birth and day 28, digestive state at day 7, caloric intake at day 7, and highest glycemia during the first week) and duration of oxygen therapy had a large but not significant effect on the association between insulin treatment and severe ROP (OR 0.40 [95% CI 0.13-1.24], p = 0.106). Limitations of this study include its observational nature and, despite the large number of patients included compared to earlier similar studies, the lack of power to analyze the association between insulin use and retinopathy.

CONCLUSIONS

In this study, we observed that exposure to high glucose concentration is an independent risk factor for severe ROP, and we identified cutoff levels that are significantly associated with increased risk. The clinical impact of avoiding exceeding these thresholds to prevent ROP deserves further evaluation.

Neonatal Refeeding Syndrome and Clinical Outcome in Extremely Low-Birth-Weight Babies: Secondary Cohort Analysis From the ProVIDe Trial

BACKGROUND

Refeeding syndrome (RS) following preterm birth has been linked to high intravenous (IV) protein intake in the presence of low electrolyte supply. In extremely low-birth-weight (ELBW) babies, we aimed to determine the incidence of RS and associations with birth characteristics and clinical outcomes.

METHOD

Prospective cohort study of ELBW ProVIDe Trial participants in 6 New Zealand neonatal intensive care units. RS was defined as serum phosphate < 1.4 mmol.L^-1 and total calcium > 2.8 mmol.L^-1 . Relationships between RS and other factors were explored using 2-sample tests and logistic regression adjusted for sex, gestation, and birth-weight z-score.

RESULTS

Of 338 babies (mean [SD] birth-weight, 780 (134) g, gestational age, 25.9 [1.7] weeks), 68 (20%) had RS. Mortality was greater in babies with RS (32% vs 11%; P < .0001). More small- than appropriate-for-gestational-age babies developed RS (22% vs 8%; P = .001). Growth from birth to 36 weeks' corrected age was not different between babies who did and did not have RS. In logistic regression, the odds of RS decreased by 70% for each 1 mmol per kg^-1 .d^-1 IV phosphate intake (odds ratio [OR], 0.3; CI, 0.1-0.6; P = .002) and increased by 80% for each 1 g.kg^-1 .d^-1 IV protein intake (OR, 1.8; CI, 1.3-2.7; P = .002).

CONCLUSIONS

Neonatal RS is common in this cohort of ELBW babies and is associated with increased morbidity and mortality. Optimizing phosphate and calcium intakes in IV nutrition solutions may reduce RS and its consequences.

[Early hypophosphataemia in at risk newborns. Frequency and magnitude]

OBJECTIVE

To determine the frequency and magnitude of neonatal hypophosphataemia (<4mg/dL) in a neonatal Intensive Care Unit and to describe risk groups.

PATIENTS AND METHODS

Retrospective study of hospitalised newborns over a 44 month period (phase 1). Retrospective study of <1,500g/<32 weeks of gestation newborns over a 6 month period (phase 2). Prospective study of <1,500g or 1,550-2,000g, and intrauterine growth restriction (IUGR) newborns. Measurements were made on the 1st, 3rd, 7th, and 14th days of life (phase 3).

RESULTS

Phase 1: 34 (2.4%) of 1,394 patients had a diagnosis of hypophosphataemia, 76% of them ≤32 weeks of gestation and <1500 grams, and 24% >32 weeks with weight<P10. Phase 2: 12 (16.4%) of 73 patients had a diagnosis of hypophosphataemia, with <2mg/dL in 5 (6.8%). Eight (75%) of those with hypophosphataemia had IUGR, and 4 (25%) weighed <1,000g. Five cases had associated hypokalaemia, and three hypercalcaemia. Phase 3: 9 (45%) of 20 patients had hypophosphataemia, all of them <1,000g or<1,200g and weight percentile <10. Thirty-three percent of samples on days 1, 3, and 7 showed hypophosphataemia, four of them <2mg/dL. There was mild hypokalaemia in 5 (55%), and mild hypercalcaemia in 2 (22%) cases. Hypophosphataemia was associated with lower enteral nutrition and higher parenteral amino acid intake in the early days of life.

CONCLUSIONS

Hypophosphataemia is common, and can be severe, in the first week of life in premature infants <1,000 grams, and newborns<1,200g with foetal malnutrition and receiving amino acids in early parenteral nutrition.