Introduction
|
Hyperglycaemia in preterm infants is likely due to a number of factors (impaired insulin secretion, insulin resistance and immaturity of glucose homeostasis regulation)1,2. Hyperglycaemia has been associated with increased mortality and morbidity in preterm infants (including IVH, NEC, infection and retinopathy of prematurity)3-5. Studies in adults suggest that using insulin to control hyperglycaemia in critically ill patients is associated with increased survival and decreased rates of sepsis6. However, it is not yet clear whether insulin use improves significant outcome in preterm infants. Evidence supporting various management strategies is also poor. Despite this, the use of insulin to manage hyperglycaemia in preterm infants has become routine practice in ANZNN units7.
Given the lack of evidence to guide effective use, this guideline aims to highlight issues to consider when hyperglycaemia occurs in preterm neonates and to promote consistency of approach in management.
|
Definition of hyperglycaemia
|
- True Blood Glucose (TBG) >10-12mmol/L
|
There is continued uncertainty as to what constitutes a level of hyperglycaemia that is likely to result in an adverse outcome and thus justifies specific intervention7. It is unusual to see TBG levels above 7mmol/L in healthy term infants, thus many authors have defined levels above 8mmol/L as hyperglycaemia3,8, with intervention suggested at various thresholds, often around 10-12mmol/L.
|
Indication for initiating intervention:
|
- TBG >12mmol/L for more than 6 -12 hours.
|
|
This is an arbitrary definition of significant hyperglycaemia as TBGs in preterm infants can vary significantly over time, particularly in the first week of life9.
It may be reasonable to continue current management over a longer period than 12 hours if TBG <15mmol/L and the infant is otherwise stable (discuss with consultant).
|
Management options include the following:
|
Reduce glucose intake
|
If infused glucose levels are high (>8-10mg/kg/min), reduction of glucose intake alone may be sufficient to decrease TBG to an acceptable level.
|
The process includes the following:
|
- change infusion solutions containing 10% glucose to normal or half normal saline (if compatible) before decreasing total fluid intake or stopping parental nutrition
- do not reduce glucose intake below 5-6mmol/kg/min (80ml/kg/day of 10% glucose or PN = 5.6mg/kg/min) as this is the minimum required to maintain adequate caloric intake.
- do not reduce total fluid intake below that required to maintain hydration.
- document glucose infusion rate on daily fluid chart for all infants with hyperglycaemia.
- count insulin infusion in daily total fluid intake.
|
|
Glucose infusion rate (mg/kg/min) =
|
| | | %glucose X mL/h
| 6 X body wgt (kg)
|
|
|
|
Breast milk/standard formula is approx 7% carbohydrate, LBW formula approx 8%, FEBM 10%.
|
Resource: online calculator (access via the following website): www.nicutools.org.
|
Glycosuria alone should not initiate reduction of glucose intake in the absence of significant hyperglycaemia as osmotic diuresis and subsequent dehydration is unlikely if TBG<12mmol/L10.
|
Insulin Infusion
|
Aim to normalise blood glucose levels (TBG to 4-10mmol/L) whilst avoiding hypoglycaemia by considering the following:
|
- insulin infusion - starting dose: 0.05 units/kg/hour – mid range dose
- adjust insulin rate gently (i.e. steps of 0.01-0.02 units/kg/hour) with sufficient time between adjustments to monitor effects (approx 4 hours)
- If feeds are stopped, or fluids changed, re-calculate glucose intake. Small adjustments of infusion and more frequent TBG monitoring may be required.
- If TBG drops sharply or HYPOglycaemia (TBG <2.6mmol/L) occurs, decrease insulin rate (e.g. halve it), rather than stopping completely. Repeat TBG at more frequent intervals until stable (e.g. hourly).
- If severe HYPOglycaemia (TBG <1.5mmol/L), stop insulin infusion, give bolus of 2ml/Kg of 10% glucose. Rarely glucagon may be considered if there is no response (discuss with consultant).
|
|
Maintenance infusion rate is likely to be less than that required to decrease TBG level.
Some infants are very sensitive to rapid changes in infusion rates with unpredictable responses, thus care is needed when increasing infusion rates.
|
Monitoring
|
Timing of TBGs:
|
- use the NISC Blood Gas Analyser to measure TBG
- test one hour after starting infusion (note: some infants are sensitive to insulin and their TBGs drop quickly with the introduction of insulin)
- once stabilised, TBG can be tested 4-6 hrly
- check blood sugar levels more frequently if:
|
 | - rate of administration of infused insulin and/or maintenance glucose / feed is changed
- medication mixed with glucose and/or an insulin infusion is disrupted
- new infusion mix is commenced.
|
|
|
|
Use of blood glucose monitor and reagent strips to minimise test blood volume is acceptable for infants with hyperglycaemia who are having frequent samples taken if TBGs are stable above 4mmol/L. All reagent strip levels <4mmol/L should be confirmed with TBG.
|
Other information
|
Variability of insulin infusate
|
The insulin concentration in the infusion as it enters the infant may increase over time as binding sites become saturated because insulin binds to plastic syringes and lines11,12. The method of flushing and sitting lines is designed to promote saturation of binding sites and thus improve stability of the solution. Regular TBG monitoring also assists in preventing hypoglycaemia, which is potentially more likely toward the end of a 24 hour period as saturation occurs and infusate concentration increases.
For more information regarding insulin infusion, refer to IV medication manual: Insulin protocol.
|
Sepsis
|
Sepsis is commonly associated with hyperglycaemia, therefore when hyperglycaemia occurs, infection should be actively sought and treated as indicated.
|
Persistent Hyperglycaemia
|
Hyperglycaemia in preterm infants tends to be a transitory phenomenon and insulin treatment can be stopped after a few days. If hyperglycaemia persists more than 2 weeks, consider alternative diagnoses such as neonatal diabetes (1:400,000); investigations include serum insulin, C-peptide and ketones and urine ketones8. Consult an Endocrinologist after discussion with neonatal consultant.
|
References
|
Evidence table: Hyperglycaemia: Management of Preterm Infants in Neonatal Intensive Care (refer to separate web page).
|
Online calculator (access via the following website): www.nicutools.org.
|
|
|
|
Published: 13 January 2009
|
| | |
|
Royal Women's Hospital Clinical Practice Guidelines (CPGs) are intended to provide guidance to health care professionals, based on a thorough evaluation of research evidence, on the practical assessment and management of specific clinical issues or situations. The guidelines allow some flexibility on the part of the health care professional based on the needs of the specific patient for whom they are caring.
|
Please remember to read our disclaimer.
|
