Measuring blood glucose in neonatal units: how does hemocue compare?

Comparison of Point of Care (POC) Testing of Glucose by B Braun Glucometer and Hemocue Glucose 201+ Analyser Versus Centralised Testing in Neonatal Intensive Care Unit (NICU)

BACKGROUND

Neonatal hypoglycemia is the most common carbohydrate metabolic disturbance seen in case of neonates and especially in preterm neonates. Accurate and rapid determination of hypoglycemia and its prompt treatment is of utmost importance to decrease morbidity and mortality of neonates.

AIMS

To estimate blood glucose in neonates and test the efficacy of HemoCue Glucose 201+ analyser and B Braun Glucometer by comparing with centralised laboratory testing. To compare the blood glucose in capillary and venous blood samples of neonates.

SETTINGS AND DESIGN

Hospital setting; Comparative Study Materials and Methods: After obtaining informed consent, all neonates admitted to Neonatal Intensive Care Unit (NICU) were screened for blood sugar. Capillary and venous blood glucose was estimated employing HemoCue Glucose 201+ analyser and B Braun Glucometer. Simultaneously, the same venous sample was collected in fluoride tube and sent to central clinical biochemistry laboratory for glucose estimation. When anaemia or polycythemia was clinically suspected the same venous sample was sent for estimation of Hematocrit (Hct).

STATISTICAL ANALYSIS

Comparison of blood glucose concentration of B Braun glucometer, HemoCue Glucose 201+ analyser and centralis/ed plasma glucose levels was done by using students test. All the statistical analysis were done using software SPSS 6 version.

RESULTS

Mean values of blood glucose (100.2 + 48.4) with B Braun glucometer was significantly higher (p=0.003) when compared to plasma glucose values (76.95 + 45.99) estimated in central laboratory and HemoCue glucose 201+ analyser (82.9 + 51.4). HemoCue glucose 201+ analyser did not show significant difference (p=0.463) with central laboratory testing. There was no significant difference between the capillary and venous sample estimated in both the instruments. Estimation with HemoCue glucose 201+ analyser correlated well with central laboratory testing in neonates with blood glucose <55mg/dl,

CONCLUSION

We conclude that HemoCue glucose 201+ analyser appears to be a suitable point of care (POC) blood glucose measurement device in neonates on both capillary and venous blood samples, as it showed a good correlation with central laboratory values without significant interference from Hct.

Neonatal glucose metabolism in offspring of mothers with varying degrees of hyperglycemia during pregnancy

The definition of neonatal hypoglycemia is controversial. Operational thresholds of blood glucose values at which intervention should be considered have been proposed. IDM and GDM infants frequently exhibit a pronounced drop of plasma glucose immediately after birth. This exaggerated physiological decline of glucose is transient and is seldom accompanied by suppressed lipolysis or clinical symptoms. It is generally attributed to hyperinsulinism elicited by maternal hyperglycemia. Alternative substrates for CNS i.e. lactate and astrocyte glycogen may explain lack of symptoms. Similarly low glucose values later on may cause clinical symptoms. Glucose production rates vary from attenuated to normal likely reflecting differences in maternal glycemic control. The HAPO study of around 25,000 non-diabetic pregnancies revealed strong associations between glucose values (75g OGTT) and increased fetal size and hyperinsulinemia at birth - findings adding strong support to the maternal hyperglycemia - fetal hypinsulinism theory. Mothers with the highest fasting glucose had infants with the highest frequency of clinical neonatal hypoglycaemia (4,6%).

Blood glucose testing at alternate sites in newborn infants

AIM

To compare a method of testing at alternate skin sites (AST) with that of the usual heel-stick approach (SM) for determining blood glucose levels in newborn infants. Our other aims were to compare these methods as regards their accuracy, the pain caused by the procedures, the times taken to obtain a result and the possible delay in accurate test results using AST during rapid changes in blood glucose.

METHODS

One hundred and eighty-six preterm and term infants were enrolled. The blood glucose levels were determined by a standard bedside method (SM, HemoCue) and AST (Freestyle), which permitted blood samples to be taken from the arm or leg.

RESULTS

The levels of blood glucose ranged between 0.6 and 8.6 mmol/l. We found a significant correlation between SM and AST (r = 0.90, p < 0.001). The coefficient of variation was similar, pain was significantly less (median pain score 3.5 vs 7.5, p < 0.01) and the time taken to obtain a result significantly shorter (mean 35 vs 111 s, p < 0.01) with AST than with SM. No significant differences were found between these methods during rapid changes in the blood glucose levels.

CONCLUSION

AST, a relatively simple and painless method of determining blood glucose levels in newborn infants, is acceptably accurate and causes minimal blood loss.

Hyperglycaemia and the very preterm baby

Neonatal hyperglycaemia, as usually defined (a whole blood glucose of >7 mmol/L), is common in the first week of life in babies born more than 12 weeks early. However, a review of a cohort of all such births in the north of England suggests that significant glycosuria is uncommon, and that there is no threat of an osmotic diuresis until the urine contains 2% glucose (by which time the blood glucose level almost always exceeds 15 mmol/L). The current statistical or epidemiological definition of hyperglycaemia (derived from data on term babies) needs to be replaced, for clinical purposes, by a more operationally relevant definition.

The investigation and management of neonatal hypoglycaemia

Assessment of neonatal glycaemic status requires accurate and reliable measurement of blood glucose concentrations. Most point-of-care technologies are, however, unsuitable for use in neonates. Although the definition of hypoglycaemia remains elusive, current knowledge allows adoption of pragmatic threshold blood glucose concentrations when clinical intervention should be considered. The vast majority of instances of neonatal hypoglycaemia are due to problems with the normal processes of metabolic adaptation after birth, and strategies to enhance the normal adaptive processes should help prevent such episodes. Further investigations and specific interventions should be considered when hypoglycaemia is of unusual severity or occurs in an otherwise low-risk infant.

Transdermal suctioning technique for serial sampling of interstitial fluid in newborn infants

OVERVIEW

Use of a suction-induced epidermal mini-erosion for serial sampling of dermal interstitial fluid (IF) in 16 newborn infants with gestational age ranging from 24 to 42 weeks is reported.

RESULTS

The mini-erosion formed reproducibly and electron microscopy showed that the split was located within the epidermis. IF was sampled serially by suctioning during 1-3 days without signs of stress or pain. IF sample volumes (10-50 microl) did not decrease with time. Glucose values in IF and blood were correlated (r(s) = 0.542; p = 0.000). IF glucose was lower than blood glucose on all 3 days. The epidermis regenerated within 4 +/- 0.9 days (mean, SD) after sampling was terminated. There were no complications.

CONCLUSION

Serial transdermal sampling was performed without stress or pain in newborn infants. Systemic and temporal differences between glucose measured in IF and blood were observed.

The effect of early feeding on the neonatal blood glucose level at 1-hour of age

Early infant feeding after birth is being promoted, although it is unclear whether this has any effect on carbohydrate metabolism. We planned to measure the capillary glucose at one hour (1 h) of age in a group of infants from non-diabetic pregnancies using the HemoCue B-Glucose system to see if the timing and method of early feeding would influence this result. Seventy-five term infants were studied, 22 of which were breast-fed, 24 bottle fed and 29 not fed during the first hour after birth. The mean whole blood glucose results were 2.34 mmol/l, 2.52 mmol/l and 2.58 mmol/l respectively (P = NS). The first two groups were fed at a median of 22 minutes before sampling. We conclude that the timing and method of early feeding in the newborn have no significant effect on the blood glucose level measured at 1 h of age, and this remains a reliable outcome measure in studies of glucose metabolism in pregnancy.