Baseline insulin/glucose ratio as a marker for the clinical course of hyperglycemic critically ill children treated with insulin

Insulin resistance and inflammation are a cause of hyperglycemia after pediatric cardiopulmonary bypass surgery

OBJECTIVES

Hyperglycemia is common after pediatric cardiopulmonary bypass (CPB) surgery and is attributed to a state of insulin resistance. We examined the role of CPB-induced inflammation on postoperative plasma glucose, insulin, and the glucose-to-insulin ratio, which was used as a marker of insulin resistance; a decrease in the ratio reflects increased resistance.

METHODS

We conducted an ancillary study on a previously published randomized trial of children undergoing CPB surgery. Serial blood glucose, insulin, and cytokines were drawn after CPB and at selected intervals for up to 48 hours after surgery. The primary outcome was plasma insulin levels and glucose-to-insulin ratio. Glucose delivery and feeding status were monitored for potential modifying effects.

RESULTS

The 299 children studied were predominantly male (55%) with a median age of 2.7 (interquartile range [IQR]: 0.5-6.5) years, and weight of 12.6 (IQR: 6.4-10.8) kg. Operations had a median Society of Thoracic Surgery-European Association for Cardio-Thoracic Surgery complexity score of 1 (IQR: 1-2) and CPB time of 82 (IQR: 58-122) minutes. Hyperglycemia occurred in 85% of subjects; odds of hyperglycemia peaked at 6 hours after CPB. Plasma glucose was associated with increased insulin and a lower glucose-to-insulin ratio. Increased interleukin (IL)-6 concentrations were associated with increased glucose (estimate [EST]: 0.55 (±0.13) mmol/L; P < .001) and insulin (EST: 1.14 (±0.12) μmol/L; P < .001) in linear regression adjusted for repeated measures. Paradoxically, increased cytokines were associated with an increased glucose-to-insulin ratio (EST: 0.21 (±0.03) mmol/μmol; P < .001).

CONCLUSIONS

Hyperglycemia after pediatric CPB surgery is associated with hyperinsulinemia, which may reflect insulin resistance in some patients. Inflammation induced by CPB may play a causative role in insulin resistance.

Insulin therapy in hyperglycemic children with severe acute asthma

OBJECTIVES

The aim of this study was to assess the effect of intravenous (IV) insulin administration in children with severe acute asthma (SAA) and hyperglycemia on IV salbutamol consumption and length of stay (LOS) in a pediatric intensive care unit (PICU).

METHODS

Retrospective, descriptive study of the clinical course before and after implementation of an insulin protocol for the treatment of hyperglycemia (i.e. blood glucose >8 mmol/L or 144 mg/dL, respectively) in the PICU of a tertiary care university hospital. Admissions between 1994 and 2010 were reviewed. The insulin protocol was introduced in 2006.

RESULTS

A total of 131 pediatric patients with SAA complicated by hyperglycemia requiring IV salbutamol were included. Severity of illness before and after implementation of the insulin protocol did not significantly differ. The insulin-treated patient group had significantly higher maximum blood glucose levels and higher cumulative IV salbutamol dose than the non-treated group. There were no differences between these groups in the duration of IV salbutamol administration and LOS.

CONCLUSIONS

In view of the lack of difference in outcomes and considering that the insulin protocol is labor-intensive, the question is whether this protocol is efficacious for the treatment of pediatric SAA associated with hyperglycemia.

Control of serum glucose concentration in critical illness

PURPOSE OF REVIEW

Hyperglycemia is a significant problem for children in the ICU. Use of tight glycemic control (TGC) to manage hyperglycemia remains controversial, especially given the potential risk of insulin-induced hypoglycemia. This review will address the latest evidence regarding TGC in critically ill children.

RECENT FINDINGS

Two randomized controlled trials (RCT) involving primarily postoperative cardiac surgery patients demonstrated the feasibility and safety of TGC in pediatric patients. The trials, however, had discrepant results with regards to the benefit of TGC. There is also uncertainty about the generalizability of these results to nonpostoperative cardiac patients. There is only one published study addressing the long-term safety of TGC in children. In this study, hypoglycemia was not associated with adverse effects on neurocognitive development. In contrast, articles from adult studies demonstrate increased risk of death with hypoglycemia.

SUMMARY

Although the clinical benefit of TGC in critically ill children is still unclear, TGC can be done safely in this population.

Does a reduced glucose intake prevent hyperglycemia in children early after cardiac surgery? a randomized controlled crossover study

INTRODUCTION

Hyperglycemia in children after cardiac surgery can be treated with intensive insulin therapy, but hypoglycemia is a potential serious side effect. The aim of this study was to investigate the effects of reducing glucose intake below standard intakes to prevent hyperglycemia, on blood glucose concentrations, glucose kinetics and protein catabolism in children after cardiac surgery with cardiopulmonary bypass (CPB).

METHODS

Subjects received a 4-hour low glucose (LG; 2.5 mg/kg per minute) and a 4-hour standard glucose (SG; 5.0 mg/kg per minute) infusion in a randomized blinded crossover setting. Simultaneously, an 8-hour stable isotope tracer protocol was conducted to determine glucose and leucine kinetics. Data are presented as mean ± SD or median (IQR); comparison was made by paired samples t test.

RESULTS

Eleven subjects (age 5.1 (20.2) months) were studied 9.5 ± 1.9 hours post-cardiac surgery. Blood glucose concentrations were lower during LG than SG (LG 7.3 ± 0.7 vs. SG 9.3 ± 1.8 mmol/L; P < 0.01), although the glycemic target (4.0-6.0 mmol/L) was not achieved. No hypoglycemic events occurred. Endogenous glucose production was higher during LG than SG (LG 2.9 ± 0.8 vs. SG 1.5 ± 1.1 mg/kg per minute; P = 0.02), due to increased glycogenolysis (LG 1.0 ± 0.6 vs. SG 0.0 ± 1.0 mg/kg per minute; P < 0.05). Leucine balance, indicating protein balance, was negative but not affected by glucose intake (LG -54.8 ± 14.6 vs. SG -58.8 ± 16.7 μmol/kg per hour; P = 0.57).

CONCLUSIONS

Currently recommended glucose intakes aggravated hyperglycemia in children early after cardiac surgery with CPB. Reduced glucose intake decreased blood glucose concentrations without causing hypoglycemia or affecting protein catabolism, but increased glycogenolysis.

TRIAL REGISTRATION

Dutch trial register NTR2079.