Value of continuous glucose monitoring for minimizing severe hypoglycemia during tight glycemic control

Department of Surgery and Medicine, Children's Hospital, Boston, MA, USA.
Pediatric Critical Care Medicine (Impact Factor: 2.34). 04/2011; 12(6):643-8. DOI: 10.1097/PCC.0b013e31821926a5
Source: PubMed


Tight glycemic control can potentially reduce morbidity and mortality in the intensive care unit but increases the risk of hypoglycemia. The most effective means to avoid hypoglycemia is to obtain frequent blood glucose samples, but this increases the burden to nursing staff. The objective of this study was to assess the ability of a real-time continuous glucose monitor to reduce hypoglycemia (blood glucose <60 mg/dL [3.3 mmol/L]) during standard care or tight glycemic control effected with a proportional integral derivative insulin titration algorithm.
Real-time continuous glucose monitor profiles obtained from an ongoing prospective randomized trial of tight glycemic control were retrospectively analyzed to determine whether the continuous glucose measure had prevented instances of hypoglycemia.
Cardiac intensive care unit.
Children 3 yrs of age or younger undergoing cardiac surgery were studied.
Intravenous insulin infusion and rescue glucose guided by the real-time continuous glucose monitor and the proportional integral derivative algorithm in the tight glycemic control arm (n = 155; target glucose 80-110 mg/dL [4.4-6.1 mmol/L]) and the real-time continuous glucose monitor in the standard care arm (n = 156).
No reduction in hypoglycemia was observed with real-time continuous glucose monitor alarms set at 60 mg/dL (3.3 mmol/L) (zero of 19 occurrences of blood glucose <60 mg/dL [3.3 mmol/L] detected); 18 of 40 subsequent incidences of hypoglycemia were detected after the alarm threshold was increased to 70 mg/dL (3.9 mmol/L). In the tight glycemic control arm, eight incidences were reduced in duration and an additional eight events were prevented with intravenous glucose. In the standard care arm, three of nine occurrences of hypoglycemia were detected with the duration reduced in all cases. On average, one to two false hypoglycemia alarms were observed in each patient.
The real-time continuous glucose monitor in combination with proportional integral derivative control can reduce hypoglycemia during tight glycemic control. The real-time continuous glucose monitor can also reduce hypoglycemia during standard care. However, false alarms increase the overall nursing workload.

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    • "As documented in recently published correspondence, opinion still differs on what are considered “correct” blood glucose levels to aim for.20 To address this issue, Steil et al performed a study to find out whether using a continuous glucose monitor would be a cost-effective and more scientifically robust method of measuring glucose levels.21 Unfortunately, the results showed that the technology required does not yet exist because a lack of consistency in cutoff values and the susceptibility to false alarms or failure to recognize hypoglycemia led to an increase in workload for nursing staff, the opposite of what was hoped for.22 "
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    ABSTRACT: This literature review examines the current evidence regarding the potential usefulness of tight glycemic control in pediatric surgical patients. In adults, fluctuations in glucose levels and/or prolonged hyperglycemia have been shown to be associated with poor outcomes with respect to morbidity and mortality. This review begins by summarizing the findings of key papers in adult patients and continues by investigating whether or not similar results have been seen in pediatric patients by performing a comprehensive literature review using Medline (OVID). A database search using the OVID interface and including the search terms (exp glucose) AND (exp surgery) AND (exp Paediatric/pediatric) AND (exp Hypoglycaemia/hypoglycemia) AND (exp Hyperglycaemia/hyperglycemia) yielded a total of 150+ papers, of which 24 fulfilled our criteria. We isolated papers utilizing pediatric patients who were hospitalized due to illness and/or surgery. Our review highlights several difficulties encountered in addressing this potentially useful clinical intervention. An absence of scientifically robust and randomized trials and the existence of several small-powered trials yielding conflicting results mean we cannot recommend tight glycemic control in these patients. Differences in study design and disagreements concerning the crucial stage of surgery where hyperglycemia becomes important are compounded by an over-reliance on the discretion of clinicians in the absence of well described treatment protocols. Closer inspection of key papers in adult patients identified fundamental discrepancies between exact definitions of both hyperglycemia and hypoglycemia. This lack of consensus, along with a fear of inducing iatrogenic hypoglycemia in pediatric patients, has resulted in professional bodies advising against this form of intervention. In conclusion, we cannot recommend use of tight glycemic control in pediatric surgical patients due to unclear glucose definitions, unclear thresholds for treatment, and the unknown long-term effects of iatrogenic hypoglycemia on the developing body and brain.
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    ABSTRACT: The practice of glycemic control with intravenous insulin in critically ill patients has brought clinical focus on understanding the effects of hypoglycemia, especially in children. Very little is published on the impact of hypoglycemia in this population. We aimed to review the existing literature on hypoglycemia in critically ill neonates and children. We performed a systematic review of the literature up to August 2011 using PubMed, Ovid MEDLINE and ISI Web of Science using the search terms "hypoglycemia or hypoglyc*" and "critical care or intensive care or critical illness". Articles were limited to "all child (0-18 years old)" and "English". A total of 513 articles were identified and 132 were included for review. Hypoglycemia is a significant concern among pediatric and neonatal intensivists. Its definition is complicated by the use of a biochemical measure (i.e., blood glucose) for a pathophysiologic problem (i.e., neuroglycopenia). Based on associated outcomes, we suggest defining hypoglycemia as <40-45 mg/dl in neonates and <60-65 mg/dl in children. Below the suggested threshold values, hypoglycemia is associated with worse neurological outcomes, increased intensive care unit stay, and increased mortality. Disruptions in carbohydrate metabolism increase the risk of hypoglycemia incritically ill children. Prevention of hypoglycemia, especially in the setting of intravenous insulin use, will be best accomplished by the combination of accurate measuring techniques, frequent or continuous glucose monitoring, and computerized insulin titration protocols. Studies on hypoglycemia in critically ill children have focused on spontaneous hypoglycemia. With the current practice of maintaining blood glucose within a narrow range with intravenous insulin, the risk factors and outcomes associated with insulin-induced hypoglycemia should be rigorously studied to prevent hypoglycemia and potentially improve outcomes of critically ill children.
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    ABSTRACT: IntroductionConclusion References
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