Original Contribution
Association of blood glucose at admission with outcomes in patients treated with therapeutic hypothermia after cardiac arrest

https://doi.org/10.1016/j.ajem.2014.05.004Get rights and content

Abstract

Background

It is well known that hyperglycemia is associated with poor outcomes in critically ill patients. We investigated the association between blood glucose level at admission and the outcomes of patients treated with therapeutic hypothermia (TH) after cardiac arrest.

Methods

A total of 883 cardiac arrest patients who were treated with TH were analyzed from the Korean Hypothermia Network retrospective registry. We examined the association of blood glucose at admission with survival and neurologic outcomes at hospital discharge. Favorable neurologic outcomes were defined as Cerebral Performance Category scores of 1 and 2.

Results

The mean age of the sample was 56.7 ± 16.2 years, 69.5% of subjects were male, and the mean blood glucose at admission was 14.1 ± 7.0 mmol/L. After adjustment for sex, age, history of diabetes mellitus, hypertension, renal disease and stroke, time from arrest to return of spontaneous circulation, initial rhythm, witness status, bystander cardiopulmonary resuscitation, cause of arrest, and cumulative dose of adrenaline, the associations between glucose and outcomes were as follows: for favorable neurologic outcomes, an odds ratio of 0.955 (95% confidence interval, 0.918-0.994); and for survival, an odds ratio of 0.974 (95% confidence interval, 0.952-0.996).

Conclusion

These results show that blood glucose level at admission is associated with survival and favorable neurologic outcomes at hospital discharge in patients treated with TH after cardiac arrest. Blood glucose level at admission could be a surrogate marker of ischemic insult severity during cardiac arrest. However, randomized, controlled evidence is needed to address the significance of tight glucose control during TH after cardiac arrest.

Introduction

Hyperglycemia is commonly seen in critically ill patients requiring intensive care. The exact mechanism of the development of hyperglycemia in critical illness is not fully understood. However, it has been proposed to be caused by the complex consequences of many factors, including increased cortisol, catecholamine, glucagon, growth hormone, gluconeogenesis, and glycogenolysis [1]. This interplay results in excessive hepatic glucose production and insulin resistance, leading to an elevation in blood glucose. In particular, ischemia-reperfusion injuries frequently result in metabolic derangements, such as hyperglycemia [2]. Hyperglycemia after cardiac arrest is likely to be the result of an interaction between the patient's characteristics and acute stress.

Focus on the association of hyperglycemia with outcomes in critically ill patients has generated interest in the importance of hyperglycemia in other disease states, including clinical outcomes. Several studies of critically ill patients have demonstrated a strong association between hyperglycemic stress and poor clinical outcomes, including mortality, morbidity, length of stay, infections, and overall complications [3], [4], [5]. However, this evidence does not prove that hyperglycemia causes poor clinical outcomes because hyperglycemia could merely be a marker of severe illness. In particular, the relationship of hyperglycemia with outcomes after cardiac arrest is not as well understood.

Several clinical trials have suggested that aggressive treatment of hyperglycemia could improve morbidity and mortality in critically ill patients [5], [6]. However, recent studies have shown that tight glucose control through intensive insulin therapy might not necessarily improve outcomes in the critically ill subpopulation of cardiac arrest patients [7], [8]. Recognizing the need for specific blood glucose control guidelines for post–cardiac arrest patients, the International Liaison Committee on Resuscitation recently recommended a more moderate target for blood glucose concentration of up to 144 mg/dL (8 mmol/L) [9]. Better understanding of blood glucose regulation after cardiac arrest would be an important step toward the creation of more specific glucose control guidelines to improve outcomes. Accordingly, our objective was to examine the association between blood glucose level at admission and outcomes in patients treated with therapeutic hypothermia (TH) after cardiac arrest, with and without a history of preexisting diabetes.

Section snippets

Patients

This was a multicenter, retrospective, observational, registry-based study. The study was one of the first research projects using the Korean Hypothermia Network (KORHN) registry data. The KORHN, a multicenter clinical research consortium for TH in South Korea, was organized in 2011, and it conducted this multicenter, retrospective, registry project in 2012. The KORHN investigators collected post–cardiac arrest TH data from 24 teaching hospitals around South Korea from 2007 to 2012. Adults with

Results

Of a total of 930 OHCA patients entered in the registry, 883 were included in the analysis, of whom 528 (59.8%) survived and were discharged from the hospital; 239 (26.3%) of these patients achieved favorable neurologic outcomes. The demographic data of the enrolled patients are summarized in Table 1. The mean age was 56.7 ± 16.2 years, and 69.5% of the subjects were male. One hundred ninety-eight patients had a history of diabetes, and the mean blood glucose at admission was 14.1 ± 7.0 mmol/L.

Discussion

The current study showed that blood glucose levels at admission were associated with survival and neurologic outcomes at hospital discharge in patients treated with TH after cardiac arrest. The subjects were enrolled from a retrospective, multicenter registry in South Korea.

Some retrospective studies have shown that higher glucose levels are associated with increased mortality and worse neurologic outcomes [8], [11], [12]. Of these studies, only 1 examined patients with TH [8], and this study

Conclusion

These results showed that blood glucose level at admission was associated with survival and favorable neurologic outcomes at hospital discharge in patients treated with TH after cardiac arrest. Blood glucose level at admission could be a surrogate marker of ischemic insult severity during cardiac arrest. However, randomized, controlled evidence is needed to address the significance of tight glucose control during TH after cardiac arrest.

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