Risk factors for developing hypoglycemia in neurocritical care patients

Introduction

The use of intensive insulin therapy (IIT) in neurocritical care patients is controversial: IIT failed to improve mortality and morbidity in brain-injury patients in a number of trials. Hypoglycemia increases the risk of death and may contribute to the development of secondary brain injury in these patients. The aim of this study was to identify risk factors for hypoglycemia in critically ill neurological patients.

Methods

We performed a retrospective nested case–control study in the ICU of a tertiary-care teaching hospital in neurological ICU patients admitted between January 2007 and July 2007. Neurological ICU patients were defined as patients admitted primarily to the ICU, as a result of their neurological illness. Patients were considered as cases if at least one episode of hypoglycemia (defined as a glucose level <3.0 mmol/l (<54 mg/dl)) occurred while admitted to the ICU. Only the first hypoglycemic event (index moment) of a patient was used to match with a control patient. Control patients were randomly selected from the same population, admitted for at least the same duration until the index moment, without previous hypoglycemic events. A number of potential risk factors for the development of hypoglycemia were predefined based on the literature in ICU patients. All variables were analyzed with univariate and multivariate regression analysis, correcting for age, gender and APACHE II score.

Results

Of the 127 neurological ICU patients, 35 developed hypoglycemia (27.6%). Mean arterial pressure (OR = 0.93; 95% CI = 0.87 to 0.99 per increase of 1 mmHg), having a Sepsis-related Organ Failure Assessment score for hemodynamic instability ≥ 1 (OR = 5.53; 95% CI = 1.23 to 24.81), dosage of norepinephrine (OR = 8.39; 95% CI = 1.38 to 51.12 per increase of 1 mg/hour), creatinine clearance (OR = 0.98; 95% CI = 0.96 to 1.00 per increase of 1 ml/min) and gastric residual volume without adjusting the insulin dosage (OR = 11.66; 95% CI = 1.24 to 109.20) were independently associated with a risk for developing hypoglycemia.

Conclusion

Hypoglycemia occurs in a significant proportion of neurological ICU patients. We suggest more frequent control of blood glucose values, especially in patients suffering from hemodynamic instability, renal failure and gastroparesis.