Hyperglycaemia after acute stroke

[Repercussions and management of perioperative hyperglycemia in cardiac surgery]

Surgery produces a neuroendocrine stress response that affects resistance to insulin, reduces insulin secretion, and increases the release of glucose from the liver. This situation can trigger hyperglycemia in both diabetics and nondiabetics. Hyperglycemia has been linked to an increase in the morbidity and mortality among patients who undergo cardiac surgery, and the benefits of correcting hyperglycemia in this setting by means of intensive insulin therapy are well documented. This review discusses various aspects of hyperglycemia, particularly the evidence supporting stricter control of this condition in patients undergoing cardiac surgery. Furthermore, based on the available data and recommendations, and our clinical experience, we suggest therapeutic strategies to improve the control of hyperglycemia in these patients.

Diabetes mellitus, insulin resistance, hyperglycemia, and stroke

It is well established that diabetes is associated with an increased risk of stroke. Once a stroke has occurred, patients with diabetes experience poorer outcomes (functional status, mortality). Convincing data now support aggressive glucose control and comprehensive cardiovascular risk factor management to prevent stroke in patients with diabetes. However, there remains a distinct paucity of information concerning secondary stroke prevention. Hyperglycemia in the acute stroke setting is a marker for poor outcomes, but it remains unclear whether intensive in-hospital lowering of blood glucose levels improves clinical outcomes. Targeting insulin resistance as a modifiable risk factor for stroke is a novel strategy currently under investigation.

Persistent perioperative hyperglycemia as an independent predictor of poor outcome after aneurysmal subarachnoid hemorrhage

OBJECT

The authors of previous studies have shown that admission hyperglycemia or perioperative hyperglycemic events may predispose a patient to poor outcome after aneurysmal subarachnoid hemorrhage (SAH). The results of experimental evidence have suggested that hyperglycemia may exacerbate ischemic central nervous system injury. It remains to be clarified whether a single hyperglycemic event or persistent hyperglycemia is predictive of poor outcome after aneurysmal SAH.

METHODS

Ninety-seven patients undergoing treatment for aneurysmal SAH were observed, and all perioperative variables were entered into a database of prospectively recorded data. Daily serum glucose values were retrospectively added. Patients were examined at hospital discharge (14-21 days after SAH onset), and Glasgow Outcome Scale (GOS) scores were prospectively documented. The GOS score at last follow-up was retrospectively determined. Serum glucose greater than 200 mg/dl for 2 or more consecutive days was defined as persistent hyperglycemia. Outcome was categorized as "poor" (dependent function [GOS Score 1-3]) or "good" (independent function [GOS Score 4 or 5]) at discharge. The independent association of 2-week and final follow-up outcome (GOS score) with the daily serum glucose levels was assessed using a multivariate analysis.

RESULTS

In the univariate analysis, increasing age, increasing Hunt and Hess grade, hypertension, ventriculomegaly on admission computed tomography scan, Caucasian race, and higher mean daily glucose levels were associated with poor (dependent) 2-week outcome after aneurysmal SAH. In the multivariate analysis, older age, the occurrence of symptomatic cerebral vasospasm, increasing admission Hunt and Hess grade, and persistent hyperglycemia were independent predictors of poor (dependent) outcome 2 weeks after aneurysmal SAH. Admission Hunt and Hess grade and persistent hyperglycemia were independent predictors of poor outcome at last follow-up examination a mean 10 +/- 3 months after aneurysmal SAH. Isolated hyperglycemic events did not predict poor outcome. Patients with persistent hyperglycemia were 10-fold more likely to have a poor (dependent) 2-week outcome and sevenfold more likely to have a poor outcome a mean 10 months after aneurysmal SAH independent of admission Hunt and Hess grade, occurrence of cerebral vasospasm, or all comorbidities.

CONCLUSIONS

Patients with persistent hyperglycemia were seven times more likely to have a poor outcome at a mean of 10 months after aneurysmal SAH. Isolated hyperglycemic events were not predictive of poor outcome. Serum glucose levels in the acute setting of aneurysmal SAH may help predict outcomes months after surgery.

Hyperglycemia independently increases the risk of perioperative stroke, myocardial infarction, and death after carotid endarterectomy

OBJECTIVE

Clinical and experimental evidence suggests that hyperglycemia lowers the neuronal ischemic threshold, potentiates stroke volume in focal ischemia, and is associated with morbidity and mortality in the surgical critical care setting. It remains unknown whether hyperglycemia during carotid endarterectomy (CEA) predisposes patients to perioperative stroke and operative related morbidity and mortality.

METHODS

The clinical and radiological records of all patients undergoing CEA and operative day glucose measurement from 1994 to 2004 at an academic institution were reviewed and 30-day outcomes were assessed. The independent association of operative day glucose before CEA and perioperative morbidity and mortality were assessed via multivariate logistic regression analysis.

RESULTS

One thousand two hundred and one patients with a mean age of 72 +/- 10 years (748 men, 453 women) underwent CEA (676 asymptomatic, 525 symptomatic). Overall, stroke occurred in 46 (3.8%) patients, transient ischemic attack occurred in 19 (1.6%), myocardial infarction occurred in 19 (1.6%), and death occurred in 17 (1.4%). Increasing operative day glucose was independently associated with perioperative stroke or transient ischemic attack (Odds ratio [OR], 1.005; 95% confidence interval [CI], 1.00-1.01; P = 0.03), myocardial infarction (OR, 1.01; 95% CI, 1.004-1.016; P = 0.017), and death (OR, 1.007; 95% CI, 1.00-1.015; P = 0.04). Patients with operative day glucose greater than 200 mg/dl were 2.8-fold, 4.3-fold, and 3.3-fold more likely to experience perioperative stroke or transient ischemic attack (OR, 2.78; 95% CI, 1.37-5.67; P = 0.005), myocardial infarction (OR, 4.29; 95% CI, 1.28-14.4; P = 0.018), or death (OR, 3.29; 95% CI, 1.07-10.1; P = 0.037), respectively. Median and interquartile range length of hospitalization was greater for patients with operative day glucose greater than 200 mg/dl (4 d [interquartile range, 2-15 d] versus 3 d [interquartile range, 2-7 d]; P < 0.05).

CONCLUSION

Independent of previous cardiac disease, diabetes, or other comorbidities, hyperglycemia at the time of CEA was associated with an increased risk of perioperative stroke or transient ischemic attack, myocardial infarction, and death. Strict glucose control should be attempted before surgery to minimize the risk of morbidity and mortality after CEA.

Non-Pharmacological Neuroprotection: Role of Emergency Stroke Management

Acute stroke should be considered a medical emergency, where actions taken in the first hours are fundamental for achieving recovery of the damaged cerebral tissue and a better prognosis for the patient. Recanalization and neuroprotective treatment has been used with mixed results. The effectiveness observed in the first hours with thrombolytic drug treatment is only applicable to a small percentage of patients, and attempts to widen this treatment window have not yet proved fruitful. Pharmacological neuroprotective treatment has not yet demonstrated the clinical effectiveness observed in experimental models. The concept of neuroprotection in cerebral ischemia also involves a series of mechanisms that take place at the cerebral level following vascular occlusion. In this context, it should be borne in mind that a series of physiological functions usually involved in the cerebral metabolism (control of blood pressure, of temperature, of glycemia and of arterial oxygen saturation) play a key role in modulation of the ischemic process. Changes in the control of these mechanisms may aggravate the process of cerebral damage in the first hours of ischemic stroke. In this work we review the prognostic importance of the main mechanisms that may influence the acute phase of cerebral ischemic stroke, as well as their therapeutic management and control in the clinical situation.

Homeostasis as basis of acute stroke treatment: stroke units are the key

INTRODUCTION

Several studies suggest that the control of blood pressure (BP), blood glucose level, body temperature, and oxygen saturation, when analyzed separately, is related with successful acute stroke outcome. However, in a biological system these parameters are interrelated and could influence the process. Recent studies highlight the importance of the appropriate maintenance of these variables that are involved in homeostasis in patients with stroke and the influence they have on outcome.

METHODS

A review was conducted of published studies which analyzed the influence of control of these physiological variables in acute stroke, whether in isolation or combinations, and we have contributed our own data derived from observational studies.

RESULTS

The maintenance of homeostasis forms the basis of acute stroke treatment, in what is termed nonpharmacological neuroprotection. Stroke units (SU) are the ideal environment for this therapeutic approach since their favorable influence on the correct management of BP, body temperature, oxygen saturation, and blood glucose in the progress of stroke patients have been proved.

CONCLUSIONS

The proper management of physiological variables (homeostasis) such as BP, body temperature, blood glucose, and oxygen saturation is the basis of acute stroke treatment, and SU are the key to this approach.

Elevated total white blood cell count with high blood glucose is associated with poor outcome after ischemic stroke

Increases in total white blood cell (WBC) count and blood glucose level have each been associated with poor outcomes after ischemic stroke. The aim of this study was to determine whether there was an added effect of elevated total WBC count with glucose level on outcome after ischemic stroke. A total of 436 consecutive patients with ischemic stroke who were admitted to Suburban Hospital, Bethesda, MD, between June 2000 and December 2002 were included in this study. Nonfasting peripheral WBC count and glucose level were obtained on hospital arrival, along with self- and family member-reported risk factors for stroke and clinical parameters. WBC count and glucose level were dichotomized into 4 groups: increased WBC count with increased glucose level (IW;IG), increased WBC count with normal glucose level (IW;NG), normal WBC count with increased glucose level (NW;IG), and normal WBC count with normal glucose level (NW;NG). Poor outcome was defined as a modified Rankin scale score >/= 2 at hospital discharge. On univariate analysis, patients with IW;IG (n = 53) had worse outcome (P < .001) than patients with NW;NG (n = 210) or elevations in either factor alone. On multivariate logistic regression analysis, after adjustment for stroke severity and other factors, the odds ratios of poor stroke outcomes were 20 (95% confidence interval [CI] = 3.3-125; P < .001) for the IW:IG group, 3.3 (95% CI = 1.1-14.3; P = .03) for the IW;NG group, and 2.5 (95% CI = 1.1-5.0; P = .03) for the NW;IG group, all compared with the NW:NG group. There may be an added effect of elevated WBC count with hyperglycemia on poor outcome after ischemic stroke. Strict control of inflammatory parameters and glucose may help improve outcome for patients with ischemic stroke.

Acute hyperglycemia adversely affects stroke outcome: a magnetic resonance imaging and spectroscopy study

Controversy exists whether acute hyperglycemia is causally associated with worse stroke outcome or simply reflects a more severe stroke. In reversible ischemia models, hyperglycemia is associated with lactic acidosis and conversion of penumbral tissue to infarction. However, the relationship between hyperglycemia, lactic acidosis, and stroke outcome has not been explored in humans. Sixty-three acute stroke patients were prospectively evaluated with serial diffusion-weighted and perfusion-weighted magnetic resonance imaging and acute blood glucose measurements. Patients with hypoperfused at-risk tissue were identified by acute perfusion-diffusion lesion mismatch. As a substudy, acute and subacute magnetic resonance spectroscopy was performed in the 33 most recent patients to assess the relationship between acute blood glucose and lactate production in the ischemic region. In 40 of 63 patients with acute perfusion-diffusion mismatch, acute hyperglycemia was correlated with reduced salvage of mismatch tissue from infarction, greater final infarct size, and worse functional outcome. These correlations were independent of baseline stroke severity, lesion size, and diabetic status. Furthermore, higher acute blood glucose in patients with perfusion-diffusion mismatch was associated with greater acute-subacute lactate production, which, in turn, was independently associated with reduced salvage of mismatch tissue. In contrast, acute blood glucose levels in nonmismatch patients did not independently correlate with outcome measures, nor was there any acute-subacute increase in lactate in this group. Acute hyperglycemia increases brain lactate production and facilitates conversion of hypoperfused at-risk tissue into infarction, which may adversely affect stroke outcome. These findings support the need for randomized controlled trials of aggressive glycemic control in acute stroke.

Blood glucose increases early after stroke onset: a study on serial measurements of blood glucose in acute stroke

The aim of this study was to evaluate if blood glucose levels change within the first 12 h after stroke onset and to investigate if the degree of change is related to stroke severity, type of stroke, or prognosis. This was a retrospective, descriptive trial based on 445 stroke patients with two blood glucose tests within 12 h of stroke onset and no history of diabetes mellitus. Blood glucose increased in the first 12 h after stroke onset; in mild to moderate stroke from 5.8 to 6.1 mmol/l (P < 0.001) and in severe stroke from 6.2 to 6.7 mmol/l (P < 0.001). In patients who died within 7 days of stroke onset, blood glucose increased from 6.8 to 7.1 mmol/l (P < 0.001). In conclusion, blood glucose increases after the onset of acute stroke and the increase is related to the severity of the stroke.

Serum glucose level and diabetes predict tissue plasminogen activator-related intracerebral hemorrhage in acute ischemic stroke

BACKGROUND AND PURPOSE

Five pretreatment variables (P<0.1 univariate analysis), including serum glucose (>300 mg/dL), predicted symptomatic intracerebral hemorrhage (ICH) in the National Institute of Neurological Disorders and Stroke rtPA trial. We retrospectively studied stroke patients treated <3 hours from onset with intravenous rtPA at 2 institutions to evaluate the role of these variables in predicting ICH.

METHODS

Baseline characteristics, including 5 prespecified variables (age, baseline glucose, smoking status, National Institutes of Health Stroke Scale [NIHSS] score, and CT changes [>33% middle cerebral artery territory hypodensity]), were reviewed in 138 consecutive patients. Variables were evaluated by logistic regression as predictors of all hemorrhage (including hemorrhagic transformation) and symptomatic hemorrhage on follow-up CT scan. Variables significant at P<0.25 level were included in a multivariate analysis. Diabetes was substituted for glucose in a repeat analysis.

RESULTS

Symptomatic hemorrhage rate was 9% (13 of 138). Any hemorrhage rate was 30% (42 of 138). Baseline serum glucose (5.5-mmol/L increments) was the only independent predictor of both symptomatic hemorrhage [OR, 2.26 (CI, 1.05 to 4.83), P=0.03] and all hemorrhage [OR, 2.26 (CI, 1.07 to 4.69), P=0.04]. Serum glucose >11.1 mmol/L was associated with a 25% symptomatic hemorrhage rate. Baseline NIHSS (5-point increments) was an independent predictor of all hemorrhage only [OR, 12.42 (CI, 1.64 to 94.3), P=0.01]. Univariate analysis demonstrated a trend for nonsmoking as a predictor of all hemorrhage [OR, 0.45 (CI, 0.19 to 1. 08), P=0.07]. Diabetes was also an independent predictor of ICH when substituted for glucose in repeat analysis.

CONCLUSIONS

Serum glucose and diabetes were predictors of ICH in rtPA-treated patients. This novel association requires confirmation in a larger cohort.