NASHVILLE—Patients who are clinically dehydrated when they present with ischemic stroke may be four times more likely to worsen during the next few days than adequately hydrated patients are, according to the results of a single-center, retrospective study presented at the 2015 International Stroke Conference.
Hydration status did not appear to affect stroke infarct volume or severity, said Mona Bahouth, MD, a neurology fellow at Johns Hopkins University in Baltimore. Nevertheless, 42% of dehydrated patients had no improvement or worsened during their stay, compared with 17% of well-hydrated patients, said Dr. Bahouth.
The number of stroke patients who receive hydration therapy upon admission is uncertain. The method for providing hydration therapy also is open to question because IV administration raises concerns about fluid overload, and oral intake may cause choking or difficulty in swallowing. But if attention to hydration could help improve outcomes of stroke, “it would be one of the easiest things in the world to do,” said Dr. Bahouth.
The literature suggests a link between fluid status and stroke. Increased hemoglobin during acute stroke may be related to clinical deterioration after stroke, and elevated blood urea nitrogen (BUN)/creatinine ratio and serum osmolality may be related to this outcome, too. Dehydration entails lower fluid volume in the blood, which contributes to the prothrombotic state and puts shear stress on vessels, said Dr. Bahouth.
She retrospectively analyzed the records of 126 patients who presented with symptoms of acute stroke at fewer than 12 hours from their last known time of normal function. In 44% of patients, the BUN/creatinine ratio was more than 15, and urine specific gravity was greater than 1.010, which indicates dehydration. All patients underwent MRI to determine infarct and perfusion volumes. The study’s primary outcomes were fluctuation in the NIH Stroke Scale (NIHSS) score and the quantitative change in NIHSS over four days post stroke.
Patients’ mean age was 65. About 15% of patients had atrial fibrillation, and one-third had diabetes. Mean NIHSS score at presentation was 7. Thrombolytic therapy was administered to 40% of patients with dehydration and 60% of those without it.
The researchers observed no between-group differences in stroke type. About 55% of patients had a large anterior infarct, 10% had a large posterior infarct, and the rest had small-vessel lesions. Mean infarct volume was 12 mL in the group with dehydration and 16 mL in those without, which was not a significant difference. The researchers also found no significant differences according to hydration status, in terms of hypoperfusion, baseline NIHSS score, infarct volume, or perfusion- or diffusion-weighted imaging mismatch ratio.
By day four, NIHSS score had improved in 83% of patients without dehydration and in 58% of those with dehydration. NIHSS score was unchanged or had worsened in 17% of patients without dehydration and 42% of patients with dehydration. Both differences were statistically significant.
A multivariate regression analysis revealed no significant associations of declining clinical status with age, gender, infarct volume, or baseline glucose level, but dehydration upon admission conferred a fourfold risk for NIHSS deterioration.
Even though dehydration appears to be associated with clinical deterioration, the best way to handle it is unclear, according to Robert Adams, MD, Professor of Neurology at the Medical University of South Carolina in Charleston. Little research has been conducted on the issue in recent years; studies undertaken in the 1980s showed that blood viscosity was an important factor, but treating it with fluids did not improve outcomes.
“There were clearly complications of pulmonary embolism in some patients, showing that it’s possible to go too far with fluids. The discussion now is [about] how much fluid would be beneficial,” said Dr. Adams.
—Michele G. Sullivan