Challenge of intravascular volume assessment in acute ischemic stroke

Retrospective data indicates that dehydration in acute ischemic stroke patients may be common, even though these patients frequently have elevated blood pressure. We sought to evaluate clinical and laboratory measures of intravascular volume status compared to more objective measures using ultrasound measurements of the inferior vena cava (IVC).

This was a prospective observation study of acute ischemic stroke patients in the emergency department. Patients with NIH stroke scale ≥4 within 12 h of symptom onset were included. A trained ultrasonographer performed bi-dimensional imaging of the IVC with passive respiration to determine the percent inspiratory collapse and maximum diameter. We defined low intravascular volume as >50% IVC collapse and a maximal diameter < 2.1 cm. Analysis was limited to patients with confirmed ischemic stroke.

There were 42 patients, of whom 31 had confirmed acute ischemic stroke. The mean age was 65 ± 15 years, 52% were female, and 71% were hypertensive. The median NIH stroke scale score was 7 (IQR 5-15). Based on IVC ultrasound, low intravascular volume was present in 63% (95% CI 44-80%) of patients. A higher proportion of hypertensive patients had low intrasvascular volume (72% vs. 33%). There was poor correlation between IVC assessment of intrasvascular volume and blinded clinician assessment or laboratory markers of dehydration.

The majority of ED acute ischemic stroke patients in this sample were hypertensive and demonstrated low intravascular volume based on IVC ultrasound.