The Role of Osmotic Therapy in Hemispheric Stroke

What is the Role of Hyperosmolar Therapy in Hemispheric Stroke Patients?

The role of hyperosmolar therapy (HT) in large hemispheric ischemic or hemorrhagic strokes remains a controversial issue. Past and current stroke guidelines state that it represents a reasonable therapeutic measure for patients with either neurological deterioration or intracranial pressure (ICP) elevations documented by ICP monitoring. However, the lack of evidence for a clear effect of this therapy on radiological tissue shifts and clinical outcomes produces uncertainty with respect to the appropriateness of its implementation and duration in the context of radiological mass effect without clinical correlates of neurological decline or documented elevated ICP. In addition, limited data suggest a theoretical potential for harm from the prophylactic and protracted use of HT in the setting of large hemispheric lesions. HT exerts effects on parenchymal volume, cerebral blood volume and cerebral perfusion pressure which may ameliorate global ICP elevation and cerebral blood flow; nevertheless, it also holds theoretical potential for aggravating tissue shifts promoted by significant interhemispheric ICP gradients that may arise in the setting of a large unilateral supratentorial mass lesion. The purpose of this article is to review the literature in order to shed light on the effects of HT on brain tissue shifts and clinical outcome in the context of large hemispheric strokes, as well as elucidate when HT should be initiated and when it should be avoided.

Guidelines for the Acute Treatment of Cerebral Edema in Neurocritical Care Patients

BACKGROUND

Acute treatment of cerebral edema and elevated intracranial pressure is a common issue in patients with neurological injury. Practical recommendations regarding selection and monitoring of therapies for initial management of cerebral edema for optimal efficacy and safety are generally lacking. This guideline evaluates the role of hyperosmolar agents (mannitol, HTS), corticosteroids, and selected non-pharmacologic therapies in the acute treatment of cerebral edema. Clinicians must be able to select appropriate therapies for initial cerebral edema management based on available evidence while balancing efficacy and safety.

METHODS

The Neurocritical Care Society recruited experts in neurocritical care, nursing, and pharmacy to create a panel in 2017. The group generated 16 clinical questions related to initial management of cerebral edema in various neurological insults using the PICO format. A research librarian executed a comprehensive literature search through July 2018. The panel screened the identified articles for inclusion related to each specific PICO question and abstracted necessary information for pertinent publications. The panel used GRADE methodology to categorize the quality of evidence as high, moderate, low, or very low based on their confidence that the findings of each publication approximate the true effect of the therapy.

RESULTS

The panel generated recommendations regarding initial management of cerebral edema in neurocritical care patients with subarachnoid hemorrhage, traumatic brain injury, acute ischemic stroke, intracerebral hemorrhage, bacterial meningitis, and hepatic encephalopathy.

CONCLUSION

The available evidence suggests hyperosmolar therapy may be helpful in reducing ICP elevations or cerebral edema in patients with SAH, TBI, AIS, ICH, and HE, although neurological outcomes do not appear to be affected. Corticosteroids appear to be helpful in reducing cerebral edema in patients with bacterial meningitis, but not ICH. Differences in therapeutic response and safety may exist between HTS and mannitol. The use of these agents in these critical clinical situations merits close monitoring for adverse effects. There is a dire need for high-quality research to better inform clinicians of the best options for individualized care of patients with cerebral edema.

Osmotherapy for malignant cerebral edema in a phase 2 prospective, double blind, randomized, placebo-controlled study of IV glibenclamide

BACKGROUND/OBJECTIVE

Malignant edema can be a life-threatening complication of large hemispheric infarction (LHI), and is often treated with osmotherapy. In this exploratory analysis of data from the GAMES-RP study, we hypothesized that patients receiving osmotherapy had symptomatic cerebral edema, and that treatment with intravenous (IV) glibenclamide would modify osmotherapy use as compared with placebo.

METHODS

GAMES-RP was a phase 2 multi-center prospective, double blind, randomized, placebo-controlled study in LHI. Patients were randomized to IV glibenclamide (e.g. IV glyburide) or placebo. Cerebral edema therapies included osmotherapy and/or decompressive craniectomy at the discretion of the treating team. Total bolus osmotherapy dosing was quantified by "osmolar load". Radiographic edema was defined by dichotomizing midline shift at 24 h. Clinical changes were defined as any increase in NIHSS1a.

RESULTS

Osmotherapy was administered to 40 of the 77 patients at a median of 39 [27-55] h after stroke onset. The median baseline DWI lesion volume was significantly larger in the osmotherapy treated group (167 [146-211] mL v. 139 [112-170] mL; P=0.046). Adjudicated malignant edema (75% v. 16%; P<0.001) was more common in the osmotherapy treated group. There were no differences in the proportion of patients receiving osmotherapy or the median total osmolar load between treatment arms. Most patients (76%) had a decrease in consciousness (NIHSS item 1A ≥1) on the day they began receiving osmotherapy.

CONCLUSIONS

In the GAMES-RP trial, osmolar therapies were most often administered in response to clinical symptoms of decreased consciousness. However, the optimal timing of administration and impact on outcome after LHI have yet to be defined.

Fluid Balance Variations During the Early Phase of Large Hemispheric Stroke Are Associated With Patients' Functional Outcome

Background: From the variety of factors underlying the ischemia-associated edema formation in large hemispheric stroke (LHS), an increased brain water content during the early phase seems to have a pivotal role for long-lasting tissue damage. However, the importance of the fluid management during the acute phase of LHS has so far not been adequately studied. Therefore, this study explored the association between the fluid balance and functional outcome in patients suffering from LHS. Methods: We analyzed hospital-based medical records of 39 consecutive patients with LHS and decompressive hemicraniectomy. Over the first 10 days after admission, the volumes of all administered fluids were assessed daily and corrected for daily urinary output and insensible loss. Functional outcome at 3 months was assessed with the modified Rankin Scale (mRS) and dichotomized into an acceptable (mRS ≤ 4) vs. a poor outcome (mRS ≥ 5). Results: Compared to patients with a poor functional outcome (n = 19), those with an acceptable outcome (n = 20) were characterized by a significantly lower cumulative net fluid balance at day 5 (1.6 ± 2.5 vs. 3.4 ± 4.4 l), day 7 (2.0 ± 2.9 vs. 4.6 ± 5.2 l), and day 10 (0 ± 2.5 vs. 5.6 ± 6.2 l). In addition to age, only the cumulative net fluid balance at day 10 served as an independent factor for poor functional outcome in multiple regression analyses. Conclusion: These data provide evidence for a critical role of the early phase net fluid balance with respect to the functional outcome after LHS. This observation leads to the hypothesis that patients with LHS might benefit from a more restrictive volume therapy. However, prospective studies are warranted to establish a causal relationship and recommendations for treatment strategies.

Treatment with Mannitol is Associated with Increased Risk for In-Hospital Mortality in Patients with Acute Ischemic Stroke and Cerebral Edema

BACKGROUND

Current guidelines state that osmotic therapy is reasonable in patients with clinical deterioration from cerebral infarction-related cerebral edema. However, there are limited data on the safety and efficacy of this therapy. We aimed to evaluate the effect of mannitol on the outcome of ischemic stroke-related cerebral edema.

METHODS AND RESULTS

We prospectively studied 922 consecutive patients admitted with acute ischemic stroke. Patients who showed space-occupying brain edema with tissue shifts compressing the midline structures received mannitol. The outcome was assessed with dependency rates at discharge (modified Rankin Scale grade 2-5) and in-hospital mortality. Rates of dependency were higher in patients treated with mannitol (n = 86) than in those who were not (97.7 and 58.5%, respectively; p < 0.001). Independent predictors of dependency were age, history of ischemic stroke and National Institutes of Health Stroke Scale (NIHSS) score at admission. Rates of mortality were higher in patients treated with mannitol than in those who were not (46.5 and 5.6%, respectively; p < 0.001). Independent predictors of in-hospital mortality were diastolic blood pressure [relative risk (RR) 1.05, 95% confidence interval (CI) 1.02-1.08, p < 0.001], NIHSS score at admission (RR 1.19, 95% CI 1.14-1.23, p < 0.001) and treatment with mannitol (RR 3.45, 95% CI 1.55-7.69, p < 0.005).

CONCLUSIONS

Administration of mannitol to patients with ischemic stroke-related cerebral edema does not appear to affect the functional outcome and might increase mortality, independently of stroke severity.