Monitoring of Cerebral Blood Flow and Metabolism Bedside in Patients with Subarachnoid Hemorrhage â€“ A Xenon-CT and Microdialysis Study

Elham Rostami,Timothy Howells,Henrik Engquist,Ulf Johnson,Anders Lewã©N,Elisabeth Ronne-Engstrã¶M,Pelle Nilsson,Per Enblad,Lars Hillered

doi:10.3389/fneur.2014.00089

Abstract

Cerebral ischemia is the leading cause of morbidity and mortality following aneurysmal subarachnoid hemorrhage (SAH). Although 70% of the patients show angiographic vasospasm only 30% develop symptomatic vasospasm defined as delayed cerebral ischemia (DCI). Early detection and management of reversible ischemia is of critical importance in patients with SAH. Using a bedside Xenon enhanced computerized tomography (Xenon-CT) scanner makes it possible to measure quantitative regional Cerebral blood flow (CBF) bedside in the neurointensive care setting and intracerebral microdialysis (MD) is a method that offers the possibility to monitor the metabolic state of the brain continuously. Here, we present results from nine SAH patients with both MD monitoring and bedside Xenon-CT measurements. CBF measurements were performed within the first 72 h following bleeding. Six out of nine patients developed DCI at a later stage. Five out of six patients who developed DCI had initial global CBF below 26 ml/100 g/min whereas one had 53 ml/100 g/min. The three patients who did not develop clinical vasospasm all had initial global CBF above 27 ml/100 g/min. High lactate/pyruvate (L/P) ratio was associated with lower CBF values in the area surrounding the catheter. Five out of nine patients had L/P ratio ≥25 and four of these patients had CBF ≤ 22 ml/100 g/min. These preliminary results suggest that patients with initially low global CBF on Xenon-CT may be more likely to develop DCI. Initially low global CBF was accompanied with metabolic disturbances determined by the MD. Most importantly, pathological findings on the Xenon-CT and MD could be observed before any clinical signs of DCI. Combining bedside Xenon-CT and MD was found to be useful and feasible. Further studies are needed to evaluate if DCI can be detected before any other signs of DCI to prevent progress to infarction.

Highlights

Positron emission tomography (PET) studies have shown that subarachnoid hemorrhage (SAH) causes both global and focal hemodynamic and metabolic disturbances in the brain early after aneurysm rupture [1], which makes the brain vulnerability for secondary insults [2,3,4]
We have introduced a new protocol for the management of SAH patients at our department adding bedside Xenon-CT to current neuromonitoring in order to measure Cerebral blood flow (CBF)
The Xenon-CT CBF measurements were performed within the first 3 days after bleeding and no complications were observed during the measurements

Summary

Introduction

Positron emission tomography (PET) studies have shown that subarachnoid hemorrhage (SAH) causes both global and focal hemodynamic and metabolic disturbances in the brain early after aneurysm rupture [1], which makes the brain vulnerability for secondary insults [2,3,4]. Cerebral vasospasm has shown to be the leading cause of morbidity and mortality following aneurysmal SAH [6]. It is estimated that 70% of the patients develop vasospasm diagnosed by angiography [7, 8], while only 30–50% develop symptomatic vasospasm [9, 10]. This discrepancy between angiographic findings and development of clinical signs is one of the reasons why the role of macrovascular narrowing has been questioned as the major mechanism for the development of ischemia. Current guidelines of the critical care management of patients with SAH recommend the use of the term delayed cerebral ischemia (DCI), defined as focal neurological impairment or decrease of Glasgow coma score, and/or radiological signs of ischemia/infarction [11]

Methods

Results

Conclusion