Implementation of cerebral microdialysis at a community-based hospital: A 5-year retrospective analysis

Abstract

Background: Cerebral microdialysis (MD) provides valuable information about brain metabolism under normal and pathologic conditions. The CMA 600 microdialysis analyzer received US Food and Drug Administration (FDA) approval for clinical use in the United States in 2005. Since then, cerebral MD has been increasingly utilized nationally in the multimodal monitoring of traumatic brain injury (TBI), stroke, aneurysmal subarachnoid hemorrhage, and brain tumors. We describe a 5-year, single-institutional experience using cerebral MD at a community-based hospital, Legacy Emanuel Medical Center (LEMC). Implications for the adoption and utility of MD in medical centers with limited resources are discussed.

Methods: This is a retrospective chart review and data analysis of 174 consecutive patients who had cerebral MD as part of multimodal brain monitoring. All cerebral MD catheters were placed by board-certified, attending neurosurgeons at LEMC. Clinical severity in the TBI patients was reported using initial Glasgow Coma Scale (GCS); radiologic severity was graded with the Marshall CT grading scale. Measures of the risks of MD placement included post-placement hemorrhage, cerebral infection, and dislodgement.

Results: Between July 2005 and July 2010, 248 cerebral MD catheters were placed in 174 patients undergoing multimodal brain monitoring. One hundred and eighty-five catheters were placed at the time of open craniotomy. None were associated with cranial infection. Patients ranged in age from 5 months to 90 years, with a mean of 49 years. The male to female ratio was 1.4:1. The underlying pathologies were: TBI (126), cerebral vascular accident (24), aneurysmal subarachnoid hemorrhage (17), and tumor (7).

Conclusions: Cerebral MD was readily implemented in a community-based hospital. No cerebral hemorrhages or infections were attributed to cerebral MD. Examples of how MD may be a useful adjunct in the clinical decision making of patients with brain injuries are presented.

Keywords: Brain glucose; microdialysis; multimodal brain monitoring; traumatic brain injury.

Figure 1

Characteristics of microdialysis monitoring at LEMC from 2005 to 2010. (a) Number of patients undergoing microdialysis monitoring each year from the inception of the program (07/01/05 until 07/01/10). (b) Number of microdialysis catheters placed each year from the inception of the program (07/01/05 until 07/01/10). These figures demonstrate the increase in the number of patients and catheters placed each year. This is likely the result of increased acceptance at our institution by both physicians and nursing staff. Most catheters remained in place during the first five days after insertion, and the majority of patients had one microdialysis catheter in place

Figure 2

Patient demographics and outcome. (a) Age distribution of patients who had MD catheters placed. (b) Initial GCS of the patients upon arrival to LEMC ED. These patients ultimately had MD catheters placed. (c) Marshall classification of the patients in this study. (d) Primary patient pathology of those undergoing MD monitoring. Note: There were patients who may have had more than one underlying process, but these were scored based on the pathology that was dominant and believed to be the major contributing factor for the neurological dysfunction. (e) Patient disposition at the time of discharge from LEMC. Although we did not have true formal Glasgow Outcome Score evaluations, this provides some indication of the level of patient function at the time of discharge. Although the majority of patients was in the expired, SNF, or rehabilitation groups, this may be a reflection of the fact that the sickest patients were the candidates at our institute for MD monitoring

Figure 3

Multimodal brain monitoring used in conjunction with microdialysis. (a) The number of patients with the indicated multimodal brain monitor in addition to microdialysis. (b) The number of patients who had from zero to four concurrent additional brain monitors with the microdialysis catheter

Figure 4

Microdialysis catheter placement. (a) Number of catheters that were determined by postoperative CT scans to be in normal or abnormal appearing brain. Abnormal appearing brain on CT scans included areas of low attenuation (edema) or areas of hemorrhage (from the injury). Some of the catheters were also in the ventricles or could not be seen. Presumably, the latter had been pulled out during the closure or transport and were not in the brain. (b) Example of a patient with a right frontal–parietal cranial defect after deompressive craniectomy. The arrow points to a left frontal microdialysis catheter inserted via a bolt. The tip appears to be in normal appearing brain by CT criteria. (c) The same patient in b demonstrating another catheter (denoted by the arrow) in an area of low attenuation suggestive of edema or ischemia

Figure 5

Tight and loose glycemic control. The protocols and definitions of tight and loose glycemic control which have been implemented at LEMC. These protocols have been defined based on our observations with brain MD glucose and LPR data and are similar to what have been reported

Figure 6

Example of a patient undergoing tight and loose glycemic control, the effect on LPR. ICU pilot data demonstrating MD sample analysis under conditions of tight glycemic (arrows) and loose glycemic control. Note the low brain glucose and corresponding high lactate/pyruvate ratios

Figure 7

MD ICU pilot data from a patient with a severe bifrontal TBI and ICPs in the 20–30 range and CPPs >60. Note the initial highly elevated LPRs with an upward trend. The MD data led us to perform an early bifrontal decompressive craniectomy (arrow). The LPRs immediately decreased to the normal range. The patient did extremely well