Elsevier

World Neurosurgery

Volume 111, March 2018, Pages e32-e39
World Neurosurgery

Original Article
Determining the Lower Limit of Cerebral Perfusion Pressure in Patients Undergoing Decompressive Craniectomy Following Traumatic Brain Injury

https://doi.org/10.1016/j.wneu.2017.11.146Get rights and content

Background

In patients with severe traumatic brain injury (TBI), maintaining systolic blood pressure >90 mm Hg, intracranial pressure (ICP) <20 mm Hg and cerebral perfusion pressure (CPP) >60–70 mm Hg is recommended to improve clinical outcomes. A recommended CPP value for patients treated with decompressive craniectomy (DC) has not been clearly studied. We aimed to determine whether the targeted CPP can be lowered in patients treated with DC.

Methods

This retrospective analysis included 191 patients who underwent DC for TBI. All patients were monitored for ICP and blood pressure during and after DC. CPP was calculated every 2 hours after DC. Patient outcomes were evaluated 6 months after initial treatment.

Results

Mean patient age was 50.8 years (median 52 years), and 79.1% of patients were male. Initial Glasgow Coma Scale score was 6.2 (median 6). Comparing clinical outcome based on postoperative ICP >25 mm Hg and <25 mm Hg, Extended Glasgow Outcome Scale score was 1.4 (>25 mm Hg) and 4.9 (<25 mm Hg) (P = 0.000). In patients maintained at ICP <25 mm Hg, mortality was increased significantly with CPP between 35 mmHg and 30 mm Hg (χ2, P = 0.029 vs. P = 0.062).

Conclusions

Patients with TBI who underwent DC with postoperative ICP maintained <25 mm Hg and CPP >35 mm Hg may have similar mortality as patients with CPP >60–70 mm Hg who did not undergo DC. For patients with TBI who undergo DC, targeted CPP might be lowered to 35 mm Hg if ICP is maintained <25 mm Hg.

Introduction

Conventional guidelines for traumatic brain injury (TBI) recommend avoiding intracranial pressure (ICP) >20 mm Hg1, 2 and systolic blood pressure <90 mm Hg1, 3 and maintaining a cerebral perfusion pressure (CPP) >60–70 mm Hg.1, 4, 5, 6, 7, 8, 9, 10, 11, 12 CPP, defined as the mean arterial blood pressure (mABP) minus ICP,2, 3, 4, 5, 11 reflects ICP and mABP simultaneously. According to the Lund theory, increased blood pressure could result in increased cerebral perfusion in patients whose cerebrovascular autoregulation is not intact.13

Decompressive craniectomy (DC) may be an alternative therapeutic strategy for patients with severe TBI with increased ICP, which can decrease the ICP and improve patient outcome.14, 15, 16, 17, 18 Most reports discuss CCP values in patients without decompressive surgery, and there are not any reports to our knowledge that recommend CCP values in patients who undergo decompression surgery. We thought that the influence of DC on not only ICP but also cerebral hemodynamics could result in a lower CPP that might be tolerable for management of patients with DC. The common practice for patients who undergo DC focuses on ICP levels. In this study, we tried to determine if a lower limit of CPP values in patients with DC surgery would lead to a good outcome.

Section snippets

Materials and Methods

This study is a retrospective observational data analysis. The treatment protocol (Figure 1) was approved by our institutional review board (UC11RISI0187). All patients or their representatives provided informed written consent for surgery.

Clinical Outcomes According to ICP Value

Comparing the clinical outcomes in patients with ICP >25 mm Hg and ICP <25 mm Hg, GOSE scores were 1.4 and 4.9, respectively (P = 0.000) (Table 1). Other prognostic factors, such as initial ICP (38.2 mm Hg vs. 26.1 mm Hg), mean arterial pressure (62.1 mm Hg vs. 71.4 mm Hg), and CPP (24.2 mm Hg vs. 59.1 mm Hg), were worse when ICP levels were >25 mm Hg compared with <25 mm Hg.

Clinical Outcomes According to CPP

Among 41 patients with postoperative ICP >25 mm Hg, only 2 patients had a favorable outcome (4.9%), and 34 patients died

Discussion

During the last several decades, much basic and clinical research has been performed on TBI. It has been reported that cerebral ischemia may be the most important secondary event affecting outcome after TBI.19, 20, 21, 22, 23, 24 Additionally, the traditional approach to treatment of patients with TBI has been to emphasize early surgical treatment of intracranial mass lesions and meticulous critical care treatment of the patient to avoid causes of secondary injury to the brain.1, 13, 14

In this

Conclusions

According to our findings, the ICP value is more important than the CPP value for the prognosis of patients with TBI. ICP >25 mm Hg and <25 mm Hg after DC surgery were more critical than CPP. If ICP is maintained at <25 mm Hg in patients undergoing DC and CPP is maintained at >35 mm Hg, the mortality is similar to patients with CPP >60–70 mm Hg without DC. The beneficial effects of DC include not only decreased ICP but also improvement of cerebral hemodynamics. Thus, we propose that CPP of 35

Acknowledgments

The authors thank Ann C. Rice, Ph.D., J. Sargeant Reynolds Community College, Richmond, Virginia, USA, for grammatical review of the manuscript.

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  • Conflict of interest statement: This research was supported by a grant from the Catholic Institute of Cell Therapy in 2016 and a grant to Do-Sung Yoo from Yuhan Pharmacy in 2015. All other authors declare that the article content was composed in the absence of any commercial or financial relationships that could be construed as a potential conflict of interest.

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