Analysis of the subdural evacuating port system for the treatment of subacute and chronic subdural hematomas
Authors: Kenning Tyler J. , Dalfino John C. , German John W. , Drazin Doniel , Adamo Matthew A. 
Published: May 2010

Object
The subdural evacuating port system (SEPS; Medtronic, Inc.) is a minimally invasive means of draining subacute or chronic subdural fluid collections. The purpose of this study was to examine a single institution's results with the SEPS.

Methods
A retrospective chart review was undertaken for all patients who underwent SEPS drainage of subdural collections. Demographic and radiographic characteristics were evaluated. Both pre- and post-SEPS CT studies were analyzed to determine the volume of subdural collection and midline shift. Hospital charts were reviewed for SEPS output, and periprocedural complications were noted. Results were classified as a success (S) or failure (F) based on the need for further subdural drainage procedures. Groups were then compared to identify factors predictive of success.

Results
Eighty-five subdural collections were treated in 74 patients (unilateral collections in 63 patients and bilateral in 11). Sixty-three collections (74%) were successfully drained. In a comparison of the success and failure groups, there were no statistically significant differences (p < 0.05) in the mean age pre-SEPS, Glasgow Coma Scale score, presenting symptoms, underlying coagulopathy or use of anticoagulation/antiplatelet agents, laterality of SDH, pre-SEPS subdural volume or midline shift, or any of the measurements used to characterize SEPS placement. There were a greater number of male patients in the success group (45 [82%] of 55 patients vs 11 [58%] of 19 patients; p = 0.04). The only statistically significant (p < 0.05) factor predictive of success was the radiographic appearance of the subdural collection. More hypodense collections were successfully treated (32 [51%] of 63 collections vs 4 [18%] of 22 collections; p = 0.005), whereas mixed density collections were more likely to fail SEPS treatment (S: 11 [17%] of 63 collections vs F: 14 [64%] of 22 collections; p < 0.00001). In the success group, the percentage of the collection drained after SEPS was greater (S: 47.1 ± 32.8% vs F: 19.8 ± 28.2%; p = 0.001) and a larger output was drained (S: 190.7 ± 221.5 ml vs F: 60.2 ± 63.3 ml; p = 0.001). In the patients with available but delayed scans (≥ 30 days since SEPS placement), the residual subdural collection following successful SEPS evacuation was nearly identical to that remaining after open surgical evacuation in the failure group. In 2 cases (2.4% of total devices used), SEPS placement caused a new acute subdural component, necessitating emergency evacuation in 1 patient.

Conclusions
The SEPS is a safe and effective treatment option for draining subacute and chronic SDHs. The system can be used quickly with local anesthesia only, making it ideal in elderly or sick patients who might not tolerate the physiological stress of a craniotomy under general anesthesia. Computed tomography is useful in predicting which subdural collections are most amenable to SEPS drainage. Specifically, hypodense subdural collections drain more effectively through an SEPS than do mixed density collections. Although significant bleeding after SEPS insertion was uncommon, 1 patient in the series required urgent surgical hematoma evacuation due to iatrogenic injury.