The KEEP SIMPLEST Study: Improving In-House Delays and Periinterventional Management in Stroke Thrombectomy—A Matched Pair Analysis

  • Silvia SchönenbergerEmail author
  • Dorothea Weber
  • Matthias N. Ungerer
  • Johannes Pfaff
  • Simon Schieber
  • Lorenz Uhlmann
  • Pia Heidenreich
  • Martin Bendszus
  • Meinhard Kieser
  • Wolfgang Wick
  • Markus A. Möhlenbruch
  • Peter A. Ringleb
  • Julian Bösel
Original Article


Background and Purpose

Although the treatment window for mechanical thrombectomy (MT) in patients with acute ischemic stroke (AIS) has been extended in recent years, it has been proven that recanalizing treatment must be administered as soon as possible. We present a new standard operating procedure (SOP) to reduce in-house delay, standardize periinterventional management and improve patient safety during MT.


KEep Evaluating Protocol Simplification In Managing Periinterventional Light Sedation for Endovascular Stroke Treatment (KEEP SIMPLEST) was a prospective, single-center observational study aimed to compare aspects of periinterventional management in AIS patients treated according to our new SOP using a combination of esketamine and propofol with patients having been randomized into conscious sedation (CS) in the Sedation versus Intubation for Endovascular Stroke TreAtment (SIESTA) trial. Primary outcome was early neurological improvement at 24h using the National Institutes of Health Stroke Scale, and secondary outcomes were door-to-recanalization, recanalization grade, conversion rate and modified Rankin Scale (mRS) at 3 months.


Door-to-recanalization time (128.6 ± 69.47 min vs. 156.8 ± 75.91 min; p = 0.02), mean duration of MT (92.01 ± 52 min vs. 131.9 ± 64.03 min; p < 0.001), door-to-first angiographic image (51.61 ± 31.7 min vs. 64.23 ± 21.53 min; p = 0.003) and computed tomography-to-first angiographic image time (31.61 ± 20.6 min vs. 44.61 ± 19.3 min; p < 0.001) were significantly shorter in the group treated under the new SOP. There were no differences in early neurological improvement, mRS at 3 months or other secondary outcomes between the groups. Conversion rates of CS to general anesthesia were similar in both groups.


An SOP using a novel sedation regimen and optimization of equipment and procedures directed at a leaner, more integrative and compact periinterventional management can reduce in-house treatment delays significantly in stroke patients receiving thrombectomy in light sedation and demonstrated the safety and feasibility of our improved approach.


Endovascular stroke treatment Thrombectomy Blood pressure Workflow Conscious sedation General anesthesia 


Author Contributions

SS designed the study protocol, organized the trial, screened and recruited study subjects, collected and interpreted data, did the literature research, and wrote the manuscript. DW did the statistical analysis, created tables, and wrote the statistical analysis section of the manuscript. MU collected and interpreted data, did the literature research, and wrote the manuscript. WW helped with study design, implementation and realization of the trial, interpreted data, planned the manuscript structure and critically reviewed the manuscript. JP, SS and PH collected data and critically reviewed the manuscript. LU helped with design of the statistical analysis and the statistical section of the manuscript and reviewed the manuscript. MM and MB contributed neuroradiological components to the study design, interpreted data, and critically reviewed the manuscript. PAR contributed to implementation and conduct of the trial, screened study subjects, interpreted data and critically reviewed the manuscript. MK provided the biostatistical contribution to the protocol, wrote the statistical analysis plan, organized statistical data analysis, wrote the statistical analysis section of the manuscript and critically reviewed the manuscript. JB had the idea for the trial, designed the study protocol, planned, prepared, organized, supervised the trial, screened study subjects, interpreted data, did the literature research and wrote the manuscript.

Source of Support

The study was performed with departmental funding only.

Conflicts of Interest

Silvia Schönenberger, Matthias Ungerer, Dorothea Weber, Lorenz Uhlmann, Meinhard Kieser and Wolfgang Wick have nothing to disclose. Johannes Pfaff has received travel and meeting expenses from Stryker, and MicroVention. Martin Bendszus has received grants and personal fees from Novartis, Guerbet and Codman, personal fees from Vascular Dynamics, Merck, BBraun, Roche, Teva, Springer and Bayer Vital, grants from Siemens, Hopp Foundation, European Union and DFG. Peter A. Ringleb has received personal fees and non-financial support from Boehringer Ingelheim, personal fees from Bayer, Daiichi Sankyo, Covidien and BMS. Markus Möhlenbruch has received personal fees from Codman, MicroVention, Phenox and Stryker. Julian Bösel has received personal fees (speaker honoraria and travel support) from Boehringer Ingelheim, Sedana Medical, CR Bard and Zoll.

Ethical Approval

The corresponding author confirms the adherence to ethical guidelines, and the trial was approved by our institutional review board (Ethikkommission Medizinische Fakultät Heidelberg, ID S-325/2015).

Supplementary material

12028_2018_667_MOESM1_ESM.docx (1.1 mb)
Supplementary material 1 (DOCX 1103 kb)


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Copyright information

© Springer Science+Business Media, LLC, part of Springer Nature and Neurocritical Care Society 2019

Authors and Affiliations

  • Silvia Schönenberger
    • 1
    Email author
  • Dorothea Weber
    • 2
  • Matthias N. Ungerer
    • 1
  • Johannes Pfaff
    • 3
  • Simon Schieber
    • 1
  • Lorenz Uhlmann
    • 2
  • Pia Heidenreich
    • 1
  • Martin Bendszus
    • 3
  • Meinhard Kieser
    • 2
  • Wolfgang Wick
    • 1
  • Markus A. Möhlenbruch
    • 3
  • Peter A. Ringleb
    • 1
  • Julian Bösel
    • 1
    • 4
  1. 1.Department of NeurologyHeidelberg University HospitalHeidelbergGermany
  2. 2.Institute of Medical Biometry and InformaticsUniversity of HeidelbergHeidelbergGermany
  3. 3.Department of NeuroradiologyHeidelberg University HospitalHeidelbergGermany
  4. 4.Department of NeurologyKassel General HospitalKasselGermany

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