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Running head: IMPROVING STROKE OUTCOME 1
Mechanical Thrombectomy in Improving Stroke Outcomes
A Scholarly Project Presented to
The Faculty of the Maryville University
Catherine McAuley School of Nursing
In Fulfillment of the Requirements
For the Degree of Doctor of Nursing Practice
Taryn Denezpi
Spring 2019
Author Note
No grant or funding was needed for this scholarly project.
IMPROVING STROKE OUTCOME 2
Table of Contents
Title Page 1
Table of Contents 2-3
Abstract 4
Chapter I: Introduction 5
Purpose and Specific Aims 6
Background and PICO Question 6-7
Significance 7-8
Practice Support for Project 8-9
Benefit of Project to Practice 9
Chapter II: Synthesis of Evidence 10
Integrated Review of Literature 10-12
Literature Critique 13-15
Concepts and Definitions 15-16
Theoretic Framework 15-16
Chapter III: Project Design and Methodology 16-17
Analysis 17-18
Resources 18
Budget and Timeline 19
Protection of Human Subjects 19
Chapter IV: Findings 20-21
Interpretation of Findings 21-23
Chapter V: Discussion 23-24
IMPROVING STROKE OUTCOME 3
Limitations 24
Implications of Findings and Recommendations 24-25
Conclusion 25
References 26-27
Appendix A: table 1 28
Appendix B: Figure 1 29
IMPROVING STROKE OUTCOME 4
Abstract
The study was developed to identify if ischemic stroke patients’ ineligible for tissue plasminogen
activator (tPA) experienced an improved outcome post thrombectomy intervention as evidenced
by using the National Institutes of Health Stroke Scale (NIHSS). Methods: A randomized
retrospective chart review including 100 cases of ischemic stroke patients’ ineligible for tPA who
received mechanical thrombectomy within a large comprehensive stroke center. Use of a paired
samples t-test was utilized when analyzing pre-and-post thrombectomy NIHSS. Results: Post-
thrombectomy NIHSS scores decreased by 9 points, indicating an overall improved outcome.
Conclusion: The research demonstrates strong support for the use of thrombectomy in patients’
ineligible for tPA administration.
Keywords: (mechanical) thrombectomy, tPA ineligible, ischemic stroke
IMPROVING STROKE OUTCOME 5
Mechanical Thrombectomy in Improving Stroke Outcomes
Introduction
Experiencing a stroke can happen quickly, in just minutes to hours and can often leave
deficits that last a lifetime. According to Casey (2018), a stroke occurs when the flow of blood is
blocked or occluded by plaque or thrombus, resulting in brain tissue death. Usually, 82-92
percent of strokes are considered ischemic in nature, meaning that an artery became blocked in
the brain by a thromboembolic event (Casey, 2018). Reperfusion whether with tPA or with
mechanical thrombectomy after a stoke is essential to stroke survival and outcome improvement
(Casey, 2018). Gautheron et al. (2018) concluded that patients with large diffusion-weighted
imaging lesions such as a devastating M1vessel occlusion, highly benefit from reperfusion
therapy. Fischer et al. (2018) implies that administration of tissue plasminogen activator (tPA)
may not completely lyse thrombi that can be retrieved via mechanical recanalization.
The incidence of stroke is rising but survival rates are similarly on the rise due to early
intervention (Casey, 2018). Since most strokes are ischemic, it is vital that the healthcare
providers recognize the signs and symptoms and distinguish between them so that early
thrombolysis therapy or intervention can take place (Casey, 2018). The decision and action of
intervention is entirely in the hands of the provider, meaning that the survival and recovery after
an ischemic stroke weighs heavily on the provider’s choice of intervention or treatment.
Therefore, knowing all intervention possibilities and associated patient outcomes has become
essential to every stroke victims care. By identifying patients eligible for early thrombectomy,
perhaps a new standard of care can be utilized for ischemic stroke patients that are ineligible for
tPA administration.
IMPROVING STROKE OUTCOME 6
Purpose and specific aims
General interest involves the stroke population and the interventions that are used to
prevent and treat strokes. The fact that the world of Neuroscience is ever changing and evolving
for the betterment of each stroke victim, is utterly fascinating. Personal experience as a charge
nurse in a Neurosurgical Intensive Care unit and a rapid Code Neuro Nurse respondent in a
Comprehensive Stroke Center, demonstrated a delay of intervention could lead to lethal
outcomes during an ischemic stroke, therefore quick reperfusion has become essential. Whether
clinicians are attempting to cease brain injury and cell death that occurs during an ischemic
stroke or give the patient a better chance of rehabilitation and outcome, prompt intervention with
either tPA or thrombectomy is now the new standard of care. In the Nurse Practitioner role, it
would be beneficial to understand which intervention is most effective in improving the outcome
of ischemic strokes. Unfortunately, the gold standard of tPA administration has become the
primary standard in ischemic stroke care, with thrombectomy being underutilized in several
areas throughout the United States. If the practice of thrombectomy can be distinguished as
equally beneficial to patient care and outcome, perhaps more healthcare centers will adapt this
intervention to improve overall stroke care practice for those who are ineligible to receive tPA.
Background and PICO question
To begin constructing a literature review a question of interest must be asked about a
specific topic (Melnyk & Fineout-Overholt, 2015). Thus, the PICO (population, intervention,
comparison, outcome) question was, among patients who have experienced an ischemic stroke
and are ineligible for tPA, does mechanical thrombectomy alone in intervention improve patient
outcome as evidenced by National Institutes of Health Stroke Scale (NIHSS)? The population
are patients who have experience an ischemic stroke and are ineligible for tPA, an intervention of
IMPROVING STROKE OUTCOME 7
mechanical thrombectomy alone in treatment, with an overall outcome of improving ischemic
strokes by evidence of NIHSS. After developing the PICO question, a web based search for peer
reviewed articles was completed to assist in answering the question through a review of
literature. Maryville University’s online library data base was utilized to find all articles. Search
terms such as stroke, tissue plasminogen activator, and thrombectomy were utilized to filter full
text articles published within the last four years that were peer reviewed. Overall, all articles
supported evidence that mechanical thrombectomy is beneficial in treating ischemic stroke in
combination with tPA. There were fifteen articles of interest found for consideration. Of which,
six became primary resource articles that were reviewed for the purpose of answering the PICO
question and review of literature.
Significance
Nursing and Advanced Practice Provider
Patient safety and advocacy are the most important duties of health care professionals.
Therefore, it is apparent that nurses, Nurse Practitioners and clinicians are aware of what
intervention will be most beneficial to their patient population while inflicting the least amount
of harm possible. Through the use of evidence based research review of new stroke
interventions, health care providers can identify adverse reactions, lethal outcomes, and best
overall stroke intervention outcomes compared to existing treatments such as administration of
tissue plasminogen activator (tPA). Finally, since intervention is the only way to save ischemic
penumbra, it becomes the duty of the clinical Nurse Practitioner and neurologist to decide which
intervention is most appropriate and beneficial to the patient’s outcome and general well-being
(Liu, Zhang & Hong, 2016).
IMPROVING STROKE OUTCOME 8
Healthcare. The motivation for this study topic selection is the lack of thrombectomy use
in my current practice environment. In New Mexico, nurse practitioners are granted a wide array
of practice privileges and are used broadly in the emergency departments to care for acute
patients. When a stroke patient arrives, nurse practitioners initiate stroke protocols and consult
neurology to collaboratively work with the neurologist to determine appropriate treatment plans.
This often includes the decision of whether to administer tPA. At this time, there is limited use of
thrombectomy for ischemic stroke treatment within the city. Now that the results of the project
were found, I have presented the results to the stoke coordinator, neurologist and emergency
personnel to advance the knowledge of thrombectomy use. The stroke coordinator and
neurologist have been following the project and are planning to share the results with the
emergency department. Since the results are in favor of thrombectomy the stroke team advised
the administrator and pushed for the intervention to be used within the hospital. The facility has
just completed their first thrombectomy for acute ischemic stroke following results and
encouragement from the project and neurological team. Furthermore, the co-investigator plans
on using the data results within the participating facility to improve their own current stroke
program in terms of treatment options for patient’s ineligible for tPA administration. In
conclusion, the results will be shared with a local hospital in Albuquerque, New Mexico and
with the participating hospital in Kansas City, Missouri.
Practice Support for Project
There was ample support for this project at both the participating facility and the
receiving facility. The participating facility encouraged data collection and analysis of these
specific patients by obtaining a list of possible electronic medical records for personal review.
Their research team was also supportive of the project by assisting with the facilities IRB
IMPROVING STROKE OUTCOME 9
process. A content expert from the facility have also supported the project by shared knowledge
of the facility’s data collection process. The receiving facility in New Mexico, who has benefited
from the results mostly, supported the project by assisting in discovery of limitations and
supporting the mentality of local practice change per projects results.
Benefits of Project to Practice
The evidence supporting efficiency and increased functional outcomes with
thrombectomy alone in treatment of ischemic stroke can easily be applied to practice. While
working closely with stroke patients, tPA therapy resides as a gold standard for ischemic strokes.
Currently protocols and policies ensure each ischemic stroke patient receive tPA if they meet
eligibility criterion. However, few hospitals in New Mexico are utilizing the intervention of
thrombectomy. To push hospitals and healthcare centers to include thrombectomy as a standard
of care for ischemic stroke the identification of this intervention alone must be evaluated. It
becomes the Nurse Practitioner and clinicians job to recommend thrombectomy when the patient
is ineligible for tPA administration.
All evidence supported thrombectomy practices that are often underutilized in
several healthcare areas. However, with new research supporting mechanical thrombectomy
perhaps a new unionized ‘gold standard’ will be placed in the near future. This could be a result
of advanced research on new versus old acute ischemic stroke treatment. The only future barriers
foreseen in practice change to incorporating mechanical thrombectomy, would be lacking
resources and clinicians that are trained and capable of performing thrombectomies. However,
with thrombectomy becoming more popular in large stroke centers this is a barrier that will not
hold or stop any Nurse Practitioner from ensuring that the patient receive a thrombectomy when
IMPROVING STROKE OUTCOME 10
deemed most beneficial or essential to the patient’s needs, even if this means a transfer to a
larger stroke center.
Synthesis of the evidence
Overall, all articles supported evidence that mechanical thrombectomy is beneficial in
treating ischemic stroke in combination with tPA. There were six articles of interest included in
the literature review which became primary resource articles that were reviewed for the purpose
of answering the PICO question. There were two articles that consisted of systematic
reviews/meta-analysis; Grech et al. (2015), and Liu et al. (2016). Gautheron et al. (2018) utilized
the THRACE database to perform a randomized control study, while Muhr et al. (2017)
consisted of an exploratory cohort study. All four primary articles presented quantitative studies
that measured patient outcome after intervention with a Modified Rankin Scale. Muhr et al.
(2017) utilized both quantitative and qualitative data by including numeric number scales and
follow up questionnaires. Evidence supported by the research was strong. In every study
presented there was a statistical significance result. However, all strong evidence supported three
themes pertaining to reperfusion therapy. First, mechanical thrombectomy is effective as an
additional intervention for treatment of patients experiencing an acute ischemic stroke. Second,
thrombectomy can improve functional outcome in stroke patients when compared to standard
treatment. Lastly, there is a need to better analyze mechanical thrombectomy without the
administration of tPA in the treatment and recovery outcome of stroke patients.
Integrated Review of Literature
Efficiency of Thrombectomy
Several articles support mechanical thrombectomy in combination with tPA in treating
acute ischemic stroke. When examining mechanical thrombectomy in the reperfusion of acute
IMPROVING STROKE OUTCOME 11
ischemic strokes research supports this method as being beneficial and effective. For example,
Liu et al. (2016) used a meta-analysis that included 16 different publications of acute ischemic
stroke patients that underwent mechanical thrombectomy. This meta-analysis supported evidence
that thrombectomy is effective in treating acute ischemic stroke. Likewise, Gautheron et al.
(2018) extracted 304 patients from the THRACE database which included patients that had
received mechanical thrombectomy after intravenous tPA versus receiving tPA alone after
stroke. This resulted in strong evidence that mechanical thrombectomy/reperfusion therapy can
benefit ischemic Middle Cerebral Artery (MCA) territory strokes. Evidence supports that
regardless of the mechanism of action, tPA or thrombectomy in combination with tPA,
reperfusion therapy remains a vital tool in the treatment of acute ischemic strokes.
Improving functional outcome. Evidence supports that patients with an acute ischemic
stroke that are treated with mechanical thrombectomy tend to have a higher functional outcome
per rehabilitation efforts as compared to standard therapy (Grech et al., 2015). Grech et al.
(2015) provided a systematic review and meta-analysis with 1288 patients to determine that
mechanical thrombectomy is highly beneficial in providing the patient with long term functional
independence. Furthermore, Muhr et al. (2017) describes reperfusion therapy as a new approach
to stroke treatment and set out to determine how reperfusion therapy effects the overall health
related quality of life (HRQoL) and activities of daily living. Although, the evidence supported
that reperfusion therapy results in mild post-stroke symptoms such as strength and long-term
functioning, these patients continue to have emotional and cognitive problems. The research
evidence supports the fact that patients that receive mechanical thrombectomy after an acute
ischemic stroke have a higher functioning outcome than those who received standard care, and
therefore it is essential that the Nurse Practitioner be aware of what specific intervention is most
IMPROVING STROKE OUTCOME 12
beneficial in stroke treatment for patients who are experiencing an acute ischemic stroke. Finally,
as evidence of benefits to mechanical thrombectomy in treatment of ischemic stroke begin to
surface, the analysis of thrombectomy without the administration of tPA in treatment of ischemic
stroke needs to be identified to provide the best intervention possible to this population.
A need for analysis. When researching mechanical thrombectomy without tPA
administration in treatment of acute ischemic stroke, the limitation and scarceness of research
became evident. Studies supported the additional need to examine the difference between
thrombectomy outcomes as primary treatment for patient’s ineligible for tPA. For example,
several articles stated this concern as a limitation to the study. In fact, the lack of comparison
between thrombectomy treatment alone and tPA therapy has been under reported and under-
researched (Liu et al., 2016). Since tPA has a shorter time window for administration than
mechanical thrombectomy, the time constraint would need to be considered an ineligible
criterion when researching the outcomes of thrombectomy intervention alone. Likewise, co-
morbidities and prior use of anticoagulants or antiplatelet can become another criterion for
ineligibility for tPA administration and would need to be addressed to ensure the research results
are valid (Muhr et al., 2017). Finally, after review of evidence it appears many factors need to be
accounted for when analyzing stroke patient outcomes after thrombectomy. The need to provide
evidence that mechanical thrombectomy alone in intervention is beneficial in treating acute
ischemic stroke is vital to ensuring the highest functional outcome in those ineligible for tPA
administration. Factors such as co-morbidities and history of anticoagulant or antiplatelet use and
time of symptom onset prior to intervention need to be addressed to fully assess the reason for
tPA ineligibility and to identify a need for thrombectomy intervention alone in treating acute
ischemic stroke.
IMPROVING STROKE OUTCOME 13
Literature Critique
The overall impression of the quality of the evidence is strong. The research studies
found were reliable and valid. Large sample sizes were utilized in most quantitative studies and
significant results were found in each article. The methods that were used were appropriate for
the questions being asked by using quantitative studies. The data collection process was
sufficient with minimal limitations and appropriate exclusions were applied. Generally, each
research study coincided with the others. They all produced results that were similar yet achieved
with different methods. The end results are easily applicable to practice and patient care.
Furthermore, there were only a few areas of research that could have been expanded and could
potentially be clarified in future research studies.
Strengths
The major strengths of the evidence presented was the similarity in the process of
extracting the data. Several of the studies utilized either a meta-analysis or a retrospective chart
review. They also mostly used quantitative data throughout the study. The process was consistent
in the approach of gathering data and utilizing similar population groups with cerebral large
vessel ischemic strokes. All studies also used a similar form of evaluating outcome such as the
Modified Rankin Scale post 90 days’ intervention. By having a specific pattern to discovery, all
the articles correlated and supported the main themes and results. All articles were also
significant in their findings. The data presented, such as the 90 day Modified Rankin Scale and
the benefit of thrombectomy, was of significant significance throughout all articles adding to the
strengths. Although several strengths were identified during the review of literature, there were
also many weaknesses found as well.
IMPROVING STROKE OUTCOME 14
Weaknesses. The major weakness of the evidence presented was the fact that most
studies participants were not completely randomized. The studies, as mentioned before used
quantitative data within a meta-analysis or retrospective chart review that for the most part are
not randomized in selection. Meaning, most patients were vetting to be a part of the review. By
adding more evidence based findings of randomized, control trials and with larger sample sizes,
the identified outcomes could be considered highly valid and reliable.
Gaps. There are a few areas missing from the synthesized evidence. Most studies based
their analysis on quantitative data with one study incorporating qualitative data. To fully
understand which intervention in the treatment of acute ischemic stroke will provide the most
functional and cognitive outcomes qualitative research should be utilized as well. Also, most
patients treated were not assessed for further contributing co-morbidities such as diabetes,
hypertension and heart disease. Patients could respond to reperfusion therapies differently due to
their co-existing disorders. Furthermore, if the patient previously received tPA and received a
mechanical thrombectomy their outcome may be more positive due to the relative ease of clot
removal, therefore this should be considered when conducting further research. Lastly, some
practices may include a combination therapy of both tPA administration followed by mechanical
thrombectomy. If combination therapy is regularly practiced, it should be identified in the data
when assessing functioning outcomes after an ischemic stroke.
Limitations of existing evidence. Limitations of the studies found were co-morbidities and
prior use of anticoagulants or antiplatelet. These factors were not determined and would need to
either be included or excluded prior to intervention to ensure the research results are valid (Muhr
et al., 2017). If the aim of the overall project is to determine patient outcome in relation to
mechanical thrombectomy after an ischemic stroke then the patients’ co-morbidities and whether
IMPROVING STROKE OUTCOME 15
they were previously taking an anticoagulant/antiplatelet or tPA needs to be assessed.
Anticoagulation is a contraindication for tPA administration but not for mechanical
thrombectomy. Likewise, if a patient has multiple co-morbidities such as hypertension, diabetes,
hyperlipidemia or heart disease they may have a different outcome with thrombectomy than
those with less disorders or diseases due to the fragility of the cerebral vessels (Bendszuz et al.,
2015). By excluding these factors from most studies and retrospective chart reviews it can be
difficult to identify which intervention is most beneficial and to which specific population.
Concepts and Definitions
While working closely with stroke patients, tPA therapy resides as a gold standard for
ischemic strokes. Currently protocols and policies ensure each ischemic stroke patient receive
tPA if in the symptom onset time window of 4.5 hours. However, few hospitals in Albuquerque,
New Mexico are utilizing the intervention of thrombectomy. To push hospitals and healthcare
centers to include thrombectomy within the gold standard for ischemic stroke care, the
identification of which intervention therapy is best suited to each individual patient’s condition,
must be evaluated. The emergency department Nurse Practitioner must evaluate tPA ineligibility
factors of each ischemic stroke patient and determine if thrombectomy is a beneficial
intervention that will provide the best functional outcome. It becomes the Nurse Practitioner and
neurologists job to recommend thrombectomy if the patient is more likely to become higher
functioning with clot retrieval or if they are outside the symptom onset time window for tPA
administration.
Theoretic Framework
Betty Neuman’s System Model Theory focuses on the holistic aspect of the patient. It
focuses on which intervention or function is best suited to stabilize and realign the patient back
IMPROVING STROKE OUTCOME 16
to their best state of wellness. She uses the idea of primary, secondary and tertiary nursing care
and intervention. Neuman’s theory was easily applied to stroke patients and their care because
there are three aspects, such as primary, secondary and tertiary approaches when caring for these
patients. Primary would include prevention and education on stroke risk factors (Neuman &
Fawcett, 2011). Throughout the data collection process, stroke risk factors such as smoking,
hypertension, atrial fibrillation, diabetes and high cholesterol will be gathered on all cases to
determine which factor is most prevalent. Education can be provided to patients about these
identified risk factors to prevent future stroke. The secondary approach included the intervention
during a stroke, such as tPA or mechanical thrombectomy, and tertiary care falls into the
rehabilitation elements of the stroke victim. The project focused mostly on Neuman’s secondary
approach because the research question of interventional thrombectomy being a beneficial
treatment to ischemic stroke patients. Furthermore, the research also encompasses the third
approach by identifying if the patients had an improved outcome after thrombectomy. Since an
improved outcome was found with thrombectomy, then the patient will be better capable of
participating in rehabilitation due to less stroke residual symptoms. Her theory also focused on
taking the best approach possible to get the patient back to full wellness which is very relevant to
the concept of whether thrombectomy is a suitable intervention for ischemic stroke patients
(Neuman & Fawcett, 2011).
Project design and methodology
The project consisted of a retrospective chart review of ischemic stroke patients
conducted within a large, 629-bed, Comprehensive Stroke Center in Kansas City, Missouri. The
chosen facility performs both thrombectomy procedures and tPA administration for eligible
ischemic stroke patients. The sample included at least 100 cases treated at the facility within the
IMPROVING STROKE OUTCOME 17
last three years (2015-2018). The sample population included both female and male candidates
over the age of 18. Race was not considered for inclusion or exclusion criteria for the project, but
gathered as demographic data as a significant indicator of stroke risk. Inclusion criteria included
patients that arrived within the symptom time frame to undergo thrombectomy who were
ineligible for tPA administration. The patients presented with ischemic stroke symptoms and had
a positive CT head angiogram/perfusion for a large vessel occlusion stroke. Pre-existing
anticoagulation therapy or antiplatelet therapy was not either inclusive or exclusive to this
project. Exclusive criteria included the use of tPA administration prior to a thrombectomy
procedure. The facility’s stroke coordinator assisted in retrieving charts for review.
By following the inclusion and exclusion criteria, a retrospective approach to reviewing
applicable patient cases was completed. Once the charts were reviewed a measurement of patient
improvement post thrombectomy was located by examining the patient’s pre-intervention NIHSS
(National Institutes of Health Stroke Scale) score as compared to their discharge NIHSS score.
This scale is included in the facility’s stroke protocol as a mandatory, standard measurement.
There was no subjectivity and was universal in any setting such as the Emergency Department
and Intensive Care Unit. Due to minimal risk of the research and the non-effect on the patient’s
rights and welfare, consent did not need to be obtained from the chosen chart reviews. However,
the facility did require additional IRB approval and mandatory requirements such as evidence of
CITI training prior to project initiation.
Analysis
The test chosen for this project’s data analysis was a paired t-test. A paired t-test is often
used when there is a need to compare two groups (Shier, 2004). For example, the need to
compare one set of values or population group to another set of values or population group. This
IMPROVING STROKE OUTCOME 18
type of statistical test is commonly seen in before and after studies to determine if a significant
change or when improvement has occurred (Shier, 2004). The data collected was quantitative
and the mean was found on both pre-and-post intervention NIHSS prior to analysis with a paired
t-test. The NIHSS change scores were calculated by subtracting the pre-thrombectomy score
from the post-thrombectomy score (post-intervention minus pre-intervention). A Paired-samples
t-test was conducted on the mean change NIHSS scores. The significance level was set at
alpha=0.05.
The rationale behind using a paired t-test was due to the need to compare pre- and –post
NIHSS to determine patient outcome. Overall, the mean of both the pre-and-post thrombectomy
NIHSS needed to be analyzed with a paired t-test to determine if the patient deteriorated or if
they improved due to mechanical thrombectomy alone in the treatment of ischemic stroke. By
comparing these means in a paired t-test a result that analyzes before and after results could be
made. Overall, this was the correct analysis to perform on this scholarly project to determine true
patient outcome.
Resources
Overall, the resources needed included leadership from the stroke coordinator to assist in
determining and identifying charts for review. Also, since the measurement of outcome was
based on a clinical NIHSS, all nursing faculty had to be compliant with the hospitals protocol on
completing a baseline NIHSS and a discharge NIHSS. The use of the emergency department for
evaluation of these stroke candidates, as well as the Neuro-Interventional radiologist needed to
be included for consistency throughout the project. The use of the CT machine was vital when
attempting to diagnose the patient with a large vessel acute ischemic stroke. Lastly, since this
project was completed as a retrospective approach the cost was completely insignificant.
IMPROVING STROKE OUTCOME 19
Budget and timeline
As stated before, this project carried no known cost, funding or grants. Once the approval
of the IRB, the plan included extracting eligible charts for review. This process was free of
charge per the facility’s stroke coordinators efforts. Furthermore, the data analysis was also free
of charge per assistance from Maryville University’s statistician, stroke coordinator and main
researcher. Although the cost of thrombectomy or CT imagining could have been considered,
since these measures have already been completed and paid for they were not considered within
this specific project. Likewise, the cost of nurse work production could also be connected,
however, again the production hours had already been accounted for. The timeline of this project
seemed to stay on tract. The IRB approval, both within the University and facility’s preference
was achieved by January 2019. Data collection began immediately and was completed
throughout the following 8 weeks. Data analysis took place during the following 3 weeks after
data collection. A final report was completed and finalized by May 2019.
Protection of Human Subjects
When data was collected for this project the main concern was conducting a breach of
confidentiality. Since, the participants did not need to be consented the use of their private
information was shared mostly without their knowledge. To protect the human rights of each
individual participant a request to remove identifying information, such as names or initials,
from the patient’s chart was included. Any further identifying information such as age and
gender was carefully used within the final phases as to not expose any of the participants. A key
linked to the data collection spreadsheet was the only file with identifying information. This key
was locked within a password protected computer within the facility. The key was then
IMPROVING STROKE OUTCOME 20
destroyed per facility after analysis had been completed. All measures were taken to protect and
respect the terms of HIPPA for the patients included within the study.
Findings
One hundred cases were obtained through a randomized retrospective chart review
between the years of 2015-2018. Of the cases fifty-eight males and forty-two females were
identified, with a mean age of seventy-three. Eighty-two present were Caucasian, fourteen
percent black with a remaining small one percent each of Vietnamese, Hawaiian and American
Indian. Also, a small one percent of the population was unknown of race due to lack of
documentation. Inclusion criteria included the presentation of an acute ischemic stroke who
received mechanical thrombectomy and who were ineligible for tPA administration. Exclusion
criteria included the administration of tPA. Stroke risk factors were also gathered from the
sample size. It was found that seventy-two percent of the 100 cases did not have diabetes, while
twenty-five percent was positive for diabetes, three percent unknown. Forty-three percent
presented with high cholesterol, fifty three percent without and four percent unknown. The risk
factor of current tobacco use (smoking) was found in thirty-one percent of the cases, however
twenty percent were found to be former smokers. Thirty-two percent of the cases did not smoke,
while an under documented seventeen percent was unknown. Of all the risk factors hypertension
was found to be the most predominant with a total of seventy-eight percent of the cases with high
blood pressure. Only eighteen percent of the cases were without hypertension and four percent
left unknown. Atrial fibrillation was seen in thirty-five percent, leaving sixty-one percent absent
of atrial fibrillation and a remaining four percent unknown.
All together the reason for tPA inedibility was mainly due to the patient
presenting outside of the ‘symptom onset time-window’ to receive tPA. A robust seventy percent
IMPROVING STROKE OUTCOME 21
of the cases did not receive tPA based upon their time of symptom onset. Nineteen percent were
without tPA because of a history of anticoagulant use. Five percent had recently had a surgery of
some sort and four percent had a history of recent stroke prior to the current episode. A small
percentage of one percent each was left without tPA due to active bleeding and uncontrolled
hypertension. National Health Institutes Stroke Scale (NIHSS) was used in comparison of pre-
and-post thrombectomy outcome. Therefore, the data collection of pre-thrombectomy NIHSS
and post-thrombectomy NIHSS were utilized in the analysis to identify patient outcome. A
paired samples t-test was completed with a mean pre-thrombectomy NIHSS score of eighteen
and a mean post-thrombectomy score of nine. The paired t-test was utilized by subtraction of
post minus pre, with a p=0.05. Overall t=- 9.89, giving a decrease of nine on the post-
thrombectomy NIHSS.
Interpretation of Findings
According to Polit and Beck (2017) the researcher must ask specific questions when
interpreting quantitative data and results. Therefore, the first question is if all the important data
is discussed. All data including, age, gender, risk factors (diabetes, hypertension, atrial
fibrillation, smoking, high cholesterol) and reason for tPA ineligibility were discussed. Age is
presented as a mean (73) while the other criteria is presented in percentages. There were 58
males and 42 females collected at random. The population consisted of Caucasian (82%), black
(14%) and only a small make up of Vietnamese, Hawaiian and American Indian (1% each).
Twenty-five percent of the cases had diabetes while only forty-three percent had high
cholesterol. Hypertension was found in seventy-eight percent of the cases and thirty-five percent
presented with atrial fibrillation. There was a split between the population who smoked. Thirty-
one percent were current smokers, twenty percent were former smokers and thirty-two percent
IMPROVING STROKE OUTCOME 22
never smoked. Overall the most common reason for tPA ineligibility was found to be time of
symptom onset outside of the tPA administration window (70%).
A paired t-test was conducted on the pre-and-post thrombectomy NIHSS scores
and is discussed in terms of a p-value of 0.05. Limitations of the study included a sample size of
100 cases only and a population predominant in the Caucasian race. There were no known
threats or biases in the study. The data was collected at random through personal chart review.
The evidence that is in support of the interpretation of thrombectomy improving patient outcome
was that the paired t-test resulted in a t=-9 when post NIHSS was subtracted from pre NIHSS.
Meaning that patients NIHSS scores improved by around 9 points after receiving thrombectomy.
This evidence was very persuasive in demonstrating a positive correlation with the treatment.
There was no supplementary analysis undertaken when conducting the paired t-test. This is
because there was no need for extra analysis. A paired t-test clearly demonstrates a difference
between means, especially in pre-and-post scores, which is exactly what this study entailed.
There were no convincing alternatives to the findings. Although risk factors were collected for
review they did not seem to imply a difference in the statistical analysis of the study.
Furthermore, age and gender did not play a role in the findings due to both male and
female, as well as age range, both responded to thrombectomy similarly. The results seem
precise due to the randomization of the data collected and the three-year period in which the
cases occurred. The magnitude of the effects was immense due to the overwhelming positive
correlation between thrombectomy and patient outcome. As far as generalizability, the research
was conducted in one facility and it is unknown if the same results would be found in another
facility. The only variable that would change is the physician performing the thrombectomy. Due
to differences in technique and practice the results may be slightly different with other physicians
IMPROVING STROKE OUTCOME 23
in another facility. However, the practice of thrombectomy can benefit other populations and be
used for other conditions, such as an acute myocardial infarction in the heart disease population.
Discussion
The overall results of the research concluded that in a sample of 100 cases who received
mechanical thrombectomy alone in the treatment of an ischemic stroke, those patients
experienced a decrease in their NIHSS scale by nine points, implying an improved patient
outcome. The risk factors gathered throughout the study implied hypertension is often found in
the presence of an acute ischemic stroke. Another large correlation found within the stroke risk
factors was smoking, due to the large sample size that were currently or had been a former
tobacco smoker. The cause for ineligibility of tPA administration was largely related to the
patient’s time of symptom onset. With the results found in this quantitative randomized
retrospective chart review with analysis of a paired t-test, promotion for the practice of
mechanical thrombectomy should be supported. In areas that are without mechanical
thrombectomy, it would be beneficial to transfer the patient to a facility capable of the procedure.
Currently, emergency departments in the local area rely of nurse practitioners to provide care
that will provide the patient with the best possible outcome. Therefore, the knowledge of
beneficial outcomes with the treatment of mechanical thrombectomy alone in the acute stroke
population is vital.
Previous research trials have found a correlation between positive patient outcome with
dual therapy (tPA plus thrombectomy) as well as tPA administration alone. In the future, it
would be beneficial if a similar research study could be conducted on mechanical thrombectomy
alone with a larger sample size and throughout several different facilities combined. Practice
recommendations include supporting the use of mechanical thrombectomy in patients’ ineligible
IMPROVING STROKE OUTCOME 24
for tPA administration as well as advocating for patient transfer to thrombectomy capable
facilities. Finally, with the clear presentation of hypertension and smoking in the majority of the
cases, smoking cessation and management of hypertension should be discussed and encouraged
with all patients. This education can be provided in any healthcare setting by advanced practice
providers and could even begin at a local community level.
Limitations
The study included a retrospective chart review by utilizing electronic medical records.
The data was quantitative in that scores of a standardized scale were collected as well as
documented stroke risk factors. The limitations found within this study were mostly found within
the data collection process. Some data pertaining to discharge NIHSS were missing in some
cases. The reason behind the absence of documentation was unknown. However, since this data
was ultimately missing in some electronic medical records, these cases could not be included
within the study. Furthermore, the data was collected by one researcher through personal chart
review, therefore there is a possibility of data entry error. Data entry error was attempted to be
minimized by ensuring that the data collected was transcribed in multiple formats for extensive
review of conflicting values after the collection process and before analysis.
Implications of Findings and Recommendations
The implications of the findings would recommend that thrombectomy be used as
treatment for patients experiencing an ischemic stroke and who are ineligible for tPA
administration. Clinical practice should incorporate the practice of thrombectomy within their
facilities. Likewise, nurse practitioners should carefully assess acute strokes for ineligible tPA
criteria and support the treatment of thrombectomy in this specific population. Studies have
suggested tPA as the gold standard of treatment and have shown benefits of dual treatment (tPA
IMPROVING STROKE OUTCOME 25
plus thrombectomy) (Gautheron, et al., 2018). However, a large population of patients present
with ineligible tPA criteria, such as time of symptom onset, prior stroke or surgery or are
currently on anticoagulants. Thus, the need for quick effective intervention to treat ischemic
stroke is vital and with proper analysis it appears thrombectomy is highly beneficial to the
patient’s outcome, regardless of age, gender and stroke risk factors. The statistical and clinical
significance parallel each other because the result which proved to be significantly significant
also plays a large role in patient outcome, implying that the patient has a significant (positive)
outcome as well.
Conclusion
In conclusion, after analysis of a paired t-test calculating the difference between means
(post NIHSS minus pre NIHSS) the results demonstrated a significant difference between
outcomes. With a p-value of 0.05 and an overall t= -9, the loss of NIHSS points after
thrombectomy dropped by 9, indicating patient improvement. Demographic data and stroke risk
factors were gathered as additional data for review and arranged as means and percentages. The
overall practice recommendation would be to assess for thrombectomy indication and support the
use of thrombectomy in the ischemic stroke population that is ineligible for tPA administration.
IMPROVING STROKE OUTCOME 26
References
Casey, G., (2018). Understanding stroke. Kai Tiaki Nursing New Zealand, 24 (2).
Fischer, U., Kaesmacher, J., Molina, C., Selim, M., Alexandrov, A., & Tsivgoulis, G., (2018).
Primary thrombectomy in tPA (tissue-type plasminogen activator) eligible stroke patients
with proximal intracranial occlusions. Stroke, 49, pg. 265-269.
Gautheron, V., Xie, Y., Tisserand, M., Raoult, H., Soize, S., Naggara, O., Bourcier, R., Richard,
S., Guillemin, F., Bracard, S., & Oppenheim, C., (2018). Outcome after reperfusion
therapies in patients with large baseline diffusion-weighted imaging stroke lesions a
THRACE trail (mechanical thrombectomy after intravenous alteplase versus alteplase
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Grech, R., Schembri, M., & Thornton, J., (2015). Stent-based thrombectomy versus intravenous
tissue plasminogen activator in acute ischemic stroke: a systematic review and meta-
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Liu, Y., Zhang, L., & Hong, P., (2016). Efficacy and safety of mechanical thrombectomy in
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IMPROVING STROKE OUTCOME 27
Shier, R. (2004). Statistics: 1.1 paired t-tests. Mathematics Learning Support Centre. Retrieved
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IMPROVING STROKE OUTCOME 28
Appendix A
Tables Table 1 Paired t-test Post/pre thrombectomy means
Post Thrombectomy Pre Thrombectomy Mean 9.24 18.2 Variance 80.56808081 63.15151515 Observations 100 100 Pearson Correlation 0.432785977 Hypothesized Mean Difference 0 df 99 t Stat -9.895981362 P(T<=t) one-tail 9.22366E-17 t Critical one-tail 1.660391156 P(T<=t) two-tail 1.84473E-16 t Critical two-tail 1.984216952
Figure 1.8- Paired t-test demonstrating post thrombectomy NIHSS means minus pre
thrombectomy means. P-value 0.05, t= -9.
IMPROVING STROKE OUTCOME 29
Appendix B
Figure 1.7- tPA ineligible criteria demonstrated in percentage in 100 thrombectomy cases for the
treatment of ischemic stroke.
70%
5% 4%
19%
1% 1%
tPA ineligibility
Outside time-window
Prior surgery
Prior stroke
Anticoagulants
Active bleeding
Uncontrolled Hypertension
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