Article, Neurology

Drill down analysis of door-to-needle time of acute ischemic stroke patients treated with intravenous tissue plasminogen activator

a b s t r a c t

Objective: Target stroke guidelines recommend a Door-to-needle time of <=60 minutes for acute ischemic stroke patients treated with intravenous (IV) Tissue-type plasminogen activator . We sought to analyze all diagnostic steps involved in the acute evaluation and treatment of AIS with IV tPA and to look for causes of delay in door to needle time (DNT).

Methods: A review of AIS patients treated in the emergency department with IV tPA. Times comparing intervals from door to head computed tomography , CT result, electrocardiogram (ECG), chest radiograph, and IV tPA treatment. Non-modifiable delays in treatment were recorded. Data are presented in minutes (min) as medians with interquartile range and logistic regression was used as appropriate.

Results: A total of 79 AIS patients, with 22 (28%) receiving IV tPA <=60 minutes were analyzed. Patients were more likely to get treated with IV tPA in <=60 minutes if symptom onset was N 90 minutes (OR 3.52; 1.03- 12.1; P b .05) or if the ECG was done after the head CT (OR 3.67; 1.29-10.5; P b .02). Unavoidable delays related to trauma, intubation, or delayed familial consent occurred in 13 (16%) patients.

Conclusions: An ECG performed before the head CT is completed increased CT time by 6 minutes and a chest radiograph obtained before the head CT increased CT time by 13 minutes. DNT <=60 minutes for AIS patients are affected by the order of diagnostic studies. In a minority of patients the DNT is affected by non-modifiable issues.

Introduction

acute ischemic stroke is a common illness presenting to emergency departments with an incidence of nearly 700,000 in the United States annually [1,2]. The American Heart Association (AHA) currently recommends the use of tissue-type plasminogen activator (tPA) for eligible patients presenting with AIS [3]. Several studies have shown that the earlier an AIS patient receives tPA the better the clinical outcomes [4-6]. Rapid treatment with IV tPA improves AIS patient outcomes including morbidity and mortality, and results in lower rates of symptomatic intracranial hemorrhage (sICH) [5-7]. Understanding this early treatment effect, the AHA recommended a door to needle time of <=60 minutes for AIS patients treated with intravenous tPA. [3] Although much emphasis has been placed on improving door to needle times in 60 minutes or less, the percentage of AIS patients in which this is achieved has remained less than 30% over the course of several years [7]. This time goal for treatment was later incorporated into the AHA’s “Get With the Guidelines” and remains a metric followed by hospitals

? This research was presented at the International Stroke Conference in Honolulu Hawaii 2013.

?? Disclosures: none.

* Corresponding author.

E-mail address: [email protected] (J.W. Schrock).

1 Both authors are responsible for study design, data collection and analysis and manuscript preparation.

designated as primary or comprehensive stroke centers by the joint commission. The AHA has recently made recommendations that all Joint Commission approved primary stroke center hospitals and free standing Emergency Departments treat at least 80% of their eligible AIS patients with IV tPA within 60 minutes of arrival [8]. As of 2011 the Joint Commission states that there are over 1000 primary stroke centers in 50 states and Puerto Rico and 74 comprehensive stroke centers.

There have been several approaches to evaluate the processes of patient flow in the emergency department and improve DNT. Olsen et al conducted a telephone interview of multiple stroke centers to determine best practices [9]. Ford et al used value stream analysis and Lean methodology developed by the automaker Toyota to determine inefficiencies and showed an improvement in DNT using a before and after study design [10].

We sought to evaluate our DNT using a drill down analysis approach. A drill down analysis (sometimes referred to as root cause analysis) takes summary data and then attempts to take a closer look at the individual data which is contained in the summary data [11]. We wanted to analyze the individual components of the evaluation of the AIS patient to see where potential delays occur.

Methods

We performed a retrospective study to evaluate delays in delivery of tPA in our AIS patients from October 2007 through March 2012.

http://dx.doi.org/10.1016/j.ajem.2014.08.002 0735-6757/

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The study obtained a waiver of informed consent from our local hospital Internal Review Board.

This study was conducted at a large county owned hospital with an emergency department (ED) census of 100000 visits per year. Our ED is part of a large urban hospital which accepts some stroke transfers but the vast majority of stroke patients arrive via EMS or self- transportation. Our institution has been a certified primary stroke center since 2004. Since we were evaluating processes in the emergency department all in-hospital strokes were excluded. Patients who went on to only receive intra-arterial tPA were excluded as well. We developed areas of analysis including; flow (performing studies in the correCT order) discovery (recognizing the patient has an acute stroke) cognition (interpreting test results in a timely fashion and making the decision to treat) communication (obtaining the test results) consent (allowing the patient time to offer informed consent), mechanical (problems with CT scanner or lab instruments not working), and medical (Severe hypertension which must be lowered before tPA can be safely administered or need for intubation). Using a structured instrument we evaluated the medical records of all AIS patients presenting to our emergency department who received intravenous tPA. Data collected included demographics, results of the National Institutes of Health Stroke Scale performed in the ED, the Modified Rankin scale (mRS) performed at ED arrival and hospital discharge, Method of arrival, disposition, rates of intracranial hemorrhage, and CT results. Hemorrhages were recorded and defined as sICH if the resulted in an increase of >=2 on the motor portion of the NIHSS or >=1 on the level of consciousness portion of the NIHSS as used in the NINDS trial [12]. Also recorded were the times during the ED stay for the following events: arrival, laboratory tests complete, arrival in CT scan, time the electrocardiogram (ECG) was performed, the time the chest radiograph was performed, time CT scan completed, CT report read, IV tPA started, and any consultation times. Particular attention was placed on the sequential order of ancillary studies such as CXR and ECG. Any other specific delays to treatment with tPA that were documented in the chart were noted as well such as problems with consent, intubation for airway protection, or medical

treatment of severe hypertension.

All data were abstracted using a structured instrument. Spot checking by the lead PI was performed on 25% of the data to ensure accuracy. All data was abstracted using EPIC (Verona, WI, USA) which is our hospital electronic medical record. Timing for all testing is time stamped in the medical record.

Data analysis

Statistical analysis was performed using STATA 11.0 (StataCorp LP; College Station, TX). Data are presented as frequencies or medians with interquartile ranges (IQR) where appropriate. Univariate analysis with odd ratios was performed to determine which order of testing and what factor the duration of the patients symptoms had on reaching the goal of DNT of b 60 minutes. For this the duration of symptoms of 90 minutes or greater was used to evaluate as it has been shown previously that patients with longer duration of symptoms were more like to achieve the DNT goal of 60 minutes [7].

Results

We evaluated 79 subjects over our study period who met inclusion criteria of which 39 (49%) were male. Demographic data can be seen in Table 1. The median NIHSS score for subjects was 12 (IQR 7-19). The median Time to administration of tPA from arrival was 84 minutes (IQR 60-110 minutes). Door to CT time was 20 minutes (IQR 13-28 minutes) while door to CXR and door to ECG were 20 minutes (IQR 13-28 minutes), respectively. Among patients who received a CXR prior to CT their door to CT time was 32 minutes (21-38 minutes) compared to 19 minutes (13-27 minutes) for those who did not have

Table 1

Demographics

Demographic N = 79 (%)

Male 39 (49)

Age 70 y (IQR 56-82)

ED NIHSS 12 (IQR 7-19)

ED mRS+- 5 (3-5)

Discharge mRS+- 4 (2-5)

EMS 68 (86)

Self 5 (6)

Flight 6 (8)

ECG prior to CT 43 (54)

CXR prior to CT 9 (11)

Disposition

Home 35 (44)

Skilled nursing facility 13 (16)

Rehab 20 (25)

Hospice 3 (4)

Morgue 8 (10)

a CXR prior to CT. Among patients who underwent ECG prior to CT their door to CT time was 23 minutes (15-36 minutes) compared to 17 minutes (10-24 minutes) for those who had their ECG after CT. Figure shows the mRS upon arrival and after treatment. The odds of treatment with tPA in 60 minutes or less was significantly higher in those who had their ECG performed after CT, OR 3.67 (1.29-10.5, P b

.02). Patients who arrived more than 90 minutes after symptoms onset were more likely to be treated in less than 60 minutes, OR 3.52 (1.03-12.1 P b .05). Having a CXR performed prior to head CT and receiving treatment with tPA in b 60 minutes was suggestive of delayed treatment; however, this was not statistically significant, odds ratio 0.29 (0.3-2.5). The number of subjects with the various patterns of testing and the times to head CT can be seen in Table 2.

Several other areas were seen to delay the administration of tPA. Areas of patient care that were seen to extend door to needle times time includED patient flow in 38(48%) patients, cognition (or interpreting tests rapidly and making a decision to treat) in 15 (19%) patients, and communication problems concerning CT results in 18 (23%) patients. In a small group we found delays in consent in 3 (4%) patients, mechanical problems including problems obtaining lab results and adequate CT images in 7 (9%) patients. Medical problems which delayed treatment included trauma presentations and severe hypertension which required medical treatment before tPA could be safely given in 10 (13%) patients. Post tPA hemorrhages occurred in 13 (16%) of which 10 (13%) were sICH. For the cohort 8 (10%) of patients expired.

Discussion

Our drill down analysis found delays in DNT created by the order in which testing occurred. We found this analysis useful in describing exactly what happens to our AIS patients as they proceed with their workup. Some advantages of this process are that it does not require a group or committee, if performed correctly, it can provide specific individualized measurements which can be acted upon, and these data points can be followed in a prospective fashion to assess future quality parameters.

We found the order of testing in AIS patients may change their times to treatment. Testing should be prioritized with head CT and blood analysis being of the utmost importance. Other testing including CXR and ECG should be delayed until the head CT is performed. If the ECG is performed prior to the head CT this will delay the CT time by 6 minutes. Likewise if the CXR is performed prior to the head CT this will increase the CT time by 13 minutes. There may be clinical scenarios where it may be prudent to move up the timing of the CXR and/or ECG. Specifically in patients with chest or back pain suggestive of acute myocardial infarction or aortic dissection where tPA administration may be life threatening. This was not the case in

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pre treatment

mRS 0

mRS 1

mRS 2

mRS 3

mRS 4

mRS 5

mRS 6

post treatment

Figure. modified Rankin Score (mRS) N = 79.

our sample as none of the subjects had either an aortic dissection or acute myocardial infarction. While it is important to consider these entities, they are present in a very small minority of patients arriving with AIS.

How centers go about reaching this goal may differ. Other centers have taken a similar approach to ours which evaluated work flow and how the patient progresses through the medical system [10,13,14]. Some institutions may utilize point of care testing to more rapidly obtain the results of International Normalized Ratios and platelet counts.

Some stroke centers are utilizing pre hospital notification to allow time to prepare their stroke team and make available the CT scanner immediately when the patients arrives [15,16]. While this would be expected to improve times it also may subject patients presenting with stroke mimics to unnecessary testing. Rates for stroke mimics presenting from emergency departments for code stroke consultation have ranged from 7% to 31% [17-20]. As many emergency physicians will have an expectation to treat with tPA in an hour or less from arrival, with a limited examination. The issues of stroke mimics raises concern that some patients with exposed to tPA unnecessarily.

Currently there are over 800 primary stroke centers in 49 states who now have an expectation of treatment with tPA for AIS in less than 60 minutes. The vast majority of these patients will present to emergency departments and will rely on emergency physicians deciding who should receive tPA for AIS.

An important distinction in our institution is the use of CT angiogram on all patients who present with acute stroke symptoms inside the time window for treatment with tPA. While this adds about 7 minutes to the evaluation of our patients as well as the overall radiation dose, we feel it is important in determining which patients may benefit from intra-arterial stroke treatment.

The rate of sICH was higher for our population than seen with other studies [12]. We believe this was due in part to the median age of 70 for this sample although other factors may play a role as well. Also as a public hospital we see a large proportion of patients with undertreated or untreated conditions such as hypertension.

Table 2

Order sequence and times to head CT in minutes

Order sequence N (%)

ECG prior to CT 43 (54)

CXR prior to CT 9 (11)

Times to head CT Median (IQR), min

Door to CT (ECG before CT) 23 (15-36)

Door to CT (ECG after CT) 17 (10-24)

Door to CT (CXR before CT) 32 (21-38)

Door to CT (CXR after CT) 19 (13-27)

Door to tPA (ECG before CT) 95 (75-111)

Door to tPA (CXR before CT) 105 (96-105)

Door to tPA (CT before both CT and ECG) 66 (51-86)

This study has several limitations. It relies on experiences from a single institution which may not be transferable to every institution. Our institution performs head and neck CTA to evaluate all AIS patients for both IV and IA tPA therapy. Other institutions may prefer to perform emergent magnetic resonance imaging either in place of, or in addition to, head CT prior to making determinations of the use of tPA. These alternate practice patterns may have different or unique variables which may impede upon the DNT for AIS. Other institutions may have different physical challenges such as distance from patient room to the CT scanner that we may not experience. There may be other variables which we have overlooked that impact the DNT. The overall number of patients included was small which limited our results and our ability to validate the methodology and accuracy. It is likely true that obtaining a CXR prior to CT will decrease the number of patients treated with tPA within 60 minutes but our sample did not have the size reach statistical significance.

Conclusions

In conclusion, we found that the ordering of adjuvant testing for AIS patients is important in reducing the potential time to treatment with tPA. Patients were more likely to receive treatment with tPA if The ECG was performed after the head CT and if their time of symptom onset at arrival was greater than 90 minutes. On average, an ECG performed before the head CT is completed increased CT time by 6 minutes and a CXR obtained before the head CT increased CT time by 13 minutes. The new AHA/American Stroke Association recommended standard will require EM physicians at Primary Stroke Centers and Comprehensive Stroke Centers to rapidly evaluate and treat AIS patients. Centers should evaluate their own operating procedures and locate barriers to determine ways to reduce treatment times.

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