Cardiology

Fibrinolytic Therapy for STEMI

Case

You are on a swing shift at a remote, island-based community hospital when a 58 year-old male presents with sudden onset chest pain. The pain started at rest, radiates to his jaw, and is associated with diaphoresis and nausea. He has a history of coronary artery disease (CAD), and during his last cardiac catheterization in 2008, a stent was placed in his proximal left anterior descending coronary artery. His past medical history is also significant for diabetes, chronic obstructive pulmonary disease, hyperlipidemia, and hypertension.  He is an active smoker.

On exam, he is not only diaphoretic and clenching his chest, but also describes the pain as “an elephant sitting on my chest.” Initial vital signs are P 110, BP 175/100, RR 20, PO2 98% on RA, T 98.9 F. You give him aspirin 324 mg and nitroglycerin sublingual 0.4 mg, and his chest pain improves from a 10/10 to 8/10. His initial electrocardiogram (EKG) is below.

Figure 1: The patient’s presenting EKG.

Figure 1: The patient’s presenting EKG.

DIAGNOSIS

ST elevation myocardial infarction (STEMI)

Management Options

You call the critical care transport ambulance, as well as the nearest cardiac catheterization team to alert them of your patient.   Unfortunately, it is a stormy evening in the middle of winter and all bridges off the island are closed; helicopters are grounded due to the storm.  There are no transfer options available to your patient at this time. What else can you do?

Indications for Fibrinolytic Therapy

According to the American Heart Association, there are several considerations when it comes to fibrinolytic therapy in myocardial infarction:

Class I recommendations:

  1. STEMI

  2. Symptom onset in the last 12 hours

  3. Percutaneous Cardiac Intervention (PCI) cannot be performed within 120 minutes of arrival to the Emergency Department

  4. Absence of any contraindications (see below)

Class II recommendations:

  1. Evidence of ongoing ischemia 12-24 hours after symptom onset

  2. Large area of myocardium affected

  3. Hemodynamic instability

Absolute contraindications:

  1. Any prior intracranial hemorrhage

  2. Known structural cerebral vascular lesion

  3. Ischemic stroke <3 months

  4. Suspected aortic dissection

  5. Known intracranial malignancy

  6. Active bleeding or bleeding diathesis

  7. Significant closed head trauma <3 months

  8. Intracranial/intraspinal surgery <2 months

  9. Severe uncontrolled HTN (>175/110)

  10. Oral anticoagulants

Relative contraindications:

  1. Significant HTN on arrival (pressure > 180 mmHg)

  2. Ischemic stroke >3 months

  3. Dementia

  4. Other intracranial pathology

  5. Traumatic CPR >10 min

  6. Major surgery <3 weeks

  7. Internal bleeding <3 weeks

  8. Non-compressible vascular punctures

  9. Pregnancy

  10. Active peptic ulcer disease

PCI versus Systemic Fibrinolytic Therapy

If you are able to transfer the patient to a hospital with PCI capability within 1 hour of presentation or they have contraindications to fibrinolytic therapy, it is recommended that you transfer the patient as soon as possible. Otherwise, the goal is fibrinolytic infusion within 30 minutes of arrival to the ER. In either case, concurrently initiate maximal medical management including full-dose aspirin, Plavix or Brilinta, and anticoagulation (unfractionated heparin or lovenox). Tenecteplase is generally the preferred fibrin-specific agent, given its ease of use and lower rates of non-cerebral bleeding compared to other agents.

Reassess After Fibrinolysis

If your patient has resolution of chest pain and >70% reduction of ST elevation, or ST elevation resolves within 60-90 minutes, you have likely restored flow. If you see <50% decrease in STE and no reperfusion arrhythmias (see below) at 2 hours after fibrinolytic dosing, you have partially improved flow but not completely restored it.

Criteria for Transfer after fibrinolytic therapy

  1. Immediate transfer: acute heart failure or cardiogenic shock

  2. Urgent transfer: failed reperfusion or reocclusion

  3. 3-24 hours: hemodynamically stable, successful reperfusion

Reperfusion Arrhythmias 

You plan for ICU admission because you are unable to transfer the patient to a PCI center when the nurse hands you the following EKG:

Figure 2: Accelerated idioventricular rhythm.

Figure 2: Accelerated idioventricular rhythm.

This is an example of accelerated idioventricular rhythm. This is a normal sign of reperfusion after STEMI and does not require treatment.   In fact, such a rhythm is generally viewed as a positive response to fibrinolytic therapy as indicates reperfusion. 

Criteria:

  1. Regular rhythm

  2. Rate 50-110bpm (slower is ventricular escape, faster is VT)

  3. Three or more ventricular complexes

  4. Fusion (F) and capture (C) beats (see below)

Figure 3: Fusion and capture beats after successful reperfusion.

Figure 3: Fusion and capture beats after successful reperfusion.

General goals of care after fibrinolytic therapy should be to transfer for diagnostic angiography and percutaneous coronary evaluation which is promptly accomplished for your patient the following day after the storm resolves.


Faculty reviewer: Dr. Kristina McAteer


References

  1. O'Gara PT, Kushner FG, Ascheim DD, et al. 2013 ACCF/AHA guideline for the management of ST-elevation myocardial infarction: executive summary: a report of the American College of Cardiology Foundation/American Heart Association Task Force on Practice Guidelines. Circulation 2013; 127:529.

  2. O'Gara PT, Kushner FG, Ascheim DD, et al. 2013 ACCF/AHA guideline for the management of ST-elevation myocardial infarction: a report of the American College of Cardiology Foundation/American Heart Association Task Force on Practice Guidelines. Circulation 2013; 127:e362.

  3. White HD. Thrombolytic therapy in the elderly. Lancet 2000; 356:2028.

  4. Armstrong PW, Gershlick AH, Goldstein P, et al. Fibrinolysis or primary PCI in ST-segment elevation myocardial infarction. N Engl J Med 2013; 368:1379.

  5. Effectiveness of intravenous thrombolytic treatment in acute myocardial infarction. Gruppo Italiano per lo Studio della Streptochinasi nell'Infarto Miocardico (GISSI). Lancet 1986; 1:397.

  6. Randomised trial of intravenous streptokinase, oral aspirin, both, or neither among 17,187 cases of suspected acute myocardial infarction: ISIS-2. ISIS-2 (Second International Study of Infarct Survival) Collaborative Group. Lancet 1988; 2:349.
    Indications for fibrinolytic therapy in suspected acute myocardial infarction: collaborative overview of early mortality and major morbidity results from all randomised trials of more than 1000 patients. Fibrinolytic Therapy Trialists' (FTT) Collaborative Group. Lancet 1994; 343:311.

  7. Labinaz M, Sketch MH Jr, Ellis SG, et al. Outcome of acute ST-segment elevation myocardial infarction in patients with prior coronary artery bypass surgery receiving thrombolytic therapy. Am Heart J 2001; 141:469.

  8. Peterson LR, Chandra NC, French WJ, et al. Reperfusion therapy in patients with acute myocardial infarction and prior coronary artery bypass graft surgery (National Registry of Myocardial Infarction-2). Am J Cardiol 1999; 84:1287.

  9. Karnash SL, Granger CB, White HD, et al. Treating menstruating women with thrombolytic therapy: insights from the global utilization of streptokinase and tissue plasminogen activator for occluded coronary arteries (GUSTO-I) trial. J Am Coll Cardiol 1995; 26:1651.

  10. Woodfield SL, Lundergan CF, Reiner JS, et al. Angiographic findings and outcome in diabetic patients treated with thrombolytic therapy for acute myocardial infarction: the GUSTO-I experience. J Am Coll Cardiol 1996; 28:1661.

  11. Mak KH, Moliterno DJ, Granger CB, et al. Influence of diabetes mellitus on clinical outcome in the thrombolytic era of acute myocardial infarction. GUSTO-I Investigators. Global Utilization of Streptokinase and Tissue Plasminogen Activator for Occluded Coronary Arteries. J Am Coll Cardiol 1997; 30:171.

Ultrasound Case of the Month: August 2018

The Case

This is an 82 year-old male who presented to the ED with acute chest pain and palpitations. He had a known history of AAA s/p repair. Patient denied abdominal, back, or flank pain. There was no loss of consciousness. An EKG was performed and was consistent with SVT with aberrancy. A bedside abdominal ultrasound was performed and the following images were obtained:

Figure 1: Proximal axial abdominal aortic ultrasound

Figure 1: Proximal axial abdominal aortic ultrasound

Figure 2: Longitudinal abdominal aorta ultrasound

Figure 2: Longitudinal abdominal aorta ultrasound

Figure 3: Distal axial abdominal aorta ultrasound

Figure 3: Distal axial abdominal aorta ultrasound

Diagnosis

Known AAA s/p repair (also SVT with aberrancy)

Case Follow-up

The patient remained HDS and adenosine was given with good effect. He was admitted to medicine, and had no further episodes of SVT. He was discharged home with cardiology follow up.

Discussion

The images were acquired using the curvilinear probe. The probe was placed on the abdomen just superior of the umbilicus and just left of midline. Both longitudinal and axial views were acquired.

Ultrasound is the initial test of choice for suspected AAA in the ED. It has sensitivity of 94-99%, and has been shown to decrease mortality in AAA patients by 20-50% compared to CT--likely due to decreased time to diagnosis.

A normal abdominal aorta is typically < 3cm in diameter. A complete AAA ultrasound should evaluate the aorta from the xiphoid process past the aortic bifurcation. US may be considered positive if the aorta is >3 cm in a patient with clinical concern for AAA,  or > 5 cm without clinical concern.

Faculty Reviewer: Dr. Kristin Dwyer

For an in-depth tutorial on the abdominal aorta ultrasound, check out this video from EM:RAP HD:

Additional Resources

https://cdemcurriculum.com/bedside-ultrasound-aaa-examination/

https://radiopaedia.org/articles/abdominal-aortic-aneurysm

https://www.acep.org/sonoguide/abdominal_aortic_aneurysm.html

http://5minsono.com/aaa/

"High Quality CPR" and You!

CPR as we know it was “invented” by numerous resuscitation scientists working in competing labs during the 1950s.  Since then, CPR has gone through a number of changes, from compression-to-ventilation rates, training programs and even the manner in which it is delivered.  In the 1990s, pubic defibrillators became mainstream.  In the mid 2000s, external CPR devices became more common and in 2010 “hands-only” CPR was the predominant layperson resuscitation method.  The latest iteration of CPR and resuscitation science is the focus on “high quality” CPR, “team-focused” CPR and “cardiocerebral resuscitation” (CCR).

When discussing CPR and the holy grail of evidence-based practice, there are a number of caveats to acknowledge.  Firstly, there have been a very limited number of prospective, randomized and controlled trials on CPR and resuscitation due to many inherent barriers to performing such a study – cost, the infrequency of out-of-hospital cardiac arrest (OHCA), and the difficulty and ethical concerns inherent in studying something which is thought to be efficacious (CPR) against something else which may not be.  Fortunately, there have been a number of trials conducted that can inform our practice, and large, curated resuscitation outcomes databases exist for retrospective studies.  In this article, we’ll discuss CPR, Rhode Island State EMS protocols, and the evidence for and against them.

LifePACT.jpg

In March of 2017, the Rhode Island Department of Health instituted new protocols requiring EMS providers to stay on the scene of an atraumatic cardiac arrest for up to 30-minutes, or until return of spontaneous circulation (ROSC) is achieved[i].  Pre-hospital medicine policies and protocols vary according to the region, state, resources, distance from definitive care, and culture.  When treating trauma patients, for example, EMS providers are instructed to transport as quickly as possible to a hospital.  Traditionally, EMS providers have also been taught to transport OHCA patients to hospitals quickly as well, so asking them to remain on-scene for up to 30-minutes is controversial.  According to the American Heart Association (AHA), approximately 355,000 people each year suffer an OHCA event (110 events per 100,000 population).  Studies vary, but the overall survival rate for OHCA is anywhere from 6-12%[ii],[iii] nationally.  Extrapolating these statistics to Rhode Island’s population of 1 million, we can estimate that approximately 1100 Rhode Islanders are having OHCA each year, or 3 people every day.  Clearly, OHCA is an important topic and is worth exerting considerable effort to improve outcomes.

Historically, we know that certain factors in OHCA have prognostic importance and are associated with better outcomes, including witnessed arrest, time to CPR and defibrillation, initial shockable rhythm (VT/VF), AED use, and patient ageiii,[iv].  Although there are a myriad of factors that play into treating OHCA patients – airway use, mechanical or manual CPR, ACLS drugs, etc., the idea behind emphasizing on-scene CPR is that it gives EMS agencies the opportunity to defibrillate as soon as possible, perform great CPR and increase a patient’s chance of ROSC by re-establishing myocardial perfusion, instead of focusing on patient packaging and transport.  In other words, the theory is that you can run a code in the field, in the ER, or in the back of an ambulance, but the sooner you run it well, the better odds a patient has of a good outcome.  Below, we’ll review some of the key concepts of high-quality CPR.

Continuous Chest Compressions

Chest compressions.JPG

Many simulation, animal and observational studies have been performed on all manner of aspects of CPR, including compression depth, recoil, and speed.  Recently, focus has been drawn to cardiocerebral resuscitation (CCR), or minimally interrupted, continuous CPR.  The concept behind this mode of CPR delivery is that of coronary perfusion pressure – that it takes time giving compressions to reach the threshold at which the heart has enough coronary blood flow to possibly begin beating again, and each pause in CPR resets the pressure to 0. In the 3-phase model of VF arrest, the first 5 minutes are the “electrical phase”, in which defibrillation can result in ROSC. After this is the “hemodynamic phase”, during which restoration of “adequate arterial pressure” by CPR can increase odds of ROSC.  Importantly, it can take up to 45 seconds to establish adequate arterial pressure.  Lastly is the “metabolic phase”, during which outcomes are poor[v],[vi].  According to this theory, the sooner patients get defibrillation and CPR, and the better the CPR is, the higher odds they have of ROSC.  To date, several registry-based studies seem to agree with this idea, and have demonstrated improved outcomes among both VF and non-VF arrests with high chest compression fraction (i.e., less CPR interruptions)[vii].  Assuming that continuous CPR, or high chest compression fraction is beneficial, it also follows that any interruptions during CPR can result in worse outcomes – for example, pauses around defibrillation, intubation and transport, and research has borne this out[viii].  It’s worth noting, however, that although many of these concepts have become resuscitation truths, not all research agrees.  In one of the few RCTs on CPR, published in the New England Journal in 2015, Nichol et al. compared continuous to interrupted chest compressions, and found no statistically-significant difference in favorable neurologic function at discharge, although the protocol compliance was low, and many variables were similar between both groups[ix].  Both groups, for example, had CPR fractions higher than typical, so both study groups may not be representative of the real world.

Passive Oxygenation and Delayed Intubation

Bag Valve Mask.jpg

One of the key exposures in the NEJM study by Nichol et al., was the mode of ventilation.  In comparing continuous to interrupted chest compressions, the “interruption” was providing rescue breaths in the traditional 30:2 ratio.  If we subscribe to the idea that it takes up to 45 seconds to develop enough coronary perfusion pressure that defibrillation might be successful, stopping CPR every 30 compressions begins to seem like a bad idea.  We also know that a provider’s focus on airway management can detract from compression quality.  One observational study found that pre-hospital providers caring for OHCA patients paused CPR a median of 109 seconds for airway placement[x].  Coupling this finding with other studies showing that CPR pause duration is associated with increased mortality[xi] leads us to consider forgetting about the airway completely (at least initially).  Other literature seems to support this idea.  McMullan et al published a paper in 2013 on data from the Cardiac Arrest Registry to Enhance Survival (CARES), evaluating different airway management techniques and their association with neurologically intact survival.  The authors found that of 10,691 OHCA patients, survival was highest among those who received neither endotracheal intubation nor supraglottic airways (OR of 1.31)[xii].  Although this appears damning for any types of airway management at face value, it’s worth noting that patients with the best outcome often will have no opportunity for airway management – in other words, they are shocked out of VF, then wake up!  More information is coming soon, with an RCT due to be published in 2020 comparing airway management methods prospectively.

CPR During Transport

Another significant factor in deciding whether to work a code on scene or transport rapidly is the quality of CPR possible.  On scene, with a team of prepared EMS personnel, it seems a reasonable assumption that CPR metrics would be superior.  Prior literature seems to support this conclusion, with a number of simulation studies demonstrating worse or more variable CPR metrics in patients during transport, such as compression depth and rate[xiii].  In a small study published by Olasveengen et al., non-traumatic OHCA patients had increased time without compressions during transport compared with when on scene (27% vs. 19%).  However, in one 2017 registry-based study in Canada, the proportion of OHCA patients receiving “high-quality” CPR, defined as depth >5cm, rate >100/min, and chest compression fraction of >0.7 was similar between on-scene and transported groups[xiv].  Even if EMS providers are able to provide high-quality CPR in the back of a moving ambulance, consideration must be made of the danger to EMS personnel, who are then required to stand and perform a physically demanding task in a moving vehicle.  The science is not completely clear on which method is superior – on-scene or in transport, though clearly these studies have implications for proponents of running on-scene codes.

Team-Focused CPR

Eager to implement these cutting-edge techniques, some EMS systems have published their results with high-quality, “pit-crew style” and “team-focused” CPR.  Stopyra published data from a prospectively collected pre and post-intervention cohort study in rural North Carolina.  Data was collected on OHCA from 1-year prior to the intervention and 1-year after the intervention implementation.  All OHCA of presumed cardiac etiology was included.  The intervention included training of all providers, including police and EMS.  They were instructed to fulfill a choreographed position based on the timing of their arrival to the code.  The first rescuer would begin CPR, the second would place defibrillation pads and insert a blind airway, the third would be the team leader.  After arrival of the third provider, parenteral access could be attempted.  Rescuers continued with resuscitation until ROSC or end tidal <10mm for 20 minutes.  They found that after protocol implementation, there was a significant increase in number of patients achieving ROSC (65.7% vs. 28.4%, p<0.001), though there was no statistically significant change in survival to discharge.  Some of the limitations of this study include the small n (105 total resuscitations), and the lack of ability to control for in-hospital care (with regards to the lack of difference in survival to discharge)[xv].

A second North Carolina was undertaken by Pearson et al, and published in Resuscitation, detailing OHCA outcomes before and after an intervention of “team-focused CPR”[xvi].  Researchers evaluated arrest characteristics of nearly 15,000 OHCA patients using CARES registry data.  EMS agencies self-reports compliance with “team-focused CPR”, which emphasized early defibrillation, high quality CPR, and airway management with BVM over advanced airways.  Authors used a logistic regression to control for arrest characteristics, such as CPR device used, witnessed or unwitnessed, race, comorbidities and hypothermia, and found that team-focused CPR had a better odds of good neurologic outcome as measured by cerebral performance category score (OR 1.5) compared with traditional CPR.

A similar effort was undertaken in Salt Lake City in 2011.  The results from SLC Fire Department’s “pit crew approach” were published in 2015 in the Journal of the American Heart Association.  This study had significantly larger numbers (737 attempted resuscitations), and was based in an urban department with 11 ALS units and 8 BLS units.   The intervention in SLC included use of defibrillator real-time feedback to rescuers, strong medical direction and QA of all OHCA calls, rhythm-filtering technology that allowed rescuers to see the rhythm during CPR prior to stopping for pulse-check, limited peri-shock pauses, and encouraged on-scene resuscitation (vs. early transport) to reduce interruptions inherent in transfer and transport.  Additionally, passive oxygen was applied via facemask for the first 6-8 minutes, and asynchronous BVM for all unwitnessed, pediatric and respiratory arrests. 

After the intervention, SLC Fire Department saw more field ROSC (44% vs. 30%, p<0.0001).  Among patients who survived to admission, there was more survival to discharge (50% vs. 37%, p=0.0005), and more patients with favorable neurologic function, defined as Cerebral Performance Category 1 or 2 (46% vs. 26%, p=0.0005), although there was no statistically significant change in survival to hospital admission.  Although these numbers are promising for high-quality CPR, several confounders are present, including improved medical control, and preferential triage of OHCA patients with ROSC to PCI-capable centers, which was not the practice in the pre-intervention period[xvii]

Rhode Island is among the first states to institute a protocol mandating 30-minutes of on-scene CPR. While some have demonstrated improved outcomes with the implementation of similar interventions, bundled together with CPR training, use of novel technology (such as real-time feedback, end-tidal CO2, and rhythm filtration programs), strong medical direction and QA, it remains to be seen whether a statewide intervention can lead to more ROSC in the field, and, more importantly, more neurologically intact survival to discharge.  Reviewing the resuscitation literature, we see the trend toward decreased initial advanced airway use, higher focus on continuous CPR and minimal interruptions, such as the peri-shock pause and, to delay transport of the patient until ROSC is achieved.  While local news reports have highlighted anecdotal success stories[xviii], the full impact of the Rhode Island intervention have yet to be described.

Faculty Reviewer: Nick Asselin, DO

References

[i] Rhode Island Statewide Emergency Medical Services Protocols.” Rhode Island Department of Health, p. 3.03a., health.ri.gov/publications/protocols/StatewideEmergencyMedicalServices.pdf.

[ii] Mozaffarian, D., Benjamin, E. J., Go, A. S., Arnett, D. K., Blaha, M. J., Cushman, M., … Turner, M. B. (2015). Heart Disease and Stroke Statistics—2016 Update. Circulation, 133(4), e38–e360. https://doi.org/10.1161/cir.0000000000000350

[iii] Becker, L. B., Aufderheide, T. P., & Graham, R. (2015). Strategies to Improve Survival From Cardiac Arrest. JAMA, 314(3), 223. https://doi.org/10.1001/jama.2015.8454

[iv] Haukoos, J. S., Lewis, R. J., & Niemann, J. T. (2004). Prediction rules for estimating neurologic outcome following out-of-hospital cardiac arrest. Resuscitation, 63(2), 145–155. https://doi.org/10.1016/j.resuscitation.2004.04.014

[v] Weisfeldt, M. L., & Becker, L. B. (2002). Resuscitation After Cardiac Arrest. JAMA, 288(23), 3035. https://doi.org/10.1001/jama.288.23.3035

[vi] Berg, R. A., Sanders, A. B., Kern, K. B., Hilwig, R. W., Heidenreich, J. W., Porter, M. E., & Ewy, G. A. (2001). Adverse Hemodynamic Effects of Interrupting Chest Compressions for Rescue Breathing During Cardiopulmonary Resuscitation for Ventricular Fibrillation Cardiac Arrest. Circulation, 104(20), 2465–2470. https://doi.org/10.1161/hc4501.098926

[vii] Vaillancourt, C., Everson-Stewart, S., Christenson, J., Andrusiek, D., Powell, J., Nichol, G., … Stiell, I. G. (2011). The impact of increased chest compression fraction on return of spontaneous circulation for out-of-hospital cardiac arrest patients not in ventricular fibrillation. Resuscitation, 82(12), 1501–1507. https://doi.org/10.1016/j.resuscitation.2011.07.011

[viii] Cheskes, S., Schmicker, R. H., Christenson, J., Salcido, D. D., Rea, T., … Powell, J. (2011). Perishock Pause: An Independent Predictor of Survival From Out-of-Hospital Shockable Cardiac Arrest. Circulation, 124(1), 58–66. https://doi.org/10.1161/circulationaha.110.010736

[ix] Nichol, G., Leroux, B., Wang, H., Callaway, C. W., Sopko, G., Weisfeldt, M., … Ornato, J. P. (2015). Trial of Continuous or Interrupted Chest Compressions during CPR. New England Journal of Medicine, 373(23), 2203–2214. https://doi.org/10.1056/nejmoa1509139

[x] Wang, H. E., Simeone, S. J., Weaver, M. D., & Callaway, C. W. (2009). Interruptions in Cardiopulmonary Resuscitation From Paramedic Endotracheal Intubation. Annals of Emergency Medicine, 54(5), 645–652.e1. https://doi.org/10.1016/j.annemergmed.2009.05.024

[xi] Brouwer, T. F., Walker, R. G., Chapman, F. W., & Koster, R. W. (2015). Association Between Chest Compression Interruptions and Clinical Outcomes of Ventricular Fibrillation Out-of-Hospital Cardiac ArrestCLINICAL PERSPECTIVE. Circulation, 132(11), 1030–1037. https://doi.org/10.1161/circulationaha.115.014016

[xii] McMullan, J., Gerecht, R., Bonomo, J., Robb, R., McNally, B., Donnelly, J., & Wang, H. E. (2014). Airway management and out-of-hospital cardiac arrest outcome in the CARES registry. Resuscitation, 85(5), 617–622. https://doi.org/10.1016/j.resuscitation.2014.02.007

[xiii] Roosa, J. R., Vadeboncoeur, T. F., Dommer, P. B., Panchal, A. R., Venuti, M., Smith, G., … Bobrow, B. J. (2013). CPR variability during ground ambulance transport of patients in cardiac arrest. Resuscitation, 84(5), 592–595. https://doi.org/10.1016/j.resuscitation.2012.07.042

[xiv] Cheskes, S., Byers, A., Zhan, C., Verbeek, P. R., Ko, D., Drennan, I. R., … Morrison, L. J. (2017). CPR quality during out-of-hospital cardiac arrest transport. Resuscitation, 114, 34–39. https://doi.org/10.1016/j.resuscitation.2017.02.016

[xv] Stopyra, J. P., Courage, C., Davis, C. A., Hiestand, B. C., Nelson, R. D., & Winslow, J. E. (2016). Impact of a “Team-focused CPR” Protocol on Out-of-hospital Cardiac Arrest Survival in a Rural EMS System. Critical Pathways in Cardiology, 15(3), 98–102. https://doi.org/10.1097/hpc.0000000000000080

[xvi] Pearson, D. A., Darrell Nelson, R., Monk, L., Tyson, C., Jollis, J. G., Granger, C. B., … Runyon, M. S. (2016). Comparison of team-focused CPR vs standard CPR in resuscitation from out-of-hospital cardiac arrest: Results from a statewide quality improvement initiative. Resuscitation, 105, 165–172. https://doi.org/10.1016/j.resuscitation.2016.04.008

[xvii] Hopkins, C. L., Burk, C., Moser, S., Meersman, J., Baldwin, C., & Youngquist, S. T. (2016). Implementation of Pit Crew Approach and Cardiopulmonary Resuscitation Metrics for Out‐of‐Hospital Cardiac Arrest Improves Patient Survival and Neurological Outcome. Journal of the American Heart Association, 5(1), e002892. https://doi.org/10.1161/jaha.115.002892

[xviii] http://wpri.com/2017/02/16/new-rule-cpr-for-30-minutes-before-taking-cardiac-arrest-victims-to-hospital/