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October 2016

 

Case Presentation:

Paramedics are called to the home of a 70 year-old female with abdominal pain. On arrival, the patient is holding her abdomen and appears uncomfortable. She complains of epigastric abdominal pain and nausea that awoke her from sleep 2 hours earlier. Past medical history includes diabetes, high blood pressure, dyslipidemia (aka high cholesterol) and gastritis.  Her vital signs are HR 40, BP 105/65, RR 22, and O2 saturation 95% on room air.  

 

1.

What is the possible etiologies of this patient's abdominal pain that the paramedics should consider? 

While the patient gives a history of gastritis, which could offer a simple explanation of her epigastric pain and nausea, the possibility of other more serious causes must be assessed first. These include cardiac ischemia or infarction, stomach/intestinal ulcers, pneumonia, and intra-abdominal infection or injury.  In this patient with multiple risk factors for cardiac disease – older age, diabetes, high blood pressure, and high cholesterol – presenting with upper abdominal pain, the possibility of atypical presentation of myocardial infarction (MI) must be considered first as this will directly impact field management and destination decision. 

2.

What essential test should be performed in the field?

In addition to a careful pulmonary, cardiac, and abdominal exam, the concern for atypical presentation of cardiac disease necessitates a field 12-lead ECG to evaluate for MI.  Up to 1/3 of patients with MI may not endorse chest pain on their initial presentation. Atypical symptoms for cardiac presentations include epigastric abdominal pain, nausea, shortness of breath, and dizziness. Previous authors have noted that women, the elderly, and diabetics are the three groups most likely to present with atypical symptoms [i]. In any patient with epigastric abdominal pain, performance of an ECG should be considered. In this patient with bradycardia and low normal blood pressure despite a stated history of hypertension, cardiac problems should be high on the list of potential primary impressions.

3.

Case Continuation?

Paramedics perform a 12-lead ECG, which is shown here.Case study

4.

What does the ECG show?

The ECG is a high quality tracing, devoid of wavy baselines and artifact. Attaining a high quality tracing is crucial to appropriate interpretation. This ECG shows ST-segment elevation in leads II, III, and aVF, consistent with a ST-segment Elevation Myocardial Infarction (STEMI) in an inferior distribution.  It is helpful to remember that recognition of an inferior infarct is often supported by “reciprocal changes” of ST-segment depression in the lateral leads. Close examination of this ECG shows depressions in leads I and aVL, otherwise thought to represent the “low lateral” or “apical lateral” region of the heart.

case study

case study

5.

What is the most important field treatment of this patient?

Aspirin is a key therapy for MI and is strongly recommended by American Heart Association and international guidelines [ii].  The only contraindications are true allergic reaction and active significant gastrointestinal bleeding. By inhibiting platelet aggregation, aspirin prevents further enlargement and hardening of the clot and can decrease the risk of death for patients with MI by nearly 25%.  The benefit of aspirin is greatest when it is given early. It should be given by prehospital providers to any patient with cardiac chest pain regardless of ECG findings, as well as to any patient for whom you suspect an MI based on ECG findings, regardless of their chief complaint. The current patient is an example of a patient who would greatly benefit from aspirin, although she did not complain of chest pain. 


 

6.

Should this patient be treated with nitroglycerin?

Caution should be exercised in the use of nitroglycerin (NTG) in this patient.  This patient’s epigastric pain can be considered a “chest pain equivalent”.  Based on the patient’s presentation and ECG, provider impression is appropriately pain of cardiac etiology - ST elevation MI (STEMI).  Therefore, NTG could be considered in this patient according to Reference 1244.  NTG work by decreasing preload, and to a lesser extent afterload, thereby reducing the workload to the injured left ventricle (LV). It is also thought to dilate coronary arteries, which may increase perfusion of heart muscle.  However, this patient is having an inferior MI. Inferior MIs are the subcategory of left ventricular (LV) infarct most likely to also involve the right ventricle (RV). The ECG only evaluates the LV.  In a patient with RV infarction, decreasing preload may cause critical hypotension, poor perfusion and/or dysrhythmias. Given the patient’s bradycardia and borderline hypotension, it is wise to hold off on administration of NTG until further evaluation in the emergency department.  It is important to note that unlike aspirin, field NTG hasnot been shown to improve outcomes in acute MI [iv].  Thus, when in your assessment the risk of administration exceeds the potential benefit of pain control, it is reasonable to defer administration.  

7.

Should this patient be treated with oxygen?

Oxygen was at one time considered to be a treatment for cardiac chest pain; in fact a mnemonic used for treatment of cardiac chest pain was MONA – Morphine, Oxygen, NTG, and Aspirin.  Patients often reported subjective improvement in their pain or breathing with oxygen therapy. Yet a significant number of studies have now demonstrated that patients with acute MI, stroke, and a variety of other emergent medical conditions who are not hypoxic actually do worse long-term if they receive high-flow oxygen at any point during their care. Current guidelines advise us to limit oxygen administration to a target peripheral saturation of 94%. In this patient with oxygen saturation exceeding 94%, oxygen should not be given. Overall the risk (of death or of a greater area of permanently damaged heart tissue) exceeds the benefit (feeling secure that the paramedic is “doing something”) of oxygen use. It’s a case of “Don’t just do something! Stand there!” and we all must overcome our entrenched desire to turn the dial on the oxygen tank every time we have a patient with chest pain.

8.

Case conclusion

The patient in this scenario demonstrated an atypical presentation of an Acute Coronary Syndrome – specifically STEMI.  Paramedics noted inferior STEMI on the ECG.  They administer aspirin 162mg PO and Zofran 4mg IV for nausea, called the nearest STEMI Receiving Center (SRC) to notify them of the possible STEMI, transmitted the ECG, and confirmed patient treatment with their base hospital.   For this patient, the paramedic’s decisions to: 1) attain an ECG in a patient endorsing epigastric pain rather than simply pursuing protocol treatment for abdominal pain, 2) provide aspirin as a prehospital therapy, and 3) transport to a STEMI receiving center (SRC) rather than the nearest 911 receiving center, made a significant positive impact on her outcome.

References

[i] Brieger D, Eagle KA, Goodman SG, et al. Acute Coronary Syndromes without chest pain, an underdiagnosed and undertreated high-risk group: Insights from the global registry of acute coronary events. Chest. 2004; 126(2): 461-469.

[ii] O’Connor RE, Bossaert L, Arntz HR, et al. Part 9: Acute coronary syndromes: 2010 International Consensus on Cardiopulmonary Resuscitation and Emergency Cardiovascular Care Science with Treatment Recommendations. Circulation. 2010;122:S422-65.

[iii] 2015 American Heart Association Guidelines Update for Cardiopulmonary Resuscitation and Emergency Cardiovascular Care. Circulation. 2015;132:S313-589.

[iv] Savino PB, Sporer KA, Barger JA,,et al. Chest Pain of Suspected Cardiac Origin: Current Evidence-based Recommendations for Prehospital Care. West J Emerg Med. 2015; 16(7): 983-995.

 


By Nichole Bosson, MD, MPH, Los Angeles EMS Agency