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Zorluk: ZorInitial Stabilization and Triage

A 62-year-old man is brought to the triage desk of the emergency department by his spouse. He is clutching his chest and reports that severe, crushing chest pain began abruptly 90 minutes ago while he was watching television. He also notes profound weakness, dizziness, and nausea. His past medical history is significant for essential hypertension and type 2 diabetes mellitus.

Upon evaluation in the resuscitation bay, he is pale, diaphoretic, and lethargic. Vital signs are:
Temperature: 36.6°C (97.9°F)
Blood pressure: 78/48 mmHg
Pulse: 52/min
Respirations: 20/min
Oxygen saturation: 96% on room air.

Physical examination reveals distended neck veins up to the angle of the mandible while sitting at a 45-degree angle. Auscultation of the lungs reveals clear breath sounds bilaterally without crackles or wheezes. Heart sounds are distant, and a regular bradycardia is appreciated with no murmurs, rubs, or gallops. The extremities are cool with delayed capillary refill.

A 12-lead electrocardiogram is rapidly obtained, demonstrating 3-mm ST-segment elevations in leads II, III, and aVF, as well as 1.5-mm ST-segment depressions in leads I and aVL.

Which of the following is the single most appropriate initial step in the hemodynamic stabilization of this patient?

  1. Administration of an intravenous isotonic crystalloid bolusCevap
  2. B
    Administration of sublingual nitroglycerin
  3. C
    Initiation of a continuous intravenous norepinephrine infusion
  4. D
    Obtaining an urgent computed tomography angiography of the chest
  5. E
    Immediate transfer to the cardiac intensive care unit for pulmonary artery catheterization

Cevap

The correct answer is the administration of an intravenous isotonic crystalloid bolus.
The correct intervention is administering an intravenous isotonic crystalloid bolus. The patient presents with classic signs of a right ventricular myocardial infarction: the triad of hypotension, clear lung fields, and elevated jugular venous pressure, in the setting of an inferior wall STEMI (ST elevations in II, III, aVF). The ischemic right ventricle loses its contractility and acts as a passive conduit. Therefore, cardiac output becomes exquisitely dependent on elevated right-sided filling pressures (preload). The most urgent stabilization step is volume expansion with intravenous fluids to augment right ventricular preload and improve left ventricular filling.

Adım Adım Çözüm

1
Analyze the electrocardiogram and clinical presentation.
The ST-segment elevations in inferior leads (II, III, aVF) confirm an acute inferior myocardial infarction. The hypotension, clear lungs, and jugular venous distention indicate right ventricular failure.
Inferior myocardial infarctions involve the right coronary artery, which supplies the right ventricle in the majority of patients.
2
Determine the pathophysiologic mechanism of the patient's shock.
Right ventricular ischemia leads to decreased right ventricular contractility and poor forward flow to the pulmonary circulation and subsequently the left ventricle. This drops cardiac output, causing severe hypotension.
Because the damaged right ventricle cannot pump effectively, it becomes highly dependent on elevated venous return (preload) to passively drive blood through the pulmonary circuit.
3
Select the most appropriate immediate stabilization intervention.
Intravenous isotonic crystalloids must be administered immediately.
Volume expansion maximizes right-sided filling pressures, directly treating the underlying preload dependence that is driving the shock state.

Anahtar Kavram

Patients with acute right ventricular myocardial infarction (characterized by inferior ST elevations, clear lungs, hypotension, and elevated jugular venous pressure) are highly preload-dependent; initial hemodynamic stabilization requires intravenous fluid boluses, while preload-reducing agents like nitrates and diuretics are strictly contraindicated.

Alternatif Yöntem

If the initial rapid administration of 1-2 liters of isotonic crystalloid fails to restore adequate blood pressure and perfusion, the next step in stabilization is the initiation of an inotrope (e.g., dobutamine) to augment right ventricular contractility.
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Initial Stabilization and Triage

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