You are on-scene with a patient who you suspect may be experiencing a myocardial infarction. He is conscious and alert, anxious, and has dilated pupils. He complains of substernal chest pain and admits to recent cocaine use. How does the use of cocaine increase the risk of experiencing an acute myocardial infarction?

Correct Answer: D

Rationale: The correct answer is D. Cocaine causes coronary artery constriction, reducing blood flow to the heart muscle. This constriction can lead to the formation of thrombus or plaque in the narrowed arteries, increasing the risk of myocardial infarction. Other choices are incorrect: A is inaccurate as asystole is not a direct effect of cocaine; B is incorrect as cocaine does not cause peripheral clotting to travel to the coronary arteries; C is incorrect as cocaine does not numb the heart, but rather constricts the coronary arteries.

Correct Answer: C

Rationale: The correct answer is C: Administer defibrillation per protocol. In this scenario, the patient is presenting with signs of unstable ventricular tachycardia or ventricular fibrillation. Defibrillation is the most effective intervention as it delivers a shock to the heart to reset the abnormal rhythm. It is crucial in cases of pulseless ventricular tachycardia or ventricular fibrillation to restore a normal heart rhythm and improve cardiac output. Administering medications like procainamide (choice A) or adenosine (choice B) would not be effective as the patient is in a pulseless state. Synchronized electrical cardioversion (choice D) is typically used for stable tachyarrhythmias, not for pulseless rhythms. Defibrillation is the immediate and appropriate intervention to save the patient's life by restoring normal cardiac function.

Correct Answer: A

Rationale: The correct answer is A: "Inserting an oropharyngeal airway" because noisy respirations and apnea indicate airway obstruction. Oropharyngeal airway can help maintain a patent airway by preventing the collapse of soft tissues in the pharynx. It does not require visualization of the airway (unlike nasopharyngeal airway or intubation methods), making it quicker and suitable for emergency situations. Surgical cricothyroidotomy is an invasive procedure and not indicated in this scenario. Fiberoptic-guided nasotracheal intubation is time-consuming and may not be feasible in a critical situation.

Correct Answer: D

Rationale: The correct answer is D because an endotracheal tube (ETT) above the carina on a chest x-ray is the least reliable sign for diagnosing esophageal intubation. This is because the placement of the ETT above the carina does not definitively confirm that the tube is in the esophagus. The ETT could still be in the trachea but positioned above the carina. Symmetrical chest movement, bilateral breath sounds, and end-tidal CO2 presence by colorimetry are more reliable signs of proper endotracheal tube placement. Symmetrical chest movement indicates bilateral lung ventilation, bilateral breath sounds confirm the presence of air in both lungs, and end-tidal CO2 presence indicates effective gas exchange in the lungs.

Correct Answer: B

Rationale: The correct answer is B, "Undergo prompt celiotomy." This is because the presence of free air on abdominal films in a seat-belted driver with diffuse abdominal tenderness indicates a likely intra-abdominal injury requiring surgical intervention. Prompt celiotomy allows for exploration of the abdomen to identify and repair any internal injuries. Choice A, peritoneal lavage, is not recommended as it does not provide definitive treatment for the underlying intra-abdominal injury. Choice C, contrast x-ray of the GI-tract, is unnecessary and delays definitive management. Choice D, observation for further evidence of intraabdominal injury, is not appropriate given the already identified signs of a serious abdominal injury that require immediate surgical intervention.