You are called to assist a 55-year-old male who complains of sudden onset chest pain, dyspnea, and palpitations. On arrival, he is found semi-conscious with a pulse rate too fast to palpate and a blood pressure of 80 systolic. Once on the monitor, he is exhibiting an irregularly wide complex tachycardia, with a polymorphic QRS appearance, at nearly 200 per minute. Which of the following would be the most effective intervention for this patient?

Correct Answer: C

Rationale: The correct answer is C: Administer defibrillation per protocol. The patient is presenting with symptoms indicative of unstable ventricular tachycardia or ventricular fibrillation, which are life-threatening arrhythmias. Defibrillation is the immediate intervention to restore normal rhythm by delivering an electrical shock to the heart. In this scenario, the patient is hemodynamically unstable with a low blood pressure and loss of consciousness, making defibrillation the most appropriate and effective intervention to potentially save the patient's life. Choice A (Administer procainamide) is not the most effective intervention as this patient is in a critical condition that requires immediate action, and procainamide infusion takes time to work. Choice B (Administer adenosine) is typically used for supraventricular tachycardias and is not appropriate for wide complex tachycardias. Choice D (Administer synchronized electrical cardioversion) is indicated for stable wide complex tachycardias

Correct Answer: D

Rationale: The correct answer is D because an endotracheal tube (ETT) above the carina on a chest x-ray is the most reliable indicator of esophageal intubation. This is because direct visualization of the ETT position relative to the carina is definitive evidence of correct placement. A, B, and C are less reliable signs as they can be misleading in certain circumstances. Symmetrical chest movement can occur even with esophageal intubation due to passive chest rise. End-tidal CO2 presence by colorimetry can be falsely positive in cases of esophageal intubation. Bilateral breath sounds can also be heard in the abdomen with esophageal intubation, leading to a false sense of correct placement.

Correct Answer: B

Rationale: The correct answer is B - Undergo prompt celiotomy. In this scenario, the presence of diffuse abdominal tenderness and free air on abdominal films indicates a high likelihood of intraabdominal injury, likely due to a gastrointestinal perforation. Prompt celiotomy (surgical exploration of the abdomen) is necessary to identify and repair the source of the perforation to prevent sepsis and other complications. Peritoneal lavage (choice A) is not sufficient for definitive diagnosis and treatment. Contrast x-ray (choice C) delays necessary surgical intervention. Simply observing (choice D) can be dangerous as the patient may deteriorate rapidly. Celiotomy allows for immediate intervention and management of the life-threatening condition.

Correct Answer: D

Rationale: The correct answer is D because cerebral blood flow is directly influenced by PaCO2 levels. When PaCO2 is below 30-50mmHg, cerebral blood vessels constrict, leading to decreased cerebral blood flow. This vasoconstriction is a protective mechanism to prevent excessive blood flow and maintain stable cerebral perfusion pressure. Therefore, the statement that cerebral blood flow is increased when PaCO2 is below 30-50mmHg is true. Explanation for why the other choices are incorrect: A: Hypotonic fluids can exacerbate brain edema by causing fluid shifts, so they should not be used to limit brain edema in severe head injury. B: Elevated intracranial pressure impairs cerebral perfusion due to decreased perfusion pressure gradient, leading to decreased cerebral blood flow. C: CSF can be displaced from the cranial vault due to changes in intracranial pressure and volume shifts.

Correct Answer: D

Rationale: The correct answer is D because retroperitoneal air on CT indicates a hollow viscus injury, such as a bowel perforation, which requires immediate surgical exploration. A is incorrect because a seat belt sign alone does not necessitate surgery. B is incorrect as grade 4 hepatic injury may not always require laparotomy. C is incorrect as extraperitoneal bladder injury can often be managed conservatively.