If an adult patient is experiencing the signs and symptoms of a myocardial infarction with perfusing arrhythmias, which of the following pre-hospital interventions will help to reduce the patient's cardiac preload and afterload?

Correct Answer: A

Rationale: The correct answer is A: The intravenous administration of 2-4 mg of morphine per a medical-control physician's order. Morphine helps reduce cardiac preload and afterload by dilating blood vessels and reducing the workload on the heart. This leads to decreased oxygen demand and improved perfusion to the heart muscle. Choice B is incorrect because controlling specific dysrhythmias does not directly reduce cardiac preload and afterload. Choice C, sublingual nitroglycerin, primarily works by dilating coronary arteries and reducing cardiac afterload, but it may not directly reduce preload. Choice D, high-flow oxygen therapy, may be beneficial for oxygenation but does not directly address preload and afterload reduction.

Correct Answer: C

Rationale: The correct answer is C: Transcutaneous pacing. In a patient with second-degree type II AV heart block and hemodynamic instability, transcutaneous pacing is the most appropriate intervention. This is because it directly stimulates the heart to maintain an adequate heart rate when other measures like atropine have failed. Synchronized cardioversion (choice B) is not indicated for bradycardia. Epinephrine (choice A) may worsen the AV block and increase the risk of ventricular arrhythmias. Administering a large IV bolus of normal saline (choice D) may not address the underlying conduction abnormality and could potentially worsen the patient's condition. Transcutaneous pacing is the most effective intervention to stabilize the patient's heart rate and improve perfusion in this scenario.

Correct Answer: C

Rationale: The correct answer is C: Level B. Level B protective clothing provides the highest respiratory system protection by using a self-contained breathing apparatus (SCBA) but offers lower skin protection compared to Level A. Level D offers no respiratory or skin protection. Level C provides chemical splash protection but less respiratory protection than Level B. Level A offers the highest level of both respiratory and skin protection. In this scenario, Level B is the best choice as it prioritizes respiratory protection while still providing some level of skin protection.

Correct Answer: B

Rationale: The correct answer is B: "Prevent secondary brain injury." In a patient with severe head injury (GCS 6), preventing secondary brain injury is crucial. This involves maintaining adequate cerebral perfusion pressure, controlling intracranial pressure, optimizing oxygenation, and avoiding factors that can exacerbate brain injury. Administering an osmotic diuretic (choice A) may help reduce intracranial pressure but does not address the overall goal of preventing secondary brain injury. Aggressively treating systemic hypertension (choice C) may lead to decreased cerebral perfusion and worsen the injury. Reducing metabolic requirements of the brain (choice D) is important but not the primary goal in this acute phase.

Correct Answer: B

Rationale: Rationale for Correct Answer (B): 1. Aspiration of bone marrow confirms appropriate positioning of the needle: This statement is true because when the needle is correctly placed within the bone marrow cavity, aspiration of bone marrow confirms proper positioning and ensures that the infusion will be successful. Summary of Incorrect Choices: A: Only crystalloid solutions may be safely infused through the needle - Incorrect, as both crystalloid and colloid solutions can be infused through the intraosseous route. C: Intraosseous infusion is the preferred route for volume resuscitation in small children - Incorrect, as while it is commonly used in pediatric emergencies, it may not always be the preferred route depending on the situation. D: Intraosseous infusion may be utilized indefinitely - Incorrect, as intraosseous infusion is typically considered a temporary measure and is not meant for long-term use.