While on-scene with a 70-year-old complaining of chest pain, what is one of the first indicators that should alert the paramedic to the probability that an acute myocardial infarction is occurring?

Correct Answer: B

Rationale: Step 1: Chest pain that is not changed or relieved by oxygen therapy alone is a key indicator of acute myocardial infarction (MI). Step 2: In a suspected MI, the lack of improvement with oxygen therapy suggests a cardiac origin for the chest pain. Step 3: Oxygen therapy may alleviate chest pain related to respiratory issues, but not typically in cases of cardiac origin. Step 4: This lack of response to oxygen therapy indicates the need for further evaluation and treatment for a suspected MI. Summary: Choices A, C, and D are incorrect because they do not specifically address the characteristic of chest pain in relation to oxygen therapy, which is a crucial differentiating factor in identifying a potential acute MI.

Correct Answer: A

Rationale: Rationale for Correct Answer (A): 1. Children's spinal cords are more flexible than adults', increasing risk of injury without x-ray abnormalities. 2. Pediatric spinal injuries may not show on x-ray initially, requiring further imaging. 3. This phenomenon is known as SCIWORA (spinal cord injury without radiographic abnormality). 4. In contrast, adults' spinal cords are less flexible, often leading to visible abnormalities on x-ray. Summary of Incorrect Choices: B: Hypotension in infants with TBI is usually due to other factors like hemorrhage, not cerebral edema. C: Methylprednisolone is not recommended for initial therapy in pediatric TBI due to lack of proven benefit. D: Children more commonly have diffuse axonal injury rather than focal mass lesions in TBI compared to adults.

Correct Answer: C

Rationale: In Class 2 hemorrhage, systolic blood pressure starts to decrease due to significant blood loss (15-30%). This reduction triggers compensatory mechanisms to maintain perfusion. In Class 0, there is no blood loss, so blood pressure remains stable. In Class 1, minimal blood loss occurs, causing little impact on blood pressure. In Class 3, severe blood loss leads to a rapid decrease in blood pressure, making it unlikely for systolic blood pressure to start decreasing gradually.

Correct Answer: C

Rationale: Rationale: Choice C is incorrect because pulse oximetry provides a spot-check measurement of oxygen saturation, not continuous monitoring. A: Surrounding light can interfere with accuracy due to the device's sensitivity. B: Dysfunctional hemoglobin can affect readings. D: The technology relies on light absorption differences to measure oxygen levels accurately.

Correct Answer: A

Rationale: The correct answer is A because cardiac tamponade is a life-threatening condition where fluid accumulation in the pericardial sac compresses the heart. Surgical intervention, such as pericardial drainage or pericardiotomy, is often required to relieve the pressure on the heart. Choice B, needle pericardiocentesis, is a temporary measure and may not definitively manage the condition. Choice C, Beck's triad (hypotension, elevated jugular venous pressure, muffled heart sounds), may be present but is not always diagnostic. Choice D, Kussmaul breathing (deep, labored breathing), is indicative of other conditions like metabolic acidosis rather than cardiac tamponade.