Venous blood samples are often obtained in the pre-hospital setting for various tests to be performed at the hospital. What color tube stopper would a paramedic want to use if law enforcement at an accident requests the patients involved have their blood drawn at the scene to be tested for the possibility of alcohol intoxication at the hospital?

Correct Answer: A

Rationale: The correct answer is A: Gray. Gray stopper tubes are used for blood samples to test for alcohol levels, such as for blood alcohol content (BAC). This is because gray stopper tubes contain sodium fluoride, which prevents blood from fermenting and preserves alcohol levels accurately. Other choices are incorrect: B (light blue) is used for coagulation testing, C (lavender) is used for complete blood count (CBC) and blood typing, and D (green) is used for chemistry tests.

Correct Answer: A

Rationale: The correct answer is A: "Inserting an oropharyngeal airway." In this scenario of a motorcycle crash with noisy respirations, apnea, and a hematoma in the pharynx, the patient is likely experiencing airway obstruction. An oropharyngeal airway helps maintain a patent airway by preventing the collapse of the tongue and soft tissues in the oropharynx. It does not require visualization or manipulation of the upper airway structures, making it the most suitable initial intervention in this emergent situation. Summary of why the other choices are incorrect: B: "Inserting a nasopharyngeal airway" - Nasopharyngeal airways are not recommended in the presence of facial trauma or suspected basilar skull fracture due to the risk of exacerbating the injury. C: "Performing a surgical cricothyroidotomy" - This is an invasive procedure reserved for extreme cases of airway obstruction when other methods fail. D

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.