You are preparing to intubate an unconscious closed head injury patient with an increased intracranial pressure due to respiratory insufficiency and inability to control his airway. Concern at an additional increase in intracranial pressure prompts you to consider the intravenous administration of which of the following prior to an intubation attempt?

Correct Answer: C

Rationale: The correct answer is C: Lidocaine. Lidocaine is used prior to intubation in head injury patients with increased intracranial pressure to minimize the potential increase in intracranial pressure caused by laryngoscopy and endotracheal tube insertion. Lidocaine acts as a local anesthetic and suppresses the cough reflex, reducing the risk of elevated intracranial pressure during intubation. Diazepam (A) and Lorazepam (B) are not typically used in this scenario and may cause respiratory depression. Procainamide (D) is an antiarrhythmic drug and is not indicated for reducing intracranial pressure during intubation.

Correct Answer: A

Rationale: The correct answer is A: Monro-Kellie Principle. This principle states that the total volume inside the skull remains constant, so an increase in one component (such as cerebral blood volume) must be compensated by a decrease in another (such as CSF volume) to maintain a normal ICP. This is crucial in head injuries to prevent dangerous elevations in pressure. B: Bernicke Principle does not pertain to intracranial pressure regulation. C: Fick Principle is related to cardiac output. D: Bernoulli's Principle is about fluid flow and pressure, not specific to ICP regulation.

Correct Answer: B

Rationale: The correct answer is B: To ensure any undeployed airbags do not discharge and cause an injury to the patient or anyone involved. It is important to disconnect the battery before attempting to enter the vehicle or extricate the driver because doing so can prevent any undeployed airbags from suddenly deploying during the extrication process. Deploying airbags can cause serious injuries to the patient or rescuers due to the force and speed at which they inflate. Disconnecting the battery helps to eliminate this risk and ensures a safer extrication process. Choice A is incorrect because the main concern is not about the vehicle moving during extrication. Choice C is incorrect as electrocution risk is more related to high-voltage components in hybrid or electric vehicles, not just the standard battery. Choice D is incorrect as the battery disconnection is primarily to prevent airbag deployment, not to prevent fires in the passenger compartment.

Correct Answer: D

Rationale: The correct answer is D: "Produce the greatest number of survivors based on available resources." This principle of triage, known as "maximizing the number of survivors," aims to save as many lives as possible by prioritizing treatment based on the likelihood of survival with available resources. By focusing on maximizing the number of survivors, it ensures efficient use of limited resources and increases overall survival rates. Other choices are incorrect because solely treating the most severely injured patients first (A) may not lead to the highest number of survivors, establishing a field triage area directed by a doctor (B) might not always be feasible in emergency situations, and rapidly transporting all patients to the nearest hospital (C) may not consider the severity of injuries or resource limitations.

Correct Answer: B

Rationale: The correct answer is B: Cerebral vasoconstriction with diminished perfusion. In severe traumatic brain injury, avoiding profound hypocarbia is important to prevent cerebral vasoconstriction, which reduces blood flow to the brain, worsening the injury. Hypocarbia causes constriction of cerebral blood vessels, leading to decreased perfusion and exacerbating brain damage. Respiratory alkalosis (A) and metabolic acidosis (C) are not direct consequences of hypocarbia in this context. Neurogenic pulmonary edema (D) is caused by increased permeability of pulmonary capillaries due to neurological insult, not by hypocarbia.