WBR0537

Author	[[PageAuthor::Rim Halaby, M.D. [1] (Reviewed by Serge Korjian M.D.)]]
Exam Type	ExamType::USMLE Step 1
Main Category	MainCategory::Pharmacology
Sub Category	SubCategory::Neurology
Prompt	[[Prompt::A researcher is studying the hemodynamic and respiratory effects of intravenous anesthetics. In one experiment, he injects a mouse with intravenous ketamine infusion. Several minutes later, he measures the mouse's heart rate (HR), blood pressure (BP), cerebral blood flow (CBF), and bronchial diameter (BDm) to assess the cardiovascular and respiratory roles of ketamine. Which of the following hemodynamic and respiratory changes are most likely to occur following ketamine infusion in this experiment?]]
Answer A	AnswerA::Increased HR, increased BP, increased CBF, and increased BDm
Answer A Explanation	AnswerAExp::Ketamine administration results in increased HR, increased BP, increased CBF, and increased BDm.
Answer B	AnswerB::Increased HR, decreased BP, increased CBF, and increased BDm
Answer B Explanation	AnswerBExp::BP increases following ketamine infusion.
Answer C	AnswerC::Increased HR, decreased BP, increased CBF, and decreased BDm
Answer C Explanation	AnswerCExp::BP and BDm increase following ketamine infusion.
Answer D	AnswerD::Increased HR, decreased BP, decreased CBF, and decreased BDm
Answer D Explanation	AnswerDExp::BP, CBF, and BDm increase following ketamine infusion.
Answer E	AnswerE::Decreased HR, increased BP, increased CBF, and increased BDm
Answer E Explanation	AnswerEExp::HR increases following ketamine infusion.
Right Answer	RightAnswer::A
Explanation	[[Explanation::Ketamine is a phencyclidine (PCP) analog used as an intravenous anesthetic drug. Ketamine acts as a non-competitive N-methyl-D-aspartate (NMDA) receptor blocker. Ketamine is known to cause dissociative anesthesia, a state of profound analgesia with only superficial sleep and spontaneous ventilation. It does not usually suppress respiratory drive unless used at very high doses. Because ketamine increases intracranial pressure, it is contraindicated among patients with brain injury. Other systemic effects of ketamine are generally also increased. Following ketamine, there is an increased heart rate, blood pressure, CVP, CO2 baroreceptor function, bronchodilation, respiratory rate, uterine tone, salivation. Educational Objective: Ketamine causes systemic effects by stimulating hemodynamic and respiratory systems. Following ketamine, there is an increased heart rate, blood pressure, cerebral blood flow, CVP, CO2 baroreceptor function, bronchodilation, respiratory rate, uterine tone, salivation. References: Stevenson C. Ketamine: a review. Update in Anaesthesia. 2005;20:25-9.]]
Approved	Approved::Yes
Keyword	WBRKeyword::Ketamine, WBRKeyword::Hemodynamic, WBRKeyword::Respiratory, WBRKeyword::Adverse effect, WBRKeyword::Drug, WBRKeyword::Anesthesia, WBRKeyword::Dissociative, WBRKeyword::Analgesia, WBRKeyword::Heart rate, WBRKeyword::Cerebral blood flow, WBRKeyword::CVP, WBRKeyword::Bronchodilation, WBRKeyword::Respiratory rate, WBRKeyword::Uterine tone, WBRKeyword::Salivation
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