NAPLEX Question of the Week: Order of Special K?

This week's question asks about a well known CNS agent.
NAPLEX Question of the Week: Order of Special K?
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Sarah, a 28-year-old female, is scheduled to undergo a short-term medical procedure that requires sedation and analgesia. Due to her history of a rash to lidocaine previously seen, the healthcare team is considering the use of ketamine for this procedure. Her current medications include Zyrtec 10 mg PRN seasonal allergies and Adderall 10 mg PO QD for ADHD. 

Vital signs –

BP: 110/88 mmHg

HR: 70 BPM

Temp: 98.7 F

O2: 100% (on room air)

BMP –

Na: 139 meq/L

K: 4.1 meq/L

BUN: 22 mg/dL

SCr: 0.8 mg/dL

Glucose: 105 mg/dL

Which of the following statements regarding the use of ketamine for short-term procedural sedation and analgesia are correct? Select all that apply.

A) Ketamine would be contraindicated due to her lidocaine allergy.

B) Ketamine would provide both analgesia and amnesia during the procedure.

C) Ketamine may increase intracranial pressure and should be monitored closely in patients with known elevated intracranial pressure.

D) Ketamine is associated with a risk of emergence reactions, such as hallucinations and vivid dreams.

E) The use of ketamine requires continuous monitoring of vital signs, including blood pressure and heart rate.

Answer with Rationale:

Ketamine is a medication primarily known for its anesthetic properties, but it is also used for analgesia and sedation in various medical settings. It belongs to the class of dissociative anesthetics and works by blocking N-methyl-D-aspartate (NMDA) receptors in the brain. Ketamine is valued for its rapid onset of action, making it suitable for emergency procedures and surgeries.

Answer A is incorrect. Ketamine is not contraindicated in patients with a history of allergic reactions to other anesthetics. In fact, it is often considered in such cases due to its distinct mechanism of action and lower risk of cross-reactivity. Lidocaine is an amide anesthetic and other amide anesthetics would likely need to be avoided in patients with documented lidocaine allergy. The other broader class of anesthetics are the "esters" such as procaine or benzocaine. Most self-reported allergies to anesthetics are not immune-mediated. 

Answer B is correct. Ketamine is known for its analgesic and amnestic properties, making it suitable for short-term procedural sedation. Patients may experience pain relief and a dissociative state during the procedure.

Answer C is correct. While ketamine is generally considered safe, it may transiently increase intracranial pressure (ICP). Caution is advised in patients with head injuries or conditions where increased ICP could be detrimental.

Answer D is correct. Ketamine administration is associated with emergence reactions, including hallucinations, vivid dreams, and delirium, especially during the recovery phase. Healthcare providers should be prepared to manage these reactions.

Answer E is correct. Continuous monitoring of vital signs, including blood pressure and heart rate, is crucial during ketamine administration. Ketamine can cause changes in hemodynamic parameters, and monitoring helps ensure the patient's safety throughout the procedure.

NAPLEX competencies:

  • 1.6 - Risk factors or maintenance of health and wellness
  • 2.1 – Pharmacology, mechanism of action, or therapeutic class
  • 3.7 – Adverse drug effects, toxicology, or overdose

This is our last question of 2023! Rest up and enjoy the holiday season as we will be back in 2024 to provide more questions to help you prepare to pass the NAPLEX! 

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