Question

Given below are two statements, one is labelled as Assertion (A) and other one labelled as Reason (R).
Assertion (A): Potassium may be supplemented by IV route at a rate over 0.5mEq/kg/hour in animals.
Reason (R): Adverse cardiac effects can occur above 0.5mEq/kg/hour rate.
In light of the above statements, choose the correct answer from the options given below.

• A. Both (A) and (R) are true and (R) is the correct explanation of (A).
• B. Both (A) and (R) are true but (R) is NOT the correct explanation of (A).
• C. (A) is true but (R) is false.
• D. (A) is false but (R) is true.

Hint:

The "potassium sliding scale" safety rule in veterinary medicine is:
Never exceed 0.5 mEq/kg/hour of IV potassium.
Infusing potassium faster than this can induce fatal cardiac arrhythmias.

Answer 1

The Correct Option is D

Step 1: Understanding the Concept:
Potassium is the primary intracellular cation.
Intravenous potassium supplementation is used to correct hypokalemia.
However, rapid infusion can cause life-threatening cardiotoxicity.

Step 2: Detailed Explanation:
Let us analyze the Assertion and Reason:
- Assertion (A) is false:
Potassium must not be administered intravenously at a rate exceeding 0.5 mEq/kg/hour (the "potassium infusion limit" or "K-max" rate).
Exceeding this rate can lead to acute hyperkalemia in the extracellular fluid.
This depolarizes the cell membrane of cardiac myocytes, leading to severe cardiac complications.
Therefore, the assertion stating that potassium may be supplemented at a rate "over" 0.5 mEq/kg/hour is medically incorrect.
- Reason (R) is true:
Infusing potassium above the rate of 0.5 mEq/kg/hour can cause adverse cardiac effects.
These include bradycardia, heart block, ventricular fibrillation, and cardiac arrest (diastolic standstill).
Thus, Assertion (A) is false but Reason (R) is true, which corresponds to Option (D).

Step 3: Final Answer:
(A) is false but (R) is true, matching Option (D).