Potassium Delivery Calculation
The patient is receiving 3 mEq of potassium per hour.
Calculation Method
The calculation is straightforward using basic dimensional analysis:
- Concentration: 40 mEq/L of KCl in the IV solution
- Infusion rate: 75 mL/hr
- Hourly potassium delivery: (40 mEq/L) × (75 mL/hr) × (1 L/1000 mL) = 3 mEq/hr
Clinical Context
This infusion rate falls well within safe parameters for potassium replacement:
Standard recommendations: The FDA label for IV potassium chloride states that administration rates should not usually exceed 10 mEq/hour when serum potassium is greater than 2.5 mEq/L 1.
Maximum rates: In urgent cases with severe hypokalemia (serum K+ <2 mEq/L with ECG changes or muscle paralysis), rates up to 40 mEq/hour can be administered with continuous ECG monitoring and frequent serum potassium checks 1.
Research validation: Studies in critically ill patients have demonstrated that concentrated potassium infusions of 20 mmol/hr (20 mEq/hr) are well-tolerated and effective, with no transient hyperkalemia or arrhythmias observed 2.
Safety Considerations
At 3 mEq/hr, this represents a conservative replacement strategy:
Daily total: At this rate, the patient receives 72 mEq over 24 hours, which is within the typical 200 mEq/24-hour limit for non-urgent situations 1.
Monitoring requirements: While continuous ECG monitoring is not mandatory at this rate, periodic serum potassium checks remain important, particularly in patients with renal insufficiency, heart disease, or those on medications affecting potassium homeostasis 3.
Route considerations: Peripheral administration is acceptable at this concentration (40 mEq/L), though central access is preferred for concentrations of 300-400 mEq/L 1.