PART 6 — Insulins & Hyperkalemia Cocktail

ICU Rule #4:

Insulin does more than lower blood sugar. In the ICU, insulin is also used to temporarily lower potassium during life-threatening hyperkalemia.

🧠 Memory Trick:

• Insulin = Sugar ↓

• Insulin + D50 = Potassium ↓ (temporarily)

What type of insulin is Lispro (Humalog)?

Rapid-acting insulin.

💡 Rationale:
Lispro begins working very quickly, making it ideal for controlling blood sugar around meals or for correctional ("sliding scale") insulin.

🧠 Memory Trick:
Lispro = Lunch insulin

When does Lispro begin working?

About 15 minutes after administration.

💡 Rationale:
Because it works so quickly, food should be available shortly after administration to prevent hypoglycemia.

When does Lispro peak?

About 1 hour.

💡 Rationale:
This is when hypoglycemia is most likely to occur.

How long does Lispro last?

Approximately 3–5 hours.

💡 Rationale:
Its short duration makes it useful for meal coverage.

What is the nurse's priority before giving Lispro?

Verify the patient's blood glucose and ensure they are able to eat.

💡 Rationale:
Giving rapid-acting insulin without food can cause severe hypoglycemia.

A nurse prepares to administer Lispro before breakfast. The dietary tray has not arrived.

What is the best nursing action?

A. Administer the insulin immediately.

B. Hold the insulin until food is available.

C. Double the insulin dose later.

D. Give D50 first.

B

💡 Rationale

Lispro acts rapidly. If food is delayed, the patient is at high risk for hypoglycemia.

What type of insulin is Regular insulin (Humulin R)?

Short-acting insulin.

💡 Rationale:
Regular insulin is the only insulin routinely given IV, making it the insulin of choice for ICU insulin infusions and hyperkalemia treatment.

🚨 High-Yield Exam Tip:
Regular insulin = ONLY insulin given IV.

When does Regular insulin begin working?

About 30–60 minutes when given subcutaneously.

💡 Rationale:
It has a slower onset than Lispro but a longer duration.

Why is IV Regular insulin given during hyperkalemia?

It shifts potassium from the bloodstream into the cells.

💡 Rationale:
Insulin stimulates the sodium-potassium ATPase pump, temporarily lowering the serum potassium level.

🧠 Memory Trick:
Insulin pushes potassium IN.

Why is Dextrose (D50) usually given with IV Regular insulin?

To prevent hypoglycemia.

💡 Rationale:
Insulin lowers blood glucose regardless of the reason it is given.

A patient has a potassium level of 6.8 mEq/L with peaked T waves on the ECG.

Which medication should the nurse anticipate?

A. Lispro

B. Regular insulin IV with D50

C. Lantus

D. Cardizem

B

💡 Rationale

IV Regular insulin rapidly shifts potassium into cells. D50 prevents dangerous hypoglycemia during treatment.

What type of insulin is Lantus (Glargine)?

Long-acting (basal) insulin.

💡 Rationale:
Lantus provides a steady level of insulin throughout the day and night without significant peaks.

🧠 Memory Trick:
Lantus = Lasts all day.

Does Lantus have a peak?

No significant peak.

💡 Rationale:
This steady effect helps maintain consistent blood glucose control.

Can Lantus be mixed with other insulins?

No.

💡 Rationale:
Mixing Lantus changes its absorption and can alter its effectiveness.

🚨 Exam Tip:
Never mix Lantus with any other insulin.

Is Lantus used to correct high blood sugar quickly?

No.

💡 Rationale:
Because it works slowly over approximately 24 hours, it is not appropriate for correctional dosing.

A nurse prepares to mix Lantus and Lispro into the same syringe.

What should another nurse do?

A. Continue because both are insulin.

B. Stop the nurse because Lantus should never be mixed.

C. Only mix if the patient is diabetic.

D. Shake the syringe well.

B

💡 Rationale

Lantus should never be mixed with any other insulin.

What is the purpose of the hyperkalemia cocktail?

To temporarily lower serum potassium while definitive treatment removes potassium from the body.

💡 Rationale:
The cocktail shifts potassium into cells but does not eliminate potassium from the body.

🚨 Exam Tip:
This is one of the most tested concepts in critical care.

What medications are commonly included in a hyperkalemia cocktail?

• IV Regular insulin

• D50 (Dextrose)

• Sodium bicarbonate (in selected patients, especially with metabolic acidosis)

• Calcium gluconate or calcium chloride (to stabilize the cardiac membrane—not to lower potassium)

• Nebulized albuterol (sometimes)

💡 Rationale:
Each medication has a different role in protecting the heart or lowering serum potassium.

Which medication actually protects the heart during hyperkalemia?

Calcium gluconate (or calcium chloride).

💡 Rationale:
Calcium stabilizes the myocardial cell membrane, reducing the risk of fatal dysrhythmias. It does not lower potassium.

🧠 Memory Trick:
Calcium = Calms the heart.

Which medication actually moves potassium into the cells?

Regular insulin.

💡 Rationale:
Insulin activates the sodium-potassium ATPase pump, temporarily shifting potassium intracellularly.

Does insulin remove potassium from the body?

No.

💡 Rationale:
Potassium remains in the body. Additional treatments (dialysis, loop diuretics, potassium binders) may be needed to remove it.

🚨 High-Yield Exam Tip:
Shift ≠ Remove

What should the nurse monitor after administering the hyperkalemia cocktail?

• Blood glucose

• Potassium level

• Cardiac rhythm

• Repeat ECG if indicated

💡 Rationale:
The patient is at risk for both hypoglycemia and recurrent hyperkalemia.

A patient has:

• Potassium: 7.1 mEq/L

• Peaked T waves on ECG

The provider orders:

• Regular insulin IV

• D50

• Calcium gluconate

Which statement is correct?

A. Calcium gluconate lowers potassium.

B. Insulin permanently removes potassium.

C. Calcium gluconate stabilizes the heart while insulin shifts potassium into the cells.

D. D50 lowers potassium.

C

💡 Rationale

• Calcium gluconate protects the myocardium.

• Regular insulin shifts potassium into cells.

• D50 prevents hypoglycemia.

• None of these medications remove potassium from the body.

🧠 THE 5 THINGS I WOULD MEMORIZE FOR YOUR MED EXAM

• Levophed = First-line for septic shock.

• Precedex doesn't suppress respiratory drive like most sedatives.

• Paralytics (Nimbex, Rocuronium, Succinylcholine) DO NOT provide sedation or pain relief.

• Regular insulin is the only insulin routinely given IV and is used in the hyperkalemia cocktail.

• Calcium protects the heart; insulin shifts potassium; neither removes potassium from the body.