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Difficulty: HardPharmacological Therapies

A practical nurse is preparing to administer 10 units of regular insulin and 20 units of NPH insulin mixed in a single syringe to a client with diabetes mellitus. Arrange the following steps in the correct sequence for this procedure.

  1. 1Roll the NPH insulin vial gently between the palms of the hands.
  2. 2Inject 20 units of air into the NPH insulin vial.
  3. 3Inject 10 units of air into the regular insulin vial.
  4. 4Invert the regular insulin vial and withdraw 10 units of insulin.
  5. 5Insert the needle into the NPH insulin vial and withdraw 20 units of insulin.

Answer

The correct sequence is to roll the NPH vial, inject 20 units of air into the NPH vial, inject 10 units of air into the regular insulin vial, withdraw 10 units of regular insulin, and finally withdraw 20 units of NPH insulin.
When mixing NPH (intermediate-acting) and regular (short-acting) insulins, the standard safety protocol is 'clear before cloudy' for withdrawing the medication to prevent contamination of the fast-acting insulin. However, to prevent a vacuum in the vials, air must first be injected into the cloudy (NPH) vial, followed by injecting air into the clear (regular) vial. The regular insulin is then withdrawn first, and the NPH is withdrawn last to complete the total dose.

Step-by-Step Solution

1
Roll the NPH insulin vial gently between the palms of the hands.
The cloudy insulin suspension is thoroughly mixed.
Rolling prevents the formation of air bubbles that can occur with shaking, ensuring an accurate dose.
2
Inject 20 units of air into the NPH insulin vial.
The NPH vial is pressurized.
Injecting air prevents negative pressure. Doing this first (cloudy first for air) prevents contamination of the regular insulin later.
3
Inject 10 units of air into the regular insulin vial.
The regular insulin vial is pressurized.
Prevents negative pressure in the regular insulin vial. The needle is left in place to immediately draw the medication.
4
Invert the regular insulin vial and withdraw 10 units of insulin.
The clear insulin is drawn into the syringe.
Drawing clear insulin first ('clear before cloudy') prevents contaminating the short-acting insulin with the longer-acting NPH insulin.
5
Insert the needle into the NPH insulin vial and withdraw 20 units of insulin.
The final combined dose of 30 units is achieved.
The cloudy insulin is drawn last. The nurse must carefully draw exactly 20 units, as it cannot be pushed back into the vial if overdrawn.

Key Concept

Safe administration and preparation of mixed insulins
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Topics

Pharmacological Therapies

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