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Difficulty: MediumPharmacological and Parenteral Therapies

A nurse is preparing to draw up a mixed dose of Regular insulin and NPH insulin into a single syringe. Arrange the following steps of the procedure in the correct chronological sequence.

  1. 1Roll the vial of NPH insulin gently between the palms of the hands.
  2. 2Inject a volume of air equal to the prescribed dose into the NPH insulin vial.
  3. 3Inject a volume of air equal to the prescribed dose into the Regular insulin vial.
  4. 4Withdraw the prescribed dose of Regular insulin from its vial.
  5. 5Withdraw the prescribed dose of NPH insulin from its vial.

Answer

The correct sequence is to roll the NPH vial, inject air into the NPH vial, inject air into the Regular vial, withdraw the Regular insulin, and finally withdraw the NPH insulin.
To safely mix insulin without cross-contamination, the mnemonic 'RN' (Regular then NPH) or 'Clear before Cloudy' is universally applied. The sequence requires pressurizing the NPH vial first with air, then pressurizing the Regular vial, immediately withdrawing the Regular insulin, and finally withdrawing the NPH insulin.

Step-by-Step Solution

1
Roll the vial of NPH insulin gently between the palms of the hands.
The NPH insulin suspension is evenly mixed without creating air bubbles.
NPH insulin is a cloudy suspension that settles over time. Rolling resuspends it safely; shaking creates bubbles that can cause inaccurate dosing.
2
Inject a volume of air equal to the prescribed dose into the NPH insulin vial.
The NPH vial is pressurized for later withdrawal.
Air must be injected to prevent a vacuum, but the medication is not withdrawn yet to maintain the critical 'clear before cloudy' drawing sequence.
3
Inject a volume of air equal to the prescribed dose into the Regular insulin vial.
The Regular insulin vial is pressurized.
The nurse pressurizes the second vial and leaves the needle in place to immediately begin withdrawing the clear insulin.
4
Withdraw the prescribed dose of Regular insulin from its vial.
The exact dose of clear, rapid-acting insulin is drawn into the syringe.
Regular insulin (clear) must always be drawn up first to prevent accidental contamination of the vial with intermediate-acting (cloudy) NPH insulin.
5
Withdraw the prescribed dose of NPH insulin from its vial.
The exact dose of NPH insulin is added to the syringe, completing the mixed dose.
The cloudy insulin is drawn last. The nurse must carefully withdraw the exact amount, as pushing fluid back into the NPH vial would contaminate it with Regular insulin.

Key Concept

When mixing insulins in a single syringe, the clear (short-acting, Regular) insulin must always be drawn up before the cloudy (intermediate-acting, NPH) insulin to prevent altering the rapid-acting properties of the clear insulin vial.
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Topics

Pharmacological and Parenteral Therapies

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