Step-by-step explanation:
a. Inject air into each vial.
The nurse should inject air into each vial when preparing to mix NPH insulin and regular insulin. This step helps maintain equal pressure within the vials, making it easier to withdraw the desired amount of insulin.
Option b is incorrect because the regular insulin should be drawn up first. Drawing up the regular insulin before the NPH insulin prevents contamination of the regular insulin vial with any residual NPH insulin.
Option c is incorrect because shaking the vials vigorously before drawing up the insulin is not recommended. Vigorous shaking can cause the formation of air bubbles, which can affect the accuracy of the insulin dose.
Option d is incorrect because using a larger syringe does not necessarily provide more accurate measurement. The appropriate syringe size should be used based on the prescribed dose to ensure accurate measurement.
Option e is incorrect because using a different needle for each vial is not necessary. As long as the same needle is used to withdraw the desired amount of insulin from each vial, it is not necessary to change the needle between vials. Changing the needle unnecessarily increases the risk of accidental needlestick injuries.