Difficulty: Hard

Average Score: 47%

Why is 70% isopropyl alcohol commonly used as an antiseptic for venipuncture instead of 100% isopropyl alcohol?

Rationale

70% isopropyl alcohol kills bacteria more effectively than 100% isopropyl alcohol.

The optimal concentration for isopropyl alcohol to act effectively as an antiseptic is around 70%. This concentration allows for adequate penetration into the cell walls of bacteria, leading to more effective cell disruption and death compared to higher concentrations, which may evaporate too quickly to achieve the desired antimicrobial effect.

A (It's less painful on contact with the skin) YOUR ANSWER

While 70% isopropyl alcohol may be perceived as less irritating than higher concentrations, the pain level is not a primary factor in its antiseptic effectiveness. The primary reason for using this concentration relates to its ability to kill bacteria rather than discomfort upon application.

B (It kills bacteria more effectively) CORRECT

Higher concentrations of isopropyl alcohol can evaporate quickly, thereby reducing contact time with the skin and bacteria, which limits effectiveness. The 70% solution provides a balance that enhances the antimicrobial action due to prolonged exposure, making it more effective at killing bacteria than the 100% solution.

C (It's less likely to cause an allergic reaction) YOUR ANSWER

Allergic reactions to isopropyl alcohol are not solely dependent on concentration. While a lower concentration may be somewhat less irritating, the likelihood of an allergic reaction is more related to individual sensitivity rather than the specific antiseptic action of the solution.

D (It's less expensive) YOUR ANSWER

Cost considerations may vary by supplier, but the price difference between 70% and 100% isopropyl alcohol is generally not significant enough to be a determining factor in selection. Effectiveness and safety are prioritized over cost in medical settings.

Conclusion

The use of 70% isopropyl alcohol as an antiseptic for venipuncture is primarily due to its enhanced ability to kill bacteria effectively, a result of optimal concentration that balances efficacy with safe application. Other factors, such as pain, allergic reactions, and cost, play lesser roles in its selection compared to its superior antimicrobial properties.

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