Medical gown standard "AAMI level"

Release date: 2020.09.28

Judgment of protection performance by 4 tests

Release date: 2020.9.28

AAMI level is a standard that classifies medical gowns such as surgical gowns, drapes, and isolation gowns according to their protective performance.
As with any PPE, medical gowns that protect healthcare professionals from risks such as infection should be selected with the right performance for their application. There is no unified standard for classifying the performance of gowns in Japan, but based on the standard set by the Association for Advancement of Medical Instrumentation (AAMI), it is divided into four levels of protection.

The AAMI level is judged by the following four tests.

1. Water resistance / impact penetration test (AATCC42)
Judging the penetration resistance when spraying water with a spray

2. Water resistance / static pressure test (AATCC127)
Judgment of permeation resistance in the case of continuous pressure contact with water

3. Synthetic blood penetration test (ASTM F1670)
Determine the permeation resistance of blood substitutes (for surgical drapes)

4. Viral entry test (ASTM F1671)
Determine the penetration resistance of blood and bacteria / viruses

4 levels of protective effect

Based on the above test results, the protection performance is divided into four levels. The highest level is 4.

AAMI level

level	Exams and results	Protective effect	Examples of suitable surgery
１	Water penetration is 4.5g or less in impact resistance test	Minimum water resistance	Short-term surgery with little exposure to blood, etc.
2	The amount of water permeation is 1.0 g or less in the impact resistance test, and 20 cm or more in the hydrostatic pressure test.	Some degree of water resistance	Endoscopic surgery, cataract surgery, etc.
3	The amount of water permeation is 1.0 g or less in the impact resistance test, and 50 cm or more in the hydrostatic pressure test.	Moderate water resistance	General laparotomy, mastectomy, etc.
4	No penetration at 2psi (13.8kPa) in synthetic blood penetration test and virus entry test	Blood / virus penetration resistance	Surgery that is expected to require large amounts of blood exposure or fluid use, such as hepatobiliary pancreatic surgery, artificial blood vessel replacement surgery, and cesarean section.

The gown is judged by the performance of the front part of the body and both arms, which have the highest risk of contamination.
In practice, it is normal to use the appropriate level of products according to the surgical procedure and the wearer's area of responsibility.
This AAMI level is divided into levels of protective performance, but it is necessary to select products in consideration of performance such as strength, durability, fire resistance, static electricity resistance, chemical resistance, hygiene, breathability and comfort.

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