PortaCount

How to perform a Visual-Seal-Check (VSC)?

by info on January 12, 2009

Totobobo mask is able to  fit a wide range of  large and small faces. However, it is not possible to claim that it always seal your face perfectly. Sometimes it may reqire adjustment of the strap and the position of the mask to improve the seal. Sometimes trimming down the mask to a smaller size may help.

The purpose of a user-seal-check is to provide a fast and reliable method to evaluate the face seal, without the need of fit-test equipments.

User-seal-check of normal respirator (e.g. N95 mask) involve the steps of cupping the filter area with hands, forcefully inhale and/or exhale to sense if there is air-leak. Such method relys on the user’s ability to feel the air movement around the leak area. Sereverl studies shown such method is not relaible.

The Totobobo Visual-Seal-Check (VSC) method (patent pending) is facilitated by a very fine texture molded on the inside of the transparent mask. In normal condition, the surface is dry and it appear as semi-transparent. The same surface turns transparent if there is water stick on the surface. Even a tiny little water trapped between the mask and the face will make the surface change from semi-transparent to complete transparent.

To do a simple Visual-Seal-Check, you apply a little moisture on your face, than put the mask on. Observe the edge of the mask. Where it is completely transparent, there is a good seal. Where there is semi-transparent, there is no seal. It will be consider as a good overall seal If there is a continuous seal circle around the nose and mouth.

Our user test using a TSI PortaCount system in a hospital, the gold standard of respirator fit test, shows there is a strong correlation (90%+) between the Visual-Seal-Check (VSC) and the standard fit-test results. In other words, it is possible to predict if the mask will pass or fail the gold standard fit-test by performing a TOTOBOBO VSC. This is particular useful for people who don’t have access to a proper fit-test system.

Milky surface indicates the face seal leak location

Milky surface indicates the face seal leak location

Transparent surface indicates good face seal of Totobobo mask

Transparent surface indicates good face seal of Totobobo mask

Buy Totobobo mask

Click on pen to Use a Highlighter on this page

{ 7 comments }

Document title
Predictive value of the user seal check in determining half-face respirator fit

Author(s)

DERRICK J. L. (1) ; CHAN Y. F. (1) ; GOMERSALL C. D. (1) ; LUI S. F. (2) ;

Author(s) Affiliation(s)
(1) Department of Anaesthesia and Intensive Care, The Chinese University of Hong Kong, Prince of Wales Hospital, Shatin, HONG-KONG
(2) Department of Medicine and Therapeutics, The Chinese University of Hong Kong, Prince of Wales Hospital, Shatin, HONG-KONG
Résumé / Abstract

Guidelines issued by the Centers for Disease Control and Prevention and the World Health Organization state that healthcare workers should wear N95 masks or higher-level protection during all contact with suspected cases of severe acute respiratory syndrome. Before use, the manufacturer recommends performing a user seal check to ensure that the mask is fitted correctly. This study aimed to test the ability of the user seal check to detect poorly fitting masks. This study is a retrospective review of a mask-fitting programme carried out in the intensive care unit of the Prince of Wales Hospital in Hong Kong. In this programme, all staff were tested with two types of N95 mask and one type of N100 mask. The results of the documented user seal check were then compared with the formal fit-test results from a PortaCount. Using a PortaCount reading of 100 as the criterion for a correctly fitted mask, the user seal check wrongly indicated that the mask fitted on 18-31% of occasions, and wrongly indicated that it did not fit on 21-40% of occasions. These data indicate that the user seal check should not be used as a surrogate fit test. Its usefulness as a pre-use test must also be questioned.

Revue / Journal Title
The Journal of hospital infection ISSN 0195-6701

Source:

Click on pen to Use a Highlighter on this page

{ 3 comments }