The Science Journal of the American Association for Respiratory Care

1997 OPEN FORUM Abstracts

RECYCLING LIMIT FOR A DISPOSABLE CAPNOMETER ADAPTER

Robert Messenger BS, RRT, Respiratory Care Division - Pulmonary Services Department, MetroHealth Medical Center, Cleveland, OH.

Introduction: One of the options available for use with the N-6000 capnometer (Nellcor-Puritan-Bennett, Haywood, CA) is a disposable "single patient use only" mainstream airway adapter (ADAP-UC). We sought to determine the recycling endpoint, beyond which the accuracy of data obtained from these adapters would be compromised. Method: 30 new airway adapters were labeled and numbered. Each adapter was evaluated using a calibrated capnometer which was restricted to use only for this study. A certified gas (5.07% CO_{2}), meeting the manufacturer's specifications for sensor verification was passed at 2 lpm through the adapter via a sampling system designed to eliminate contamination with ambient air, and the resulting values were recorded. After the initial test, all of the adapters were placed into clinical service until either the capnographic waveform dampened or end-tidal monitoring was no longer indicated. The adapters were cleaned of gross matter using either a nylon tube brush or cotton tipped swabs. Next they were sterilized by soaking in a cold activated gluteraldehyde solution for 30 minutes, followed by a 20 minute water rinse and drying in a tube dryer. Each adapter was tested again by the previously described method and the results recorded. 14 of the original 30 adapters underwent 16 use-sterilization-testing cycles, while 16 adapters were lost or disposed of during the 7 month testing period. Results: Not until 15 resterilization cycles did any adapter yield a CO_{2} value outside of the manufacturers specified range (cycle 15 - 1 failure, cycle 16 - 2 failures). Mean adapter calibration values exhibited a progressively increasing trend with each sterilization cycle. However, when compared using one-way ANOVA, no significant difference was seen between sterilization groups, until 16 cycles were reached (p=0.0409). See table below:

Test gas [CO_{2}]= 5.07%

Test Initial 1 2 ~ 8 9 10 11 12 13 14 15 16

n 30 30 30 28 28 28 28 25 20 17 17 14

High 5.3 5.3 5.3 ~ 5.3 5.3 5.3 5.3 5.3 5.3 5.3 5.4 5.7

Low 4.9 5.0 5.0 ~ 5.0 5.0 5.0 5.0 5.0 5.0 5.1 5.1 5.1

Mean 3 5.12 5.14 ~ 5.16 5.15 5.14 5.17 5.18 5.17 5.21 5.19 5.22

SD 0.09 0.10 0.10 ~ 0.08 0.09 0.10 0.09 0.09 0.07 0.06 0.09 0.15

Test Initial 1 2 ~ 8 9 10 11

p 0.8922 0.774 ~ 0.6545 0.7407 0.827 0.7747

p[cont'd] 12 13 14 15 16

0.5984 0.6086 0.3133 0.1996 0.0409

Conclusion: Following cold sterilization with activated gluteraldehyde, these disposable adapters can be recycled 15 times without adversely affecting the accuracy of values obtained from their use. Further study is needed to determine the effects of other sterilization methods on the durability and accuracy of these adapters.

OF-97-017

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