[Leakage in anesthesia circuits--a comparison between 1998 and 2005 investigations].

BACKGROUND

We checked for the occurrence of any leakage in an anesthesia circuit to estimate the present situation of airtightness of an anesthesia circuit in 55 anesthesia machines at various medical institutions in Okinawa.

METHODS

Leakage was detected and measured by a leak checker.

RESULTS

A certain degree of leakage was found in 28 of the anesthesia machines (51%). The average and maximal amounts of leakage in the anesthesia machines were 0.26, and 1.29 l x min(-1), respectively. Thirty-eight of anesthesia machines met the standards of a low flow leak test (69%). The average and maximal amounts of leakage in the inside circuit were 0.02, and 0.20 l x min(-1), respectively. The leak points of the inside circuit were present in a unidirectional valve for an oxygen sensor (14%) and for unknown reason (7%). The average and maximal amounts of leakage in the outside circuit were 0.24, and 1.29 l x min(-1), respectively. Leak points in the inside circuit were found in the corrugated breathing tube (82%) and canister (32%).

CONCLUSIONS

Most instances of leakage of the above described anesthesia circuits were identified in the corrugated breathing tube and canister. As a result of our findings, we strongly recommend that these parts be checked very carefully during pre-anesthetic leak tests.