Checking anaesthetic breathing filters for obstructions or leaks
A recent incident where a patient was unable to be ventilated was caused by a plastic film remaining on the anaesthetic breathing filter at the Y-piece (see picture, on the right).
The product was a Fairmont Medical Anaesthetic Filter #DAF9020 (manufacture date April 2025). Fairmont Medical have identified that during assembly the adhesive film remained on the filter and have classified this as an isolated non-systemic event.
There were no clinical consequences on this occasion, although it could lead to patient distress (during pre-oxygenation), delayed ventilation while troubleshooting, or possibly a mis-diagnosis of severe bronchospasm or endotracheal tube misplacement.
ANZCA professional document PG31 Checking anaesthesia delivery systems includes protocols for conducting checks. A Level 2 two-bag test (as per Part 4.2.3.4.3) would detect an obstruction and leak in the breathing filter, but only if the filter was attached to the Y-piece at the time.
As such, the Y-piece should be considered to include the breathing filter, if it is to be used. Many will already undertake this practice, but all those who perform Level 2 and 3 circuit checks should be informed.
As the breathing filter is changed for each patient, Part 4.3.2 of the Level 3 check should apply (that is, check the breathing system as it has been changed).
