This is quite a frequently asked question at the present time, therefore we are offering an explanation of why this is not necessary.

All dedicated inhalation sedation flowmeters operate in a similar manner.  The fresh (titrated) gases from the flowmeter outlet are ‘split’ into two flow conditions.  They enter the outlet (often referred to as the bag tee) and due to the bias on the flowmeter non-return valve, a portion of fresh gas is directed into the reservoir bag.  This is often used for patient monitoring, except when using a Porter Silhouette breathing system when no reservoir bag is present.

Due to this dedicated one-way flow of gases, the interior of the reservoir bag will not become contaminated and the exterior will only suffer light aerosol contamination, due to its usual position behind the chair head.  It is therefore recommended to only wipe the bag exterior between patients and then autoclave at the end of the sedation session, if required.

Autoclaving will shorten the life of the reservoir bag.  In normal circumstances, these 2  or 3 litre grey latex free bags will last 12-18 months.  Regular autoclaving will shorten this life expectancy period considerably.

A regular programme of checking the reservoir bag should be in place.  This takes two steps:

  1. Inspect the body of the bag for any deterioration
  2. Grasp the thick ferule neck whilst still on the bag tee, supporting with one hand.  With the other hand, gently pull down on the body of the bag to inspect the area between the ferrule neck and body.  This is the area most likely to exhibit the first signs of perishing – or even small holes may appear during this step.

If any signs of damage, wear or perishing are observed, the bag should be replaced immediately.  It is recommended a spare should be kept at all times.

The use of green single patient use  bags is not recommended with relative analgesia machines due to the differing materials and the method in which they operate.

If there are any queries regarding the above, or more information is required, please contact Mrs Janet Pickles on