Circulation 76,548 • Volume 20, No. 4 • Winter 2005   Issue PDF

Absorbent Wrapper Design Questioned

Tom Wright, MD; Jeff Mack; Eldon P. Rosentrater; David Baines; Michael Mitton

Editor’s Note: Although Dr. Wright may have later determined the manufacturer of the product in question, the Editors subsequently located at least 2 additional reports of circuit obstruction by unwrapped absorbent canisters, apparently manufactured by other companies. Our focus, then, is not to implicate any particular brands, but to allow manufacturers to address the issue of safety. ~ Drs. Morell and Olympio

Dear SIRS:

I am aware of 2 instances where the plastic wrapper on the soda lime was not removed prior to installation into the machine. Both instances occurred late in the day and were accompanied by unexpected ventilation problems. Both instances were “solved” before a catastrophe occurred, but there was much “running around” during the trouble-shooting.

I am concerned that this will result in a patient death.

This could all be avoided if we always checked our machines before induction, but I know that my colleagues don’t always do that once the day is underway. Also, we instituted a protocol whereby the anesthesia “aide” who changes the lime is to write a note and set it on the gas machine warning the anesthetist that the lime has been changed. This was not done in the most recent case. That case was also accompanied by a change in nursing personnel at 3:00 pm. The new nurse was not informed that the lime had been changed, nor was I.

The problem here is that the line of communication can always be broken.

If, however, the canister could not be closed with a properly designed wrapper on it, then it would be impossible to close the cage over an unwrapped canister. The wrapper on these canisters is clear plastic with some fenestrations (which allowed some airflow through them) and printed on that plastic in red letters is the following:

“THIS WRAPPER MUST BE REMOVED PRIOR TO USE.” It is repeated numerous times on each canister, and is hard to miss.

I would appreciate your thoughts. Thanks for listening, and thanks for the APSF.

Tom Wright, MD
Minneapolis, MN

This photograph is an example of one manufacturer’s reminders to remove the wrapper on an absorbent canister before installation into the anesthesia machine.


Dear SIRS,

Grace has taken several steps to ensure that end users are aware of the wrapping around our pre-pak cartridges and that said wrapping should be removed prior to use. The first step is a clear, written statement printed on the wrap stating clearly “STOP!!! – remove this shrink wrap before use.” Second, we have a red “easy open” tear strip around the top of the package that has clearly written on it “STOP – remove before use.” Third, and even more important, Grace does not tighten the wrapping to the point at which it fully adheres to the sides of the container. We purposefully “blouse” the wrapping so it protrudes from the sides of the container, making the wrapping not only more evident, but also making it more difficult for the end user to put the cartridge into the delivery unit. I have attached a photo as a visual aid to show you what I mean.

I would very much like to get further details from Dr. Wright to determine whether it was a Sodasorb brand cartridge that was put into use prior to the wrapping being removed, and if so, to get additional details so we can enter this incident into our formal quality follow-up process.

Jeff Mack
Global Sales & Marketing Manager, Sodasorb
Grace Performance Chemicals
W.R. Grace & Co.-Conn


Dear SIRS,

Carbolime is shipped with a shrink wrapper that incorporates a label within the wrapper material itself. The label clearly states that the wrapper must be removed before use. Additionally, when the wrapper is shrunk onto the canister, the “corners” of the wrapper protrude from the circumference of the canister making it difficult to insert the canister into an anesthesia machine without removing the wrapper. Despite these factors, there have been—albeit extremely infrequent—reports of users placing Carbolime canisters in anesthesia machines without removing the wrapper from the canister. Allied encourages users of its Carbolime product to read and heed all labels associated with the product.

Eldon P. Rosentrater
VP Administration
Allied Healthcare Products, Inc.


Dear SIRS:

We are committed to working together with our distributors, equipment manufacturers, and designers, as well as the end users to ensure ease and proper use of our products and to participate in proper training.
Sofnolime is shipped to this end with safety features in mind.

  1. Clear markings are placed in the outer wrapper of cartridges to enable user-friendly reminders and facilitate training in the preparation and use of “one shot” cartridges.
  2. Cartridges are shrink-wrapped with clear markings and instructions.

We believe that the concept of “better by design” in combination with these 2 principles can make a difference.

Molecular Products encourages all distributors and customers to spread the “good practice” of reading all labels and instructions before use of consumables. Continuous training and re-enforcement programs are an integral part of these good practice regimes.

Our carton and product markings are under constant review, and we welcome suggestions as to more effective, internationally recognizable, and attention-seeking labels that would reduce further any instance that threatens patient safety.

“Designed for purpose” is the ultimate goal of every product and this incident has provoked debate about removable packaging that could aid in avoiding repeat instances.

The “better by design” approach can have some unexpected consequences. It is quite easy to introduce a safety feature that, while preventing one form of misuse, inadvertently introduces an unexpected effect.

These effects can include both safety and commercial issues. Introducing a tear off safety tag that prevents insertion of the absorber can lead to people forcing the disposable cartridge into place, which causes damage to the ventilator equipment and in turn potentially leads to an even larger hazard to the patient than the original issue. It may also prevent insertion of further cartridges.

There is also the issue of increased cost. For instance, apart from the extra cost of the safety device itself, there can also be manufacturing process costs or packing density effects, which can alter the shipping costs and storage efficiency.

An apparently “simple” solution is not always “simple” and, without extensive field research, does not always have the expected or desired effect.

David Baines
Sales and Marketing Director
Molecular Products Limited


Dear SIRS:

The letter from Tom Wright, MD, to the APSF Newsletter describes what may most likely be seen by any anesthesia provider as an immediate high-priority problem, the unexpected inability to ventilate a patient (the lack of visibility of the root cause, the absorbent wrapper, complicated this event). Typical techniques may ultimately find the problem but, as the author states, “there was much ‘running around’ during the trouble-shooting.”

The author further suggests possible solutions that may help prevent this event from occurring in the future and, while some solutions may be explored, the preoperative checkout procedure required by the FDA1 provides users with an appropriate method to help avoid these events today. The FDA procedure provides both an accurate and reliable method to detect an anesthesia machine that is not functioning properly. The FDA procedure is designed to be conducted at the beginning of the work day and, in an abbreviated form, prior to each subsequent anesthetic.

The FDA checkout procedure is currently being reviewed2 and recommendations for changes may be presented shortly. In the meantime, this checkout procedure should remain a crucial portion of every safe anesthetic.

Michael Mitton
Director of Clinical Affairs
GE Healthcare, Life Support Solution


  1. Anesthesia Apparatus Checkout Recommendations, 1993. Available at: Accessed November 28, 2005.
  2. Feldman J. Efforts under way to revise the preuse checkout recommendations. ASA Newsletter 2005;69(10): Available at Accessed November 28, 2005.