To the Editor
On November 18, 1996, Abbott Laboratories Hospital Products Division issued an “Important Drug Recall” for sevoflurane – Lot # 10-590-DK. This was initially sent to directors of pharmacies, directors of anesthesia departments, hospital administrators, distributors, and associated wholesalers who purchased sevoflurane directly. Our hospital, which purchases indirectly through a wholesaler, was notified by fax on November 21: “The reason for this recall is the development in the field of acidic levels outside [Abbott’s] acceptable range. This occurrence may be associated with a slight pressure buildup and the presence of a pungent odor and/or cloudiness in the liquid.”
Several factors prompt my letter. First, our hospital received and we used bottles of sevoflurane from the affected lot. Second, sharing our experience might alert others who may be faced with a similar situation. [Editor’s Note: an Abbott spokesperson states that all bottles of the identified lot have been accounted for.] This will continue to be relevant until the mechanism for the presence of hydrofluoric acid is determined and the final analysis of any other, possibly toxic breakdown products is completed and made available. Third, it is hoped that it might contribute to the development of a generic protocol for dealing with any other extraordinary situation in the future.
On November 22, one of our staff opened a partially used bottle of sevoflurane and noted both a demonstrably increased pressure within the bottle and a strong odor. I also sniffed what was an overwhelming acrid odor. Because it seemed certain that this bottle of the sevoflurane was contaminated, I immediately directed the temporary discontinuation of the use of sevoflurane and the removal and isolation of all 10 of our sevoflurane vaporizers. I then measured (in the Chemistry Laboratory under a hood) the pH in the partially opened bottle and a bottle from another lot, finding a pH of 1.0 in the first and 5.0 in the second. Next, I contacted Dr. Clair Callan of Abbott Laboratories who confirmed my suspicion that the contaminated bottle contained hydrofluoric acid. Abbott also immediately contacted Ohmeda who advised against the further use of the sevoflurane vaporizers or anesthesia machines which could possibly have been corroded by the acid or contaminated with other, as yet unknown, breakdown products. Abbott sent a representative who emptied all the vaporizers and took a sample from the partially opened bottle which, by that time, contained an amorphous crystalline formation. Ohmeda quickly implemented replacement of all vaporizers and potentially contaminated machine parts. Five machines were completely refitted within two days of notification and five others within another three days.
I subsequently reviewed the records of the more than 90 patients given general anesthesia during the time we had the contaminated sevoflurane. Approximately 10% actually received sevoflurane. No operative or postoperative record revealed evidence of undue respiratory responses (e.g. excessive coughing), unexpected pulmonary pathology, or other irritation.
The potential effect of the contaminants on vaporizer function and on sevoflurane in the vaporizer lead to concern that may be resolved with discovery of the cause of the contamination. Presently, it is not known whether the cause might affect sevoflurane in the vaporizer (e.g., produce degradation of sevoflurane and further production of acid) and whether the generation of acid or other byproducts would influence vaporizer function. Similarly, it was difficult to determine, in retrospect, which vaporizers might have been filled with contaminated sevoflurane. These concerns led to the replacement of all sevoflurane vaporizers at our hospital.
Both Abbott and Ohmeda acted diligently and responsibly to remove any possible threat to our patients’ health as a consequence of the sevoflurane contamination. We understand that Abbott is vigorously engaged in determining the cause and means for prevention of future contamination. Until the cause is determined and safeguards enacted, it is incumbent on the anesthesia practitioner to be aware of the possibility of this contamination and how to recognize it, primarily by the presence of an obvious increase in pressure in a contaminated bottle and a strong, very acrid odor easily distinguished from the nonpungent normal odor of sevoflurane. [Editor’s Note: Abbott urges users not to directly inhale any vapors; were there to be hydrofluoric acid, it is irritating and potentially toxic.]
John Parkhurst Leary, M.D. Glen Falls (NY) Hospital