After a needle is inserted through the stopper of a medication vial, a small piece of the stopper is sometimes sheared off (known as coring) and may not be noticed. This small foreign body can then be aspirated into a syringe and injected into a patient. For many years, the contamination of parenteral fluids and medications by particulate matter has been recognized as a potential health hazard and has been associated with adverse reactions ranging from clinically occult pulmonary granulomas detected at autopsy to local tissue infarction, pulmonary infarction, and death.1,2 Riess and Strong recently reported a case where a cored piece of stopper blocked the intravenous infusion of propofol during a total intravenous anesthetic (TIVA), requiring the immediate insertion of another intravenous catheter.3 Others have reported coring when drawing up propofol.4-6 The first author has also experienced coring when drawing up vecuronium. Although there are no data, it would seem likely that coring events may be both unrecognized and underreported.
There are strategies that both we and the manufacturers can employ to help reduce or eliminate the risk of coring. If the needle must pierce a stopper, there is a needle insertion technique that reduces the risk of coring during needle insertion through the stopper of a medication vial.6-7 The needle should be inserted at a 45-60° angle to the plane of the stopper with the opening of the needle tip facing up (i.e., away from the stopper). A small amount of pressure is applied and the angle is gradually increased as the needle enters the vial. The needle should be at a 90° angle just as the needle bevel passes through the stopper. Second, if the stoppers were made of a material that always floated and were of a noticeable color, they would be easier to spot and would be less likely to be injected in a vertically-oriented syringe. In Riess and Strong's report, their coring sank to the bottom of the propofol vial, thus explaining why it was not noticed until it blocked the intravenous catheter.3 Also, medications can be drawn up via a needle with a filter such as that found in various spinal anesthetic kits. It is unclear whether the incidence of coring varies with the use of a blunt fill needle versus a conventional sharp needle.3,8
Another strategy would be to eliminate the need to pierce a stopper with a needle altogether. This can be accomplished in several ways. First, a vial can have a stopper held in place by a crimp ring that is designed to easily peel off (e.g., 2% lidocaine HCl, Abraxis Pharmaceutical Products, Schaumburg, IL). Alternatively, we can remove a crimped stopper with a pliers-like device (e.g., Kebby Decapper, Kebby Industries, Inc., Rockford, IL). Additionally, the pharmaceutical manufacturers can provide us with single use medication vials where one just pulls off the entire top (e.g., various local anesthetics from AstraZeneca LP, Wilmington, DE), or where syringes attach directly to the vials (e.g., various local anesthetics from AstraZeneca LP, Wilmington, DE). Lastly, medications can be supplied in prefilled syringes (e.g., propofol from AstraZeneca LP, Wilmington, DE). An additional benefit of not having to pierce a stopper is that it removes any concern of latex contamination in latex allergic patients.
We hope this communication will bring to the attention of the readership a probably infrequent but potentially serious problem that is not well known in the anesthesia community. We hope this letter prompts the manufacturers to consider an engineering solution, of which several suggestions were presented above. In the meantime, we should utilize the technique described above when piercing a stopper with a needle, which adds no financial cost and takes at most an additional 1 or 2 seconds.