Problem: Many hospitals have replaced medication carts and open-floor stock systems with automated dispensing cabinets. These devices can streamline the distribution process, improve first dose turn-around time, and aid in securing drugs. More and more, however, we are finding that access to a wide assortment of medications has the potential to increase the risk of errors because the usual system of double checks is being bypassed. Orders might not be screened appropriately for allergies, duplicated therapies, drug interactions, or maximum doses before drugs are administered. If cabinets contain large quantities of specific medications, it is possible that staff members, unaware of the maximum doses, might administer overdoses.
We were recently reminded how simply minimizing the quantity and dosages of drugs stored in the cabinet might avert a potential drug overdose. In the first incident, a physician ordered 2 grams of magnesium sulfate to be infused over four hours. He soon changed his mind, slashed out the “2” and wrote a “5” before it. The nurse reading the order thought that he had written 51 grams. She mixed the solution using five 10-gram vials that she had obtained from an automated dispensing module. After the infusion had run for about an hour, the patient experienced a feeling of paralysis in her legs and arms and screamed that she was blacking out. A nearby nurse quickly responded, and the pa tient was transferred to the intensive-care unit for ventilation, where she subsequently recovered. Her serum magnesium level was 16.7 mEq/liter (normal serum Mg = 1.5-3).
In another case, after the pharmacy in a small hospital was closed, an order was written for “1 gram calcium gluconate IV.” The nurse misread the label and believed that each 10-ml vial contained only 98 mg. Thus, she thought that she needed 10 vials when each milliliter actually contained 98 mg, or 1 gram per 10-ml vial. A 10-fold overdose was avoided because the cabinet contained only six vials of calcium gluconate, not 10. The error was detected when the nurse contacted a pharmacist at home to obtain additional vials.
Other errors have been reported when staff members filled cabinets without a double-check system or when nurses removed more medications than ordered and returned unused doses to the dispensing cabinet. Errors are more likely if medications are accidentally stocked in or returned to the wrong location.
Safe Practice Recommendation: To prevent errors, the following procedural safeguards should be considered for use with automated dispensing cabinets in patient-care areas: