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Potassium May No Longer Be Stocked on Patient Care Units, But Serious Threats Still Exist!

Problem: In the 1980s and 1990s, ISMP, the United States Pharmacopeia (USP), The Joint Commission (TJC), and the Institute for Healthcare Improvement (IHI) drew much-needed attention to the removal of concentrated potassium chloride vials from patient care areas. A 2002 TJC National Patient Safety Goal sustained this effort, and now, virtually all US hospitals have removed the drug from floor stock on typical patient care units. The tragic errors that gave rise to this system change were caused by knowledge deficits about the dangers of rapid IV administration of concentrated potassium or, more often, mental slips or selection errors when grabbing a vial of medication. There's no doubt that limiting access to this drug has reduced fatal errors. However, healthcare providers should not be complacent about the risks associated with this high-alert medication. Below we have detailed some lingering problems associated with concentrated potassium chloride that still represent serious threats to patients.  

Nursing access to pharmacy or night cabinet stock of concentrated potassium. In hospitals where 24-hour pharmacy services are not available, nurses may obtain medications from a night/weekend cabinet or a discrete, secured area in the pharmacy. Vials of concentrated potassium chloride may be available in these areas, risking accidental selection of this medication when attempting to obtain another medication. As recently as 6 months ago, this occurred in a critical access hospital and led to a patient's death. The patient was extremely short of breath, and his physician had prescribed an IV dose of furosemide. The pharmacy was closed, so a nurse entered the secured section of the pharmacy to obtain the drug. She mistakenly selected a vial of potassium chloride instead of furosemide, both of which were kept on nearby shelves just above the floor. She took the vial to the unit, withdrew the medication, and administered it to the patient. A mental slip-erroneous association of potassium on the label with the potassium-excreting diuretic-likely resulted in the nurse's failure to recognize the error until she went back to the pharmacy to document removal of the drug.    

Vials dispensed for specific patients. Since TJC prohibits floor stock of concentrated potassium chloride vials, some hospitals now dispense vials of the drug as needed for specific patients, particularly pediatric patients, to be added to existing parenteral solutions. This dangerous practice exposes the patient to the risk of receiving undiluted potassium if the nurse selects the wrong vial when preparing medications. The vial or an unlabeled syringe containing potassium could also be placed on the counter in common medication areas, exposing other patients to the risk of a similar error. 

Vials available in specialty areas. Potassium chloride vials are sometimes stocked in specialty areas such as the cardiac bypass surgical suite for use during surgery. However, the availability of concentrated potassium chloride in the operating suite risks accidental IV administration of the undiluted drug.

Vials available in outpatient settings. During onsite hospital visits, ISMP staff occasionally find vials of concentrated potassium chloride in hospital-associated adult ambulatory care clinics and women's centers. The drug is used to prepare IV solutions or treatments, such as bladder instillations to diagnose interstitial cystitis (a controversial practice in recent years). The presence of these vials represents a serious risk since some patients in these clinics also receive IV medications or solutions. In some cases, nurses did not know the vials were in the clinic, further increasing the risk of an error. Another risk factor is that clinic staff sometimes order the potassium chloride vials along with other medications and solutions directly through a wholesaler. In these cases, when the drug supplies reach the pharmacy, they may be delivered directly to the clinic without pharmacy staff's awareness that the box contains concentrated potassium vials.  

Mix-ups in the pharmacy. ISMP has previously published reports of serious errors associated with concentrated potassium chloride that originated in the pharmacy. For example, in one report, a pediatrician prescribed an IV infusion of 3.5 mEq of potassium chloride for a 3.5 kg infant. The order was entered into the computer properly as 3.5 mEq/17.5 mL using the hospital's standard 0.2 mEq/mL concentration. The drug was typically withdrawn from a premixed 20 mEq/100 mL bag, but in this case, a pharmacist inadvertently obtained the drug from a vial of concentrated potassium chloride. A 35 mEq dose was drawn into a syringe labeled 3.5 mEq. The infant developed ventricular tachycardia, which was treated successfully with cardioversion and amiodarone. However, patients have died as a result of similar errors, including one in which a batch of dialysis solutions was prepared using a look-alike carton of potassium chloride vials instead of sodium chloride vials.

Safe Practice Recommendations

Removing concentrated potassium chloride vials from floor stock is not enough to prevent all tragic errors with this high-alert medication. Consider the following additional strategies:

Use premixed solutions. Standardize electrolyte replacement therapy. Use premixed solutions or commercially out-sourced admixtures whenever possible.

Prohibit nursing access to pharmacy. Nurses should not enter the pharmacy when it is closed. A discrete stock of carefully selected, after-hours medications, including premixed small and large volume potassium chloride solutions, should be available in a secured area, preferably a controlled-access cabinet. 

Segregate and label. In the pharmacy, store bulk supplies and immediate inventory of concentrated electrolytes in an area segregated from other drugs, and distinctly separated by product type. On all storage shelves and bins, affix warning labels about the need to dilute these products.

Prohibit the dispensing of vials. Vials of potassium chloride should not be dispensed for individual patients. Pharmacy should dispense premixed solutions or prepare patient-specific admixtures as needed. Vials also must not be provided as floor stock. While some hospitals may make an exception for perfusionists in the cardiac bypass surgical suite, please be aware that many hospitals have been able to eliminate vials in all areas by providing premixed or pharmacy-prepared mini-bags of selected concentrations. If vials are dispensed to a cardiac bypass surgical suite, they should carry bold auxiliary warnings. Upon delivery, two individuals should independently verify that the correct product has been received, that it is labeled properly with auxiliary warnings, and that it has been placed in the proper, secured storage area.

Perform double-checks. Require a pharmacist to perform a final, independent check of all products used for IV admixtures of electrolyte solutions.

Procure through pharmacy. For clinics associated with hospitals, medications should be purchased through the pharmacy. All packages delivered to the pharmacy should be inspected before distribution to the clinics.

Conduct safety rounds. Conduct regular rounds at affiliated outpatient facilities and on inpatient units to verify floor stock and ensure safe storage of medications.

Perform failure mode and effects analysis (FMEA). Inventory all concentrated electrolytes in the organization and perform an FMEA. Be sure to evaluate the look-alike potential of product containers. When possible, purchase concentrated electrolytes from different vendors to avoid packaging similarities.