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POTASSIUM OVERDOSE: A PREVENTABLE TRAGEDY Lethal or near lethal overdoes of potassium by the intravenous route remains one of the most frequent serious mishaps associated with intravenous fluid therapy. Accidental rapid infusion of potassium causes ventricular fibrillation followed by cardiac arrest. The three most common errors causing a sudden potassium overdose are: 1. Incorrect identification of the vial. 2. Administration of the wrong dosage. 3. Inadequate mixing. Incorrect identification of the vial of potassium chloride is one of those medication errors which is bound to happen unless the vials are clearly marked. They are usually not marked. They look just like vials of sodium chloride or sterile water, used for flushing IV lines and mixing medications for parenteral use. Surely in this era of increased litigation, drug companies, hospitals and physicians should be demanding the added safety of clearly marked containers! Administration of the wrong dosage is less common. Potassium is usually supplied in 20 meq. vials, the usual dose to be added to a liter of IV fluid for an adult; but it may be enough to overdose an infant. Incorrect mixing has always been a problem. Concentrated Potassium chloride solution is hyperbaric and layers out at the bottom unless thoroughly mixed. The last ten years have seen most hospitals resorting to the use of either a very pliable plastic bag such as those manufactured by Travenol or semi-rigid containers. While these containers have real advantages over those made of glass because they are lighter, more easily stored and more durable, they come with their own problems. Inadequate mixing is more likely to occur with flexible containers. When a bolus of potassium or other additive is added to an inverted rigid container, enough turbulence is created to give a mixing effect. Because the flexibility of the travenol bags causes damping, very little mixing occurs if potassium is added to an inverted bag. The first 100 cc's or less may contain the entire dose, resulting in overdose. Package inserts, advisory warnings and numerous case reports have failed to diminish the number of disasters. If a patient receiving IV fluids sustains a sudden and unexpected cardiac arrythmia, hyperkalemia should be suspected. The smaller the patient, the more prone he is to develop hyperkalemia - and from a smaller dose. Treatment is usually effective if the condition is quickly recognized and involves: 1. treatment of the cardiac toxicity with calcium. 2. treatment of the serum hyperkalemia by making the blood more alkaline with sodium bicarbonate which drives potassium into the cells and/or administration of glucose and insulin which similarly drives the potassium into the cells. 3. cardiopulmonary resuscitation. The diagnosis of hyperkalemia is easily made by: 1. drawing blood for a serum potassium level. 2. Sending a sample of the remaining IV fluid for laboratory analysis. If most of the added potassium reached the patient in a rapid bolus, the remaining IV fluid should have much less potassium in it than expected. 3. Characteristic EKG changes. Suggested methods of avoiding the problem: 1 . Mark all concentrated potassium chloride with colored labels and make sure that all personnel who mix IV's are aware of the marker. 2. Buy already mixed IV fluids. 3. Have all IV fluids mixed before they are taken to the nursing units so that they receive adequate mixing. 4. Require that all nursing personnel attend demonstrations in which potassium chloride and a dye such as indigo carmen are added to an inverted IV bag. The layering of potassium at the bottom of the bag is dramatic! 5. Discourage the addition of additives to an already hung IV. The cost of a new bottle of IV fluid is cheap compared to a disaster. Other medications known for their lethal potential when given in an improperly mixed IV are: 1. Insulin 2. Heparin 3. Aminophylline 4. Calcium If no serum potassium level is obtained, the IV bottle is trashed, and the patient dies without postmortem blood samples, the diagnosis of iatrogenic cardiac arrest from a rapid infusion of potassium can be easily overlooked (even by the nurses and physicians involved). BIBLIOGRAPHY-HYPERKALEMIA Barber, Kenneth N.: Unit-dose injectables and the hospital medication error problem. Bulletin of the Parenteral Drug Association, 20:157-164,1966. Bergman, Neil et al: Potential life-threatening variations of drug concentrations in intravenous infusion systems. The Medical Journal of Australia, 2:170-171, 1982. Bighley, Lyle D. et al: Mixing of additives in glass and plastic intravenous fluid containers. The American Journal of Hospital Pharmacies, 31:736-739, 1974. Flack, F. C.: Behavior of standard gravity-fed administration sets used for intravenous infusion. The British Medical Journal, 3:439-443,1974. Jick, Hershel et al: Comprehensive drug surveillance. The Journal of the American Medical Association, 213:1455-1460, 1970. Kowaluk, Elizabeth A. et al: Interactions between drugs and intravenous delivery systems. The American Journal of Hospital Pharmacists, 39:460-467, 1982. Levinsky, Norman G.: Management of emergencies: hyperkalemia. The New England Journal of Medicine, 274:1076-1077, 1966. Sanders, Lonnie H. et al: Evaluation of compounding accuracy and aseptic techniques for intravenous admixtures. The American Journal of Hospital Pharmacies, 35:531-536, 1978. Shapiro, Samuel et al: Fatal drug reactions among medical inpatients. The Journal of the American Medical Association, 216:467-472,1971. Shemer, Joshua et al: Incidence of hyperkalemia in hospitalized patients. The Israel-journal of Medical Sciences, 19:659661, 1983. Stephen, M. et al: Complications of intravenous therapy. The Medical Journal of Australia, 2:557-559, 1976. Thompson, Leigh et al: Incomplete mixing of drugs in intravenous infusions. Critical Care Medicine, 8:603-607, 1981. Thur, Michael P. et al: Medication errors in a nurse-controlled parenteral admixture program. The American Journal of Hospital Pharmacies, 29:298-304, 1972. Watkins, E.E.A.: Hazards of intravenous potassium administration. The Pharmaceutical Journal, 210:71-72, 1973. Woodside, W. et al: Addition of potassium to non-rigid plastics intravenous containers. The Journal of Hospital Pharmacies, 192-195,1973. -----:Plastic containers for intravenous solutions. The Medical Letter, 22:43-44, 1980.

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