We describe a patient in whom sodium bicarbonate solution was used to restore patency of a central venous access device that was occluded by precipitate of phenytoin sodium injection. A 63-year-old man was admitted to our hospital for ventilator management complicated by distal esophagitis, deep venous thromboses requiring an inferior vena caval filter, recurrent aspiration pneumonia, line infections, respiratory failure requiring intubation, and seizures. A Groshong catheter (Bard Access Systems, Salt Lake City, Utah) was in the right subclavian vein. The patient had received antibiotics and vasopressor agents. At the time of the incident, medications were phenytoin by intravenous injection, 125 mg every 8 hours; norepinephrine by infusion, 8 mg in 250 mL of 5% dextrose in water; dopamine by infusion, 800 mg in 250 mL of 5% dextrose in water; vancomycin by injection, 1 g in 250 mL of normal saline every 36 hours; furosemide by injection, 20 mg every 8 hours; and total parenteral nutrition by continuous infusion.

After 30 doses of phenytoin sodium (USP, 250 mg/5 mL, Elkins-Sinn, Inc., Cherry Hill, New Jersey), the right subclavian Groshong port was found to be occluded. Urokinase, 5000 U (Abbokinase Open-Cath, Abbott Laboratories, Abbott Park, Illinois), was unsuccessfully given by injection to restore patency. The instillation of two 5-mL injections of sodium bicarbonate (8.4% sodium bicarbonate injection, USP, Abbott Laboratories) to the central line at 30-minute intervals resulted in good blood return in the line.

Injected phenytoin sodium crystallizes into insoluble phenytoin when admixed with solutions of 5% dextrose in water. A key factor in the precipitation of phenytoin is the pH of the solution. A solution of 5% dextrose in water, which is acidic (pH, 4.0), caused the phenytoin sodium injection, a basic solution (pH, 12.0), to precipitate. Instillation of sodium bicarbonate solution into the central line restored the pH to basic, with subsequent dissolution of the precipitate. Occlusion of the central line is common, and phenytoin precipitation may be overlooked as a source of occlusion. Admixing phenytoin sodium in 100 mL of normal saline and infusing it over 30 minutes may minimize the chance of precipitation. Only one report of a similar incident was found [1].

Injected sodium bicarbonate can clear phenytoin precipitate in central venous catheters. A syringe smaller than 5 mL should be avoided because it may generate high pressure and dislodge blood clots or phenytoin precipitate into the bloodstream. Clinical trials are needed to establish standardized procedures.