Possible association between the Norplant contraceptive system and thrombotic thrombocytopenic purpura.

BACKGROUND: Thrombotic thrombocytopenic purpura (TTP) is a rare, potentially fatal disease of uncertain etiology. Early diagnosis and treatment are essential to patient survival. The ]purpose of this report is to describe three patients with levonorgestrel implants (Norplant system) who developed TTP. CASES: A 24-year-old woman with levonorgestrel implants in place for 7 months was admitted to our hospital for treatment of TTP. Clinical symptoms included easy bruising, menorrhagia, headaches, and fever; laboratory evaluation revealed thrombocytopenia (18 x 10(9)/L) and microangiopathic hemolytic anemia. She was treated with plasmapheresis, and the implants were removed. Through the Freedom of Information Act, we reviewed all adverse events associated with Norplant use reported to the Food and Drug Administration (FDA) as of the end of 1992. Two additional cases were identified. CONCLUSIONS: Although a causal relationship between progestogen-only contraceptives and TTP is not established by the data presented, these three cases may represent an increased incidence of TTP in women using levonorgestrel implants. Patients who receive Norplant should be advised to seek medical attention if symptoms appear. Physicians and other health care providers should be aware of the possible association between use of the Norplant system and TTP and are urged to report similar cases to the FDA.

Evaluation of a blood warmer that utilizes a 40 degrees C heat exchanger.

Most commercial blood warmers are unable to warm blood components to greater than 35 degrees C at rapid flow rates (greater than 100 mL/min) because of problems with inefficient heat transfer and resistance to the flow of blood through the instrument's tubing. A new blood warmer, using a closed-flow 40 degrees C counter-current water bath and large-bore tubing, is able to warm cold (10 degrees C) packed red cells to temperatures greater than 35 degrees C even at flow rates of 500 mL per minute. To evaluate the effects on red cells of prolonged exposure to the 40 degrees C heat exchanger, blood from five volunteers stored for 42 days in AS-1 was run through the blood warmer using flow rates equivalent to the transfusion of a unit of blood over 4 hours. Compared with unwarmed blood, these blood units showed no significant changes in plasma hemoglobin, mean corpuscular hemoglobin concentration, potassium, ATP, pH, and osmotic fragility. In vivo survivals of chromium-51-labeled warmed autologous red cells were greater than 75 percent in four volunteers and 49.5 percent in the fifth volunteer, whose abnormally low unwarmed red cell ATP level suggested a storage problem. Thus, this blood warmer, which warms blood efficiently at high flow rates, causes no red cell damage, even with prolonged exposure of old red cells to the 40 degrees C heat exchanger.