Can storage of thawed cryoprecipitate be extended to more than six hours?

Fresh-frozen plasma (FFP) and cryoprecipitate both contain Factors I and VIII, however thawed FFP may be stored at 1-6 degrees C for 24 hours, but thawed cryoprecipitate may only be stored at 1-6 degrees C for six hours when used for Factor VIII content. To determine whether it would be safe and effective to extend the storage period of thawed cryoprecipitate from 6 to 24 hours, Factor VIII (and fibrinogen) levels were measured in 25 units of cryoprecipitates immediately on thawing and at 6 hours and 24 hours thereafter. The Factor VIII activity level decreased to 86% of the original activity level within 6 hours, but the drop between 6 and 24 hours was relatively small. Eighty percent of the original activity was still present at 24 hours after thawing. The fibrinogen level decreased to 87% of the original level within 6 hours but remained stable between 6 and 24 hours. Additional testing showed that fibrinogen levels remained stable between 6 and 74 hours. These data suggested that the storage of thawed cryoprecipitate might be extended to 24 hours when this blood product is used for Factor VIII content and to 74 hours when it is used for fibrinogen content. Furthermore, the lack of prohibition on the use of cryoprecipitate that has been thawed for more than six hours and stored at 4 degrees C for its fibrinogen content seems reasonable.

Use of a table-top analyzer for predonation screening for alanine aminotransferase--a cost-effective approach?

To reduce the transmission of non-A-non-B hepatitis, the American Association of Blood Banks has required that all blood donations with alanine aminotransferase (ALT) levels above a certain cut-off level to be discarded. This discard rate resulting from high ALT levels was 5.3% at the authors' donor center, which was more than double the expected rate of 2.3%. If blood donors could be tested for their ALT levels before blood donation, unnecessary discarding of blood and related expenses could be eliminated. Therefore, the authors evaluated a table-top ALT analyzer for screening donors before blood donation. The method was precise and linear and correlated well with the SMAC-II analyzer. Based on a cost-savings analysis, the authors found it to be financially beneficial to perform predonation ALT testing. Because the cost of labor and reagents may vary from institution to institution, however, other facilities should perform their own cost-savings analyses before implementing predonation ALT testing.

Vaginal fluid zinc concentration as a marker for intercourse.

Zinc is present in high concentration in semen, but in low concentration in vaginal fluid. We evaluated vaginal zinc levels as a marker for intercourse by measuring precoital (greater than 11 h after intercourse) or postcoital (less than 5 h after intercourse) zinc and acid phosphatase levels in 26 specimens of vaginal fluid from 18 women. The approximate 95% reference range for zinc in precoital vaginal fluid was 1.2 to 15 micrograms/mL (mean 4.5), and in postcoital vaginal fluid 4.0 to 135 micrograms/mL (mean 24). There is an overlap between the precoital and postcoital reference ranges. Provided that the vaginal fluid zinc level is less than approximately 4.0 micrograms/mL or greater than approximately 15 micrograms/mL, vaginal fluid zinc concentration may be useful as an indicator of intercourse.

Microwave heating of intravenous fluids.

Microwave heating of intravenous (IV) fluids is a viable alternative to heating by conventional means, such as by blood warmer(s) or an on-site warming oven, for administration to hypothermic patients and trauma victims. Three 1-l bags each of lactated Ringer's solution, normal saline solution, 1/2 normal saline solution, and 5% dextrose in water were packaged in parenteral containers and heated in a microwave oven from room temperature (21 degrees C) to 40-42 degrees C in 3 minutes. Little difference between temperatures of the four solutions was detected at each of five intervals up to two hours after heating for 3 minutes. Samples were taken before and after heating to assess any potential alterations in sodium, potassium, chloride, calcium, glucose, and lactate levels; differences were within the range of variation of the methods used. Though the plasticizer in the polyvinyl chloride containers is stable to microwave heating, data on other components is incomplete.