From Sylvia Bunting, Children’s Healthcare of Atlanta: We do an immediate and incubated mixing study. For deciding on whether there is a time-dependent inhibitor, what criteria do you use to decide that the PTT was prolonged after incubation? Any prolongation beyond the immediate mix PTT? Thanks.
Hi, Sylvia, and thank you for your question. If the PTT immediate mix corrects, prepare a new patient plasma-normal control plasma mix and incubate. Simultaneously incubate an aliquot of the normal control plasma. Perform a PTT on the incubated mix and the incubated control plasma. If the mix result is prolonged by more than 13% beyond the incubated control plasma, the result is uncorrected, indicating a time-dependent inhibitor. Less than 10% difference indicates correction and no inhibitor. Repeat, ensuring the patient plasma was platelet poor, if the ratio is between 10 and 13% longer than the control.
Also, please check out audio module 25 for more details on mixing studies. Geo.
Yes, actually you can, Joe, provided you start with enough v
Yes, actually you can, Joe, provided you start with enough volume in your initial mix to aliquot for both the immediate and incubated study. Also, there are a number of labs that simply skip the initial non-incubated study altogether and just do the incubated study, given tat some LAs may be time-dependent.
George, why do you suggest preparing a new patient-PNP mix f
George, why do you suggest preparing a new patient-PNP mix for the incubation phase? Couldn’t you just use the original 1:1 mix?