Ординатура / Хирургия / Библиотека им академика М.И. Перельмана / Книга_35_библиотеки_им_акад_М_И_Перельмана

For a long time, the use of cell salvage during obstetric hem­orrhage was considered controversial due to the possibility of amniotic uid embolism (AFE) and maternal alloimmuniza­tion to fetal RBC antigens [43, 47, 48]. Newer data suggests that the risk of AFE and maternal-fetal alloimmunization can be decreased by use of leukocyte depletion lters (LDF) and separation of suction for blood and amniotic uid prior to pla­cental delivery [48]. Newer generation LDF are effective in decreasing the number of amniotic uid proteins, bacterial contamination, free hemoglobin, and potassium [48]. With these new separate lters, large case series have demonstrated a lower risk prole for salvaged blood, with no cases of AFE reported, and are now supported in current guidelines.

tion tests such as prothrombin time (PT), partial thromboplastin time (PTT), and clauss brinogen assays do not give the full picture of hemostasis during obstetric hemorrhage and only provide guidance on initial clot formation [ recognized that these traditional coagulation tests are poor predictors of bleeding [42]. During obstetric hemorrhage, PT and PTT often remain within normal range even until blood loss reaches 4000–5000ml [42]. Further, these tests may have long turnaround times (60–90minutes); thus results are less relevant in an acutely changing situation, and many clinicians may decide to transfuse based on a protocol-based approach or upon clinical judgment [42]. The issue with formulaic transfusion is that not all obstetric hemorrhage is the same, and patients may present with a variety of bleeding pheno­types. In many cases administering FFP may cause a dilu­tional coagulopathy, especially in the case of hypobrinogenemia. Plasma transfusion must occur in large volumes to be effective, which may lead to volume overload or other transfusion reactions [

Viscoelastic testing via thromboelasography (TEG) or thromboelastometry (ROTEM) overcome many of the short­falls of traditional coagulation tests. TEG and ROTEM assess and graphically display the viscoelastic properties from clot formation to clot lysis, provide actionable information within minutes, and allow for specic goal-directed therapy. An important advantage of these assays is the quick turnaround time, with an evaluation of clot kinetics generated in 5–10minutes [42]. Studies in the obstetric population have shown both agreement and correlation between viscoelastic testing parameters and traditional coagulation assays, with a decreased time for data acquisition [60, 61]. This is espe­cially true for measurements of brinogen, which has been shown to be a prognostic indicator and therapeutic target in obstetric hemorrhage. A FibTEM A5, which is the amplitude of the FibTEM trace at 5minutes after the start of clot forma­tion, measures the effect of brinogen by eliminating the contribution of platelets to clot strength by way of the addi­tion of cytochalasin D and has been shown to correlate with plasma brinogen level [62]. A FibTEM A5 of 12mm cor­relates approximately with a plasma brinogen level of

2.2g/L [62]. In 2019, McNamara etal. presented 4years of data on a ROTEM-guided algorithm for obstetric hemor­rhage. The data compared the use of shock packs, which included four units of PRBC, four units of FFP, and one dose of platelets, and a ROTEM-guided algorithm with adminis­tration of brinogen concentrates. The data showed a signi­cant reduction in morbidity, specically transfusion-associated circulatory overload (TACO) likely secondary to a decrease in the transfusion of FFP, and a decrease in the number of units and total volume of blood products transfused per patient [62]. Comparator studies are ongoing, with early results demonstrating that viscoelastic testing driven algorithms can decrease the amount of products given

Two therapeutic options are available for brinogen replacement: cryoprecipitate and brinogen concentrate [42]. The brinogen concentration in cryoprecipitate ranges from 3 to 30g/L, leading to a potentially inconsistent effect, and requires two to three freeze-thaw cycles prior to admin­istration, which can potentially cause a delay in administra­tion [42]. Also, cryoprecipitate is not virally inactivated and is not available in all locations [68]. Fibrinogen concentrate has been used as a rapid alternative for brinogen repletion in obstetric hemorrhage [49, 63, 67]. Fibrinogen concen­trates are a manufactured concentrated form of brinogen produced from human plasma. It comes as a powder to be reconstituted, does not require refrigeration, and therefore may easily be stored near the patient in a controlled release compartment system such as Pyxis [42]. Unlike cryopre­cipitate, brinogen concentrates do not require cross-match [45, 48] and have decreased risk of infectious complications since viral activation and the removal of antigens and anti­bodies occurs during the manufacturing process [42, 48]. Appropriate brinogen concentrate therapy can prevent unnecessary product transfusion and complications of trans­fusion such as volume overload and allergic reactions [45]. The cost of brinogen concentrate varies by location; how­ever studies looking at the cost of utilizing brinogen con­centrate instead of traditional MTP or shock packs have found it to be either cost saving or cost neutral when taking into account the complications from transfusion reactions and the cost of wasted blood products [49, 63]. The cost­effectiveness of brinogen concentrate and cryoprecipitate in the management of severe obstetric hemorrhage should be further explored [49]. A nal and important limitation of brinogen concentrate is that unlike cryoprecipitate, brin­ogen concentrate contains no brin stabilizing factors or

In the setting of intractable obstetric hemorrhage, recom­binant activated factor VIIa (rFVIIa) may be considered. Like PCC, rFVIIa is associated with arterial and venous thrombosis [47], continues to be recommended only as a last ditch effort to stop life-threatening bleeding when all other efforts have failed, and has no proven survival benet [48]. Although there is no optimal dose range for the parturient, 60–90 μg/kg IV is mentioned in guidelines [47]; however lower doses including 40 μg/kg and 20 μg/kg have been attempted and may carry less risk of thrombosis [72]. It should be noted that women who receive rFVIIa during man­agement of amniotic uid embolism may have worse out­comes compared to those who did not [73]. A novel topical application of rFVIIa has been described in a ve patient case series in patients with placenta previa [74]. Bleeding was well-controlled in all cases; however, more data is needed to determine both safety and efcacy of this technique.