It cannot be overemphasized that treatment of serious hemorrhage demands prompt and adequate reilling of the intravascular compartment with crystalloid solutions. These rapidly equilibrate into the extravascular space, and only 20 percent of crystalloid remains intravascularly in critically ill patients after 1 hour (Zuckerbraun, 2010). Because of this, initial luid is infused in a volume two to three times the estimated blood loss.
Resuscitation of hypovolemic shock with colloid versus crystalloid solutions has been debated. In a Cochrane review of resuscitation of nonpregnant critically ill patients, Perel and coworkers (2013) found equivalent benefits but concluded that colloid solutions were more expensive. Similar results were found in the Saline versus Albumin Fluid Evaluation (SAFE) randomized trial of almost 7000 nonpregnant patients (Finfer, 2004). We concur with Zuckerbraun and colleagues (2010) that acute volume resuscitation is preferably done with crystalloid and blood.
The hematocrit level or hemoglobin concentration that mandates blood transfusion is controversial. Cardiac output does not substantively drop until the hemoglobin concentration falls to approximately 7 g/dL or hematocrit of 20 volume percent. At this level, several organizations recommend consideration for red cell transfusions (Carson, 2017). Also, Military Combat Trauma Units in Iraq used a target hematocrit of 21 volume percent (Barbieri, 2007). In general, with ongoing obstetrical hemorrhage, we recommend rapid blood infusion when the hematocrit is <25 volume percent. This decision is dependent on whether the fetus has been delivered; surgery is imminent or ongoing operative blood loss is expected; or acute hypoxia, vascular collapse, or other factors are present.
Scant clinical data elucidate these issues. In a study from the Canadian Critical Care Trials Group, nonpregnant patients were randomly assigned to restrictive red cell transfusions to maintain hemoglobin concentrationr>7 gl dL or to liberal transfusions to maintain the hemoglobin level at 10 to 12 gl dL. he 30-day mortality rate was similar-19 versus 23 percent in the restrictive versus liberal groups, respectively (Hebert, 1999). Transfusion therapy in nonpregnant patients with septic shock had similar mortality rates when 7 g/dL was compared with 9 gl dL as targets for transfusions (Holst, 2014). he number of units transused in a given woman to reach a target hematocrit depends on her body mass and on expectations of additional blood loss.
Contents and efects of transfusion of various blood components are shown in Table 41-8. Compatible whole blood is ideal
TABLE 41 -8. Blood Products Commonly Transfused in Obstetrical Hemorrhage
Whole blood About 500 mL; Hct RBCs, plasma, 600-700 mg Restores blood volume and �40 percent fibrinogen, no platelets fibrinogen, increases Hct
Packed RBCs 250-300 mL; RBCs, minimal fibrinogen, no Increases Hct 3-4 volume percent
Fresh-frozen About 250 mL; 30-minute Colloid, 600-700 mg fibrinogen, no Restores circulating volume and plasma (FFP) thaw platelets fibrinogen 3-4 g will increase �Cryoprecipitate About 15 mL, frozen One unit �200 mg fibrinogen, 15-20 units or other clotting factors, no platelets baseline fibrinogen 150 mg/dL Platelets About 50 mL, stored at One unit raises platelet count about 6-10 units transfused: single-donor room temperature 5000/�L; single-donor apheresis bag preferable to raise platelets