Page 74 - JSOM Summer 2022

hemorrhage without proper marrow response. Although un- Blood transfusion goals center on the need to support tissue
likely in active-duty populations, renal causes can be suspected oxygenation through improved hemoglobin concentration.
in nonmilitary personnel with known or suspected chronic A single unit of packed red blood cells increases hemoglobin
kidney disease, especially when renal function testing reveals concentrations by approximately 1g/dL, whereas a unit of WB
45
a glomerular filtration rate of <30mL/min. High reticulocyte increases levels by 2g/dL and adds additional platelets and co-
counts in the setting of normocytic anemia should prompt a agulation factors. 1,26,56 Combat literature recommends assess-
Coombs test for further evaluation because high counts may ing hemoglobin levels every hour in the hemorrhagic patient
indicate acute microcytic hemolytic anemia resulting from during transfusion efforts until a concentration of 8g/dL is
RBC membrane defects. 21 reached, then every 6 hours thereafter. 29

Macrocytic anemia (MCV >100fL) is generally classified into Although blood products can improve anemia and coagulop-
nonmegaloblastic and megaloblastic anemia, the latter describ- athy in the hemorrhagic patient, there are several limitations,
ing an enlarged, oval erythroblast with an immature, “lacy” particularly preservative mechanisms that bind serum calcium
29
appearing nucleus. 1,46,47 Most macrocytic anemias are meg- to prevent clotting during storage. Transfused WB lacks cal-
aloblastic, usually caused by vitamin deficiencies of B and/ cium, needed for the coagulation pathway and healthy car-
12
or folate. 1,46,47 Megaloblastic anemia may be of initial concern diac function. 29,57 In the hemorrhagic patient, medics should
with a patient history of nutritional imbalance, possibly with therefore give supplemental calcium, generally through cal-
vegetarian regimens, or in cases of chronic alcohol use. 46,48 Low cium gluconate, with WB to further correct coagulopathy. 29,57
laboratory values for B and folate can support the diagnosis, Additionally, tranexamic acid (TXA) should be considered
12
but measured vitamin levels can rebound quickly with acute for additional coagulation assistance for those receiving care
dietary or supplemental changes and therefore should not be within 3 hours of the injury in the setting of trauma. 29,30 TXA
considered definitive in evaluation. 1,46 Acute toxins or drugs should also be considered in suspected or confirmed atrau-
(most commonly alcohol) are more likely to cause a nonmeg- matic hemorrhage, including gastrointestinal and reproductive
aloblastic anemia; thus, further evaluation should include (i.e., uterine) sources. 58–60
a detailed history of medications such as hydroxyurea (used
in sickle cell anemia) and methotrexate (used in rheumatoid Any infectious cause of anemia should be addressed imme-
arthritis). 47 diately with specific therapies targeting the underlying cause.
These include conditions that provoke acute hemolytic ane-
Ancillary tests may help directly identify the source of anemia mia, such as DIC, HUS, and TTP (Table 3). Additionally, when
based on RBC morphology. This is most important for op- malaria is suspected (endemic region, presence of fever, pref-
erational environments such as sub-Saharan Africa and parts erably with confirmation from BinaxNOW and/or peripheral
of Asia, where malaria is endemic. 49–53 BinaxNOW (Abbott smears), antimalarial treatment should be initiated immedi-
Diagnostics) is a simple point-of-care test to identify malarial ately. This includes atovaquone/proguanil (Malarone) or ar-
39
infection and distinguish between types of malarial parasites temether/lumefantrine (Coartem). Blood transfusion should
39
for targeted therapy. Thick and thin smears enable direct mi- be considered in patients with hemoglobin concentrations of
croscopic examination for malarial parasites or sickled RBCs; <7g/dL.
however, their clinical value has been debated. 39,42,54,55 Never-
theless, this testing is still recommended to aid the evaluation Patients without an obvious source of hemorrhage who are
of the undifferentiated sick and anemic patient. 4,39,42 clinically stable (i.e., normal vital signs, non–ill appearing) de-
spite anemia should be further investigated for a cause through
<1>Management a focused history and evaluation prior to intervention. Some
Initial management of anemia focuses on control of any ac- anemic patients who are hemodynamically stable may not re-
tive bleeding to halt preventable blood loss and improve tis- quire further emergent evaluation or management. 1,20 Histori-
sue perfusion and hemodynamic status. This may include cally, universal transfusion thresholds for the nonhemorrhagic
the use of supplemental oxygen when hypoxemia is present. patient held indications at a hemoglobin level of <10g/dL;
Importantly, medics should continually assess for indications however, these have shifted with growing literature for a more
for blood product transfusion. Resuscitative fluids other than restrictive strategy. 26,27,61 A hemoglobin threshold of 7g/dL is
blood, such as crystalloids and colloids, should be restricted, supported by multiple trials involving acute illnesses such as
given concerns for hemodilution and coagulopathy. 26,29,30 sepsis and gastrointestinal bleeding. 62–65

Unstable patients with suspected or confirmed hemorrhage Those who are incidentally anemic but otherwise stable may
require immediate pressure on exposed sites, with tourniquet be managed with close follow-up when they are otherwise
application on affected extremities. Whole blood (WB) trans- healthy and the hemoglobin level is >6g/dL. 1,66 This will likely
fusion is warranted in these cases, and if prestored supplies require medical evacuation from austere locations, and prior-
are lacking, a walking blood bank should be initiated. 29,30 In ity should be based on overall clinical presentation, including
hospital settings, emergency-release type O-negative is ideal hemodynamic stability. When the medic is suspicious for IDA,
for women of reproductive age (to prevent sensitization and daily supplementation with 300mg tabs of ferrous sulfate
future pregnancy complications) and O-positive in all other should be considered, along with vitamin C, which increases
populations. Operational situations should consider the use absorption. 44,66 Generic multivitamins often contain iron, but
1
of low-titer group O whole blood (LTOWB) or group-specific not at these levels, and patients should not attempt to compen-
matching if LTOWB is unavailable. In suspected or visual- sate by simply increasing the vitamin dosing regimen because
29
ized internal hemorrhage (e.g., hematemesis, hematochezia, doing so can cause toxicity from other ingredients. In hospi-
melena), proper surgical consultation is needed in preparation tal settings, intravenous iron formulations can markedly help
for evacuation. with IDA, lifting hemoglobin levels 2 to 3g/dL within weeks of

72 | JSOM Volume 22, Edition 2 / Summer 2022