Hematological and oncological emergencies are sometimes overlooked in EMS planning and off-line medical direction and may seem less frequent than some trauma and medical conditions. However, these conditions are no less fatal and often seemingly complex when training and education in these areas are neglected. In some cases, the EMS physician stands to have a significant impact on the outcome of the patient with these conditions, and in other cases, may positively impact an important phase in the dying process for terminal patients. In this chapter, we will review likely hematological and oncological emergencies that may be encountered in the field where there is opportunity for the EMS physician to provide treatment in the field and improved medical direction to system providers on the proper management of these sometimes-complicated patient encounters.
List common causes of anemia in prehospital patients.
Describe the initial prehospital evaluation and management of acute blood loss anemia.
Describe the initial prehospital evaluation and management of hereditary anemias.
Describe the initial prehospital evaluation and management of hereditary bleeding disorders.
Describe the initial prehospital evaluation and management of disseminated intravascular coagulation.
Discuss prehospital use of blood, blood products, and factors for acute nontraumatic anemia.
Describe the initial prehospital evaluation and management of patients on chemotherapy.
Briefly discuss care of terminal cancer patients in the prehospital environment.
The focus of this section will be on anemia related to factors other than traumatic anemia which is covered in Chapter 57. The prehospital provider will often encounter symptomatic anemia which may be at the root of activating the 9-1-1 system though not as obvious as a 9-1-1 call for clinical bleeding. The chief complaint with symptomatic anemia is more likely to be related to the ramifications of decreased oxygen-carrying capacity than the knowledge that the RBC volume is compromised. The physical examination findings are well known to the reader as are the general principles of management. The question is what parts of the standard emergency department schema are applicable to the prehospital environment and how much of it is truly needed? We will divide the discussion into three sections. The first two sections will relate to insufficient RBC production or excessive RBC destruction with the third focusing on acute blood loss other than from traumatic causes.
Whether this reflects nutritional deficiency, bone marrow disorder, or dysregulation, there is little to do in the prehospital environment to diagnose the cause. Though history and physical may yield a working diagnosis this is of little practical importance as therapy will remain supportive with oxygen and maintenance of effective circulating volume. While empiric treatment with folic acid or iron may seem reasonable if the diagnostic impression is strong enough, it is hard to argue that the effect of that treatment will be brisk enough that it is worth the trade of confounding the formal diagnostic evaluation to follow.
Hemolysis is defined as RBC lifespan less than 100 days.1 There are many conditions both acquired and inherited that may result in decreased RBC lifespan. Unlike the insufficient production algorithm above where we have little to offer prehospitally there are more opportunities within this population. The inherited hemolytic disorders offer the prehospital provider treatment opportunities related to the morphologic RBC changes that occur in these conditions.
The acute presentations of sickle cell disease revolve around the vasoocclusive aspects of the disorder.2 The most dramatic examples of these include the acute chest syndrome and CVA.3–5 The prehospital physician, being able to recognize these states, can intervene with substantial but measured fluid therapy that might not otherwise fit standard prehospital protocols.6 The EMS physician also has the opportunity to initiate early antibiotic therapy in those select patients who present with a sickle cell crisis with or without evidence of target organ embarrassment who have significant fever.7 Given the functional asplenism of many of these patients, untreated bacteremia of encapsulated organisms can be rapidly fatal.8,9 This is a true opportunity for the EMS physician to impact outcome to no lesser extent than securing an airway. Ideally the EMS physician who carries antibiotics would also carry blood culture vials to provide true ED standard of care within the prehospital setting. The national awareness of sepsis and its early treatment only underscore the impact that can be made in this population.10
While the vasoocclusive complications of sickle cell disease are not typical of this disorder, there are significant issues of hypersplenism increasing the index of suspicion for splenic injury in these patients.11 The other vulnerability here owes to the high proportion of these patients who eventually undergo splenectomy which places them at risk for the encapsulated organisms offering the EMS physician the same opportunities here as in sickle cell disease in the context of suspected sepsis.11
Gastrointestinal hemorrhage is the prototype for this disease state but retroperitoneal hemorrhage and spontaneous hemorrhage into muscle or viscera are also significant sources of morbidity and even occasional mortality.12 The opportunity for the EMS physician here revolves around a deeper understanding of the multiple mechanisms in play including therapeutic or intrinsic coagulopathy. Rapid assessment of hemorrhage and the degree of circulatory compromise will fit standard prehospital practice but assessment of coagulopathy both clinically and through assessment of the patient’s medication list may reveal opportunities not available to the ALS provider. Clinical signs of coagulopathy inclusive of purpura, hyphema, gingival bleeding, and/or inappropriate free bleeding from small hemostatic challenges such as IV punctures may be clues. Clinical tendency to bleed may also reflect platelet aggregation defects which are generally pharmaceutically induced.13 In the setting of clinical coagulopathy and significant hemorrhage with evidence of anticoagulant administration or chronic liver disease the EMS physician is in a position to administer vitamin K empirically just as one would in the emergency department with laboratory confirmed elevated INR.14 Acknowledging that the full normalization effect of this dose may not be seen for 24 hours, there is clinically important reversal within 6 hours and certainly earlier administration is better than later.14 Immediate warfarin reversal may only be achieved with FFP or PCC discussed below.14
Tranexamic Acid (TXA) is an antifibrinolytic administered to control bleeding through its interruption of usual homeostatic fibrinolysis that is counterproductive in the setting of acute hemorrhage.15–17 TXA has been studied in trauma populations with the 2010 CRASH-2 trial being the largest with over 20,000 randomized patients.18 A significant mortality reduction from hemorrhage was seen along with an all-cause mortality reduction (5.7%-4.9% [P = 0.0077] and 16%-14.5% [P = 0.0035] respectively). Of note, administration of TXA more than 3 hours after injury was associated with significantly increased mortality (3.1%-4.4%, P = 0.004). In a US Military (MATTER trial) study of combat trauma in Afghanistan the positive effect was even more robust than seen in CRASH-2 with an all-cause mortality reduction from 23.9% to 17.4% (P = 0.03).19 There is precedent for this intervention in the prehospital setting with London’s Air Ambulance actively using TXA.20
Another avenue to consider is qualitative and/or quantitative platelet defects. A review of the patient’s medication list and OTC medications may reveal ASA or NSAID use impairing platelet function. Platelet aggregation can be significantly improved through the administration of DDAVP 0.3 µg/kg over 30 minutes.21 The clinical effect is rapid with platelet function assays returning to normal by 30 minutes and lasting up to 4 hours mediated through the liberation of stored vWF and Factor VIII.21–23 This also makes this intervention ideal for acute bleeding in the setting of known von Willebrand disease or Factor VIII deficiency.24
DIC and dilutional coagulopathy are indistinguishable without laboratory evaluation and even then can be difficult to discern unless dilutional coagulopathy can be excluded because massive hemorrhage is not present. In either event the transfusion of plasma is indicated and hypofibrinogenemia may be the most important piece of this coagulopathy.25 Many will use cryoprecipitate in the setting of DIC due to its high fibrinogen content per unit volume. It is important to realize that plasma is also an appropriate choice and will just as surely raise your fibrinogen level though with higher overall transfusion volume to deliver the same dose of fibrinogen.26 In the setting of massive hemorrhage this is likely of little clinical concern and may even be preferable as all plasma factors are being lost while the patient bleeds whole blood. It is important to remember that DIC is a secondary process.26 Treatment of the primary process must at least be entertained while clotting factors are replaced. Control of hemorrhage as the inciting event is obvious but it is conceivable that occult sepsis might be missed as the primary insult among the drama of the DIC. This again presents a very real opportunity to initiate broad antibiotic therapy as soon as the patient enters the system rather than after the significant delay inherent to transport and standard ED evaluation. The treatment of DIC assumes access to blood products which is by no means ensured in the prehospital setting and discussed in the following section.
The presence of an EMS physician on scene simplifies many of the major clinical blockades to the use of blood products prehospitally but does little to ameliorate the administrative and regulatory obstacles inherent to this process.27 Setting those aside for the moment and examining the clinical literature there is very little in the civilian EMS world to make a case for routine transfusion prehospitally. As physicians we well understand the need for blood transfusion to replace dramatic acute blood loss. We also understand that there is a growing literature about the role or acquired coagulopathy in the setting of hemorrhage and the role for coagulation factor administration to reverse it.25 While this is standard validated practice in the ED, it is not yet clear that there is positive patient impact prehospitally though intuitively we would reason it should. There are EMS services both nationally and internationally that administer blood products prehospitally.20,28 There are published descriptive studies notably from Australia, the United Kingdom, and the United States that demonstrate feasibility but no randomized trials to look at efficacy.20,28 It is not known if studies done in the combat theater (which are largely descriptive and retrospective in nature as well) can be extrapolated to the civilian experience. For now it is simply not known whether prehospital transfusion improves patient outcome. It bears mentioning that a very old product, freeze dried plasma (FDP), may have new life in this realm as French lyophilized plasma (FLYP).29,30 FLYP is obtained from freeze-drying FFP and exposing it to ultraviolet light to inactive RNA and DNA pathogens.30,31 The resultant compound is a dry powder with a 2-year shelf life that is ABO universally compatible and contains all clotting factors in physiologic ratios in almost identical doses to FFP.30,31 Much of the complexity of storage and administration of standard blood products that complicates their use prehospitally is solved with this product. Though plasma will not carry oxygen it surely will reverse coagulopathy. It is not currently available in the United States. This will remain an area of controversy and avenue for further investigation in the immediate future. It will be up to each system to decide if the added complexity, cost, and potential transport delay associated with these interventions are justified in their particular patient population.