Hematological Disorders and Oncological Emergencies

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Hematological Disorders and Oncological Emergencies

Barbara Mayer

Objectives

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Be sure to check out the bonus material, including free self-assessment exercises, on the Evolve web site at evolve.elsevier.com/Urden/priorities/.

Understanding the pathology of a disease, the areas of assessment on which to focus, and the usual medical management allows the critical care nurse to more accurately anticipate and plan nursing interventions. This chapter focuses on hematological and oncological disorders commonly seen in the critical care environment.

Disseminated Intravascular Coagulation

Disseminated intravascular coagulation (DIC) is a syndrome that arises as a complication of other serious or life-threatening conditions. Although DIC is not seen often, it can seriously hamper diagnostic and treatment efforts for the critically ill patient. An understanding of the etiological and pathophysiological mechanisms of DIC can assist in anticipating the syndrome’s occurrence, recognizing its signs and symptoms, and prompting intervention. Also known as consumptive coagulopathy, DIC is characterized by bleeding and thrombosis, both of which result from depletion of clotting factors, platelets, and red blood cells (RBCs). If not treated quickly, DIC will progress to multiple organ failure and death.1

Etiology

Many clinical events can prompt the development of DIC in the critically ill patient, but the exact underlying trigger may not be identifiable (Box 27-1). There are, however, some commonly known conditions associated with the development of DIC.

The most common precipitating events for DIC are sepsis and trauma.1 In sepsis, endotoxins serve as a trigger for activation of tissue factor and the extrinsic coagulation pathway. Metabolic acidosis and hypoperfusion associated with shock syndromes can result in increased formation of free radicals and damage to tissues. Tissue factor is activated, resulting in DIC.2 Massive trauma or burns are frequently associated with DIC. Direct tissue damage activates the extrinsic coagulation pathway, and damage to endothelial surfaces activates the intrinsic pathway.2 Obstetric emergencies, such as abruptio placentae, retained placenta, or incomplete abortion, are also associated with the development of DIC. Tissue factor is concentrated in the placenta, and damage or disruption of this structure can activate coagulation pathways, resulting in coagulopathy.3

Pathophysiology

Regardless of the cause, the common thread in the development of DIC is damage to the endothelium, which results in activation of the coagulation mechanism (Figure 27-1).1 The extrinsic coagulation pathway plays a major role in the development of DIC. Direct damage to the endothelium results in the release of tissue factor and activation of this pathway. The secondary surge of thrombin formation as a result of activation of the intrinsic coagulation pathway leads to the massive disruption of the delicate balance that is hemostasis. Excessive thrombin formation results in rapid consumption of coagulation factors and depletion of regulatory substances—protein C, protein S, and antithrombin.4 With no checks and balances, thrombi continue to form along damaged epithelial walls, resulting in occlusion of the vessels. As occlusion reaches a critical level, tissue ischemia ensues, leading to further tissue damage and perpetuating the process. Eventually, end-organ function is affected by the ischemia, and failure is evident.1

In response to the formation of clots, the fibrinolytic system is activated. As plasmin breaks down the fibrin clots, fibrin split products are released, and they act as anticoagulants.2,3 Coupled with depletion of circulating clotting factors, activation of fibrinolysis results in excessive bleeding. The end result is shock and further tissue ischemia that aggravate end-organ dysfunction and failure. Death is imminent if this destructive cycle is not interrupted.5

Assessment and Diagnosis

Favorable outcomes for patients with DIC depend on accurate and timely diagnosis of the condition. Realization of the role underlying pathology plays, recognition of clinical manifestations, and assessment of appropriate laboratory values are key steps in this process.

Clinical Manifestations

Clinical manifestations are related to the two primary pathophysiological mechanisms of DIC: the formation of thrombi and bleeding. Thrombi in peripheral capillaries can lead to cyanosis, particularly in the fingers, toes, ears, and nose. In severe, untreated cases, this peripheral ischemia may progress to gangrene.2,46 As the condition progresses, ischemia worsens, and end organs are affected. The result of this more central ischemia can be respiratory insufficiency and failure, acute tubular necrosis, bowel infarction, and ischemic stroke. The tissue damage that results perpetuates the anomalies of DIC.1

As coagulation factors are depleted, bleeding from intravenous and other puncture sites is observed. Ecchymoses may result from even routine interventions such as the use of a manual blood pressure cuff, bathing, or turning.2 Bloody drainage may also occur from surgical sites, drains, and urinary catheters. With progression of DIC, the patient is at risk for severe gastrointestinal or subarachnoid hemorrhage.2,6 Table 27-1 lists many of the common signs and symptoms of DIC.

TABLE 27-1

COMMON SIGNS AND SYMPTOMS OF DISSEMINATED INTRAVASCULAR COAGULATION

SYSTEM SIGNS RELATED TO HEMORRHAGE SIGNS RELATED TO THROMBI
Integumentary Bleeding from gums, venipunctures, and old surgical sites; epistaxis; ecchymoses Peripheral cyanosis, gangrene
Cardiopulmonary Hemoptysis Dysrhythmias, chest pain, acute myocardial infarction, pulmonary embolus, respiratory failure
Renal Hematuria Oliguria, acute tubular necrosis, renal failure
Gastrointestinal Abdominal distention, hemorrhage Diarrhea, constipation, bowel infarct
Neurological Subarachnoid hemorrhage Altered level of consciousness, ischemic stroke

Laboratory Findings

Laboratory tests used to diagnose DIC essentially assess the four basic characteristics of this syndrome: (1) increased coagulant activity, (2) increased fibrinolytic activity, (3) impaired regulatory function, and (4) end-organ failure.

Continuous activation of the coagulation pathways results in consumption of coagulation factors. Because of this, the prothrombin time (PT), the activated partial thromboplastin time (aPTT), and the international normalized ratio (INR) values are elevated. Although the platelet count may fall within normal ranges, serial examination reveals a declining trend in values. An unexpected drop of at least 50% in the platelet count, particularly in the presence of known contributing factors and associated signs and symptoms, strongly indicates DIC.7 Fibrinogen levels drop as more and more clots are formed. Thrombus formation in small vessels narrows the vessel lumen, forcing RBCs to squeeze through. The resulting damage and fragmentation of these cells can be seen on microscopic examination of blood samples. Damaged, fragmented RBCs are called schistocytes.2,6,8

In response to the excess clotting activity, the fibrinolytic process accelerates, and levels of by-products increase. This is reflected in markedly elevated levels of fibrin degradation products. Another key laboratory test used to evaluate the degree of clot dissolution—and therefore the severity of the coagulopathy—is the D-dimer level.7 D-dimers exclusively indicate clot degradation because, unlike fibrin degradation products, which also result from the breakdown of free circulating fibrin, D-dimers result only from dissolution of clots.2 With progression of the coagulopathy, normal regulatory mechanisms are disrupted, as reflected in decreasing levels of inhibitory factors such as protein C, factor V, and antithrombin III.2,6

Unchecked DIC resulting in occlusion of vessels and tissue ischemia leads to end-organ dysfunction.1 Respiratory failure, indicated by abnormal arterial blood gas (ABG) levels; liver failure, indicated by increasing liver enzymes; and renal impairment, indicated by rising blood urea nitrogen (BUN) and creatinine levels, are common findings in advanced DIC.5

No single laboratory study can confirm the diagnosis of DIC, but several key results are strong indicators of the condition (Table 27-2). The International Society of Thrombosis and Hemostasis emphasizes early detection of DIC through observation of abnormal trends in laboratory values.4

TABLE 27-2

KEY LABORATORY STUDIES IN DISSEMINATED INTRAVASCULAR COAGULATION

TEST VALUE
Prothrombin time (PT) >12.5 sec
Platelets <50,000/mm3, or at least 50% drop from baseline
Activated partial thromboplastin time (aPTT) >40 sec
D-dimer >250 ng/mL
Fibrin degradation products (FDP) >40 mcg/mL
Fibrinogen <100 mg/dL

Medical Management

Without question, the primary intervention in DIC is prevention. Being aware of the conditions that commonly contribute to the development of DIC and treating them vigorously and without delay provide the best defense against this devastating condition.2,4,6,8 After DIC is identified, maintaining organ perfusion and slowing consumption of coagulation factors are paramount to achieving a favorable outcome.1,2

Multiple organ dysfunction syndrome (MODS) frequently results from DIC and exacerbates the underlying pathology. It is essential to prevent end-organ ischemia and damage by supporting blood pressure and circulating volume. Administration of intravenous fluids and inotropic agents, and, if overt hemorrhaging is evident, infusion of packed RBCs are appropriate interventions to replace blood volume and essential, oxygen-carrying RBCs.

In the presence of severe platelet depletion (<50,000/ mm3) and severe hemorrhage, platelet transfusions are often indicated.4,6 However, caution must be used when administering platelets because antiplatelet antibodies may be formed. These antibodies may become activated during future platelet transfusions and elicit DIC.2

Replacement of clotting factors in the patient with DIC is thought by some authorities to perpetuate the coagulopathy; however, there is little scientific evidence to support this theory.1 Fibrinogen levels less than 100 mg/dL indicate the appropriateness of administering cryoprecipitate. A prolonged PT indicates the need for fresh-frozen plasma.2,4,6

Slowing consumption of coagulation factors by inhibiting the processes involved in clot formation is another strategy used in treating DIC. The use of heparin, particularly low-molecular-weight heparin, to prevent formation of future clots is controversial.5 It is contraindicated in patients with DIC associated with recent surgery or with gastrointestinal or central nervous system (CNS) bleeding. However, heparin has been beneficial in obstetric emergencies such as retained placenta or incomplete abortion, severe arterial occlusions, or MODS caused by microemboli.2,6

The use of recombinant activated protein C is gaining popularity in treating DIC, especially in the setting of severe sepsis. Activated protein C acts as an anticoagulant and works to restore normal inhibition of coagulation pathways. However, it has been associated with an increased incidence of intracerebral bleeding and must be used with caution in patients with severely decreased platelets.2,4

Thrombin production in DIC surpasses that of antithrombins and other regulatory factors that would normally be present to inactivate thrombin and its subsequent actions. The use of antithrombin III has recently been approved in the United States. Ongoing research is yielding mixed results in the treatment of DIC.4 One interesting area of research is the use of protease inhibitors. Protease molecules normally inhibit the conversion of fibrinogen to fibrin in the coagulation mechanism, but in DIC, this inhibitory mechanism is impaired. The introduction of protease inhibitors by intravenous infusion may be advantageous in arresting DIC.2

Nursing Management

Nursing management of the patient with DIC incorporates a variety of nursing diagnoses (see the Nursing Diagnosis Priorities Box on Disseminated Intravascular Coagulation). Assessment and monitoring are the primary weapons in the critical care nurse’s arsenal against DIC. Knowing the diseases and conditions that are most often associated with DIC and understanding the pathophysiological mechanisms involved enables the critical care nurse to anticipate its development and intervene quickly. Nursing priorities are directed toward (1) supporting the patient’s vital functions, (2) initiating bleeding precautions, (3) providing comfort and emotional support, and (4) maintaining surveillance for complications.

Supporting Patient’s Vital Functions

Frequent assessments should include parameters for neurological status, renal function, cardiopulmonary function, and skin integrity that indicate impaired tissue or organ perfusion. Particular parameters to include are mental status, BUN and creatine levels, urine output, vital signs, hemodynamic values, cardiac rhythm, arterial blood gas and pulse oximetry values, skin breakdown, ecchymoses, or hematomas.6

The critical care nurse must recognize and support the patient’s vital physiological functions. Administration of intravenous fluids, blood products, and inotropic agents to provide adequate hemodynamic support and tissue oxygenation is essential in preventing or combating end-organ damage. Close monitoring of vital signs, hemodynamic parameters, intake and output, and appropriate laboratory values assists the critical care nurse in administering and titrating appropriate agents.

Initiating Bleeding Precautions

Awareness of the patient’s bleeding potential necessitates adjustments to normal nursing interventions. The nurse avoids unnecessary venipunctures that may result in bleeding, bruising, or hematomas by drawing blood from and administering medications through existing arterial or venous lines. The use of manual or automatic blood pressure cuffs is avoided whenever possible. If tracheal or oral suctioning is necessary, the use of low-level suction is recommended.6 Meticulous skin care is advised, keeping the skin moist and using specialty mattresses and beds as appropriate to prevent breakdown. Gentle care should be used when bathing or turning the patient to prevent bruising or hematoma formation.

Providing Emotional Support

The development of DIC in the already critically ill patient can be stressful for the patient and his or her significant others. It is imperative to provide psychosocial support throughout this crisis. Calm reassurance and uncomplicated explanations of the care the patient is receiving can help to allay much of the anxiety experienced. The critical care nurse must answer all questions and provide information in terms best understood by all parties. The use of an interpreter when English is not the primary language can enhance understanding and help avoid misconceptions. Providing spiritual support as requested may also be of assistance.

Please see the Collaborative Management Box on Disseminated Intravascular Coagulation for more information.