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HIT-Heparin Induced Thrombocytopenia Simulation Case

Audience: The aim of this simulation is to educate emergency medicine interns, residents and advanced providers on the recognition, diagnosis, and management of heparin-induced thrombocytopenia (HIT). Communication, teamwork, and crisis resource management are incorporated into the case. Introduction: Heparin-induced thrombocytopenia is a life-threatening complication of heparin exposure (eg, unfractionated heparin, low molecular weight [LMW] heparin) that occurs in a small percentage of patients exposed.1 It results in a consumptive coagulopathy in which the clotting cascade is inappropriately activated, leading to a low platelet count yet hypercoagulable state. HIT is associated with mortality rates of 20-30%, with a similar percentage of patients becoming subsequently disabled due to severe complications including limb amputation, multi-system organ failure, stroke or other causes of morbidity.2 Heparin-induced thrombocytopenia often presents 5 to 15 days after starting heparin treatment, and with more outpatients being treated with heparin products, it is likely that a first-line provider, such as an emergency medicine physician, would be the first clinician to encounter these patients. The combination of thrombocytopenia and hypercoagulability, along with the rarity of the disease, can make this difficult to diagnose and puts the first line clinician at risk for mismanagement. It is important to be familiar with the signs and symptoms of HIT and to refrain from starting heparin or platelets upon discovery of thrombosis or thrombocytopenia because it will lead to severe and rapid patient deterioration. Therefore, the ability to quickly recognize and treat this condition properly is an essential skill for emergency medicine physicians. Our goal is to create a simulated case that familiarizes emergency providers to this condition so they can be comfortable diagnosing and managing it in a real clinical scenario. Educational Objectives: After completing this simulated case, participants will be able to: 1. Obtain a detailed history that includes recent medications, medical, surgical, and social history to evaluate for HIT risk factors.


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2. Perform an adequate neurovascular exam including evaluation of motor function, sensation, skin color, pulses, and capillary refill. 3. Order appropriate laboratory testing and imaging for diagnosis of thrombocytopenia and arterial occlusion, including bed side doppler or ultrasound. 4. Discuss and recognize the symptoms of HIT and the contraindications of platelet and heparin administration in the emergency department. 5. Avoid administration of heparin in the emergency department setting and recognize that platelets may worsen thrombus formation and lead to limb amputation. 2 6. Select appropriate medications for treatment and determine appropriate disposition for a patient presenting with HIT. 7. Demonstrate interpersonal communication with patient and family. 8. Recognize that HIT with thrombosis is a potential complication in hospitalized patients and outpatient settings and is associated with high mortality rates.
Educational Methods: This is a high-fidelity simulation case that allows participants to diagnose and treat HIT in a safe environment. The case is followed by a debriefing and small group discussion to review patient care skills, medical knowledge, interpersonal communication, and practice-based learning and improvement.

Research Methods:
The educational content and efficacy were evaluated by oral feedback and a debriefing session immediately after completion of the simulation. Participants were provided with an evaluation at the completion of the debriefing session to provide qualitative feedback on the simulation case. A quality Likert Scale was used for the evaluation.
Results: Post-simulation feedback resulted in positive reception, and learners found it useful to run through a high-risk case potentially seen in the emergency department. Out of the 21 participants, 14 responded to the evaluation. Feedback was overwhelmingly positive with the majority rating the simulation as excellent or good.

Discussion:
The simulation improved awareness of the symptoms of HIT and contraindications of immediate platelet and/or heparin initiation upon vessel occlusion and thrombocytopenia discovery.

Linked objectives and methods:
It is important for emergency medicine physicians to use this high-fidelity simulation method to quickly diagnose HIT and provide an appropriate treatment plan because HIT is associated with high morbidity and mortality (objective 8). 1,2 Learners will need to take a comprehensive history to identify risk factors for HIT as well as perform a thorough neurovascular exam. At this time learners should also order labs and perform a bedside doppler/ultrasound. Upon lab and imaging results learners should discover an arterial occlusion and thrombocytopenia. If learners decide to prematurely treat patient for thrombocytopenia and initiate platelets, they should recognize onset of symptoms and worsening condition of patient (objective 4). However, if the learners demonstrate efficient interpersonal communication with patient and family, they will learn she was treated for DVT (deep vein thrombosis)/PE (pulmonary embolism) as outpatient through her hematologist and has been on unfractionated heparin daily (objective 5,7). This information will lead learners to properly diagnose HIT and disposition the patient accordingly (objective 6).

Recommended pre-reading for instructor:
We recommend any of the reference in the references section.

Results and tips for successful implementation:
This case was written for a high-fidelity simulation scenario and allows learners to diagnose and treat a patient presenting with HIT. This simulation was implemented to be run on emergency medicine interns and residents. The learners were assessed throughout the simulation and given graded percentages on related competencies in the debriefing session. It was noticed that learners were more successful during the simulation when there was optimal teamwork from all participants. The overall feedback from learners and instructors was positive. Out of the 21 residents who participated in this simulation, 14 emergency medicine residents responded and gave feedback. Overall, there was a positive response on this simulation case. Using the Likert scale (1: not a great case to 5: excellent case), 50% of the residents gave the scenario a 5 (excellent), 42.9% rated the case as 4 (Good), and the other 7.1% rated the case as N/A.

Objectives:
By the end of this simulation case and debriefing session, the learner will be able to: 1. Obtain a detailed history that includes recent medications, medical, surgical, and social history to evaluate for HIT risk factors. 2. Perform an adequate neurovascular exam including evaluation of motor function, sensation, skin color, pulses, and capillary refill. 3. Order appropriate laboratory testing and imaging for diagnosis of thrombocytopenia and arterial occlusion, including bed side doppler or ultrasound. 4. Discuss and recognize the symptoms of HIT and the contraindications of platelet and heparin administration in the emergency department. 5. Avoid administration of heparin in the emergency department setting and recognize that platelets may worsen thrombus formation and lead to limb amputation. 2 6. Select appropriate medications for treatment and determine appropriate disposition for a patient presenting with HIT. 7. Demonstrate interpersonal communication with patient and family.
8. Recognize that HIT with thrombosis is a potential complication in hospitalized patients and outpatient settings and is associated with high mortality rates. year-old female who arrives as a walk-in and is alert, awake and oriented at time of arrival. She complains of localized right-hand pain and tingling.

Initial presentation:
The patient presents in the emergency department with right hand pain, decreased sensation, and tingling. Patient's skin is flushed, there is edema present, and baseline vital signs show elevated heart rate and blood pressure. Additionally, there are no lacerations, patient has full range of motion, and poor capillary refill.

How the scenario unfolds:
The patient presents to the emergency department with localized right-hand pain and tingling.
The participants should place patient on the monitor and obtain a full set of vital signs as they gain history from patient and family. Patient denies any trauma, provides some of her history, and states she was recently treated for a DVT (Deep Vein Thrombosis) or pulmonary embolism (PE) seven days ago by her hematologist. She explains that her pain started 12 hours ago. It was also noted that patient was on unfractionated heparin daily. The learners should perform a complete neurovascular exam signaling to the learner there is a vascular problem. Additionally, laboratory and bedside imaging (doppler/ultrasound) may be requested at this time. It is likely the learner may order an alternative modality of imaging to evaluate extremity vasculature that may include angiography or computed tomography with contrast. In the case of the learner ordering a different modality of imaging, the learner should be informed that this imaging is not available in this hospital setting or the CT is not currently functioning. Ideally, the learner should come to the conclusion that bedside ultrasound is the imaging of choice to evaluate the patient's findings. The arterial occlusion and thrombocytopenia should then be discovered after appropriate orders have been placed. If learner does not recognize possible arterial occlusion, the patient continues to complain of worsening pain. If the learner continues to fail to make the appropriate diagnosis of arterial occlusion, the patient's symptoms may evolve to more classic signs of arterial occlusion that can include pain out of proportion, pallor, paralysis, pulselessness or cold extremity. Upon discovery of thrombocytopenia, platelets should not be immediately transfused. If learners do not properly diagnose patient with HIT and platelets or heparin is given, the patient begins to decompensate. Learners should recognize elevation in blood pressure, respiratory rate, and onset of shortness of breath following initiation of platelets. Additionally, patient's pain in right hand will worsen and pain will begin in calf. If learners do properly diagnose patient with HIT, they should recognize the need for admission, obtain vascular and hematology consults, and initiate argatroban and/or lepirudin. If the operator believes the case should be more challenging, they can provide the learner with a "poor historian" patient.

HIT-Heparin Induced Thrombocytopenia
Background/Causes: • Heparin induced thrombocytopenia is a life-threatening immune-mediated adverse drug reaction caused by the production of antibodies that activate platelets in the presence of heparin. 1 A potential life-threatening complication of HIT is thrombosis that can occur anywhere in the body but commonly causes extremity arterial occlusion, atrial appendage thrombosis, cardiac ischemia and stroke. Thrombosis typically occurs concurrently with thrombocytopenia and contributes to high rates of disease mortality. 1,2 Clinical Presentation: • Acute symptoms include pain, swelling, flushing, hypertension, tachycardia, and dyspnea but can also include more severe signs including skin necrosis or multi-organ system failure. 3 • Onset of thrombocytopenia within 5-10 days following heparin treatment 1 • Learners should look for the "4 T's" of HIT to help identify patients who are at risk which include Thrombocytopenia, Timing, Thrombosis and other causes for Thrombocytopenia. 1,3 Workup findings: • Right hand arterial occlusion • Thrombocytopenia Treatment/management: • Medications: o Some alternative anticoagulants available for treatment include argatroban and lepirudin they do not cross-react with HIT antibodies 1 • Argatroban: o The recommended initial dose is 2μg/kg per minute, regulated to achieve aPTTs 1.5-3 times the baseline value 3 o Treatment with argatroban has shown no evidence of antibody generation on prolonged or repeated administration and has no reported anaphylactic deaths 1 • Lepirudin: