A 55-year-old man with a history of chronic obstructive pulmonary disease (COPD) (no home O2 , FEV1 67% predicted) presents to the emergency department with shortness of breath and lightheadedness that started suddenly 4 hours prior. He underwent a right knee replacement 6 months prior but otherwise has not been in the hospital recently and has felt well. His only current medication is an albuterol inhaler. He has no other past medical history.
His vitals are:
On examination, he is anxious, with clear lung fields and cold extremities and mottled skin. A chest radiograph does not reveal any acute process, and a chest computed tomography (CT) with pulmonary angiography demonstrates bilateral segmental pulmonary emboli. He is given 2 L of intravenous (IV) lactated ringers (LR) solution and is complaining of dizziness and noted to be confused. His repeat vitals are HR 105 beats/min, BP 70/40 mm Hg, respiratory rate 20/min, and SpO2 88% on room air. In addition to supportive care and appropriate triage, what is the most appropriate next step?
A. Administer an additional 1 L of LRCorrect Answer: D
This patient presents with obstructive shock from pulmonary embolism (PE). PE may be categorized as “massive” based on the presence of sustained hypotension (systolic BP <90 mm Hg for at least 15 minutes or requiring inotropic support, not because of a cause other than PE, such as arrhythmia, hypovolemia, sepsis, or LV dysfunction), pulselessness, or persistent profound bradycardia (HR <40 beats/min with signs or symptoms of shock). In the setting of massive PE, clinical guidelines recommend administration of systemic thrombolytic therapy based on evidence demonstrating improved mortality. Thrombolysis may be contraindicated if patients have a high-bleeding risk, including having undergone major surgery within 3 weeks or presentation, however our patient’s distant surgery and lack of other risk factors make him a good candidate for full-dose systemic thrombolysis (answer D is correct). Systemic thrombolysis at half dose has been examined in patients at increased bleeding risk and in the treatment of submassive PE. Data are not conclusive about the benefit of this strategy over others in submassive PE, and full-dose systemic thrombolysis would be most appropriate in massive PE.
IV heparin infusion will ultimately be necessary for this patient, but alone is insufficient; heparin stabilizes the clot while the endogenous fibrinolytic system reduces the clot size over the course of days to months (answer C is incorrect). When administered in PE, a bolus should be performed as it allows a therapeutic level of anticoagulation to be achieved at a faster rate (answer B is incorrect).
Administration of additional IV crystalloid targets suspected intravascular volume depletion. However, the patient has worsened despite receiving 1L of IV fluids. In addition to the fact that fluids do not correct the underlying disease, in acute right heart failure, aggressive volume repletion can worsen interventricular dependence and decrease LV cardiac output.
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