In anticipation of EM Cases Episode 113 Diagnosis an Workup of Pulmonary Embolism with Dr. Kerstin DeWit and Dr. Eddy Lang, we have Dr. Peter Reardon telling us his Best Case Ever (Coding in the Scanner) of a young woman who presents with a seizure followed by hemodynamic instability, who codes while in the CT scanner…
Produced by Rajiv Thavanathan, Editing & Sound Design by Anton Helman, August 2018
Blog post by Anton Helman
Massive pulmonary embolism may responsible for 8-13% of unexplained cardiac arrests . With early CPR and thrombolysis patients with massive pulmonary embolism can have a remarkable recovery. While robust evidence for thrombolysis of pulmonary embolism in cardiac arrest is lacking, in two retrospective studies, ROSC was more frequently achieved in those who received thrombolysis (67%-81%) compared with those who did not receive it (43%),  while the MAPPET study showed an amazing 35% survival to hospital discharge . A review in 2014 of prospective studies totalling about 700 patients suggested that thrombolysis should be considered as early as possible in patients in unexplained PEA arrest with major risk factors for pulmonary embolism and/or show signs of right heart strain on POCUS.
Pulmonary embolism results in cardiac arrest from a downward spiral involving right ventricular obstruction, increased oxygen demand, decreased left ventricular filling and cardiac ischemia. Patients usually present in PEA and POCUS may show intraventricular thrombus, RV dilatation, septal bowing (‘D’ sign), and RV hypokinesis with normal apical contractility (McConnell sign). While POCUS has it’s limitations for the diagnosis of PE, there are techniques that can help differentiate chronic pulmonary hypertension from acute PE as outlined in this POCUS Cases video.
While contraindications to thrombolysis and the risk of major bleeding including intracranial hemorrhage (up to 10% of patients) needs to be considered in all patients with massive pulmonary embolism, some have suggested that the cardiac arrest patient with massive pulmonary embolism should be considered for thrombolysis on an individual basis even the presence of traditional contraindications . In particular, while CPR has been included as a relative contraindication to thrombolysis for STEMI siting a two-fold risk of bleeding, in patients with pulmonary embolism there is nonetheless a survival benefit and no association between prolonged CPR and increased bleeding .
Dosing thrombolytics for suspected pulmonary embolism in cardiac arrest
The recent PEAPETT study suggested that ‘half-dose’ Alteplase (50 mg of tPA) “is safe and effective in restoration of spontaneous circulation in PEA due to massive PE leading to enhanced survival and significant reduction in pulmonary artery pressures.” While Tenectaplase has not been approved for use in patients with massive pulmonary embolism, in some centres it is the only thrombolytic available.
For easy recall the initial dose of both Alteplase and Tenectaplase is 50mg IV bolus
Alteplase (tPA) 50mg IV bolus or
Tenectaplase (TNK) 50mg IV bolus
CPR should be continued for at least 60-90 minutes after thrombolysis according to The European Resuscitation Council Guidelines .
Great review of management of high risk pulmonary embolism published Aug 2018 by Dr. Peter Reardon in Journal of Intensive Care Medicine.
Drs Thavanathan, Helman & Reardon have no conflicts of interest to declare.
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Other FOAMed Resources on Thrombolysis for Massive PE in Cardiac Arrest
Pulmcrit – Eight pearls for the crashing patient with massive PE
Rebel EM – The PEAPETT Trial: Half dose tPA for PEA due to Pulmonary Embolism
ALieM – What’s the code dose of tPA?