Extracorporeal membrane oxygenation in life-threatening massive pulmonary embolism.

INTRODUCTION: In massive pulmonary embolism (PE) with circulatory collapse or with cardiac arrest, treatment can be difficult. Often, the diagnosis is unclear, and the time to treatment is crucial. Our institution has had an out-of-hospital team intended for the treatment of accidental hypothermia with extra corporeal membrane oxygenation (ECMO) since 2004. The team has occasionally been involved in patients suffering massive PE. METHODS: We were called to 38 patients with PE, but two were assessed as untreatable. Seventeen were treated with cardiopulmonary resuscitation followed by veno-arterial ECMO. Nineteen were prepared for ECMO with sheaths in the femoral vessels and were intensively observed during diagnosis and treatment. Five of these patients later progressed to ECMO due to cardiac arrest during treatment with thrombolytic medication. Most of the patients were treated with heparin and thrombolytic medication, but if the medications were contraindicated, they were treated with either surgical thrombectomy or only with heparin awaiting spontaneous thrombolysis. RESULTS: Of the 36 patients we intended to treat, 25 (69%) survived one month and 20 survived one year (56%). Of the 22 patients treated with ECMO, 11 survived one month (50%) and 10 survived one year (45%). DISCUSSION: The treatment could have been more uniform. It seems reasonable to build up a PE alert team with ECMO capability to take care of patients with massive PE. CONCLUSION: The treatment of thrombolytic medications in massive PE is risky, but if the patient is treated or prepared for ECMO, it can be lifesaving.

Extracorporeal cardiopulmonary support may be an efficient rescue of patients after massive pulmonary embolism. An experimental porcine study.

INTRODUCTION: Treatment of massive pulmonary embolism leading to cardiac arrest is controversial but restitution of circulation within a shorter time is crucial. Cardiopulmonary support and therapeutic hypothermia is an option for cardiac arrest and could be used to treat massive PE. However, hypothermia may influence the effect of the ongoing intrinsic fibrinolysis. OBJECTIVES: To establish a porcine model of massive pulmonary embolism, to show that cardiopulmonary support can rescue pigs with massive pulmonary embolism and to examine the effect of hypothermia on fibrinolysis. METHODS: Pigs ~80 kg were anesthetised and prepared for cardiopulmonary support. Repetitive injections of preformed blood thrombi into the right atrium were done until cardiac arrest. Cardiopulmonary support was established and eighteen pigs were randomised into 3 groups: Normothermia (38-39 °C); hypothermia (33-34 °C); or medication with recombinant tissue plasminogen activator. After three hours the pigs were weaned from cardiopulmonary support, and after 15 minutes with spontaneous circulation assassinated and autopsied. Remaining thrombi in the lungs were weighed. RESULTS: The development of fatal pulmonary embolism was highly reproducible. All 18 pigs could be weaned from cardiopulmonary support and survived more than 15 minutes. The amount of remaining thromboemboli was substantial in all groups and not significantly different between groups. Normothermic group 20.0 ± 2.2 g, Hypothermic group 17.0 ± 3.7 g, and rt-PA group 14.3 ± 3.2 g. CONCLUSIONS: Cardiopulmonary support could rescue pigs with massive pulmonary embolism. Hypothermia did not reduce the emboli but may for other reasons be beneficial. The optimal additional treatment is still unknown but treatment modalities can be tested in this model.