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


OBJECTIVE
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.
Department of Cardiothoracic Surgery, Cardiovascular Research Centre, Aalborg Hospital, Aarhus University Hospital, Aalborg, Denmark. benedict@dadlnet.dk
Benedict
B
Kjærgaard
Bodil Steen
BS
Rasmussen
Susanne
S
de Neergaard
Lars Hvilsted
LH
Rasmussen
Søren Risom
SR
Kristensen
D000818:Animals; D016887:Cardiopulmonary Resuscitation / Q000379:methods*; D003131:Combined Modality Therapy; D004195:Disease Models, Animal; D005112:Extracorporeal Circulation / Q000379:methods*; D006801:Humans; D007036:Hypothermia, Induced / Q000379:methods*; D011655:Pulmonary Embolism / Q000503:physiopathology* / Q000534:rehabilitation*; D013552:Swine; D016896:Treatment Outcome