To PE or not to PE?

A male in his 70s presented by ambulance to ED Resus with a 2 day history of worsening shortness of breath. He looked sweaty, pale and pre-syncopal. PMHx: Active bowel cancer on chemotherapy. 

Vitals: RR45, S80% on 15L non- rebreather, BP56/30mmHg, T36.5ºC, GCS 14. 

VBG: Ph 7.12, pCO2 7.02, HCO 18, Lac 7.4 

An urgent portable CXR showed clear lung fields. ECG S1Q3T3. Top differential at this point was pulmonary embolism, however given haemodynamic instability, too unstable for a CTPA. ICU team were en route. A bedside ECHO was done:

A Parasternal Long view showing a distended RV consistent with the distended IVC seen on the Sub-xyphoid view, in keeping with an impression of severe RV strain. Furthermore there aren't any signs of tamponade as a cause of the shock and the Aortic outflow tract (AOFT) is noted to be under 4cm which is reassuring that there isn't a distended aneurysmal aortic root - a useful observation in the risk stratification for thrombolysis.