@susannaprice gives us a whirlwind tour of VENOUS RETURN. Going back to basics is vitally important. This is her talk in the form of a Tweetorial at #ESICMphysio #FOAMed - don't forget to get involved in the conversation! #POCUS
"When asking about the RIGHT heart... Which RIGHT heart do you mean?" Normal? Pathological? It's complicated... #FOAMed #ESICMphysio 
Starling = what goes in 'must' (hopefully) come out. Although venous return leads to COutput; COutput must dictate venous return! BOTH must be equal.... or it can't quite 'flow'.... #ESICMphysio
Under steady state... vascular volume = a constant. There's also a pulsatile component to static energy potential as well as the potential for volume to be redistributed. #ESICMphysio
Most anaesthetists will remember this from FRCA-land... V=IR. The cardiovascular equivalent – I is the cardiac output, Resistance is frictional loss of energy – and at constant volume, the pressure drop changes with resistance. #ESICMphysio
An overview of normal CVS function...
Let's consider compliance... a measure of distensibility. When we look at venous compliance – it is the sum of all!
40x greater than arterial vessels.
Dominated by systemic venous compliance.
#ESICMphysio
40x greater than arterial vessels.
Dominated by systemic venous compliance.
#ESICMphysio
The left heart isn't everything.... RHS get's sometimes forgotten about! The heart has to be looked after... careful not to over-fill :P #ESICMphysio
Cardiac output is determined by the interaction of a cardiac function and a return function. MSFP is mean systemic filling pressure, Rv is the resistance to venous return, and Pra is right atrial pressure #ESICMphysio
We need to take care of the right heart... it has a hard time sometimes! Constraints both in terms of external pressure and time! :P #ESICMphysio
In real life, it's not a textbook - and the vasculature has multiple different beds with differing characteristics. We as have compensatory mechanisms. #ESICMphysio
Compliance changes with PATHOLOGY and AGE. #ESICMphysio
(A recap on definitions...) #ESICMphysio
We have volume therapy and adrenergic drugs as our usual go-to's in difficult situations... #ESICMphysio
Let's summarise.... :-) #ESICMphysio DON'T IGNORE VENOUS PRESSURE! RHS heart abn may significantly affect cardiac output and venous pressure. #FOAMed
