May 272019

Jon-Emile S. Kenny MD [@heart_lung]

There is no power for change greater than a community discovering what it cares about.

-Margaret J. Wheatley

Between the 22nd and 24th of May, I participated in the galvanic, second-annual “Hospitalist and the Resuscitationist” conference in Montreal, Canada.  The entirety of this meeting was organized by Dr. Philippe Rola [@thinkingcriticalcare]; I was fortunate to speak alongside his EMCrit Crew members Drs. Rory Spiegel [@EMNerd_] and Josh Farkas [@pulmcrit].  Again, I was humbled by my solicitous and brilliant co-speakers: Kylie Baker [@kyliebaker888], Segun Olusanya [@iceman_ex], Peter Weimersheimer [@VTEMsono], Korbin Haycock [@korbinhaycock2], Laura Duggan [@drlauraduggan], Felipe Teran [@FTeranMD], Robert Chen [@OttawaheartRob], Haney Mallemat [@criticalcarenow], Andre Denault, Sheldon Magder and many others.

Included below is a summation of IVC collapse physiology and its current clinical evidence.  Before viewing, consider scrutinizing my previous writings on this topic.  Earlier, I employed a Guytonian approach to IVC variation and used this framework to pontificate on the sensitivity and specificity of using respiratory variation in IVC diameter to predict fluid responsiveness in spontaneously breathing patients without assisted ventilation.  I have also argued that the application of positive pressure in patients with spontaneous efforts may make interpretation tenuous.

Additionally, I have considered the physiology of venous Doppler velocimetry and its relationship to the central venous pressure.  In this brief lecture, I hope to tie together these various concepts – through the idea of ‘cardiac efficiency’ – to better refine hemodynamic interpretation at the bedside.



Dr. Kenny is the cofounder and Chief Medical Officer of Flosonics Medical; he is also the creator and author of a free hemodynamic curriculum at

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Integrating the Evidence and Physiology of IVC Collapse: A Lecture from the Hospitalist & Resuscitationist Conference in Montreal