So just got what I think is an excellent and common question from a reader, worth addressing with a mini-podcast:
Dr Rola, my name is Pedro Alvarado, i’m a Mexican critical care fellow (currently in the 2/2 training year). Been very interested in the last year on being able to answer the question: is my patient going to benefit form fluid administration? (particularly in the case of an objectively diagnosed distributive shock + ARDS, i think by the way, a very difficult to answer question in the majority of Mexican ICU´s).
To answer this question i thought, until recently, one should start by answering if the patient is fluid responsive. The concept of venous congestion and fluid tolerance seems to be the counterbalance that might complete the equaition of benefit/harm ratio of fluid administration on an already high-output state. As it is, i’ve been very interested in what you have recently been describing as the VexUs score. One question, you mention this US tool as a useful stop point for fluid administration in septic (distributive I assume) patients. I understand from your explanation that the further you document ultrasonographic sings of venous hypertension from the RA (hepatic -portal-renal vein), the worse the hypertension and possibly its consequences might be. Also you imply that the earliest you document signs of venous hypertension, the better, so that you can counterbalance benefit/harm ratio of fluid administration as soon as possible.
Understanding that the first, relatively easy measurable macrostructure to be affected by right-sided hypertension is the RA, what makes VExUS more valuable than a good,old CVP monitoring for this purpose? Far more expensive and time consuming, the US is. Also CVP absolute values and trends can be continuously measured.
So at our last webinar (still to be edited due to an unfortunate trolling event), we briefly touched on modes of ventilation but really didn’t delve into it very deeply, so, being fortunate enough to know some really smart people, I figured I might gather up these two for a quick chat. They are both known for no-nonsense, out-of-the-box thinking, paired with solid physiological thinking, which in my mind is the only way to approach complex problems and system failure. Plus, with Rory (@EMnerd) and his powerful nihilistic approach, there would be no chance for a whimsical approach, it would have to have a base in physiology, evidence (bedside or literature) or both!
So just as a little brain teaser, I would like anyone reading to think about how many severe respiratory failure syndromes they are aware of that attack the lungs in a predictable volumetric fashion, where one can say, for instance, that consistently, X% of the parenchyma is affected. Kinda hard, huh? Yet, if asked how best to ventilate these patients, most of us who feel we have a good grasp of severe respiratory failure would answer without thinking twice: “lung protective ventilation: good peep and 4-6 ml/kg.” In a lear, confident tone, most likely as well.
Now I would say that only the first part is correct: lung protective ventilation. As to the second part, it would, to me, only hold true with uniform pathology and uniform patients. But I’ll let Rory rant about that himself, it’s far more entertaining!