Tuesday, February 21, 2017

Perils of Intravenous Fluids

PulmCCM - February 13, 2017 - By Jon-Emile S. Kenny 
"The provision of intravenous fluids is no trivial intervention. Indeed, one eminent nephrologist has called for medical students to receive, not a ‘white coat ceremony’ at the outset of their education, but instead a ‘normal saline ceremony.’ This pomp is an occasion whereby the fledgling physician imbibes a reverence for sodium chloride. To hold a bag of resuscitation fluid should rouse veneration no different than grasping an ampule of morphine or vial of piperacillin-tazobactam. Thus, a zealous awareness of the balance between therapy and toxicity is required for all things we inject into another beings’ veins.
Yet, the administration of intravenous fluid is so ubiquitous and commonplace that we take the aforementioned for granted; it certainly isn’t – emotionally – on par with mixing mannitol or readying dantrolene. We ‘bolus’ and ‘challenge’ patients continuously with crystalloid so much so that these terms lose meaning; what, exactly, is indicated when one says ‘bolus’ or ‘challenge?’..."
PulmCCM - February 14, 2017 - By Jon-Emile S. Kenny 
"Fluids and the Glycocaylx
Critically-ill patients all likely have endothelial dysfunction to some degree. This perturbation in microvascular physiology may be underpinned by abnormal glycocalyx structure and function. Sepsis, trauma, surgery and ischemic insults are all known to disrupt the glycocalyx which will increase vascular fluid capacitance. Indeed, at 90 minutes, 20% of crystalloid volume remains within the vascular space, while in sepsis only 5% does. Further, in sepsis, precapillary arteriolar dilation increases capillary filtration pressure which favours interstitial edema. Thus, the use of alpha agonists such as norepinephrine may protect the microvascular beds from excessive filtration pressure..."