We should engineer a new crystalloid?

My post on bag wars was hardly posted when Josh Farkas’ excellent PulmCrit posted an recipe for a Universal Panacea. http://emcrit.org/pulmcrit/crystalloid/

My own foray into this arena was 19 years ago ncbi.nlm.nih.gov/pubmed/9349085 “An improved Hartmann’s solution for anaesthetists in the 1990s”. Before you read it, please note it is heavily laden with Irony (not Fe++), which younger readers may find confusing. What follows is therefore irony-free. I’m going to presume Josh is talking about an extracellular resuscitation fluid. He never considers bicarbonate buffered haemofiltration solutions (BBHS), which are currently available.

I completely agree that continuing to debate the merits of NS vs. LR or Plasmalyte is to repeat the wrong question. But the first flawed premise Josh gives us is “whatever abnormality the patient may have, [the universal] crystalloid infusion will pull them closer to target serum concentrations.”  We are most often dealing with vasopressinaemic patients in critical care, and they are quite capable of “desalinating” an infused litre of isotonic salt solution and becoming more hyponatraemic. The lower the sodium concentration in the bag, the easier desalination occurs, and so a bad situation can be exacerbated.

The second flawed premise lies in Josh’s “Composition” table. Compare it to a slide I’ve nicked from a lecture by Andrew Eynon on the dangers of hypotonic solutions for patients at risk of hypotonic encephalopathy.

osm table

Notice that the contributors to a solutions actual osmolality are not all entirely active. The osmolality of a solution is often significantly less than the sum of its ions. I suspect Farkas’ Solution will actually be hypotonic. He may wish to reconsider Hamburger Solution for the “first bag” as it truly isotonic, and a litre or two while awaiting labs and assessment will be quite benign. See the other great slide I’ve nicked from Dr Eynon;

hypotonic slide

If you reflect on this slide, you’ll never again attempt to resuscitate someone at risk of raised ICP with a hypotonic solution, even if only slightly hypotonic.

There you go. Visit PulmCrit and post your comments, we can start a debate!

 

 

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