Hyponatremia Illustrated

The term hyponatremia causes most interns to break out in a cold sweat mixed with anxiety, terror and panic, and the condition often flummoxes even the most astute internist/hospitalist. Management of hyponatremia is indeed quite tricky - and complicated calculations of free water excess by nerdy nephrologists make the whole issue seemingly insurmountable for most trainees. Not surprisingly, attempts to simplify management are very popular, ranging from a popular version floating around in the interwebs, to the European guidelines, which seem to strike a pretty good balance between appropriate simplification without oversimplification. Nevertheless, one cannot call oneself a nephrologist without clearly understanding the various mechanisms of hyponatremia, prepared for every eventuality from the easy pseudohyponatremia to the not-so-easy reset osmostat. Enter the ‘Hyponatremia Illustrated’ powerpoint-based tool from Tamim Hamdi and colleagues, which won one of the educational innovations awards from the American Society of Nephrology.

 The illustrator is rather easy to begin with - just use this link to download and then open the presentation. The first few slides walk you through how one should use the illustrator tool - don’t skip these, the instructions are very useful, and indeed necessary to understand how to use this. This slide in particular demonstrates the various compartments and forces at play, and I would recommend spending some time looking at this - or coming back to use this as a reference.

The small red pump is the heart, the blue pump represents ADH response, the two big tanks represent intracellular and extracellular volume and so on. The video embedded below also walks through the the best way to use the illustrator powerpoint. The creators have used some very reasonable simplified assumptions, and then walk through the most common cases, slowly ramping up the level of understanding needed, on a case-by-case basis. Over a few animated slides, one will appreciate how the homeostatic mechanisms come into play and hyponatremia happens. There is user input needed to press certain buttons, so one can learn at your own pace and take time to absorb all the information before moving on to the next step. The variety of cases offered means that the illustrator has a lot of depth, and you can use the table of contents to jump to the pressing issue you have at the moment.

 Overall, this illustrator is a herculean effort from Dr Hamdi and colleagues - a lot of effort, and math, have gone into this making this extremely useful illustrator. It is a useful addition to other resources out there (eg PBFluids, especially this lecture slideset). The graphics and visuals may help get certain key concepts across to trainees. It is currently available as a link on the ASN website as an interactive powerpoint slideshow, so it does require a desktop, so I hope a mobile version is coming soon. Join us on Tuesday June 27th to chat with the creator Dr Hamdi, and other innovation award winners on #AskASN.

Swapnil Hiremath