Subclavian subterfuge and "Catheter Last"

While performing an electronic chart biopsy prior to examining a consult patient, I noticed a "nephrologic no-no," which can be seen on the patient's chest x-ray coursing under the right clavicle (see image). This finding was confirmed on my physical examination. The surgical team decided intra-operatively that the patient might need dialytic intervention so a right subclavian temporary dialysis catheter was placed. I had never seen one before, but I am sure many nephrologists who are no longer junior woodchucks like myself were around when subclavian dialysis catheter use was common. As my co-fellow Dr. McMahon pointed out in a previous post, the subclavian route was popular until an association was noticed between this route and subclavian thrombosis and stenosis.

Ted Steinman, one of our attendings at The Brigham, co-wrote a paper this year entitled, "Dialysis at a crossroads: 50 years later." In it, he and other pillars of nephrology propose a new path for dialysis therapy, and this is worth a read. One component of this path recommends changing the mantra "Fistula First" to "Catheter Last" given the unexplained augmented use of catheters and increased catheter-associated infections during the fistula first initiative. In other words, catheters should be the "last" choice for dialysis intiation given all of the complications caused by their use compared to grafts and fistulae. Furthermore, fistulae are not always attainable and cannot always be created in a timely fashion; thus, a graft is the next best thing and a very suitable alternative. The authors also propose that the Center for Medicare and Medicaid Services should consider catheter use to be sub-standard care. The overall premise behind the "Catheter Last" remains roughly the same, but this is an interesting way to think about our patients who are nearing the need for dialytic intervention that may motivate us more to prevent use of the dreaded catheter, especially when a subclavian one slips through the cracks.

Posted by Will Pendergraft

Methylene blue and refractory hypotension

My name is Will Pendergraft, and I just completed the clinical portion of the joint nephrology fellowship between Brigham and Women’s Hospital and Massachusetts General Hospital. I was inspired for the first time by Nate Hellman during my residency at UCSF when I started to peruse this blog. If you have any free time, it’s worth looking back at his very first post from 2008. I am astonished by how he wrote these posts on a daily basis! As a contributor to the blog, my goal will be to provide short and useful, or at least interesting, nephrocentric snippets for first-year fellows.

With that said, I was walking through the cardiac surgery ICU at MGH a few months ago on my way to provide moral support for one of my co-fellows who was placing a difficult dialysis catheter in someone with almost no access, and upon entering the patient’s room, I noticed that the urine in the collection bag was of a Mediterranean shade (see image)! Given that we are differentialists by trade, www.urinecolors.com has a pretty good list of what can cause different urine colors.

The surgical team said they were intravenously infusing methylene blue “to improve the patient’s refractory hypotension,” an idea with which I was unfamiliar, so I sprinted to the nearest computer to look into this more deeply.

Methylene blue was created in 1876 and was first used in humans in 1881 by nobel laureate Paul Ehrlich to treat mild cases of malaria. It now has multiple indications, most notably including reduction of methemoglobin to hemoglobin in methemoglobinemia. Intravenous and oral formulations are easily excreted into the urine turning it blue to bluish-green. Interestingly, methylene blue also inhibits guanylate cyclase, a second messenger involved in nitric oxide-mediated vasodilation; thus, it prevents smooth muscle relaxation. In cases of shock where fluids, standard pressors du jour and steroids are ineffective, methylene blue may be another medication in the anti-hypotensive toolkit. Surprisingly, there are over ten clinical trials with positive results using methylene blue in refractory septic shock, and it is even used by anesthetists and surgeons to treat vasoplegia after cardiopulmonary bypass. The dosing regimen is 2 mg/kg IV once as a bolus followed by continuous infusion. Remember methylene blue the next time you see this shade of urine and be on the lookout for it in the cardiac surgery ICUs.

Posted by Will Pendergraft