Just saw this:
Nice.
When did UpToDate add links to PubMed?
How I used my newly acquired PubMed skills
Yesterday I gave one of my favorite lectures, Renal Adventures in Imaging.
After I finished the lecture I spent some minutes playing with my new skills on PubMed and found this article: N-acetylcysteine effect on serum creatinine and cystatin C levels in CKD patients that completely goes against one of the figures and points of my newly scribed chapter:
[The inability of acetylcysteine to prevent dialysis or mortality] maybe because acetylcysteine alters creatinine handling in the proximal tubule. Acetylcysteine, actually accelerates the excretion of creatinine resulting in decreased serum creatinine.
After Tepel published his original work on acetylcysteine in 2000 everyone went a little crazy drinking the Mucomyst cool-aid. Here was a cheap, safe and already approved, remedy to the pervasive problem of contrast nephropathy. Everyone was so drunk with the excitement that they didn’t note that the 85% reduction in contrast nephropathy was not associated with a reduction in the need for acute dialysis or a reduction in patient morbidity and mortality.
In 2004, Hoffmann Et al. published the above quoted article which showed a modest but significant reduction in serum creatinine following ingestion of acetylcysteine. This seemed to me to be the best explanation for why a therapy could prevent an increase in creatinine but not prevent dialysis. (Data on the lack of prevention of dialysis from Miner et al. Am Heart J 2004.)
Apparently the patron saint of contrast nephropathy, Richard Solomon, recently reevaluated this theory and found it lacking. He took 30 patients with GFR < 60 mL/min and given 1,200 mg of acetylcysteine every 12 hours for four doses. Creatinine and cystatin C were measured at baseline, 4 and 48 hours after the last dose of acetylcysteine. They found:
Serum creatinine and cystatin C levels did not change significantly at either 4 h or 48 h following the last dose of NAC compared with the baseline values (Table 2; Figures 1 and 2). However, a small but statistically significant reduction in the ratio of serum creatinine to cystatin C was observed at 4 h but not 48 h.
click to enlarge
Solomon postulates that in patients with chronic kidney disease (a population that better represents the people who actually are given contrast nephropathy prophylaxis) the proximal tubule secretion of creatinine may already be maximized so that it cannot be further upregulated by acetylcysteine.
The end result is that changes in creatinine found during acetylcysteine administration likely represent changes in GFR and are not merely artifactual.
Just spent 15 minutes getting better at PubMed
This is time that will pay major dividends down the road.
The mayo clinic libraries have posted a series of screencasts that will make you better at PubMed. Spend the time.
https://videopress.com/v/wp-content/plugins/video/flvplayer.swf?ver=1.18
https://videopress.com/v/wp-content/plugins/video/flvplayer.swf?ver=1.18
PubMed on Tap for the iPhone: the NLM in your pocket
Last week at the end of a morning conferance there was an impromptu discussion of the problem of residents ordering IV contrast for patients with acute kidney injury. The residents see a patient on dialysis and feel that its open season for contrast.
As part of the discussion one of the attendings mentioned this is also a problem with his PD patients with residual renal function and the residents need to know that contrast should be avoided in these patients to preserve residual renal function. I mentioned that actually the data doesn’t support the common sense notion that contrast accelerates the loss of residual renal function. Immediately all eyes were on me and the consensus was that no one else had seen that data and that I was way off the reservation. Pretty uncomfortable place to be.
I had buttoned holed Paul Palevsky at the 2006 ASN Renal Week after a talk on contrast nephropathy and in that hallway conversation he had mentioned that he had just finished research on this vary question. he only reason I remember it was that the results were so counter intuitive. Contrast has no measurable affect on residual renal function. I had actually never seen the article but now I had put up or shut up.
After the conference I had to run to an outside hospital but I stopped at a Tim Hortons (the best thing to come out of Canada since Douglas Coupland) and fired up PubMed on Tap (PMT).
PMT is an app dedicated to adapting the PubMed database to the constraints of a mobile platform. I used an app by the same name on my old Treo. Adding Palevsky as author, and then contrast and residual renal function as text words.
Bingo! One article:
You can pull up the abstract:
The PDF:
:and the PubMed listing:
I then did a less specific search by dropping the author name and found a higher quality study:
I was able to send the references to my colleagues right from the application. Sweet.