Over a decade ago, rat studies were done comparing low flow and high flow sevoflurane. Investigators noted that the fluoride by-product coined compound A was associated with tubular necrosis as evidenced by proteinuria, glucosuria and enymuria. On the basis of these findings, the FDA recommended against low flow anesthesia despite a lack of a controlled, prospective, randomized human trials. The above study looks at human patients exposed to long duration low-flow (<1L) sevo and iso anesthesia. The average exposure time was 9 hrs. Post-op renal function as measured by serum Cr, BUN, Cr clearance and urinary protein and glucose were not significantly different between the two groups. Specifically, there was no correlation between renal function and compound A exposure. There was an increase in proteinuria and glycosuria that was seen across all groups (des, sevo, iso, propofol). Not sure why this is but imagine that tissue trauma can lead to more protein loss and elevated cortisol (stress response) leads to hyperglycemia. Nonetheless, this effect was not unique to sevo. So compound A may be a problem for a rat kidney but not so in surgical patients. So the take home point for me was to be careful when translating animal data into human data. It doesn't always work. And yes, low dose sevoflurane is fine for any duration (at least in my mind). I brought this up since it came up on another thread. Anybody have a strong preference on sevo flow rates?