constant site cannulation predisposes to aneurisms. That does not include buttonhole technique.
My small wife uses 30 liters at 5 days so that is the minimum you should be at. Hopefully you will get good results with 30 liters. What blood speed and dialysate speed and total time are you running? What abou UF? How do you feel on it? Great idea on the alarms. Hopefully you wont have many.
I am considering NxStage but the one thing putting me off is the buttonhole part. Is this really necessary?
Just to help you with the time and blood speed, I did a generic calculation for a male 220 lbs(100kg) at 6 ft 2 inches . I dont know how close this is to you but here is what I got. The volume recommended is 40 liters . What is really interesting is that with a blood speed of 450 , then the same parameters at a blood speed of 350 the only difference was, it recommended 10 minutes longer at 350 then 450. This is at 5 days per week. 350 blood speed was 3hours 30 min. and 450 blood speed was 3 hours 20 minutes. So based on that you can see the blood speed has very little effect on the dialysis calculations. It is really the volume that matters with NXstage. I hope this helps.