Sorry - I completely forgot this question. My comments are as follows:
My blogs on UF rate at KidneyViews are directed - primarily at least - at the stable stage of maintenance dialysis, but it remains a truism that the rate of volume removal is a potentially destabilising variable at any stage in the dialysis journey.
In the acute phase of APO where there is a more urgent need to diminish preload, the approach of UF modeling is attractive … in other words, a higher ml/kg/hr UF rate early, followed by adopting a slower, gentler volume reduction protocol in the later part of the treatment. UF modeling in APO has not - at least to my knowledge - been investigated, but it is one clinical situation where it might make sense.
The approach you describe is not unreasonable, but to me, it confuses two separate situations, unless I have read it wrongly.
As I read it, your first set of circumstances deal with an initiating approach to the freshly (previously un-dialysed) uraemic patient in their first introduction to dialysis. Here, your approach …
1st session: duration 3 hours, blood flow 200 ml, heparin 4000 unit
2nd session (2nd day): duration 3 hours, blood flow 250 ml, heparin 4000 unit
3rd session (3 rd day): duration 4 hours, blood flow 300 ml, heparin 4000 unit approach
… seems more than reasonable, and likely reflects a generally middle of the road regime that many would use to commence dialysis, although there is a growing trend towards a more incremental [or accretive] regime applied from earlier on in the CKD slide, though this described regime would certainly fit a crash-lander.
For incremental dialysis, see my two KidneyViews blogs [plus some of the references: e.g. Kalanter-Zadeh and Alan Davenport]
The second circumstance … a patient presenting in APO … might also be advantaged by nuanced dialysis. Although I know of no trials of data that would support what I am about to write, in this circumstance there is a cogent argument for ultrafiltration modeling … a higher UF rate (arguable 13 ml/kg/hr in the first hour of dialysis to provide some early pre-load relief, followed by a reduction in the UF rate to slower, gentler volume reduction in the subsequent hours to remove any additional fluid overload.
As to the absolute volume to remove? … well, that still comes down to an individual patient assessment - weight, size, body habitus, age, etc etc. Clearly 4 litres in a 50 kg elderly woman may be overestimating the safe amount to remove and threaten organ stunning while 4 litres in a 150 kg young man be far more easily tolerated. Here, clinical judgment remains important to get ‘the guess’ right … and it is a guess. But, a higher applied UF given early, followed by a gentler, longer subsequent dialysis run seems wise.
The same comments can be applied to the patient not in APO where there is less hurry to remove fluid and longer gentler dialysis wins out again.
I am not sure if that answers your question. I can but hope so. As for systems that allow direct ml/kg/hr entry … no, not that I know of.