Dialysis time: what you prescribe is what you get? (WYPIWYG)

The duration of a dialysis session is an essential parameter in determining dialysis efficiency and hence adequacy. The aim of this study was to measure the real dialysis time and to compare it to the prescribed time. For 12 months, 8412 dialysis treatments were allocated a number and a random sample of 100 was selected using a computer generated randomisation code. At the end of each dialysis, the time prescribed, the real time achieved, the blood volume exchanged, and any incidents occurring during the dialysis were noted. All the staff was aware of the study but nobody except the controller knew which dialysis was going to be controlled. The study population consisted of 48 patients, 25 males and 23 females. The mean duration of the prescribed dialysis time was 3.30 hours. Three patients used the same monitor per day. Results showed a loss of 10 minutes for 180 minutes dialysis prescription, 9.5 minutes for 210 minutes and 10.5 mintutes for 240-dialysis prescription. The dialyses with the greatest difference in time measured and prescribed occurred on the second (12 am to 3 am) shift (-6.23) which might be explained by the necessity for changing the bicarbonate cartridge during the shift. This loss of time represents a mean of 7 dialyses per year per patient. In conclusion, the prescribed time for a dialysis is very often not respected. A readjustment of the time during the treatment will be necessary to compensate for this loss of diffusion time and consequent efficiency.