Prevention of dialysis hypotension episodes using fuzzy logic control system.
BACKGROUND
Automatic systems for stabilizing blood pressure (BP) during dialysis are few and only control those variables indirectly related to BP. Due to complex BP regulation under dynamic dialysis conditions, BP itself appears to be the most consistent input parameter for a device addressed to preventing dialysis hypotension (DH).


METHODS
An automatic system (ABPS, automatic blood pressure stabilization) for BP control by fluid removal feedback regulation is implemented on a dialysis machine (Dialog Advanced, Braun). A fuzzy logic (FL) control runs in the system, using instantaneous BP as the input variable governing the ultrafiltration rate (UFR) according to the BP trend. The system is user-friendly and just requires the input of two data: critical BP (individually defined as the possible level of DH risk) and the highest UFR applicable (percentage of the mean UFR). We evaluated this system's capacity to prevent DH in 55 RDT hypotension-prone patients. Sessions with (treatment A) and without (treatment B) ABPS were alternated one-by-one for 30 dialysis sessions per patient (674 with ABPS vs 698 without).


RESULTS
Despite comparable treatment times and UF volumes, severe DH appeared in 8.3% of sessions in treatment A vs 13.8% in treatment B (-39%, P=0.01). Mild DH fell non-significantly (-12.3%). There was a similar percentage of sessions in which the planned body weight loss was not achieved and dialysis time was prolonged.


CONCLUSIONS
In conclusion, FL may be suited to interpreting and controlling the trend of a determined multi-variable parameter like BP. The medical knowledge of the patient and the consequent updating of input parameters depending on the patient's clinical conditions seem to be the main factors for obtaining optimal results.
Mancini
Elena
E
Malpighi Nephrology Department, Dialysis & Hypertension Division, Policlinico S. Orsola-Malpighi, Via P. Palagi 9, 40138 Bologna, Italy.
Mambelli
Emanuele
E
Irpinia
Mina
M
Gabrielli
Danila
D
Cascone
Carmelo
C
Conte
Ferruccio
F
Meneghel
Gina
G
Cavatorta
Fosco
F
Antonelli
Alessandro
A
Villa
Giuseppe
G
Dal Canton
Antonio
A
Cagnoli
Leonardo
L
Aucella
Filippo
F
Fiorini
Fulvio
F
Gaggiotti
Enzo
E
Triolo
Giorgio
G
Nuzzo
Vitale
V
Santoro
Antonio
A
D001676:Biofeedback, Psychology / Q000502:physiology; D001794:Blood Pressure / Q000502:physiology; D005260:Female; D017143:Fuzzy Logic; D006801:Humans; D007022:Hypotension / Q000209:etiology / Q000517:prevention & control* / Q000523:psychology; D007676:Kidney Failure, Chronic / Q000503:physiopathology / Q000523:psychology / Q000628:therapy; D008297:Male; D008875:Middle Aged; D011446:Prospective Studies; D006435:Renal Dialysis / Q000009:adverse effects* / Q000295:instrumentation / Q000379:methods*