Use of a mean systemic filling pressure analogue during the closed-loop control of fluid replacement in continuous hemodiafiltration.
OBJECTIVE
To assess the use and validity of a mean systemic filling pressure analogue (Pmsa) in the closed-loop control of fluid replacement in continuous hemodiafiltration.


METHODS
Cardiovascular variables were computer acquired from bedside monitor. Pmsa was calculated and compared with a target value. Gravitational fluid replacement to the extracorporeal hemodiafiltration circuit was regulated with a computer-controlled clamp.


RESULTS
Ten patients (mean acute physiology and chronic health evaluation II score, 29.7; range, 21-33) received continuous venovenous hemodiafiltration for acute renal failure. Fluid replacement therapy was closed loop controlled to a target Pmsa for a total of 601 hours. During this period, 417 L of ultradiafiltrate were lost, and 409 L of replacement and nutritional fluids were administered. Despite such large fluid shifts, measured hemodynamic variables were kept within a narrow range (hour to hour variability: right atrial pressure, 1 +/- 0.1 mm Hg; mean arterial pressure 5.9 +/- 0.5 mm Hg; cardiac index, 0.44 +/- 0.05 L/m2/min). No complications of the technique occurred.


CONCLUSIONS
The stability of cardiovascular variables achieved during Pmsa-based fluid replacement of critically ill patients with major fluid losses supports the validity of the use of the Pmsa as a measure of intravascular volume status. Such an analogue may be useful in nondialytic environments. The use of Pmsa as the basis for automated fluid replacement was safe.
Parkin
G
G
Monash Medical Centre, Melbourne, Australia.
Wright
C
C
Bellomo
R
R
Boyce
N
N
D058186:Acute Kidney Injury / Q000503:physiopathology / Q000628:therapy*; D000328:Adult; D000368:Aged; D001810:Blood Volume; D016638:Critical Illness; D005260:Female; D005440:Fluid Therapy / Q000379:methods*; D017583:Hemodiafiltration / Q000379:methods*; D006439:Hemodynamics; D006801:Humans; D008297:Male; D008875:Middle Aged; D008991:Monitoring, Physiologic; D015203:Reproducibility of Results; D012815:Signal Processing, Computer-Assisted; D013813:Therapy, Computer-Assisted / Q000379:methods*