×

Peritoneal dialysis systems and methods employing pneumatic pressure and temperature-corrected liquid volume measurements

  • US 5,474,683 A
  • Filed: 03/03/1993
  • Issued: 12/12/1995
  • Est. Priority Date: 03/03/1993
  • Status: Expired due to Term
First Claim
Patent Images

1. A method for performing peritoneal dialysis comprising the steps ofestablishing flow communication with a patient'"'"'s peritoneal cavity through a pumping mechanism that comprises a pump chamber and a diaphragm, andemulating a selected gravity flow condition by applying pneumatic pressure to the diaphragm through an actuator to operate the pump chamber to draw dialysis liquid into the pump chamber and to expel dialysis liquid from the pump chamber to either move dialysis liquid from the peritoneal cavity or move dialysis liquid into the peritoneal cavity, andderiving a measurement of liquid volume pumped through the pump chamber by deriving an initial air volume measurement Vi, after operating the actuator to draw liquid into the pumping chamber;

  • deriving a final air volume measurement Vf after operating the actuator to expel liquid from the pumping chamber; and

    deriving the liquid volume delivered (Vd) by the pumping chamber as follows;

    
    
    space="preserve" listing-type="equation">V.sub.d =V.sub.f -V.sub.i, andwherein Vi and Vf are derived by controlling communication between a reference chamber having a known air volume Vs and the actuator by;

    (i) applying a temperature correction factor (Ft) to the known volume of the reference chamber Vs to derive a temperature-corrected reference air volume Vst, as follows;

    
    
    space="preserve" listing-type="equation">V.sub.st =F.sub.t * V.sub.s(ii) when liquid is either drawn into or expelled from the pump chamber, closing communication between reference chamber and the actuator to initialize the reference chamber to a measured initial air pressure (Ps1) while applying a measured pressure to the actuator (Pd);

    (iii) opening communication between the reference chamber and the actuator to allow pressure equilibration at a measured new air pressure in the actuator (Pd2) and a measured new air pressure in the reference chamber (Ps2), and (iv) deriving the air volume measurement Vi or Vf as follows;

    ##EQU11##

View all claims
  • 1 Assignment
Timeline View
Assignment View
    ×
    ×