Continuous peritoneal dialysis apparatus

#The invention relates to a dialysis process for purifying the blood by exchange across the peritoneal membrane during a continuous peritoneal process.

#Heretofore, artificial kidney users have relied basically on two processes for purifying the blood. Hemodialysis involves the circulation of blood through a dialysis machine in which an exchange of toxic metabolites takes place across an artificial membrane outside the patient's body. This process requires the assistance of trained personnel and subjects the patient to dangers of mechanical malfunction, and rapid shifts of fluid and metabolites, and surgery involving blood vessels, is involved.

#Peritoneal dialysis involves the installation of a sterile dialysate into the peritoneal cavity. The dialysate is discarded after absorbing waste metabolites. The process is repeated until the blood level of metabolites is reduced to a desired level. This method is commonly referred to as the "Batch" method due to the fact that numerous one or two liter bottles or bags of fresh dialysate solution are utilized, requiring multiple connections to be made to the catheter inserted in the peritoneal cavity. The multiple connections made during the course of the dialysis have been thought to be a major cause of the high instance of peritonitis.

#The construction designed to carry out the invention will hereinafter be described, together with other features thereof. The invention will be more readily understood from a reading of the following specification and by reference to the accompanying drawings forming a part thereof, wherein an example of the invention is shown and wherein:

#FIG. 1 is a schematic diagram of a peritoneal dialysis system and process according to the invention;

#FIG. 2 is a graph illustrating a ready cycle of a sterilization process for a dialysis process according to the invention;

#Referring now in more detail to the drawings, an illustrative embodiment of the invention will now be described. There is a reverse osmosis (RO) unit A to which water is delivered through an input filter 10 which may consist of a carbon element to remove chlorine and chloramines followed by a particle filter. A suit RO unit is manufactured by Servall Corporation of Anderson, S.C., as model 2114B. There is a main water valve 12 which is always on except in the recirculating sterilize mode. Next comes a manual pressure regulator 14 which essentially sets the product water pressure. A conductivity/temperature (C/T) probe 16 measures the incoming water conductivity and temperature and signals the electronics of RO unit A. The word "conductivity" is common in water treatment systems, and the term "TDS" as used herein stands for total dissolved solids. Pump 18 is the main RO water pump and supplies the flow and pressure to drive water across a RO membrane 20 of RO unit A. After passing through an inlet side of the RO membrane case 22 the water flow normally enters a second manual pressure regulator 24, monitored by a pressure gauge 26 which sets the membrane inlet pressure in the range of 150 to 175 psi. This is followed by a manually adjusted fluid restrictor 28 (and check valve) which adjusts the amount of water recirculating in the loop back to the connection point of probe 16. The waste water then flows down a drain 30. A valve 32 is actuated momentarily by a computer C at the beginning of a READY/RINSE cycle to allow a high flow of water through to flush inlet side 22 of membrane 20. The pressure in the output product water is monitored by a gauge 34. Note that an outlet side 36 of the membrane housing includes a formaldehyde inlet 38 where formaldehyde is introduced during a STERILIZATION. A probe 40 measures the conductivity and temperature of the product water and signals the RO electronics. The RO electronics watch both the ratio of the incoming and product water conductivity (% rejection) and the output conductivity and communicate with the computer. Both the output conductivity and the % rejections have alarm limits set by the RO electronics which signal the computer. There is a loop back from a point prior to probe 40 through two check valves which essentially diverts flow back to the connection point at probe 16 to regulate the product water pressure.

#The sterile product water at 41 passes into a dialysis production unit (DPU) module B. Production unit B includes a manually set pressure regulator 42 which controls the flow rate through a check valve to a volumetric proportioning pump 44. Pump 44 precisely proportions a concentrate 46 through a valve 48 and water through 42 to make dialysate. It also proportions bleach 50 at the start of a STERILIZE/BLEACH cycle. The output of pump 44 passes through a manually set fluidic restrictor to the heat exchanger input. The proportioning pump 44 may be in the range of a 34:1 to 20:1 to allow use of available peritoneal dialysis concentrate formulations. After passing through an inlet side 52 of a heat exchanger 54, the dialysate is heated by a heater means 56, controlled by thermistor 58 and the computer, to a temperature of 70.degree. to 80.degree. C. and monitored by thermistor 60 and the computer. A storage means in the form of a small reservoir 62 following thermistor 60 serves two purposes, holding the fluid at that temperature for a short time to provide backup sterilization, and providing a point for air removal. In summary, heater 56 serves the dual purpose of backup sterilization and air removal. The dialysate then flows back through an opposite side 64 of heat exchanger 54 in a counterflow direction and is cooled below a heater 66 temperature set point. Heater 66 heats the dialysate to the proper patient temperature and is controlled by thermistor 68 and the computer. C/T probe 70 monitors both the temperature and conductivity of the dialysate. The computer receives the output of probe 70 and by controlling a valve 72 allows flow into a reservoir 74 only when both conductivity and temperature are within preset alarm limits. Otherwise the dialysate is diverted to drain.

#The amount of fluid in reservoir 74 is precisely measured by first weighing means which includes a load cell 76 which generates a first weight signal 76a input to computer C. When the amount of fluid in reservoir 74 is correct and the cycle time is correct, the computer opens an inflow delivery means, in the form of a reservoir valve 78, to allow fluid to enter (FILL) the peritoneal cavity 81 of a patient through a flowmeter 80. Flowmeter 80 provides an inflow monitoring means which monitors a function of fluid inflow, i.e. flow rate, accumulation, etc., to measure the amount of fluid delivered into the peritoneal cavity, and generate an inflow signal 80a. The pulse output of flowmeter 80 may be totaled by computer C as a monitor or backup to the measurement by the load cell/computer system. An optional filter, such as a suitable micro pore filter, may be employed in the flow path at 83 to sterilize the dialysis fluid in the event a sterilized source is not used. After an optional dwell time (DWELL) the fluid is drained (DRAIN) by an outflow delivery means having a valve 84 opened by computer C. Note that the "A" port of valve 84 is connected to a manual sampling valve which is used to check the formaldehyde residual concentration. The drain fluid (which includes any ultrafiltrate) then passes through a flowmeter 86 which acts in a manner similar to flowmeter 80 as a backup/monitor to the fluid measurement of a load cell 88. Flowmeter 86 provides an outflow monitoring means for monitoring the outflow of fluid from the peritoneal cavity and generates an outflow signal 86a representing the amount of fluid drained which is transmitted to the computer. Flowmeters 80 and 86 may be any suitable sterilizable digital flowmeter such as an Opflowmeter manufactured by Headland Company of Racine, Wis.