Patent GB-1492386-A (GB)
Title: Automated apparatus for monitoring of physiological parameters and control of fluid therapy including extracorporeal circulation of blood
IPC: A61M1/16
Filed: 1974-09-06
Abstract: 1492386 Treating blood in extracorporeal circuit E S LICHTENSTEIN 6 Sept 1974 [31 July 1974] 39035/74 Heading A5R [Also in Divisions B1 F2 G1 and G3]  Apparatus for treating blood extracorporeally comprises means for circulating the blood from the body through a treatment chamber, means for sensing and signalling operating conditions including pressure and rate of flow of blood through the apparatus and the cardiovascular state of the patient, controllers for controlling components of the apparatus in accordance with the desired operating conditions, a master controller into which preset limits for operating conditions corresponding to specific patients and specific treatments can be programmed, the master controller being operatively connected to the controllers for adjusting the components in accordance with selected relationships among the various operating conditions, the cardiovascular state of the patient and the state of the treatment in progress, and a fail-safe inductor for shutting down the apparatus in the event that any of the operating conditions deviates beyond selected limits. The apparatus comprises means for taking blood from the patient, a blood treatment chamber 13, a bubble-trap 11 and means for returning blood to the body, interconnected by ducts D 1 , D 2 , D 3 , D 4  a pump P 1  supplying blood from the body to the treatment chamber through a valve V 1  and a pressure sensing, measuring and signalling means PS 1 , means for periodically halting the flow of blood so that the pressure sensed by themeans PS 1  the patients' blood pressure the pump P 1  being controlled within preselected limits -in response to the means PS 1  by a first controller C 1 , a sensing means S 1  for sensing the cardiovascular state of the body in response to which a second controller C, which is capable of overriding the first controller C 1  closes the valve V 1  if the cardiovascular state of the patient deviates beyond the preselected limits, the first controller C 1  controlling a second pump P 2  for introducing anticoagulant from a reservoir 14 into the blood and the fail-safe monitor M controlling the controllers C 1  and C 2  in accordance with the preset limits. The pressure in the blood treatment chamber 13, which may provide for dialysis or oxygenation of the blood, is maintained within preset limits in response to the pressure in the chamber as sensed by a sensor PS 2 . Similarly the level of blood in the bubble trap 11 is maintained by the addition of saline and the adjustment of a valve V 4  in the duct D 4  by a fourth controller C 4  in response to a signal from a level sensor LS 1 . Gas is vented from the bubble trap through a valve V 5  by the action of a controller C 5  in response to a gas pressure sensor PS 5  within the bubble trap. The controllers C 1 -C 4  are associated with a master controller MC which may provide a preselected programme of operating conditions and to the fail-safe monitor M which may operate an alarm on shutting down the apparatus. The treatment chamber 13 may include a semipermeable membrane for permitting removal of solutes and water by dialysis; the pumps P 1  and (P 3 ) Figure 2 (not shown) determining the rates of flow of blood and dialysate respectively, and being controlled in accordance with the selected operating conditions, the fail-safe monitor M shutting down the system if the temperature, sensed by a sensor (TS 1 ), or conductivity of the dialysate, measured by a device (CM) deviates outside preselected limits or if a detector (Hb) indicates a leakage of blood into the dialysate. The dialysate may be premixed or mixed in the apparatus and may include water separated from used dialysate by a reverse osmosis canister 23 and recirculated. The blood and dialysate circulating pumps P 1 , P 3 , P 4  and the pump P 2  for adding anticoagulant may be synchronised, each pump comprising flexible tubing sequentially compressed by moving fingers or rollers driven by a single motor, the flow rate ratios being determined by the sizes of the tubing. An integrator I associated with flow rate measuring devices FR 1  and FR 2  enables the volume of water removed from the blood to be determined. Conduits of the apparatus are flexible and may be formed from plastics sheets sealed together in an appropriate pattern. Valves in the apparatus may each comprise two flexible tubes (131, 132) Figures 7 and 8 (not shown) laid in cross channels defined between blocks (133, 134) so that pressurisation of one tube (131) closes the other tube (132).