Blood pressure alarm system for dialysis machines

• US 4,148,314 A
• Filed: 10/18/1976
• Issued: 04/10/1979
• Est. Priority Date: 10/18/1976
• Status: Expired due to Term

• Current Assignee: Baxter Travenol Laboratories Incorporated (Baxter International Inc.)
• Original Assignee: Baxter Travenol Laboratories Incorporated (Baxter International Inc.)
• Inventors: Yin, Chieh-Kung
• Primary Examiner(s): Michell, Robert W.
• Assistant Examiner(s): Jaworski, Francis J.
• Application Number:
  US05/733,585
• Time in Patent Office: 904 Days
• Field of Search: 128/214 E, 128/214 F, 128/DIG. 1, 128/DIG. 3, 128/DIG. 12, 128/DIG. 13, 128/2.05 R, 128/2.05 A, 128/214 R, 128/214 B, 128/2.05 D, 23/258.5, 23/258.5 R, 210/22 A, 210/22 C, 210/22 D, 210/90, 210/321 A, 210/321 B, 210/22, 210/85, 210/321 R
• US Class Current: 604/6.11
• CPC Class Codes: A61M 1/16 with membranes
• CPC Class Codes: A61M 1/36 Other treatment of blood in a by-pass of the natural circulatory system, e.g. temperature adaptation, irradiation ; Extra-corporeal blood circuits
• CPC Class Codes: A61M 1/3607 Regulation parameters
• CPC Class Codes: A61M 1/3639 Blood pressure control, pressure transducers specially adapted therefor
• CPC Class Codes: A61M 2205/18 with alarm
• CPC Class Codes: A61M 2205/3331 Pressure; Flow
• CPC Class Codes: A61M 2205/3344 Measuring or controlling pressure at the body treatment site
• CPC Class Codes: A61M 2205/3351 Controlling upstream pump pressure
• CPC Class Codes: A61M 2205/3355 Controlling downstream pump pressure
• CPC Class Codes: A61M 2205/52 with memories providing a history of measured variating parameters of apparatus or patient
• CPC Class Codes: Y10S 128/13 Infusion monitoring

Abstract

There is disclosed herein a blood pressure alarm system for use in a dialysis machine whereby alarms may be activated, and a blood pump deactivated if the actual blood pressure increases above or decreases below predetermined levels. The levels are determined by setting a particular blood pressure point and setting the amount by which the pressure can vary above and below the set point; the range of variation is sometimes referred to as the alarm window. A digital memory is provided for storing the set point and preventing variation of the set point with time.

Claims

1. In a dialysis machine an alarm means operative in response to blood pressure changes to operate, said alarm means including in combination:

blood pressure sensing means operative to develop a pressure signal which varies in accordance with blood pressure;

memory means operative to receive said pressure signal, said memory means including storage means for storing said received pressure signal in digital form as a digital signal, and means coupled to said storage means operative in response to said stored digital signal to develop a memory signal;

pressure variation selection means operative to develop a variation signal representing blood pressure variation limits;

comparison means coupled to said sensing means, memory means and pressure variation selection means and operative in response to said pressure signal greater than said memory signal plus said variation signal to develop a first comparison signal and operative in response to said pressure signal less than said memory signal minus said variation signal to develop said first comparison signal; and

control circuit means coupled to said comparison means and operative in response to said first comparison signal to operate for providing an alarm, said means coupled to said storage means including digital to analog converter means coupled to said storage means and operative to receive said digital signal from said storage means and to develop an analog memory signal, said memory means further including second comparison means coupled to said digital to analog converter means for comparing said analog memory signal and said pressure signal and developing a second comparison signal in accordance with the difference therebetween, and logic circuit means coupled to said storage means and said second comparison means and operative in response to said second comparison signal to vary said digital signal, said logic means including an oscillator for developing clock signals, gate means selectively operative to couple said clock signals to said storage means, and bistable means coupled to said second comparison means and operative in response to a second comparison signal having a first value to develop a first bistable signal and a second comparison signal having a second value to develop a second bistable signal, said storage means including counter means for storing said digital signal, said counter means coupled to said gate means and bistable means and operative in response to selective operation of said gate means to count said clock signals and vary said stored digital signal, said counter means counting up in response to said first bistable signal and down in response to said second bistable signal.

2. The dialysis machine of claim 1, wherein said memory means is selectively operative to receive said pressure signal and store a digital signal corresponding to said pressure signal.

3. The dialysis machine of claim 1, wherein said memory means includes switch means for selectively actuating said memory means to store said digital signal.

4. The dialysis machine of claim 1, wherein said blood pressure sensing means includes a pressure transducer for developing a pressure signal which varies in accordance with blood pressure, calibration adjustment means coupled to said pressure transducer for adjusting a minimum and maximum pressure signal, meter means coupled to said calibration adjustment means and operative in response to said pressure signal to provide an output indicating of said blood pressure, and filter means coupled to said calibration adjusting means for filtering undesired signals from said pressure signal.

5. In a dialysis machine an alarm means operative in response to blood pressure changes to operate, said alarm means including in combination:

blood pressure sensing means operative to develop a pressure signal which varies in accordance with blood pressure;

memory means operative to receive said pressure signal, said memory means including storage means for storing said received pressure signal in digital form as a digital signal and means coupled to said storage means and operative in response to said stored digital signal to develop a memory signal;

pressure variation selection means operative to develop a variation signal representing blood pressure variation limits;

comparison means coupled to said sensing means, memory means and pressure variation selection means and operative in response to said pressure signal greater than said memory signal plus said variation signal to develop a first comparison signal and operative in response to said pressure signal less than said memory signal minus said variation signal to develop said first comparison signal;

said comparison means including, summing circuit means coupled to said pressure variation selection means for developing a first summing signal varying in accordance with said variation signal plus said pressure signal, and a second summing signal varying in accordance with said variation signal minus said pressure signal, and comparison circuitry coupled to said summing circuit means and said memory means and operative in response to a correlation between one of first and second summing signals and said memory signal to develop said first comparison signal, and

control circuit means coupled to said comparison means and operative in response to said first comparison signal to operate for providing an alarm.

6. The dialysis machine of claim 5, wherein said summing circuit means includes a first summing circuit for developing said first summing signal and a second summing circuit for developing said second summing signal, said comparison circuitry including a first comparator coupled to said first summing circuit and said memory means and operative in response to a correlation between said first summing signal and said memory signal to develop said first comparison signal, and a second comparator coupled to second summing circuit and said memory means and operative in response to a correlation between said second summing signal and said memory signal to develop said second comparison signal.

7. In a dialysis machine an alarm means operative in response to blood pressure changes to operate, said alarm means including in combination:

blood pressure sensing means operative to develop a pressure signal which varies in accordance with blood pressure;

memory means operative to receive said pressure signal, said memory means including storage means for storing said received pressure signal in digital form as a digital signal and means coupled to said storage means and operative in response to said stored digital signal to develop a memory signal;

pressure variation selection means operative to develop a variation signal representing blood pressure variation limits;

comparison means coupled to said sensing means, memory means and pressure variation selection means and operative in response to said pressure signal greater than said memory signal plus said variation signal to develop a first comparison signal and operative in response to said pressure signal less than said memory signal minus said variation signal to develop said first comparison signal;

said comparison means including, summing circuit means coupled to said pressure sensing means and said memory means for summing said blood pressure signal and memory signal to develop a summing signal, and comparison circuitry coupled to said summing means and to said pressure variation selection means and operative in response to a correlation between said variation signal and said summing signal to develop said first comparison signal, and

control circuit means coupled to said comparison means and operative in response to said first comparison signal to operate for providing an alarm.