Air emboli detection

• US 4,280,495 A
• Filed: 11/24/1978
• Issued: 07/28/1981
• Est. Priority Date: 11/24/1978
• Status: Expired due to Term

• Current Assignee: Minnesota Mining and Manufacturing Co (3M Company)
• Original Assignee: Sarns, Inc. (Terumo Corporation)
• Inventors: Lampert, Seymour R.
• Primary Examiner(s): Michell, Robert W.
• Assistant Examiner(s): Jaworski, Francis J.
• Application Number:
  US05/963,311
• Time in Patent Office: 977 Days
• Field of Search: 128/214 R, 128/214 C, 128/214 E, 128/214 F, 128/DIG. 3, 128/DIG. 13, 73/19, 73/194 E, 73/DIG. 11, 250/573, 356/39, 356/410-411, 137/177, 340/603, 340/608, 340/630, 340/632, 422/44-48, 210/85-86, 210/94
• US Class Current: 604/6.11
• CPC Class Codes: A61M 1/3626 Gas bubble detectors
• CPC Class Codes: A61M 2205/3313 used specific wavelengths

Abstract

Air emboli detection method and apparatus for use in cardiopulmonary bypass surgery or the like comprising modular sensor, control and power units. The sensor unit is adapted to releasably clamp a blood flow tubing or conduit in a vertical orientation below a blood deaerator, and includes an LED infrared source and a phototransistor detector. The control unit applies pulsed power to the light source only at preselected periodic intervals, and monitors for an output from the detector only at times corresponding to the preselected intervals to achieve an enhanced signal-to-noise ratio. The power unit includes a solid state relay responsive to detection of emboli for removing power from a blood pump or the like.

Claims

1. In apparatus for use in cardiopulmonary bypass surgery or the like and including a blood pump, means coupled to said pump for providing an extracorporeal blood flow path and sensor means disposed adjacent said path for detecting emboli in said path and coupled to said pump for deactivating said pump upon detection of any said emboli, said sensor means comprising a light source and light detection means disposed adjacent to said path and alarm means responsive to light incident upon said detection means from said source for indicating emboli in said path and deactivating said pump, the improvement wherein said sensor means further comprises electrical power supply means for energizing said source only at preselected periodic intervals with said source being otherwise de-energized and gate means electrically connected to said detection means, said power supply means and said alarm means for monitoring said detection means and enabling operation of said alarm means responsive to said detection means only at preselected times corresponding to said preselected periodic intervals.

2. The apparatus set forth in claim 1 wherein said supply means comprises an oscillator for energizing said source for durations of fifty microseconds at one millisecond intervals.

3. The apparatus set forth in claim 2 or 1 wherein said preselected periodic intervals comprise durations of source energization in the range of 50 to 70 microseconds at intervals in the range of 1 to 1.2 milliseconds.

4. In a process for controlling blood circulation during cardiopulmonary bypass surgery or the like comprising the steps of:

(a) pumping blood through an extracorporeal translucent blood path, (b) monitoring for an emboli in said path by positioning a source of infrared energy and an infrared detector on opposite sides of said blood path and detecting any said emboli as a function of energy incident upon said detector from said source, and (c) terminating pumping in said step (a) in response to any such detected emboli, a method of improving the signal-to-noise ratio at said detection means comprising the steps of;

(d) pulsing said source only at preselected periodic intervals and (e) monitoring for infrared energy at said detector indicative of air emboli in said extracorporeal path only at preselected times corresponding to said preselected periodic intervals.