公开(公告)号：WO1992018196A1

公开(公告)日：1992-10-29

申请号：PCT/US1992002993

申请日：1992-04-10

Applicant: PHYSIO-CONTROL CORPORATION

Inventor： PHYSIO-CONTROL CORPORATION ,  MORGAN, Carlton, B. ,  YERKOVICH, Daniel ,  MAIER, Donald, C.

IPC: A61N01/00

CPC classification number: A61N1/39 ,  A61N1/3906 ,  A61N1/3912 ,  G01K1/18

Abstract: Circuits for controlling the current flow of an energy pulse as a function of the temperature of a resistive element (10) in the circuit so that the current flow varies over time in accordance with a predetermined waveform. The circuits include at least one negative temperature coefficient thermistor (10) connected between an energy storage device (6) and connectors for delivering energy stored in the storage source (6) to an external load (12). Heat sinks (50) may be attached to the thermistor (10) for cooling the latter so as to increase the rate at which energy pulses may be delivered by the circuits.

公开(公告)号：WO1988001148A1

公开(公告)日：1988-02-25

申请号：PCT/US1987002018

申请日：1987-08-17

Applicant: PHYSIO-CONTROL CORPORATION

Inventor： PHYSIO-CONTROL CORPORATION ,  PROSSER, Stephen, J. ,  SMITH, Robert, E.

IPC: A61B05/00

CPC classification number: A61B5/14551

Abstract: The disclosed invention is for use in extracting more accurate information from signals employed in pulse oximetry. Basically, pulse oximetry involves the illumination of arterial blood flowing in tissue with light at two wavelengths. Upon emerging from the tissue the light is received by a detector (38) that produces signals that are proportional to the intensity of the light received at each of the wavelengths. Each signal includes a slowly varying baseline component representing the attenuation beta(t) of light produced by bone, tissue, skin, and hair. The signals also include pulsatile components representing the attenuation alpha(t) produced by the changing blood volume and oxygen saturation within the finger. The signals produced by the detector (38) are converted by an analog-to-digital (A/D) converter (72) for subsequent analysis by a microcomputer (16). The microcomputer (16) extracts the following information from the signal corresponding to each wavelength. VH is determined to be the signal magnitude at a second pulse diastole. VL is, similarly, the signal magnitude at systole of the same pulse. A term DELTAV is identified equal in value to the difference in signal magnitudes at the adjacent systoles. Finally, values are determined for DELTAts and DELTAtp, being the interval between an adjacent systole and diastole and the pulse period, respectively. The microcomputer (16) then determines a value for ROS in accordance with the relationship (I). Empirically derived oxygen saturation curves are used to develop an indication of the oxygen saturation from the value of ROS computed.

公开(公告)号：WO1988001147A1

公开(公告)日：1988-02-25

申请号：PCT/US1987002016

申请日：1987-08-17

Applicant: PHYSIO-CONTROL CORPORATION

Inventor： PHYSIO-CONTROL CORPORATION ,  CHEUNG, Peter, Wing-Poon ,  GAUGLITZ, Karl, F. ,  MASON, Lee, R. ,  PROSSER, Stephen ,  SMITH, Robert, E. ,  WAGNER, Darrell, O. ,  HUNSAKER, Scott, W.

IPC: A61B05/00

CPC classification number: A61B5/14551

Abstract: A feedback control system for use in processing signals employed in pulse transmittance oximetry. The signals are produced in response to light transmitted through, for example, a finger at two different wavelengths. Each signal includes a slowly varying baseline component representing the relatively fixed attenuation of light produced by bone, tissue, skin, and hair. The signals also include pulsatile components representing the attenuation produced by the changing blood volume and oxygen saturation within the finger. The signals are processed by the feedback control system before being converted by an analog-to-digital (A/D) converter (72) for subsequent analysis by a microcomputer (16). The feedback control system includes a controllable offset subtractor (66), a programmable gain amplifier (168), controllable drivers (44) for the light sources (40, 42), and the microcomputer (16). The microcomputer (16) receives signals from the offset subtractor (66), gain amplifier (68), drivers (44) and A/D converter (72) to produce signals that control the function of the subtractor (66) and drivers (44) in the following manner. Normally, the drivers (44) are maintained within a predetermined current range. In the event the microcomputer (16) senses an output from the converter (72) that is not within a predetermined range, the drive signal is adjusted to produce an acceptable signal. The magnitude of the offset removed by the subtractor (66), as controlled by the microcomputer (16), is maintained at a constant level when the converter (72) output is within a first predetermined range and is a predetermined function of the converter (72) output when that output falls within a second predetermined range.