Abstract: A feedback control system is disclosed 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 (68), controllable drivers (44) for the light sources (40, 42), and the microcomputer (16).

Abstract: The present invention discloses a method and apparatus for indicating perfusion and oxygen saturation trends in oximetry. In transmittance and reflectance oximetry, LEDs (40, 42) are typically employed to expose tissue to light at two different wavelengths. The light transmitted through, or reflected by, the tissue is received by a detector (38) where signals proportional to the intensity of light are produced. These signals are then processed by oximeter circuitry (14, 16) to determine oxygen saturation, pulse rate, and perfusion. Displays (20) are provided including a display (132, 134) of the change in the oxygen saturation during a specified interval. This display may include first (132) and second (134) trend indication displays that indicate when the oxygen saturation has either been increasing or decreasing at a rate in excess of some predetermined level. Preferably, these displays are triangular, upwardly and downwardly directed light-emitting diodes.

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. V.sub.

Abstract: A feedback control system is disclosed 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 (68), controllable drivers (44) for the light sources (40,42), and the microcomputer (16).

Abstract: The present invention relates to the processing of signals containing information about the pulse rate and oxygen saturation of arterial blood flowing in tissue. These signals have a relatively periodic pulsatile component superimposed upon a varying baseline component. To determine the pulse rate and oxygen saturation from the signals, the positive peaks, negative peaks, and period of the signal must be determined. The present invention accomplishes this by first searching for a sustained positive sloping region of the signal. Then the first derivative of the signal with respect to time is analyzed and points on the signal before and after the occurrence of a slope reversal marked. If the slope at the first point is positive, the interval between the two points is searched for a maximum amplitude that is identified as a positive peak. After the occurrence of a negative sloping region of the signal, another pair of points are marked occurring before and after a subsequent slope reversal.

Abstract: An electrode (10) adapted for external heart stimulation, and a connector (52) therefor. The electrode includes a first conductive member (14) having a sheet-like configuration and an area resistivity of at least 0.003 ohm-cm.sup.2, and a second conductive member (16) having a sheet-like configuration, and having one surface in contact with the first conductive member and a second surface adapted to engage the patient's skin. Current is introduced at a centrally located portion of the first conductive member. The second conductive member has an area resistivity greater than the area resistivity of the first conductive member, such that the first conductive member acts as a distributor to distribute current density over the area of the electrode.

Abstract: A medical instrument such as a defibrillator that includes first and second hand-held electrodes for applying an electric shock to a patient, wherein the two electrodes are respectively adapted for right and left-handed use. Each electrode comprises an elongated member (62) adapted for gripping by the fingers of an operator's hand, an actuator (26) positioned adjacent one end of the elongated member, and blocking means (52) positioned adjacent one side of the elongated member. The blocking means is adapted to hinder an operator from gripping the elongated member with one of the operator's hands while simultaneously positioning the thumb of that hand adjacent the actuator. The electrode is therefore adapted for either left-handed or right-handed use. The blocking means may comprise one sidewall (52) of a cup-shaped depression (50), and the elongated member may comprise a handle (62) spanning the cup-shaped depression in a direction parallel to the sidewall.

Abstract: A connector for establishing electrical connection between a conductor and a patient engaging electrode that includes a conductive post extending from the electrode. The post has a proximal portion, a distal portion, and an intermediate portion having a diameter smaller than the diameter of the distal portion. The connector comprises insulation means shaped to form a socket open at one end, a pair of first spring members, a pair of second spring members, and means for electrically connecting the conductor to the second spring members. The first spring members are laterally positioned with respect to one another in the socket, and the second spring members are laterally positioned with respect to one another in the socket closer to said one end than the first spring members.

Abstract: An apparatus for connecting first and second physiological instrument components. The first component has an exterior first surface, and the second component has an exterior second surface. The apparatus comprises means forming a plurality of mutually parallel blades extending outward at the first surface at an acute angle with respect to a direction normal to the first surface, and means forming a plurality of mutually parallel slots extending inwardly at the second surface at the acute angle with respect to a direction normal to the second surface. The slots are sized and spaced to receive the blades to thereby connect the components. Latch means are provided for selectively latching one of the blades in its corresponding slot, and for preventing unlatching of the components when only one of the components is supported. In a preferred embodiment, the acute angle is approximately 75.degree..

Abstract: A physiological instrument that includes a first component comprising an ECG monitor and a second component comprising a defibrillator. The second component may also include a pacemaker mounted to and electrically connected with the defibrillator. The first and second components may communicate with one another entirely by means of three optical communication channels, each channel including an optical signal path that includes windows through which the optical signals pass into and out of the components. The components may therefore operate in a fully integrated manner despite the fact that no electrical signal path exists between the components.