Abstract: An apparatus is provided for detecting each of the five known anesthetic agents, CO2, and N2O when monitoring a patient's respiratory gas stream during anesthesia. A source of infrared radiation emits the infrared tight through a gas stream and onto the infrared detector/sensor. The detector may contain ten analytical channels, each channel containing an independent infrared detector and a specific bandpass infrared filter which only permits certain wavelengths of the infrared radiation to reach the respective infrared detector. One of the channels is a blocked detector which serves as the reference point. A calibration and processing means is also provided to compensate for factors such as offset voltage, cross coupling, wideband changes and thermal drifts which may affect the accuracy of the gas measurements.

Abstract: A method for improving the quality of electrocardiogram (ECG) signals for input to a cardiac monitor and obtained from a patient undergoing magnetic resonance imaging (MRI) wherein the ECG leads attached to the patient are exposed to rapidly changing magnetic fields produced by the MRI which induce relatively high levels of rapid voltage changes in the ECG leads, the method including the steps of conducting the ECG signals having MRI induced noise signals superimposed thereon to the input of a slew rate limiter (SRL) circuit having a preselected maximum slew rate, the circuit providing an output signal having a maximum dv/dt which is slightly greater than the maximum typical ECG dv/dt, connecting the output of the SRL circuit to the input of a low pass filter circuit having an attenuation above the ECG typical fundamental frequency and connecting the output of the low pass filter circuit to a cardiac monitor.

Abstract: A method and device are disclosed for the detection of the relative percentage of at least one light absorber in the blood stream of living tissue. The method and device are based upon the employment of a narrow band width amplifier and pulses of different wavelength light sources wherein the frequency of the pulses of the light sources are selected so that a large component of the signal falls within the frequency of the narrow band amplifier, so that there is reduced likelyhood of interference from extraneous electromagnetic waves.

Abstract: An instrument housing having an improved means for storing a roll of paper of selected width and maximum diameter for use by a printer in which the housing has a rectangular opening in the top adjacent the housing front and a rectangular opening in the front forward of and below the opening in the top. A paper trough is positioned within the instrument housing below the top opening and rearwardly of the front opening, the trough having an open top and having opposed parallel sides and a rearward wall and a bottom wall which merge into a quarter circular integral intersection, the radius of curvature of the intersection being about one-half of the maximum diameter of the paper roll for which the trough is dimensioned.