Patent ID: 6172743
Filing Date: 2001-01-09
Classification: A61B

Abstract:
A non-invasive pulsed infrared spectrophotometer for measuring the concentration of at least one predetermined constituent of a patient's blood, comprising:an infrared source which emits broadband pulses of infrared light including n different wavelengths, said pulses of infrared light containing energy at each of said n wavelengths being differentially absorbed by said at least one predetermined constituent whereby each predetermined constituent readily absorbs pulses of infrared light at one of said n wavelengths and minimally absorbs pulses of infrared light at another of said n wavelengths, and which directs said pulses of infrared light through an arterial blood vessel of the patient;at least one infrared detector which detects light at said n wavelengths which has passed through said arterial blood vessel of the patient and has been selectively absorbed by said at least one predetermined constituent and which outputs at least one detection signal;synchronizing means for synchronizing the application of said pulses of infrared light from said infrared source to said arterial blood vessel of the patient with the systolic and diastolic phases of cardiac cycle of the patient, said synchronizing means including a cardiac monitor and means responsive to an output of said cardiac monitor for modulating said pulses of infrared light so that said infrared light passes through said arterial blood vessel of the patient only during diastolic and systolic time intervals respectively occurring during the systolic and diastolic phases of said cardiac cycle of the patient; andmeans for determining the concentration of said at least one predetermined constituent of the patient's blood from said at least one detection signal.