Abstract: A therapeutic system provides a clinician with an appropriate course of treatment for a patient whose cardiovascular system is operating outside the normal range of values for the left cardiac work index (LCWI) and the systemic vascular resistance index (SVRI). The left cardiac work index and the systemic vascular resistance index are calculated from the cardiac index (CI) and mean arterial blood pressure (MAP) and are displayed as relative values so that the clinician can readily determine which of the vascular parameters are outside the normal range. Preferably, the cardiac index and the other cardiac parameters are measured by an electrical bioimpedance monitor that provides continuous dynamic measurement of the parameters. The left cardiac work index and the systemic vascular resistance index are calculated by a personal computer that displays the calculated parameters in an easily discernible manner.

Abstract: An electrical bioimpedance measuring device is used to measure changes in the electrical resistance of a segment of the thorax of a human body caused by changes in the blood perfusion in that segment resulting from the pumping action of the heart. The electrical resistance of also changes as a result of respiration, and the respiratory-induced changes are typically much larger than the cardiac-induced changes and cause large changes in the voltages in the measuring equipment. In order to suppress the large voltage changes, a clamping circuit is included that is synchronized with the electrical activity of the heart. The clamping circuit is timed to clamp the voltages in the measuring equipment to a baseline reference voltage in the time preceding the beginning of mechanical systole. The voltage clamping is released during the mechanical systole of the heart so that the changes in the voltages (i.e., the bioimpedance changes) caused by the pumping action of the heart during mechanical systole can be measured.

Abstract: An array of electrical bioimpedance electrodes are provided on a hollow, flexible tube that is insertable into the esophagus of a patient. Four electrodes are positioned on the outer wall of the tube. Four wires are run through the hollow center portion of the tube and are connected through the wall of the tube to a respective one of the four electrodes. The four wires are connectable to an electrical bioimpedance measurement device. Two of the electrodes are connected to a high frequency, low magnitude constant current source so that a current can be injected into the thorax of the patient between the two electrodes. The other two electrodes are connected to the sensing input of the electrical bioimpedance measurement device and detect a voltage induced in the thorax of the patient that varies in accordance with the electrical bioimpedance changes in the patient.

Abstract: An apparatus and a method use noninvasive electrical bioimpedance measurments to monitor the mean arterial blood pressure of a patient on a continuous (heartbeat-by-heartbeat) basis. The apparatus and method process the electrical impedance across two segments of body tissue to provide a signal for each segment that indicates the increase in blood flow in each segment at the beginning of each cardiac cycle. The apparatus and method process the signals corresponding to each segment to measure the arterial pulse propagation delay between the two segments. The arterial pulse propagation delay is inversely related to the mean arterial blood pressure of the patient. The apparatus and method use the measured arterial pulse propagation delay to calculate the mean arterial blood pressure of the patient. The cardiac output of the patient is also advantageously measured and the cardiac index of the patient calculated from the cardiac output.

Abstract: An apparatus and method are disclosed for measuring and recording the arterial blood pressure waveform or a portion thereof in a patient by detecting the momentary increases in pressure in an occlusive cuff caused by the passage of blood through an artery beneath the cuff. The magnitudes and times at which the momentary pressure increases occur and disappear with respect to the R-wave in an electrocardiograph signal are recorded as the pneumatic pressure applied to the cuff is gradually increased or decreased. The sampled times and magnitudes are processed to accurately reproduce the arterial blood pressure waveform of the patient. The apparatus includes an improved pressure cuff having a separate occlusive bladder and a sensing bladder to increase the accuracy of the pressure measurements.