Evaluation of a thoracic bioimpedance cardiac output monitor during cardiac catheterization.

OBJECTIVE: To evaluate the accuracy and precision of an advanced thoracic bioimpedance cardiac output monitor by comparing it with conventional thermodilution. DESIGN: Prospective data collected from 47 patients undergoing routine cardiac catheterization. The new bioimpedance system differs from its predecessors in electrode system configuration, advanced signal processing, use of a modified Kubicek equation, and a reliable estimate of left ventricular ejection time from the time derivative bioimpedance signals. SETTING: A cardiac catheterization laboratory in a university affiliated teaching hospital. PATIENTS: A series of 47 relatively homogenous patients undergoing routine cardiac catheterization for suspected cardiac disease. MEASUREMENTS AND MAIN RESULTS: The data from the first 20 patients was used to determine optimal values for coefficients in the bioimpedance cardiac output equations. The coefficients found were used when the system was tested in the subsequent 27 patients. For the last 27 patients, a total of 80 simultaneous pairs of cardiac output measurements were made by conventional thermodilution and by thoracic bioimpedance. The mean difference between the two methods was -0.31 L/min and the standard deviation of the differences was (0.76 L/min). The correlation coefficient was r2 = .72 (p < .001). CONCLUSIONS: The correlation between conventional thermodilution and thoracic bioimpedance cardiac output estimates was good and the standard deviation of the differences was lower than that reported for commercially available devices. The system can be used in the cardiac catheterization lab for reliable and continuous noninvasive measurement of cardiac output.

Evaluation of a new advanced thoracic bioimpedance device for estimation of cardiac output.

OBJECTIVE: This study is an evaluation of a new thoracic bioimpedance cardiac output monitoring system which incorporates a modified form of the Kubicek equation and a method of estimating the left ventricular ejection time from the time derivative bioimpedance signals. METHODS: The performance of the new system was compared with conventional thermodilution in a porcine model. One hundred and ninety nine (n = 199) paired measurements of thermodilution cardiac output (TDCO) (range 1.20-18.00 L/min) and thoracic bioimpedance cardiac output (BICO) were collected in 7 pigs. The bioimpedance measurements were adjusted for the animal's weight and chest circumference, thus compensating for the differences in the anatomy of pigs when compared to humans. Data were compared using weighted correlation coefficient and Bland-Altman analysis. RESULTS: The weighted correlation coefficient between TDCO and BICO values was 0.87 (n = 199). The Bland-Altman technique yielded a precision of the device of +/-1.69 L/min with a bias of 0.11 L/min. CONCLUSION: The results from the porcine study show that the new system performed well over a wide range of cardiac outputs, comparing favorably with data from other new bioimpedance cardiac output devices currently available in the market.

[Mechanism of action of electromagnetic fields biologically adequate to man]. / K voprosu o mekhanizme deistviia bioadekvatnykh cheloveku élektromagnitnykh polei.

The paper analyzes 10-year experience in making experimental observations and clinically using electromagnetic fields (EMF) biologically adequate to man. Basic investigations of the electromechanical process that lead to the occurrence of currents in the bone tissue and blood vascular walls in their functional deformation were conducted. They showed that the piezoelectric effect is the most marked in the intact bone tissue. Experimental studies determined the amplitude and shape of impulses of currents emerging in the intact bone tissue of the extremities and in the walls of blood vessels during pulse blood filling. The bioelectric tissue metabolism changes in various human locomotor abnormalities. The lost part in the diseased area can be restored by means of external EMF. On this basis, devices for human biologically adequate electromagnetic therapy were designed. The efficiency of each session of electromagnetic therapy was evaluated from the normalization of blood circulation in the diseased area. The efficiency of this therapy in vascular disease was noted to depend on the synchronization of the generated electromagnetic pulse with the pulse wave of a patient and its phases. An experiment on 13 intact mongrel dogs was made to reveal the impact of EMF biologically adequate to man on bone marrow hemopoiesis. EMF 2 was found to have a stimulating effect on granulocytopoiesis. Platelet counts were elevated in the peripheral blood of animals. Analysing 2000 clinical cases and canine experimental findings provided evidence for the following mechanism of action of the electromagnetic fields biologically adequate to man. The fields exert a primary initial and virtually rapid action on the active areas of nerve structures and smooth muscle of blood vascular walls. They show a primary, but slower action on blood cells and on the vascular endothelial structure. There may be a secondary impact of EMF on some endocrine glands, which causes changes in the protein metabolism of a biological object and appears as stimulation of granulocytopoiesis and depot platelet release into the peripheral blood stream.

[Non-contact, biologically adequate, electromagnetic stimulation of reparative regeneration of osseous, cartilagenous and muscular tissues in children]. / Beskontaktnaia bioadekvatnaia élektromagnitnaia stimuliatsiia reparativnoi regeneratsii kostnoi, khriashchevoi i myshechnoi tkanei u detei.

The authors analyse the results of using a Kaskad electromagnetic apparatus in 508 children with long-term ununited fractures, false joints, contractures, sluggish wounds, decubituses, trophical ulcers, osteochondropathies, Pertes' disease, and crush syndrome. The efficiency of the therapy was 75-90%, depending on the type of an abnormality. The authors had developed and put into practice a Kaskad-synchro electromagnetic apparatus synchronized with the pulse of a patient's arterial vessel. Such a high efficiency of the electromagnetic therapy bioadequate to man is likely to be explained by the exposure of electromagnetic waves directly to the areas of bone marrow hemopoiesis. To elucidate this, the authors made an experiment on dogs. The results of this experiment are being processed.