Changes of heart rate and blood pressure in registration of forced respiration flow-volume loop.

Changes in heart rate (HR) and finger mean blood pressure (MBP) during registration of the flow-volume loop of forced respiration in healthy young subjects were studied. Breathing patterns of performing the flow-volume loop of forced respiration (forced respiratory manoeuvre, FRM) as well as the related responses of cardiovascular parameters in different subjects were found to vary to a large extent. FRM has a remarkable influence on the cardiovascular system: during FRM the peak values of MBP were 19 +/- 9 mmHg higher than baseline values and the peak values of HR were 30 +/- 11 beats min-1 higher. We conclude that it is essential to pay attention to a remarkable elevation of blood pressure in functional breathing tests in patients with high blood pressure.     

Disorders of external respiration and oxygen transport and utilization in stress

A specific hypoxic condition characterized by a combination of signs of hypoxic, circulatory, and primary tissue hypoxia develops in rats after 6-hour immobilization stress. Post-stress hypoxia is accompanied with accumulation of lactate, decompensated metabolic acidosis, and activation of lipid peroxidation processes in the blood and tissues. Besides, a complex of changes of external respiration, its regulation and biomechanics, inhibition of pulmonary gas exchange is encountered after the stress, which is linked with the development of specific stress damage to the lungs which can be characterized as the stress lung syndrome.     

An improved algorithm for respiration signal extraction from electrocardiogram measured by conductive textile electrodes using instantaneous frequency estimation

In this paper, an improved algorithm for the extraction of respiration signal from the electrocardiogram (ECG) in home healthcare is proposed. The whole system consists of two-lead electrocardiogram acquisition using conductive textile electrodes located in bed, baseline fluctuation elimination, R-wave detection, adjustment of sudden change in R-wave area using moving average, and optimal lead selection. In order to solve the problems of previous algorithms for the ECG-derived respiration (EDR) signal acquisition, we are proposing a method for the optimal lead selection. An optimal EDR signal among the three EDR signals derived from each lead (and arctangent of their ratio) is selected by estimating the instantaneous frequency using the Hilbert transform, and then choosing the signal with minimum variation of the instantaneous frequency. The proposed algorithm was tested on 15 male subjects, and we obtained satisfactory respiration signals that showed high correlation (r ² > 0.8) with the signal acquired from the chest-belt respiration sensor.     

An electrochemical method for determination of cell respiration

The respiration of microorganisms was determined with a sensor composed of microorganisms and an oxygen electrode. The microorganisms (suspensions of about 100 microliters) are sedimented by centrifugation in a special tube on a very thin paper layer (diameter 4 mm). This paper layer is sandwiched between a polyethylene membrane and a dialysis membrane. A linear relationship is obtained between the current and the cell mass of Bacillus subtilis (between 0.05-0.35 mg dry weight per electrode preparation). When an assimilable substrate is added to the measuring solution the respiration rate is increased. It is possible to determine very fast changes in the respiration rates (1-5 sec). The application of this electrode system for investigations of the physiological state of cells during the growth cyclus is demonstrated.