Biomedical subjects

S S Reisman

Publications and source records attributed to S S Reisman.

3 recordsLinked to original sources

PubMed1995

Influence of respiration on metabolic, hemodynamic, psychometric, and R-R interval power spectral parameters.

Because respiration modulates autonomic activity, we determined the magnitude of perturbation of changing breathing frequency and tidal volume on metabolic, hemodynamic, psychometric, and R-R interval power spectral parameters. Seated subjects breathed at three different rates and five different volumes with each of the different rates. Breathing rates and volumes were percentages of the subject's resting breathing pattern and, therefore, identical across all subjects. Increases in rate and volume resulted in significant perturbations in end-tidal CO2 production, CO2 production, ventilatory equivalent for O2, comfort levels, and R-R interval power spectra (P < 0.05). The magnitude of the perturbations in the above parameters indicated a substantial upset in all subjects' metabolic, hemodynamic, and comfort homeostasis, precipitating a significant loss of vagal tone. The implications of our findings are that imposed breathing patterns used to modulate autonomic outflow should be tailored to the individual's resting breathing pattern. These data further support the urgent need for concomitant metabolic and respiratory measurements when analyzing and interpreting heart rate variability data.

Adult↗

PubMed1989

Assessment of autonomic regulation of heart rate variability by the method of complex demodulation.

Complex demodulation was used to examine the effect of both divisions of the autonomic nervous system (sympathetic and parasympathetic) on heart rate. Data were analyzed from dogs during classical conditioning procedures which caused different changes in the autonomic regulation of heart rate. Two significant peaks in the heart rate variability spectrum were examined by this technique. The amplitude of the peak at the respiration frequency showed parasympathetic changes, while the amplitude of the low frequency peak (0-0.124 Hz) showed both sympathetic and parasympathetic effects. Complex demodulation results at these frequencies clearly showed the activities of both branches of the autonomic nervous system in regulating heart rate. During the CS+ period, when trained dogs were presented with a tone predicting a subsequent shock, the observed tachycardia was due to decreased parasympathetic activity and a transient increase in sympathetic activity. During the CS- period where a different tone predicts no shock, parasympathetic and sympathetic activities were unchanged from the baseline condition. The use of complex demodulation enables us to examine autonomic contributions to heart rate regulation in conditioning and a variety of other physiological and environmental conditions where autonomic input can be expected to change rapidly.

Animals↗

PubMed1985

Variable threshold R wave detector: use in automated ECG processing.

Reliable R wave detection is difficult under many commonly found conditions of varying baseline and changing morphology such as varying R wave amplitude and reduced R/T ratio. An instrument has been developed which overcomes many of these problems. The device employs a variable detection threshold which is based on the amplitude of the last occurring R wave. For large R wave amplitudes, the threshold is raised, thus providing good noise immunity. For low R wave amplitudes, the threshold is lowered, thus providing continued detection. An R wave filter de-emphasizes noise as well as P and T waves, and an adjustable refractory period following R wave detection prevents false detection during this period. The variable threshold R wave detector has been used to process ECG in a heart rate study in nearly 100 diabetic patients as well as in healthy controls. The detector provides much improved automatic R wave detection over fixed level detectors and can be constructed with parts costing under 100 dollars.

Animals↗