Biomedical subjects

S S Reisman

Publications and source records attributed to S S Reisman.

7 recordsLinked to original sources

PubMed1999

A simple biofeedback digital data collection instrument to control ventilation during autonomic investigations.

Autonomic evaluation using the heart rate spectrum is sensitive to changes in breathing parameters, but few studies using this technique have controlled both the rate and depth of breathing. Fewer still have also measured or controlled inspiration and expiration times, or end-tidal carbon dioxide. This study describes the development of a digital instrument that can be used to alter tidal volume, ventilation rate and the time of inspiration and expiration with paced breathing visual templates displayed on a computer monitor. The digital instrument runs during data acquisition and displays the ventilatory signal from the subject superimposed on the paced breathing templates. Thus, adjustment of ventilatory parameters is achieved by matching the actual breathing signal to the target template. By regulating the ventilation rate and the tidal volume, end-tidal carbon dioxide could be increased or decreased in small increments. This instrument provided ventilatory control to investigate the effects on the heart rate spectrum of breathing depth, ventilation rate, end-tidal carbon dioxide and the time of expiration.

Biofeedback, Psychology↗

PubMed1998

Is spectral analysis of the surface electromyographic signal a clinically useful tool for evaluation of skeletal muscle fatigue?

Normal values for initial median frequency (IMF) of the electromyographic (EMG) power-density spectrum must be determined before EMG spectral analysis can be used to evaluate clinically muscle fatigue. This study attempts to establish normal values in four muscles. Thirty-one healthy subjects performed isometric contractions of the biceps brachii, triceps, deltoid, and tibialis anterior muscles at 50% maximum voluntary contraction. Linear regression analysis was used to compute the IMF and the slope of the median frequency as it decayed with fatigue over 45 seconds. The IMF of the tibialis anterior (mean +/- standard deviation, 116 +/- 20 Hz) was significantly higher (p < 0.001) than that of the biceps (90 +/- 18 Hz), triceps (85 +/- 18 Hz), and deltoid (87 +/- 15 Hz). The deltoid and tibialis anterior had the steepest slopes. The IMF of all muscles was greater in men than in women, but gender did not affect the slope. This study attempted to establish normal values for IMF and slope in specific muscles. However, the range of normal values is so broad that it may preclude the clinical use of spectral analysis to evaluate muscle fatigue.

Adult↗

PubMed1997

Respiration response curve analysis of heart rate variability.

A noninvasive study was conducted on intact awake humans to characterize the dynamic response of the heart to the vagus during slow-, comfortable-, and fast-paced respiration (8, 12, and 18 breaths/min), under both sitting and standing conditions. The respiration response curve (RRC) of respiration-associated vagal effects on the heart was estimated, and characteristics of entrainment and frequency dependence on respiration were demonstrated. It was shown that the degree of entrainment and magnitude of phase resetting decrease with increase of pacing rate from 8 to 18 breaths/min. Further, the RRC was examined by overlapping equivalent phase shifts in different respiration cycles. This examination of the RRC can help us not only to find the common pattern underlying the RRC during different respiration cycles but also to perceive its variation related to degree of entrainment.

Electrocardiography↗

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↗

PubMed1994

Pattern recognition and interpretation of electromyogram data from cat jaw muscle.

This study investigates the effect of emotional behavior on the masseteric muscle EMG response patterns. Two experimental protocols are utilized: (1) does not elicit emotional behavior (stick chewing) and (2) elicits emotional behavior (hypothalamic stimulation). The Karhunen-Loève transform is used to compute features which exactly represent the correlated patterns of mean-zero observations, with data compression and noise immunity. Using nonparametric tests, it is found that the populations of biting and hissing features are significantly different (p < 0.05), with increased statistical significance as the size of the training set is increased. No statistically significant difference is seen in a test of the two biting populations.

Animals↗

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↗