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Biomedical subjects

R Lahoda

Publications and source records attributed to R Lahoda.

12 recordsLinked to original sources
PubMed1991

A beat-by-beat analysis of electrocardiograms from cardiac transplant recipients.

A software system is described for producing a beat-by-beat analysis of the electrocardiograms from patients after heart transplantation. Pacemaker spikes are automatically detected and eliminated from the signals. R waves are located by a robust and accurate two-step algorithm. Based on the variable length of single heart beats, the Fourier coefficients of three orthogonal surface leads and of two intracardiac leads are calculated beat-by-beat. Power spectra are then obtained by combining contributions from the variable fundamental frequency and its multiples (harmonics) into fixed frequency classes of 1 Hz width and averaging over 60-120 cardiac cycles. Additionally, averaged beat-by-beat power spectra are calculated for windowed QRS complexes and T waves. As by-products, single beat quantities, such as R-R and R-T intervals, averaged signals for all leads, and the orientational autocorrelation function of the electrical vector of the heart, are obtained. Following beat-by-beat evaluation, mean values and standard deviations are obtained for all quantities.

Algorithms↗
PubMed1977

[Maximum exercise testing during hypobaria and normoxia (author's transl)].

The effects of high altitude (3000 m, low-pressure chamber) on maximum exercise and maximum oxygen uptake were studied in four normal subjects. In order to separate the effects of hypobaria and of hypoxia, exercise testing was performed under normoxic, hypobaric conditions and compared with the results under normoxic, normobaric conditions. There was no significant difference in performance, nor in the effects of exercise on the measured cardiovascular parameters.

Adult↗
PubMed1976

[Evaluation of an experimental method for testing analgesic drugs by electrical stimulation of the skin (author's transl)].

The pain threshold and pain tolerance were determined by electrical stimulation of the skin employing a newly-developed apparatus. The efficacy of the method was evaluated in a double-blind cross-over study on ten healthy subjects with administration of 50 mg pentazocine plus 500 mg acetylsalicylic acid (P + A) orally in comparison with a placebo. The sensitivity of this method in determining the pain threshold was compared with a fixed intensity-variable time modification of the radiant heat method. The presence of sedative side effects of the drugs was tested by measurement of the reaction time to visual stimuli. All measurements were performed before and then 60 and 90 minutes after drug administration and an analysis of variance was carried out on the data. There was a significant elevation of both the pain threshold and pain tolerance as determined electrically after the administration of P + A as compared with the placebo experiments. A similar tendency was obtained with the thermal method, but the increase in pain threshold was not statistically significant. No significant changes were found in optical reaction time. It may be concluded that the apparatus developed by us appears to be a valuable tool in the evaluation of effectiveness of analgesic drugs.

Adult↗
PubMed1975

Effect of acupuncture of pain threshold and pain tolerance determined by electrical stimulation of the skin: a controlled study.

The effect of needling traditional acupuncture loci (Ho-Ku, LI4; Nei-Kuan, EH-6) compared to arbitarily chosen points was measured in twelve healthy subjects. In a crossover blind study pain tolerance and pain threshold were measured by electrical stimulation of the skin in the thyroid area. Traditional acupuncture was found to be significantly more effective in elevating pain threshold than needling of arbitarily chosen points. Pain tolerance also rose more under "real" acupuncture, the difference, however, being statistically not significant. In one subject, threshold and tolerance increased more under needling of nonacupuncture loci, while two subjects did not show any changes under either procedure.

Acupuncture Therapy↗