Clinical autonomic research : official journal of the Clinical Autonomic Research Society
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Quantitative sensory testing (QST) is a subjective method of assessing thermal sensation, but it does not provide an objective measure of physiological changes. Our aim was to establish whether fluctuations in sudomotor autonomic activity correlate with warmth and heat pain (thermoalgesic) perception. ⋯ In all stimuli paradigms, the mean delay time of the SSR was 1.6 s after the warmth or pain sensation. There was an association between the low amplitude (predominantly negative) SSR and warm stimuli, and the large amplitude (predominantly positive) SSR and heat pain stimuli (chi-square; P < 0.05). Mean EDA was significantly higher during the pain phase in comparison with pre-perception, warmth and post-perception phases. INTEPRETATION: Thermoalgesic stimuli induce reflex changes in sudomotor activity that correlate with subjective perception of warmth and heat pain sensations. This association may be useful in clinical practice.
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We evaluated cardiac vagal activity during sevoflurane anesthesia in neurosurgical patients. Heart rate variability was determined by power spectral analysis and entropy with the patient awake and during sevoflurane anesthesia. High frequency power (0.15-0.50 Hz) and heart rate entropy decreased during sevoflurane and these effects were significantly correlated (r = 0.71 +/- 0.12, P < 0.05). The results confirm that cardiac vagal activity was the primary determinant of heart rate variability, which was attenuated by sevoflurane.
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Heart rate recovery (HRR) after exercise and spectral decomposition of heart rate variability (HRV), measures of autonomic nervous system function, are predictors of cardiovascular morbidity/mortality. QT interval, an index of ventricular depolarization and repolarization attained from surface ECG, is also associated with morbidity/mortality and is strongly influenced by autonomic tone. The purpose of this study was to assess the association between HRR after exercise, resting HRV and resting rate corrected QT interval in young healthy men. ⋯ There was no correlation between high frequency power of HRV (a marker of parasympathetic modulation) and QTc interval. There was a negative relationship between absolute LF power (a marker of both sympathetic and parasympathetic modulation) and QTc interval for Karjalainen, Framingham, and Bazett correction methods (r = -0.33 to -0.47, P < 0.05). Resting LF power of HRV and HRR after exercise are inversely associated with resting QTc interval in young healthy men, supporting a relationship between cardiac autonomic nervous system function and ventricular depolarization and repolarization.
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Placement in the Trendelenburg position has successfully reverted two patients with supraventricular tachycardia back into sinus rhythm. This technique may provide a safe, non-invasive method for terminating supraventricular tachycardias without the need for drugs.