Clinical physiology and functional imaging
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Clin Physiol Funct Imaging · Mar 2011
Randomized Controlled TrialThe effects of clonidine on arterial baroreflex sensitivity and cardiopulmonary baroreflex control of sympathetic nerve activity in patients with left ventricular dysfunction.
Clonidine is a potent sympatholytic drug with central neural effects. The aim of this study was to evaluate the effects of clonidine on arterial baroreflex sensitivity (BRS) and cardiopulmonary (CP) baroreflex control of muscle sympathetic nerve activity (MSNA) in patients with left ventricular (LV) dysfunction. ⋯ Clonidine enhanced BRS and CP baroreflex control of MSNA while reducing baseline sympathetic activity in patients with LV dysfunction.
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Clin Physiol Funct Imaging · Nov 2010
Randomized Controlled TrialThe influence of a fast ramp rate on peak cardiopulmonary parameters during arm crank ergometry.
The influence of a very fast ramp rate on cardiopulmonary variables at ventilatory threshold and peak exercise during a maximal arm crank exercise test has not been extensively studied. Considering that short arm crank tests could be sufficient to achieve maximal oxygen consumption (VO₂), it would be of practical interest to explore this possibility. Thus, this study aimed to analyse the influence of a fast ramp rate (20 W min⁻¹) on the cardiopulmonary responses of healthy individuals during a maximal arm crank ergometry test. ⋯ There was no other difference in ventilatory threshold and peak exercise variables when 1st and 2nd fast protocols were compared. Fast protocol seems to be useful when healthy young individuals perform arm cardiopulmonary exercise test. The usefulness of this protocol in other populations remains to be evaluated.
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Clin Physiol Funct Imaging · Jul 2010
Randomized Controlled Trial Comparative StudyA comparison of transcutaneous electrical nerve stimulation (TENS) at 3 and 80 pulses per second on cold-pressor pain in healthy human participants.
Electrophysiological studies suggest that there are differential frequency effects during TENS. The aim of this experimental study was to assess the effects of strong non-painful TENS administered at 3 pulses per second (pps) and 80 pps on cold-pressor pain in healthy human participants. A repeated measure design was used with participants receiving TENS at 3 pps and 80 pps in the same experiment. ⋯ The differences after 15 min of TENS were 1.70 s to 3.70 s (95% CI) for threshold and 6.63-15.5 mm (95% CI) for pain intensity. In conclusion, strong non-painful TENS at 3 pps was superior to 80 pps at reducing experimentally induced cold-pressor pain. The implications of these findings are discussed.
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Clin Physiol Funct Imaging · Nov 2009
Randomized Controlled TrialRespiratory muscle strength and muscle endurance are not affected by acute metabolic acidemia.
Respiratory muscle fatigue in asthma and chronic obstructive lung disease (COPD) contributes to respiratory failure with hypercapnia, and subsequent respiratory acidosis. Therapeutic induction of acute metabolic acidosis further increases the respiratory drive and, therefore, may diminish ventilatory failure and hypercapnia. On the other hand, it is known that acute metabolic acidosis can also negatively affect (respiratory) muscle function and, therefore, could lead to a deterioration of respiratory failure. ⋯ Metabolic acidemia significantly decreased airway resistance in asthma and COPD patients, as well as in healthy subjects. Moreover, acute metabolic acidemia slightly improved blood gas values in COPD patients. The results suggest that stimulation of ventilation in respiratory failure, by induction of metabolic acidemia will not lead to deterioration of the respiratory failure.
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Clin Physiol Funct Imaging · Jul 2009
Randomized Controlled TrialA preliminary investigation into the effect of coffee on hypolagesia associated with transcutaneous electrical nerve stimulation.
Transcutaneous electrical nerve stimulation (TENS) is a non-invasive, inexpensive analgesic technique used to relieve pain. It has been suggested that caffeine, an adenosine antagonist, may interfere with TENS action. This double-blind controlled pilot study investigated the effect of coffee on response to TENS in healthy human participants experiencing experimentally induced pain. ⋯ The statistical analysis modelled the responses for the coffee and decaffeinated coffee conditions during TENS (i.e. as a standard crossover) and detected no statistically significant effects between coffee and decaffeinated drinks for the natural logarithm (ln) transformed values of electrical pain threshold [ln EPT Coffee-ln EPT Decaffeinated coffee mean (standard error) = 0.0147 (0.2159)], mechanical pain threshold [ln MPT Coffee-ln MPT Decaffeinated coffee mean (standard error) = 0.1296 (0.0816)] and cold pain threshold [ln CPT Coffee-ln CPT Decaffeinated coffee mean (standard error) = 0.0793 (0.1139)]. We conclude that a single cup of coffee (100 mg caffeine) had no detectable effect on TENS outcome. Reasons why coffee did not produce a detectable effect on pain threshold are discussed.