Clinical physiology and functional imaging
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Clin Physiol Funct Imaging · Jan 2010
Urea clearance: a new method to register local changes in blood flow in rat skeletal muscle based on microdialysis.
Increasing evidence suggests that local blood flow should be monitored during microdialysis (MD) as the recovery of analytes is affected by local blood flow. At present ethanol clearance is the standard technique for this purpose, but it is not functional at very low perfusion velocities. Here, we introduce a technique for MD whereby local tissue blood flow is recorded by the use of urea clearance (changes inflow/outflow concentration), in conjunction with measurements of tissue metabolism (glucose, lactate and puruvate). ⋯ These were characterized by dose-dependent changes in the urea clearance as well as blood-flow-specific changes in the MD metabolic markers (reduction in glucose and increase in lactate). The sensitivity for blood flow changes as assessed by urea clearance (MD) was increased at 0.4 compared with the 0.6 microl min(-1) perfusion speed. The results indicate that inclusion of urea to the perfusion medium may be used to monitor changes in skeletal muscle blood flow at low perfusion velocities and in parallel assess metabolic variables with a high recovery (>90%).
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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 · Sep 2009
Comparative StudyTracer kinetics analysis of dynamic contrast-enhanced CT and MR data in patients with squamous cell carcinoma of the upper aerodigestive tract: comparison of the results.
(i) To evaluate the feasibility of tracer kinetics analysis of dynamic contrast-enhanced (DCE) CT and T2-weighted MR data of squamous cell carcinoma (SCCA) of the upper aerodigestive tract. (ii) To compare functional parameters derived by both modalities and examine the interchangeability of them as well as the intra- and inter-rater agreement. ⋯ The estimation of functional parameters in SCCA is feasible using DCE-CT and -MR with a DP model. The parameters are mostly significantly different and the interchangeability of them is limited.
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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.
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Clin Physiol Funct Imaging · Jul 2009
Heart rate variability during sleep and sleep apnoea in a population based study of 387 women.
Increased sympathetic activity during sleep has been suggested as a link between obstructive sleep apnoea syndrome and cardiovascular disease. Heart rate variability (HRV) is a measure of autonomic effect on the heart. Different parameters have been associated with sympathetic and parasympathetic activity. ⋯ In slow wave sleep the parameters decreased. In conclusion, moderately increased prevalence of obstructive apnoeas was associated with signs of higher sympathetic activity. High AHI was however associated with a HRV-pattern suggestive of depressed sympathetic drive and lowered ability to increase it during REM.