Clinical physiology (Oxford, England)
-
Clinical Trial
The effect of three electrotherapeutic modalities upon peripheral nerve conduction and mechanical pain threshold.
The current study was designed to examine the neurophysiological and hypoalgesic effects of three types of electrical stimulation. Following approval by the University's Research Ethical Committee, healthy volunteers (n=40; 20 males and 20 females; age 20-40 years; mean age 26.18 years) were recruited and screened for contraindications. Subjects were randomly allocated in equal numbers to the following groups: control, transcutaneous electrical nerve stimulation (TENS; 150 Hz, 125 micros), interferential therapy (IFT; 150 Hz, 125 micros) or action potential stimulation therapy (APS; 153 Hz, 6.4 ms). ⋯ Mann-Whitney U-tests indicated a significant increase in PPA in the IFT group compared with all other groups at 25 and 35 min and compared with the TENS and APS groups at 45 min. No significant differences were found for the MPT data. This study has therefore demonstrated that none of the aforementioned modalities produced a significant hypoalgesic effect; however, IFT produced a significant change in PPA compared with TENS and APS.
-
This study was conducted to describe the relationship between anthropometric parameters and lung function in Estonian children, to determine the reference values for spirometry, and to compare these results with other data sets. The results are based on 1170 healthy non-smoking children (643 girls and 527 boys), aged 6-18 years. ⋯ Prediction equations for forced vital capacity (FVC), forced expiratory volume in 1 s (FEV1), peak expiratory flow, forced expiratory flows when 50 and 75% of FVC has been exhaled, and mean forced expiratory flow over the middle 50% of the FVC for both sexes are presented. In comparison with recent data from European children the reference values were close for FVC, the differences were bigger for FEV1 and forced expiratory flows, especially in taller children.
-
The purpose of this study was to compare the applicability of four different measures of heart rate variability (HRV) in the assessment of cardiac vagal outflow, with special reference to the effect of breathing pattern. The anticholinergic effects of an intravenous glycopyrrolate infusion (5 microg x kg(-1) x h(-1) for 2 h) during spontaneous and controlled (15 min(-1)) breathing rate were investigated in eight volunteers, and the effects of different fixed breathing rates (6-15-24 min(-1)) and hyperventilation in 12 subjects. Cardiac vagal activity was assessed by ECG recordings in which the following measures of HRV were computed: the high-frequency (HF) spectral component, the instantaneous RR interval (RRI) variability (SD1) analysed from the Poincaré plots, the percentage of differences between successive RRIs greater than 50 ms (pNN50), and the square root of the mean squared differences of successive RRIs (RMSSD). ⋯ Rapid breathing rate (24 min(-1)) decreased the HF component, but had no effects on the other measures. A controlled breathing rate is needed for a reliable assessment of cardiac vagal outflow by the spectral analysis technique. The quantitative geometrical analysis of short-term RRI variability from the Poincaré plots and the time domain measure RMSSD were not significantly affected by changes in the breathing rate, suggesting that these indices are more suitable for the measurement of cardiac vagal outflow during the 'free-running' ambulatory conditions.
-
Comparative Study
Comparison of ultrasound assessment of flow-mediated dilatation in the radial and brachial artery with upper and forearm cuff positions.
In the published literature relating to flow-mediated dilatation (FMD), there are substantial differences between centres in terms of normal FMD amongst healthy subjects. This present study attempts to identify the effect of differing methodologies on FMD. High frequency ultrasound was used to measure blood flow and percentage brachial and radial artery dilatation after reactive hyperaemia induced by forearm or upper arm cuff occlusion in 24 healthy subjects, less than 40 years, without known cardiovascular risk factors. ⋯ The local ischaemia of the brachial artery with a proximal occlusion may explain why the brachial artery dilated more after upper arm occlusion compared with after forearm occlusion. The study has also shown that FMD of the radial artery could be assessed by B-mode ultrasound technique. FMD was greater using the radial artery compared with the brachial artery, suggesting that the radial artery may be a useful way to assess FMD in future clinical studies.
-
In the elderly, standing can frequently be accompanied by blood pressure (BP) changes and cerebral symptoms such as dizziness, fall, or even syncope, but this may vary from day-to-day. Therefore, we aimed to investigate the reproducibility of orthostatic responses of cerebral cortical oxygenation and systemic haemodynamics in elderly subjects. In 27 healthy elderly subjects (age 70-84 years), changes in systolic BP (SBP), diastolic BP (DBP), heart rate (HR) and stroke volume (SV) were continuously monitored by Finapres (Finger Arterial Pressure), and changes in oxyhaemoglobin ([O2Hb]) and deoxyhaemoglobin ([HHb]) concentrations were continuously measured over the right frontal cortex by near infrared spectroscopy (NIRS) during supine rest and 10 min of active standing on two separate occasions. ⋯ Cortical oxygenation changes were not accompanied by severe cerebral symptoms. Active standing induced reproducible group-averaged frontal cortical oxygenation declines in healthy elderly subjects, although an intraindividual day-to-day variability was present, possibly related to the variability of orthostatic BP responses. These findings indicate that cerebral autoregulation fails to compensate completely for postural changes in elderly subjects, which might predispose elderly subjects to ischaemic cerebral symptoms.