Sonographic evaluation of diaphragmatic function during breathing control.

OBJECTIVE: To investigate the effect of "breathing control" on sonographic diaphragmatic excursion. METHOD: A prospective, randomized, assessor-blinded study design involving 20 physiotherapy students; ten with knowledge of the breathing control technique (Group BC) and ten without (Group CON). All participants were asked to perform a Chester step test. Group BC performed BC, while Group CON adopted their own breathing pattern during recovery after the step test. Respiratory rate and sonographic parameters of the diaphragm including diaphragmatic excursion, speed of diaphragmatic contraction (slope of contraction), and inspiratory time were recorded before and after the step test. RESULTS: All baseline data were similar for both groups except age. Respiratory rate at 1 min post-step test was higher in Group CON (24.6±4.9 bpm) compared to Group BC (15.6 ± 3.8 bpm) (p < 0.001). Post-step test sonographic evaluation demonstrated an increase in diaphragmatic excursion with a significant time and group interaction (F(4,72) = 5.499, p = 0.005). Post hoc analysis revealed that the diaphragmatic excursion was significantly higher in Group BC compared to Group CON at first, second and third minute post-step test. Time and group interactions were not significant in inspiration time (F(4,72) = 2.459, p = 0.082) nor the slope of contraction (F(4,72) = 0.655, p = 0.582)]. CONCLUSION: Post-exercise diaphragmatic excursion was higher in participants applying BC. Non-invasive ultrasonography is able to promote objective evaluation of the relationship between breathing techniques and diaphragmatic function.

Changes in bone density and geometry of the radius in chronic stroke and related factors: a one-year prospective study.

OBJECTIVES: To describe the changes in bone density and geometry of the radius after chronic stroke and the associated clinical factors. METHODS: Twenty stroke patients (12 men and 8 women, age=42-78 years, time post-stroke=12-166 months) and 23 control participants (14 men and 9 women, age=53-77 years) were assessed at the time of enrolment and one year later. Peripheral quantitative computed tomography was used to scan the radius epiphysis (4% site) and diaphysis (33% site). Grip strength, spasticity, paretic arm disuse, physical activity, and vascular health were also evaluated. RESULTS: During the follow-up period, only the cortical thickness and cortical bone mineral content (BMC) in the paretic radius diaphysis showed a decline that exceeded the least significant change value (p=0.002). Paretic arm disuse, lower vascular elasticity and physical activity level at initial assessment were significantly related to more decline in cortical thickness at this site (p<0.01). CONCLUSIONS: The paretic radius diaphysis sustained significant reduction in cortical thickness and cortical BMC over time in chronic stroke, but these changes were less pronounced than those previously reported in sub-acute stroke. Strategies to modify vascular health, disuse, and physical activity may be important in improving upper limb bone health but will need further investigations.

Relative impact of neuromuscular and cardiovascular factors on bone strength index of the hemiparetic distal radius epiphysis among individuals with chronic stroke.

UNLABELLED: The objective of this study was to examine the associations of neuromuscular and cardiovascular impairments with the bone strength index of the hemiparetic distal radius epiphysis in chronic stroke survivors. The results showed that grip strength is the most predominant predictor of the bone strength index. INTRODUCTION: The purpose of the study was to examine the associations of neuromuscular and cardiovascular impairments with the bone strength index of the hemiparetic distal radius epiphysis in chronic stroke survivors. METHODS: Sixty-five chronic stroke survivors and 34 healthy control subjects underwent scanning of the distal radius epiphyseal site on both sides using peripheral quantitative computed tomography to measure trabecular volumetric bone mineral density (vBMD) (mg/cm(3)), total vBMD (mg/cm(3)), total area (mm(2)), and compressive bone strength index (cBSI) (g(2)/cm(4)). Various indicators of neuromuscular (grip strength, spasticity) and cardiovascular function (vascular elasticity, oxygen consumption during 6-min walk test) were evaluated. RESULTS: Analysis of variance revealed a significant main effect of side (p < 0.001) and group × side interaction (p < 0.05) for total BMC, total vBMD, trabecular vBMD, and cBSI (p < 0.05), with the stroke group showing greater side-to-side difference in these variables. However, no significant side-to-side difference in total area was detected in either group (p > 0.05). Sex-specific analysis yielded similar results. Multiple regression analyses revealed that the cBSI of the hemiparetic distal radius epiphysis had a stronger association with neuromuscular factors than cardiovascular factors. Overall, grip strength was the strongest determinant of the cBSI of the hemiparetic distal radius epiphysis (p < 0.01). CONCLUSIONS: Muscle weakness is the most predominant determinant of cBSI in the hemiparetic distal radius epiphysis among chronic stroke patients. Future studies should investigate the efficacy of different muscle-strengthening strategies in enhancing bone strength of this skeletal site in the chronic stroke population.

End-expiratory carbon monoxide levels in healthy subjects living in a densely populated urban environment.

Carbon monoxide (CO) has a high affinity for haemoglobin and is a common cause of poisoning in industry and the home. Exhaled CO levels in patients with respiratory disease have been reported but exhaled CO in a large cohort of healthy subjects grouped by age and gender has not been reported. Exhaled CO levels and spirometry lung function data were recorded from 1032 subjects at a university campus and two commercial plazas. Subjects were also asked to complete a respiratory symptom questionnaire. Ninety-eight subjects reported respiratory disease and were excluded from the study. Non-smoking male subjects (n=508) had higher exhaled CO levels (4.36+/-2.54 ppm) [range 0-21 ppm] compared with female (n=348) subjects (3.72+/-2.12 ppm) [range 0-14 ppm] (p<0.0005), and older subjects (>60 years) had lower exhaled CO levels compared with young subjects (<22 years) (p=0.018). Over 13% of non-smokers had an exhaled CO greater than 7 ppm. Smokers showed significantly higher exhaled CO levels compared with non-smokers (p<0.0005) and smokers who complained of frequent cough and sputum production had higher levels of exhaled CO compared with smokers without such complaints. Smoking history (pack-years) was directly related to age (r=0.59) but correlated inversely with forced expiratory flow in the 1st second (FEV1) (r=-0.29) and peak expiratory flow rate (PEFR) (r=-0.25) (p<0.05). If a city's micro environmental CO concentrations and human activity patterns is available, regular monitoring of exhaled CO in healthy subjects has the potential to be used as a functional index of air pollution.

Respiratory health of bus drivers in Hong Kong.

OBJECTIVE: We conducted a cross-sectional study to evaluate the lung function and respiratory symptoms of Hong Kong bus and tram drivers exposed to air pollutants. METHODS: Demographic information, vital signs, pulmonary function, respiratory symptoms and blood lead levels in 358 male drivers of air-conditioned buses (ACB) were compared with 129 male drivers of non-air-conditioned buses and trams (NACB). Particulate matter (PM10), carbon dioxide (CO2) and carbon monoxide (CO) levels were measured in 16 air-conditioned and 15 non-air-conditioned trams along the same route. RESULTS: Forced vital capacity, forced expiratory volume in 1 s and maximal voluntary ventilation were lower but blood lead levels were higher in the NACB drivers compared with ACB drivers. More NACB drivers compared to ACB drivers reported frequent productive cough, dry cough, as well as sore throat. The measured lung function parameters in the NACB drivers were lower than a cohort of personnel working in an academic environment. The work-year duration was longer and scheduled days off per month were shorter for NACB (13.4+/-8.8 years and 4.3+/-1.3 days) compared to ACB drivers (11.5+/-9 years and 5.4+/-0.8 days), respectively (P < 0.001). The PM10 and CO2 levels were higher in ACB (265+/-83 microg/m3 and 2,114+/-69.6 ppm) compared to non-air-conditioned trams (161+/-103 microg/m3 and 500 ppm, respectively) (P < 0.005). CONCLUSION: We hypothesise that prolonged exposure to air pollutants adversely affects lung function in our NACB drivers but air recirculation could result in higher blood lead levels in ACB drivers.

Changes in heart rate and R-wave amplitude with posture.

BACKGROUND: Effect of gravity on heart rate and blood pressure are well documented but the effect of posture on R-wave amplitude has not been studied. AIM: To investigate the effect of posture on the heart rate (HR) and R-wave amplitude (RWA). METHODS: The electrocardiograph (ECG) was recorded in 20 young subjects on two occasions. A 5 minute recording of resting ECG was taken with the subject adopting the following postural cycle: lying, sitting, standing, sitting and lying positions. RESULTS: The standing HR was significantly higher than that in sitting and lying positions, but the RWA was significantly lower in standing compared to the sitting and lying postures. The HR significantly increased at the initial phase of postural changes, irrespective of the position. For example, the HR increased from lying to sitting (66.6+/-2.3 to 85.0+/-10.9 beat x min(-1)) but also increased when changed from sitting to lying (70.6+/-10.6 to 85.2+/-8.7 beat x min(-1)). CONCLUSION: Body posture has an effect on HR and RWA. The changes are probably related to orthostatic haemodynamic stress as well as changes in cardiac electrical axis. Whether the cause of the initial increase in the HR during postural change was attributed to skeletal muscle reflex or venous return requires further investigation.

Interrelationships between anxiety, lifestyle self-reports and fitness in a sample of Hong Kong University students.

Although anxiety in university students has been well documented, the influence of lifestyle and fitness status in relation to anxiety has not been investigated from a cultural perspective previously. To make recommendations regarding the avoidance or management of anxiety in this anxiety-prone cohort that are rationally based, this preliminary investigation examined the interrelationship between anxiety, lifestyle self-reports and aerobic fitness in Hong Kong Chinese University students. The State Trait Anxiety Inventory (Form Y-2) and a lifestyle questionnaire were completed by 213 students. Female students were more anxious than male students. Subjects with high anxiety reported more deleterious lifestyle behaviours including higher salt consumption and lower levels of exercise; in addition to more frequent symptoms of anxiety such as headaches and daytime somnolence. The extremes of this sample were stratified into a low anxiety group (n = 17) and a high anxiety group (n = 14) to compare their fitness status. Although both groups had below normal aerobic capacity, the higher systolic blood pressure observed for the high anxiety group is consistent with signs of anxiety, or greater deconditioning in this group or both. The results of this study have highlighted anxiety as a concern in Hong Kong University students and identified some lifestyle and fitness correlates. Understanding lifestyle and pathophysiological correlates of anxiety in Hong Kong University students that may have a cultural basis, is a crucial step toward averting or managing anxiety when these students are studying either in Hong Kong or abroad.