Cardiorespiratory fitness as a mediator in the relationship between lung function and blood pressure in adults.

It is unclear whether physical activity and cardiorespiratory fitness (CRF) are pathways that link low pulmonary function (LPF) to increased blood pressure (BP). Therefore, we investigated the extent to which CRF and moderate-to-vigorous physical activity (MVPA) mediate the relationship between LPF and high BP in adults. We conducted a cross-sectional study with 1,362 participants that underwent cardiopulmonary exercise testing (CPET), spirometry, and wore an accelerometer to determine physical activity patterns. We performed mediation analyses using structural equations considering peak oxygen uptake (V̇O2) and MVPA as mediators, forced vital capacity (FVC) and forced expiratory volume in the first second (FEV1) as independent variables, and systolic and diastolic blood pressure (SBP, DBP) as dependent variables. The probability of alpha error was set at 5%. We found a significant total effect of FVC on SBP and DBP considering V̇O2 as mediator (P<0.01). Indirect effects were also significant, with 42.6% of the total effect of FVC on SBP and 77% on DBP mediated by V̇O2 (P<0.01). We did not observe a direct effect of FVC on SBP and DBP. Considering FEV1 as an independent variable, the total effect on SBP was also significant, as were the indirect effects, mediated by V̇O2 at 14.8% for SBP and 7.6% for DBP (P<0.01). We did not find an indirect effect of FVC or FEV1 considering the MVPA as a mediator. CRF mediates the pathway that links LPF and elevated BP. Therefore, CRF is more sensitive to variations in FVC and FEV1 than MVPA.

Cardiorespiratory fitness as a mediator in the relationship between lung function and blood pressure in adults

It is unclear whether physical activity and cardiorespiratory fitness (CRF) are pathways that link low pulmonary function (LPF) to increased blood pressure (BP). Therefore, we investigated the extent to which CRF and moderate-to-vigorous physical activity (MVPA) mediate the relationship between LPF and high BP in adults. We conducted a cross-sectional study with 1,362 participants that underwent cardiopulmonary exercise testing (CPET), spirometry, and wore an accelerometer to determine physical activity patterns. We performed mediation analyses using structural equations considering peak oxygen uptake (V̇O2) and MVPA as mediators, forced vital capacity (FVC) and forced expiratory volume in the first second (FEV1) as independent variables, and systolic and diastolic blood pressure (SBP, DBP) as dependent variables. The probability of alpha error was set at 5%. We found a significant total effect of FVC on SBP and DBP considering V̇O2 as mediator (P<0.01). Indirect effects were also significant, with 42.6% of the total effect of FVC on SBP and 77% on DBP mediated by V̇O2 (P<0.01). We did not observe a direct effect of FVC on SBP and DBP. Considering FEV1 as an independent variable, the total effect on SBP was also significant, as were the indirect effects, mediated by V̇O2 at 14.8% for SBP and 7.6% for DBP (P<0.01). We did not find an indirect effect of FVC or FEV1 considering the MVPA as a mediator. CRF mediates the pathway that links LPF and elevated BP. Therefore, CRF is more sensitive to variations in FVC and FEV1 than MVPA.

Classification of cardiorespiratory fitness using the six-minute walk test in adults: Comparison with cardiopulmonary exercise testing.

BACKGROUND: The six-minute walk test (6MWT) distance could facilitate the assessment of cardiorespiratory fitness (CRF) in clinical practice as recommended. We aimed to develop a CRF classification using the 6MWT distance in asymptomatic adults considering the treadmill maximum oxygen uptake (V˙O2max) as the gold standard method. METHODS: We evaluated V˙O2max and 6MWT distance in 1295 asymptomatic participants aged 18-80 years (60% women). Age- and sex-related CRF was classified based on the percentiles as very low (<5th percentile), low (5th-25th percentile), regular (26th-50th percentile), good (51st-75th percentile), excellent (76th-95th percentile), and superior (>95th percentile) for both V˙O2max and 6MWT distance. We investigated the 6MWT distance cut-off (%pred.) with the highest sensitivity and specificity for identifying each V˙O2max classification. RESULTS: V˙O2max declined by 8.7% per decade in both men and women. The 6MWT distance declined by 9.3% per decade in women and 9.5% in men. We formulated age- and sex-related classification tables for CRF using the 6MWT distance. Moreover, the 6MWT distance (%pred.) showed excellent ability to identify very low CRF (6MWT distance ≤ 96%; AUC=0.819) and good ability to differentiate CRF as low (6MWT distance=97%-103%; AUC=0.735), excellent (6MWT distance=107%-109%; AUC=0.715), or superior (6MWT distance>109%; AUC=0.790). It was not possible to differentiate between participants with regular and good CRF. CONCLUSION: The CRF classification by the 6MWT distance is valid in comparison with V˙O2max, especially for identifying adults with low CRF. It could be useful in clinical practice for screening and monitoring the cardiorespiratory risk in adults.

Use of cardiopulmonary exercise testing to assess early ventilatory changes related to occupational particulate matter.

Spirometry has been used as the main strategy for assessing ventilatory changes related to occupational exposure to particulate matter (OEPM). However, in some cases, as one of its limitations, it may not be sensitive enough to show abnormalities before extensive damage, as seen in restrictive lung diseases. Therefore, we hypothesized that cardiopulmonary exercise testing (CPET) may be better than spirometry to detect early ventilatory impairment caused by OEPM. We selected 135 male workers with at least one year of exposure. After collection of self-reported socioeconomic status, educational level, and cardiovascular risk data, participants underwent spirometry, CPET, body composition assessment (bioelectrical impedance), and triaxial accelerometry (for level of physical activity in daily life). CPET was performed using a ramp protocol on a treadmill. Metabolic, cardiovascular, ventilatory, and submaximal relationships were measured. We compared 52 exposed to 83 non-exposed workers. Multiple linear regressions were developed using spirometry and CPET variables as outcomes and OEPM as the main predictor, and adjusted by the main covariates. Our results showed that OEPM was associated with significant reductions in peak minute ventilation, peak tidal volume, and breathing reserve index. Exposed participants presented shallower slope of ΔVT/ΔlnV̇E (breathing pattern), i.e., increased tachypneic breathing pattern. The OEPM explained 7.4% of the ΔVT/ΔlnV̇E variability. We found no significant influence of spirometric indices after multiple linear regressions. We conclude that CPET might be a more sensitive feature of assessing early pulmonary impairment related to OEPM. Our cross-sectional results suggested that CPET is a promising tool for the screening of asymptomatic male workers.

Use of cardiopulmonary exercise testing to assess early ventilatory changes related to occupational particulate matter

Spirometry has been used as the main strategy for assessing ventilatory changes related to occupational exposure to particulate matter (OEPM). However, in some cases, as one of its limitations, it may not be sensitive enough to show abnormalities before extensive damage, as seen in restrictive lung diseases. Therefore, we hypothesized that cardiopulmonary exercise testing (CPET) may be better than spirometry to detect early ventilatory impairment caused by OEPM. We selected 135 male workers with at least one year of exposure. After collection of self-reported socioeconomic status, educational level, and cardiovascular risk data, participants underwent spirometry, CPET, body composition assessment (bioelectrical impedance), and triaxial accelerometry (for level of physical activity in daily life). CPET was performed using a ramp protocol on a treadmill. Metabolic, cardiovascular, ventilatory, and submaximal relationships were measured. We compared 52 exposed to 83 non-exposed workers. Multiple linear regressions were developed using spirometry and CPET variables as outcomes and OEPM as the main predictor, and adjusted by the main covariates. Our results showed that OEPM was associated with significant reductions in peak minute ventilation, peak tidal volume, and breathing reserve index. Exposed participants presented shallower slope of ΔVT/ΔlnV̇E (breathing pattern), i.e., increased tachypneic breathing pattern. The OEPM explained 7.4% of the ΔVT/ΔlnV̇E variability. We found no significant influence of spirometric indices after multiple linear regressions. We conclude that CPET might be a more sensitive feature of assessing early pulmonary impairment related to OEPM. Our cross-sectional results suggested that CPET is a promising tool for the screening of asymptomatic male workers.

Evaluation of dose-response relationship between smoking load and cardiopulmonary fitness in adult smokers: A cross-sectional study.

OBJECTIVE: To evaluate the dose-response relationship between smoking load and cardiopulmonary fitness, as measured with cardiopulmonary exercise testing (CPET), in adult smokers free of respiratory diseases. METHODS: After a complete clinical evaluation and spirometry, 95 adult smokers (35 men and 60 women) underwent CPET on a treadmill. RESULTS: The physiological responses during CPET showed lower cardiorespiratory fitness levels, regardless of smoking load, with a peak [Formula: see text] lower than 100% of the expected value and a lower maximum heart rate. We observed a significant moderate negative correlation between smoking load and peak [Formula: see text] . The smoking load also presented a significant negative correlation with maximum heart rate(r=-0.36; p<0.05), lactate threshold(r=-0.45; p<0.05), and peak ventilation(r=-0.43; p<0.05). However, a dose-response relationship between smoking load quartiles and cardiopulmonary fitness was not found comparing quartiles of smoking loads after adjustment for age, sex and cardiovascular risk. CONCLUSION: There appears to be no dose-response relationship between SL and cardiopulmonary fitness in adult smokers with preserved pulmonary function, after adjusting the analysis for age and cardiovascular risk. Our results suggest that smoking cessation might be useful as the primary strategy to prevent cardiopulmonary fitness decline in smokers, regardless of smoking load. Thus, even a very low dose of tobacco use must be avoided in preventive strategies focusing on becoming people more physically active and fit.

Correlation between heart rate variability and pulmonary function adjusted by confounding factors in healthy adults

The autonomic nervous system maintains homeostasis, which is the state of balance in the body. That balance can be determined simply and noninvasively by evaluating heart rate variability (HRV). However, independently of autonomic control of the heart, HRV can be influenced by other factors, such as respiratory parameters. Little is known about the relationship between HRV and spirometric indices. In this study, our objective was to determine whether HRV correlates with spirometric indices in adults without cardiopulmonary disease, considering the main confounders (e.g., smoking and physical inactivity). In a sample of 119 asymptomatic adults (age 20-80 years), we evaluated forced vital capacity (FVC) and forced expiratory volume in 1 s (FEV1). We evaluated resting HRV indices within a 5-min window in the middle of a 10-min recording period, thereafter analyzing time and frequency domains. To evaluate daily physical activity, we instructed participants to use a triaxial accelerometer for 7 days. Physical inactivity was defined as <150 min/week of moderate to intense physical activity. We found that FVC and FEV1, respectively, correlated significantly with the following aspects of the RR interval: standard deviation of the RR intervals (r =0.31 and 0.35), low-frequency component (r =0.38 and 0.40), and Poincaré plot SD2 (r =0.34 and 0.36). Multivariate regression analysis, adjusted for age, sex, smoking, physical inactivity, and cardiovascular risk, identified the SD2 and dyslipidemia as independent predictors of FVC and FEV1 (R2=0.125 and 0.180, respectively, for both). We conclude that pulmonary function is influenced by autonomic control of cardiovascular function, independently of the main confounders.

Correlation between heart rate variability and pulmonary function adjusted by confounding factors in healthy adults.

The autonomic nervous system maintains homeostasis, which is the state of balance in the body. That balance can be determined simply and noninvasively by evaluating heart rate variability (HRV). However, independently of autonomic control of the heart, HRV can be influenced by other factors, such as respiratory parameters. Little is known about the relationship between HRV and spirometric indices. In this study, our objective was to determine whether HRV correlates with spirometric indices in adults without cardiopulmonary disease, considering the main confounders (e.g., smoking and physical inactivity). In a sample of 119 asymptomatic adults (age 20-80 years), we evaluated forced vital capacity (FVC) and forced expiratory volume in 1 s (FEV1). We evaluated resting HRV indices within a 5-min window in the middle of a 10-min recording period, thereafter analyzing time and frequency domains. To evaluate daily physical activity, we instructed participants to use a triaxial accelerometer for 7 days. Physical inactivity was defined as <150 min/week of moderate to intense physical activity. We found that FVC and FEV1, respectively, correlated significantly with the following aspects of the RR interval: standard deviation of the RR intervals (r =0.31 and 0.35), low-frequency component (r =0.38 and 0.40), and Poincaré plot SD2 (r =0.34 and 0.36). Multivariate regression analysis, adjusted for age, sex, smoking, physical inactivity, and cardiovascular risk, identified the SD2 and dyslipidemia as independent predictors of FVC and FEV1 (R2=0.125 and 0.180, respectively, for both). We conclude that pulmonary function is influenced by autonomic control of cardiovascular function, independently of the main confounders.

Intensity and physiological responses to the 6-minute walk test in middle-aged and older adults: a comparison with cardiopulmonary exercise testing

The 6-minute walk test (6MWT) is a simple field test that is widely used in clinical settings to assess functional exercise capacity. However, studies with healthy subjects are scarce. We hypothesized that the 6MWT might be useful to assess exercise capacity in healthy subjects. The purpose of this study was to evaluate 6MWT intensity in middle-aged and older adults, as well as to develop a simple equation to predict oxygen uptake ( V ˙ O 2 ) from the 6-min walk distance (6MWD). Eighty-six participants, 40 men and 46 women, 40-74 years of age and with a mean body mass index of 28±6 kg/m2, performed the 6MWT according to American Thoracic Society guidelines. Physiological responses were evaluated during the 6MWT using a K4b2 Cosmed telemetry gas analyzer. On a different occasion, the subjects performed ramp protocol cardiopulmonary exercise testing (CPET) on a treadmill. Peak V ˙ O 2 in the 6MWT corresponded to 78±13% of the peak V ˙ O 2 during CPET, and the maximum heart rate corresponded to 80±23% of that obtained in CPET. Peak V ˙ O 2 in CPET was adequately predicted by the 6MWD by a linear regression equation: V ˙ O 2 mL·min-1·kg-1 = -2.863 + (0.0563×6MWDm) (R2=0.76). The 6MWT represents a moderate-to-high intensity activity in middle-aged and older adults and proved to be useful for predicting cardiorespiratory fitness in the present study. Our results suggest that the 6MWT may also be useful in asymptomatic individuals, and its use in walk-based conditioning programs should be encouraged.

Intensity and physiological responses to the 6-minute walk test in middle-aged and older adults: a comparison with cardiopulmonary exercise testing.

The 6-minute walk test (6MWT) is a simple field test that is widely used in clinical settings to assess functional exercise capacity. However, studies with healthy subjects are scarce. We hypothesized that the 6MWT might be useful to assess exercise capacity in healthy subjects. The purpose of this study was to evaluate 6MWT intensity in middle-aged and older adults, as well as to develop a simple equation to predict oxygen uptake ( V ˙ O 2 ) from the 6-min walk distance (6MWD). Eighty-six participants, 40 men and 46 women, 40-74 years of age and with a mean body mass index of 28±6 kg/m2, performed the 6MWT according to American Thoracic Society guidelines. Physiological responses were evaluated during the 6MWT using a K4b2 Cosmed telemetry gas analyzer. On a different occasion, the subjects performed ramp protocol cardiopulmonary exercise testing (CPET) on a treadmill. Peak V ˙ O 2 in the 6MWT corresponded to 78±13% of the peak V ˙ O 2 during CPET, and the maximum heart rate corresponded to 80±23% of that obtained in CPET. Peak V ˙ O 2 in CPET was adequately predicted by the 6MWD by a linear regression equation: V ˙ O 2 mL·min-1·kg-1 = -2.863 + (0.0563×6MWDm) (R2=0.76). The 6MWT represents a moderate-to-high intensity activity in middle-aged and older adults and proved to be useful for predicting cardiorespiratory fitness in the present study. Our results suggest that the 6MWT may also be useful in asymptomatic individuals, and its use in walk-based conditioning programs should be encouraged.

Immune responses to tetanus vaccination in Italian healthy subjects and children with recurrent infections.

The ability of vaccine antigen to generate protection is a challenge that cannot be restricted to the antibody response; however, the contribution of T cell-mediated mechanisms has not been extensively analyzed. Age and administration to specific categories of patients, i.e. children with recurrent infections (RI), are some of the factors that might affect the vaccine immune response. We investigated the humoral and cellular response to tetanus toxoid (TT) vaccine in 104 healthy children (HC), 11 newborns and 22 healthy adults to characterize the status of immunity according to age and compared it to 118 RI children. Humoral and cellular responses varied in both groups according to age and doses of TT administered. The prevalence of antibody and cellular response was similar in both cohorts (HC 88 percent and 82 percent versus RI 86 percent and 85 percent), however, TT antibody values were significantly higher in 12-18 months old RI children compared to HC (median: 5 IU/ml vs 1.10 IU/ml) (p = 0.02). The lack of an efficient immune response was observed in 12-15 percent of children from both cohorts. Our data showed that specific antibodies were responsible for early protection, whereas cell-mediated mechanisms may contribute to the generation of long-term immunity after an appropriate vaccine recall. The occurrence of higher TT antibody values in 12-18 months old RI children deserves additional research to determine whether they are caused by different infectious agents and/or by other environmental factors. Clarification of this issue is important for categorizing patients into an optimal vaccine policy.

Limb salvage using bypass to the perigeniculate arteries.

OBJECTIVE: To describe bypass to perigeniculate vessels for limb salvage. DESIGN: Retrospective cohort study. MATERIAL AND METHODS: Between 1995 and 2009, 47 bypass procedures to perigeniculate collateral arteries were performed in 46 patients (15 women, 31 men; median age, 68 years). All patients presented with critical ischaemia (tissue loss in 87.5%, rest pain in 12.5%). Mean ankle brachial index was 0.27 ± 0.17. The site of distal anastomosis was the descending genicular artery (DGA) in 23 bypasses (1 bilateral) and the medial sural artery (MSA) in 24. Proximal anastomosis was to the external iliac artery in 2 cases, common femoral artery in 23 cases, superficial femoral artery in 8 cases, deep femoral artery in 8 cases, above-knee poplitaeal artery in 2 cases, and previous graft in 4 cases. RESULTS: There were four deaths during the immediate postoperative period. Mean follow-up duration was 27 months. Ten patients required major amputation. Mean ankle brachial index post-operatively was 0.60 ± 0.21. At 3 years, primary patency was 74.7 ± 7%, secondary patency was 83.4 ± 8%, and the limb salvage and survival rates were 73.5 ± 7% and 77.4 ± 7%, respectively. CONCLUSION: Bypass to perigeniculate arteries is a viable treatment option for critical limb ischaemia in selected patients.

Coaches' perspectives on implementing an evidence-informed injury prevention programme in junior community netball.

OBJECTIVE: For effective sports injury prevention, information is needed about the implementation context for interventions. This study describes coaches' feedback on the implementation of an evidence-informed injury prevention programme in community junior netball using coaches' perceptions and the RE-AIM framework. METHODS: A lower-limb injury prevention programme (Down to Earth; D2E), for teaching safe-landing techniques, was delivered to 31 coaches from 31 junior community netball teams in a 1-h workshop. Coaches then delivered a 6-week programme at team training sessions starting in the week before the competition season commenced. 65% of coaches completed a feedback survey 17 weeks after they had delivered the programme. RESULTS: Most (88%) coaches believed that D2E improved their players' ability to perform correct landing techniques in games and that players had retained these improvements over the season. The majority (83%) indicated that an improvement in player athletic attributes was the greatest advantage of D2E, followed by a reduction in injury risk. Identified barriers to implementing D2E were running out of time and very young players finding the drills too difficult. Coaches reported that they needed more ideas for training drills that could be incorporated into their programmes and believed that their own coaching training did not adequately prepare them to implement an injury prevention programme. CONCLUSIONS: Although coaches believed that D2E was effective in developing correct landing techniques, some modifications are needed to make it more suitable for younger players and coach education by accreditation courses could be improved to support the implementation of injury prevention programmes.

A prospective cohort study of the incidence of injuries among junior Australian football players: evidence for an effect of playing-age level.

OBJECTIVE: To determine the rate of injury in junior Australian football, and to describe the patterns and severity of these injuries across nine levels of play (U9 to U18). DESIGN: Prospective cohort study. SETTING: Junior Australian football games and training sessions were observed for 54 teams from New South Wales and Victoria over the 2004 playing season. PARTICIPANTS: Six teams from each level of play were invited to participate in the study. Overall, data were collected for 51 teams over 40 208 hours of player exposure. INDEPENDENT VARIABLES: Participation and injury data were collected prospectively. MAIN OUTCOME MEASURES: Injury was defined as "any trauma that causes some disability or pain". Injury severity was identified by the action of players immediately after the injury event. RESULTS: The overall injury rate was 18.0 (95% CI 16.6 to 19.3) injuries per 1000 player hours. The main cause of injury was body contact (67.3%). There was an increased frequency of sprains and strains, and injury severity with increasing level of play. The rates of injury for players who stayed off the field (6.4 injuries per 1000 hours, 95% CI 5.6 to 7.2) or were advised to seek off-field medical advice (5.0 injuries per 1000 hours, 95% CI 4.3 to 5.7) were low. CONCLUSION: Compared with the adult game, junior Australian football is relatively safe. However, injury rates increase as children progress across age-determined levels of play towards the more adult form of the game.

Humoral immune responses and CD27+ B cells in children with DiGeorge syndrome (22q11.2 deletion syndrome).

The spectrum of T-cell abnormalities in 22q11.2 syndrome is quite broad, ranging from profound and life threatening to non-existent defects. Humoral abnormalities have been described in some of these patients, although no data are currently available on their phenotypical and functional B cell subsets. The purpose of this study was to investigate humoral immune function in a cohort of 13 children with DiGeorge syndrome by immunophenotyping B and by analysing their functionality in vivo. Humoral immunity was assessed by serum immunoglobulin evaluation, IgG subclasses determination, and testing of specific antibody titers to recall antigens. B cells were analyzed by flow cytometry and the relevant percentage of membrane surface expression of CD27, IgM, IgD was evaluated. In our cohort, one of 13 children (7.7%) had a complete IgA deficiency, four of 13 (30.7%) had minor immunoglobulin abnormalities, and five (38%) had an impaired production of specific antibodies. Five of 13 children (38%) had recurrent infections. Interestingly, peripheral CD27+ B cells were reduced in our patients as compared with age-matched healthy controls, and this decrement was statistically significant for IgM+ IgD+ CD27+ B cells. Immunoglobulin abnormalities were associated with the occurrence of recurrent infections. We conclude that a significant proportion of patients with DiGeorge syndrome have defective humoral immunity, which may represent an additional pathogenic mechanism underlying the increased susceptibility to infections. Whether the decreased CD27+ B-cell subset might be one of the defects that contribute to impaired humoral immunity, and to susceptibility to infection remains to be elucidated.

The distal zone of the deep femoral artery as the inflow site in femorodistal bypass grafting.

The distal zone of the deep femoral artery has been used as an inflow site for femorodistal bypass grafts. Eleven such bypass grafts were performed in patients who had critical limb ischemia either to avoid a hostile groin (n=7) or because of an insufficient length of vein (n=4). The posteromedial route was used. Two of the 11 grafts had early failure and a third failed at 3 months: redo surgery restored arterial blood flow to the limb in all three patients. The procedure was safe and is a widely applicable, effective alternative that extends the limits of infrainguinal vein bypass grafting.

Meta-analysis of allograft bypass grafting to infrapopliteal arteries.

OBJECTIVE: To determine graft patency and limb preservation after allograft bypass grafting to infrapopliteal arteries for different allograft materials. DESIGN: Meta-analysis of case series that used survival analysis to describe outcomes. METHODS: Studies published from 1982 through 2003 were identified from electronic databases and pertinent original articles. Four series of cryopreserved arterial allografts, 10 series of cryopreserved vein allografts, three series of cold-storaged vein allografts, and 16 series of umbilical-cord vein allografts were included in separate random-effects meta-analyses. RESULTS: A graphical display of pooled survival curves of graft patency showed cold-storaged veins to have the best outcome in the first 4 years, followed by cryopreserved arteries, umbilical-cord veins, and cryopreserved veins. The respective 5-year pooled patency were 24, 21, 30, and 19%. For foot preservation, the best outcome was achieved with cryopreserved arteries followed by cryopreserved veins, umbilical-cord veins, and cold-storaged veins. A reference meta-analysis of polytetrafluoroethlylene grafts occupied the top position for graft patency and the second position for foot preservation. CONCLUSION: In leg revascularisation for critical ischaemia, graft patency is poor for allografts generally, but using peripheral allografts in repeat attempts at revascularisation is a valid strategy to prevent major amputation. A role for umbilical-cord vein allografts remains uncertain.