Comparison of Mechanical Insufflation-Exsufflation and Endotracheal Suctioning in Mechanically Ventilated Patients: Effects on Respiratory Mechanics, Hemodynamics, and Volume of Secretions.

CONTEXT: Cough assist (CA) is a device to improve bronchial hygiene of patients with secretion in the airways and ineffective cough. AIMS: To compare the physiological effects and the volume of secretion of mechanical insufflation-exsufflation (CA device) with isolated endotracheal suctioning in mechanically ventilated patients. SETTINGS AND DESIGN: Randomized crossover trial. MATERIALS AND METHODS: The patients were randomly allocated to the first technique, then the following technique was performed in the next day. We collected the variables related to oxygen saturation, hemodynamics (heart rate, systolic blood pressure, diastolic blood pressure, and mean arterial pressure [MAP]), and respiratory mechanics (tidal volume, minute volume, respiratory rate, and lung compliance and resistance), pre- and postimplementation (immediately and after 15 and 30 min), and the aspirated volume of secretion. STATISTICAL ANALYSIS USED: We used two-way analysis of variance followed by the Student-Newman-Keuls t-test to compare the variables at different time points. Student's t-test was used to compare secretion volumes. All data were stored and analyzed in SPSS for Windows Version 19.0. The significance level was set at 5%. RESULTS: Forty-three patients were included in the study. When we compared the results before and after the application of the techniques, we observed no significant difference in lung compliance, pulmonary resistance, MAP, peripheral oxygen saturation, and secretion volume in both groups. CONCLUSIONS: The mechanical insufflation-exsufflation does not alter respiratory mechanics and hemodynamic stability, and it does not improve airway clearance in mechanically ventilated patients.

TP53 p.R337H is a conditional cancer-predisposing mutation: further evidence from a homozygous patient.

BACKGROUND: Adrenocortical carcinomas (ACCs) are among the most common childhood cancers occurring in infants affected with the Li-Fraumeni and Li- Fraumeni-like (LFS/LFL) syndromes, which are caused by dominant germline mutations in the TP53 gene. In Brazil, a particular mutation, occurring in the tetramerisation domain of the gene, p.R337H, is exceedingly common due to a founder effect and is strongly associated with ACC. In this report, we describe the phenotype and long-term clinical follow-up of a female child diagnosed with ACC and homozygous for the TP53 p.R337H founder mutation. CASE PRESENTATION: At age 11 months, the patient was diagnosed with a virilising anaplastic adrenal cortical tumour, which was completely excised without disturbing the adrenal capsule. Family history was consistent with an LFL tumour pattern, and genotyping identified the TP53 p.R337H mutation in both alleles in genomic DNA from lymphocytes and fibroblasts. Haplotype analysis confirmed the occurrence of the mutation in the same founder haplotype previously described in other Brazilian patients. No other germline or somatic TP53 mutations or rearrangements were identified. At age 9 years, the child was asymptomatic and had no evidence of endocrine derangements. Full body and brain magnetic resonance imaging (MRI) failed to detect any suspicious proliferative lesions, and cardiopulmonary exercise testing results were within the normal reference for the child's age, ruling out a major exercise capacity deficiency. CONCLUSION: This is the first clinical and aerobic functional capacity documentation of a patient who carries two mutant TP53 alleles and no wild-type allele. Our results support the hypothesis that TP53 p.R337H, the most common TP53 mutation ever described in any population, is a conditional mutant. Furthermore, our observations over a long period of clinical follow-up suggest that TP53 p.R337H homozygotes do not have a more severe disease phenotype than do heterozygote carriers of the same mutation. Patients with the homozygous TP53 p.R337H genotype will require careful surveillance for lifetime cancer risk and for effects on metabolic capacity later in life.

Hemodynamic responses to resistance exercise with restricted blood flow in young and older men.

Exercise with blood flow restriction promotes significant improvements, and it has been considered an attractive exercise strategy, especially for older individuals. However, the acute cardiovascular responses to resistance exercise with blood flow restriction (BFR) are not fully known. The purpose of this study was to evaluate the hemodynamic responses during resistance exercise with BFR in young and older individuals. We compared hemodynamic responses in 15 young (30 ± 3 years) and 12 older (66 ± 7 years) subjects during low-intensity resistance biceps curl exercise with (BFR-RE) or without (RE) BFR in a random and crossover design. Heart rate (HR), mean blood pressure (MBP), calf blood flow (CBF), and calf vascular resistance (CVR) were evaluated. Both groups presented similar values at baseline. Compared with RE, HR and MBP were higher during BFR-RE for both the groups, and these changes were maintained during the recovery period. In both the groups, BFR-RE elicited larger decreases in CBF and increased CVR. Both groups showed a significant increase in double product during BFR-RE. In conclusion, resistance exercise with BFR elicits greater hemodynamic changes in healthy young and older subjects, with responses of similar magnitudes in both groups. The safety of BFR in clinical practice demands further study in vulnerable populations.

Effect of transcutaneous electrical nerve stimulation on muscle metaboreflex in healthy young and older subjects.

Transcutaneous electrical nerve stimulation (TENS) increases local blood flow. It is not known whether increase in blood flow may be caused by inhibition of sympathetic activity, mediated by muscle metaboreflex activity. The purpose of this study was to evaluate the effect of TENS on metaboreflex activation and heart rate variability (HRV) in young and older individuals. Eleven healthy young (age 25 ± 1.3 years) and 11 healthy older (age 63 ± 4.2 years) were randomized to TENS (30 min, 80 Hz, 150 µs) or placebo (same protocol without electrical output) applied on the ganglion region. Frequency domain indices of HRV and hemodynamic variables were evaluated during the pressor response to static handgrip exercise at 30% of maximal voluntary contraction, followed by recovery with (PECO+) or without (PECO-) circulatory occlusion, in a randomized order. At the peak exercise, the increase in mean blood pressure was attenuated by TENS (P < 0.05), which was sustained during PECO+ and PECO-. TENS promoted a higher calf blood flow and lower calf vascular resistance during exercise and recovery. Likewise, TENS induced a reduction in the estimated muscle metaboreflex control both in young (placebo: 28 ± 4 units vs. TENS: 6 ± 3, P < 0.01) and in older individuals (placebo: 13 ± 3 units vs. TENS: 5 ± 3, P < 0.01). HRV analysis showed similar improvement in sympatho-vagal balance with TENS in young and older individuals. We conclude that application of TENS attenuates blood pressure and vasoconstrictor responses during exercise and metaboreflex activation, associated with improved sympatho-vagal balance in healthy young and older individuals.

Blunted vascular responses but preserved endothelial vasodilation after submaximal exercise in chronic heart failure.

BACKGROUND: Patients with chronic heart failure (CHF) have abnormal vascular responses to acute exercise; however, regular aerobic training improves endothelial function in these patients. We hypothesized that, because of their attenuated vascular responses, CHF patients would present abnormal endothelium-dependent vasodilatation after a single exercise session. METHODS: Thirteen CHF patients and 13 healthy controls participated in two experiments, on different days, using a cross-over design: (i) control (25-min seated at rest), and (ii) a submaximal exercise session (25-min cycling). Measurements of heart rate, blood pressure (BP), venous occlusion plethysmography forearm blood flow (FBF), and reactive hyperemia were made before and after (immediately, 10, 30, 60 min, and 24 h) each experimental condition. RESULTS: CHF patients had no changes in the mean BP throughout the protocols, whereas mean BP was reduced up to 60 min after exercise in controls. In CHF patients, FBF was increased and forearm vascular resistance was reduced up to 10 min after exercise, whereas these changes were sustained up to 30 min after exercise in controls. Reactive hyperemia was significantly increased up to 30 min after exercise in both groups. CONCLUSION: Patients with CHF have increased postexercise FBF and decreased forearm vascular resistance; however, these responses last longer in healthy individuals. Despite the attenuated postexercise vascular responses, patients with CHF respond to a single-cycle exercise session with improved forearm endothelium-dependent vasodilation.

Inspiratory resistive loading after all-out exercise improves subsequent performance.

We have previously shown that post-exercise inspiratory resistive loading (IRL) reduces blood lactate ([Lac(b)(-)]). In this study, we tested the hypothesis that IRL during recovery could improve subsequent exercise performance. Eight healthy men underwent, on different days, two sequential 30-s, cycle ergometer Wingate tests. During the 10-min recovery period from test 1, subjects breathed freely or through an inspiratory resistance (15 cm H(2)O) with passive leg recovery. Arterialized [Lac(b)(-)] values, perceptual scores (Borg), cardiac output by impedance cardiography (QT), and changes in the deoxygenation status of the M. vastus lateralis by near-infrared spectroscopy (DeltaHHb), were recorded. [Lac(b)(-)] was significantly reduced after 4 min of recovery with IRL (peak [Lac(b)(-)] 12.5 +/- 2.3 mmol l(-1) with free-breathing vs. 9.8 +/- 1.5 mmol l(-1) with IRL). Effort perception was reduced during late recovery with IRL compared with free-breathing. Cardiac work was increased with IRL, since heart rate and QT were elevated during late recovery. Peripheral muscle reoxygenation, however, was significantly impaired with IRL, suggesting that post-exercise convective O(2) delivery to the lower limbs was reduced. Importantly, IRL had a dual effect on subsequent performance, i.e., improvement in peak and mean power, but increased fatigue index (P < 0.05). Our data demonstrate that IRL after a Wingate test reduces post-exercise effort perception and improves peak power on subsequent all-out maximal-intensity exercise.

Effects of concurrent and aerobic exercises on postexercise hypotension in elderly hypertensive men.

Despite the fact that simultaneous performance of resistance and aerobic exercises (i.e., concurrent exercise) has become a standard exercise prescription for the elderly, no information is available on its effects on post-exercise hypotension (PEH) in elderly men with hypertension. PURPOSE: To compare the effects of different types of exercise on PEH in elderly men with hypertension. METHODS: Twenty elderly men with essential hypertension participated in three crossover interventions, in random order, and on separate days: a non-exercise control session at seated rest, aerobic exercise performed for 45min, and 45min of concurrent resistance and aerobic exercise consisted of 4 sets of 8 repetitions at 70% 1RM of resistance exercise followed by aerobic exercise on treadmill. After each session, blood pressure (BP) was measured continuously for 1h in the laboratory and for 24h under ambulatory conditions. RESULTS: During the first hour in laboratory, diastolic BP was lower after aerobic (-5mmHg) and concurrent exercise (-6mmHg) in comparison with Control. Day-time diastolic BP was significantly lower after aerobic exercise (-7mmHg) when compared to the control. No significant differences were found among the three experimental sessions for night-time and 24-hour diastolic BP, as well as day-time, night-time and 24-hour systolic BP. CONCLUSION: Concurrent exercise produced acute PEH similar to aerobic exercise but such effect did not last as long as aerobic exercise in elderly patients with essential hypertension.

Skeletal muscle metaboreflex in patients with chronic renal failure.

The sympathetic nervous system is affected in patients with chronic renal failure (CRF). This study tested the hypothesis that patients with CRF have an altered skeletal muscle metaboreflex. Twenty patients with CRF and 18 healthy subjects of similar age participated in the study. The muscle metaboreflex was determined based on heart rate (HR), mean arterial pressure, calf blood flow and calf vascular resistance (CVR) in response to handgrip exercise. The control of vascular resistance in the calf muscle mediated by the metaboreflex was estimated by subtracting the area under the curve with circulatory occlusion from that without occlusion. Arterial pressure and HR responses during exercise and recovery were similar in two groups of subjects. In the control group, CVR increased during exercise and remained elevated during circulatory occlusion, whereas no significant change was seen in the patients. Thus, the index of the metaboreflex was 7·82 ± 9·57 in the patients versus16·52 ± 14 units in the controls. The findings demonstrate that patients with CRF have a decreased vascular resistance response in the calf during the handgrip exercise, which suggests that CRF condition attenuates this reflex.

Inspiratory loading and limb blood flow in COPD: The modulating effects of resting lung hyperinflation.

Inspiratory resistive loading (IRL) may have deleterious cardiocirculatory effects leading to poor peripheral perfusion in severely-hyperinflated patients with COPD. Nineteen patients (13 severely-hyperinflated with inspiratory capacity/total lung capacity ratio≤0.28) underwent calf blood flow (CBF) measurements by venous occlusion plethysmography at rest and during IRL at 60% maximal inspiratory pressure. Severely-hyperinflated patients had lower resting CBF and greater calf vascular resistance (CVR) than moderately-hyperinflated patients (p<0.05). All severely-hyperinflated patients had markedly reduced CBF (p=0.01). Opposite to our main hypothesis, however, IRL did not further reduce CBF in these patients (p>0.05). Conversely, it significantly decreased CBF and increased CVR in moderately-hyperinflated patients; in fact, end-trial CBF and CVR did not differ between the groups (p>0.05). In conclusion, marked impairments in resting appendicular blood flow in severely-hyperinflated patients with COPD were seen only after acute IRL in less hyperinflated patients. These findings set the stage for studies investigating the effects of lung deflation on peripheral hemodynamics in patients with severe hyperinflation.

Effects of aerobic exercise intensity on ambulatory blood pressure and vascular responses in resistant hypertension: a crossover trial.

BACKGROUND: Resistant hypertension often exposes patients to poor blood pressure (BP) control, resulting in clinical vulnerability, possible need for device-based procedures (denervation) and increased therapy costs. Regular exercise markedly benefits patients with hypertension, including resistant patients. However, little is known about short-term exercise effects in resistant hypertension. OBJECTIVE: To evaluate acute hemodynamic effects of exercise in resistant hypertension. METHOD: After maximal exercise testing, 20 patients (54.0 ±â€Š5.7 years, 30.2 ±â€Š4.9 kg/m) with resistant hypertension participated in three crossover interventions, in random order, and on separate days: control (45' of rest), and light intensity and moderate intensity (45' of aerobic exercise at 50 and 75% of maximum heart rate, respectively). Ambulatory BP, forearm blood flow (with subsequent calculation of vascular resistance), and reactive hyperemia were measured before and after interventions trough venous occlusion plethysmography. RESULTS: Compared with control, both exercise intensities reduced ambulatory systolic pressure over 5 h (light: -7.7 ±â€Š2.4 mmHg and moderate: -9.4 ±â€Š2.8 mmHg, P < 0.01), whereas only light intensity reduced diastolic pressure (-5.7 ±â€Š2.2 mmHg, P < 0.01). Light intensity also lowered systolic and diastolic pressures over 10-h daytime (-3.8 ±â€Š1.3 and -4.0 ±â€Š1.3 mmHg, respectively, P < 0.02), night-time (-6.0 ±â€Š2.4 and -6.1 ±â€Š1.6 mmHg, respectively, P < 0.05), and diastolic pressure over 19 h (-4.8 ±â€Š1.2 mmHg, P < 0.01). Forearm blood flow changed (decreased) compared with baseline only at 50 min after light intensity (P < 0.05). After the control and light intensity sessions, vascular resistance increased at the end of 1 h, and after moderate intensity, it decreased only at the moment (∼2 min) immediately after intervention (P < 0.05). CONCLUSION: A single session of light or moderate aerobic exercise acutely reduces ambulatory BP in resistant hypertension, although benefits persist longer following light intensity.

Factors associated with inspiratory muscle weakness in patients with HIV-1.

BACKGROUND: the impact of human immunodeficiency virus type 1 (HIV-1) on lung function is well known and associated with a reduction in pulmonary ventilation. Moreover, the use of highly active antiretroviral therapy has been associated with mitochondrial dysfunction and decreased muscle strength. However, there is scarce information about the factors associated with inspiratory muscle weakness in these patients. OBJECTIVE: the purpose of the present study was to investigate the factors associated with inspiratory muscle weakness in patients with HIV-1. METHODS: two-hundred fifty seven patients with HIV-1 were screened and categorized into two groups: (1) IMW+ (n=142) and (2) IMW- (n=115). Lung function (FEV1, FVC and FEV1/FVC), maximum inspiratory pressure, distance on the six-minute walk test and CD4 cell count were assessed. RESULTS: the mean duration of HIV infection was similar in the two groups. The following variables were significantly different between groups: mean duration of highly active antiretroviral therapy (81±12 in IMW+ versus 38±13 months in IMW-; p=0.01), and CD4 cell count (327±88 in IMW+ versus 637±97cells/mm(3) in IMW-; p=0.02). IMW+ presented reduced lung function (FEV1, FVC, FEV1/FVC). CONCLUSION: patients with IMW+ had lower distance on the six-minute walk test in comparison to the IMW- group. The duration of highly active antiretroviral therapy, distance traveled on the 6MWT and CD4 count were determinants of IMW in patients with HIV.

Sympathetic ganglion transcutaneous electrical nerve stimulation after coronary artery bypass graft surgery improves femoral blood flow and exercise tolerance.

We tested the hypothesis that transcutaneous electrical nerve stimulation (TENS) over the stellate ganglion region would reduce sympathetic overstimulation and improve femoral blood flow (FBF) after coronary artery bypass graft surgery. Thirty-eight patients (20 men, 24 New York Heart Association class III-IV) were randomized to 5-day postoperative TENS (n = 20; 4 times/day; 30 min/session) or sham TENS (n = 18) applied to the posterior cervical region (C7-T4). Sympathetic nervous system was stimulated by the cold pressor test, with FBF being measured by ultrasound Doppler. Femoral vascular conductance (FVC) was calculated as FBF/mean arterial pressure (MAP). Six-min walking distance established patients' functional capacity. Before and after the intervention periods, pain scores, opiate requirements, and circulating ß-endorphin levels were determined. As expected, preoperative MAP increased and FBF and FVC decreased during the cold pressor test. Sham TENS had no significant effect on these variables (P > 0.05). In contrast, MAP decreased in the TENS group (125 ± 12 vs. 112 ± 10 mmHg). This finding, in association with a consistent increase in FBF (95 ± 5 vs. 145 ± 14 ml/min), led to significant improvements in FVC (P < 0.01). Moreover, 6-min walking distance improved only with TENS (postsurgery-presurgery = 35 ± 12 vs. 6 ± 10 m; P < 0.01). TENS was associated with lesser postoperative pain and opiate requirements but greater circulating ß-endorphin levels (P < 0.05). In conclusion, stellate ganglion TENS after coronary artery bypass graft surgery positively impacted on limb blood flow during a sympathetic stimulation maneuver, a beneficial effect associated with improved clinical and functional outcomes.

Neuromuscular electrical stimulation improves clinical and physiological function in COPD patients.

BACKGROUND: Neuromuscular electrical stimulation (NMES) improves muscle performance and exercise tolerance in chronic obstructive pulmonary disease (COPD) patients. In contrast, no study has assessed the effect of NMES on dynamic hyperinflation (DH) in COPD. This study investigated the effect of short-term, high-frequency NMES on DH in patients with COPD. METHODS: Twenty patients were randomly allocated to either a NMES applied bilaterally to the quadriceps muscles (n = 11: 8 weeks, 5 days/week, twice/day, 45 min/session) or a control group (n = 09). All patients received respiratory physical therapy and stretching exercises. Free fat mass, pulmonary function, time to exercise tolerance (Tlim), 6-min walk test distance (6-MWTD), tumor necrosis factor (TNF-α) and ß-endorphin levels, Borg dyspnea and leg score (BDS and BLS) and quality of life by the St. George's Respiratory Questionnaire score (SGRQ) were examined before and after the intervention. RESULTS: Compared with the control group, NMES increased FEV1 and FEV1/FVC, 6-MWD and Tlim (P < 0.01) and reduced BDS and SGRQ (P < 0.01). Additionally, changes in the Tlim were positively correlated with respiratory improvements in FEV1 (rho = 0.48, P < 0.01). Also, NMES reduced TNF-α and increased ß-endorphin levels, compared with the control group (P < 0.001). CONCLUSION: In summary, 8 weeks of NMES promotes reduction of the perceived sensation of dyspnea during exercise in patients with COPD. This finding is accompanied by improvements in FEV1, exercise tolerance and quality of life, and DH. Interestingly, these findings may be associated with enhanced vasodilatory function and a reduction in inflammatory responses. CLINICAL TRIAL REGISTRATION: NCT01695421.

Exercise capacity in adolescent and adult patients with post infectious bronchiolitis obliterans.

BACKGROUND: Post-infectious bronchiolitis obliterans (PBO) is a chronic lung disease characterized by the persistence of continuous obstructive respiratory symptoms following an acute and severe respiratory infection in children under 3 years old. The purpose of the present study was to investigate if adolescents and adults with diagnosis of PBO have reduced aerobic capacity and identify factors related with exercise performance. METHODS: A convenience sample of 16 patients (10-23 years) that have consulted with established diagnosis of PBO in a tertiary care clinic were studied. Fourteen healthy matched subjects were selected from the community to serve as controls. They performed resting lung function tests and cycle incremental cardiopulmonary exercise tests. RESULTS: Peak aerobic capacity (peak V˙O(2)) was significantly lower in patients compared to controls (84 ± 15 vs. 101 ± 17% pred; P < 0.01). Peak V˙O(2) was correlated with rest inspiratory capacity (IC) (r = 0.60; P = 0.02) and marginally with forced expiratory volume in the first second (FEV(1)) (r = 0.45; P = 0.09). Additionally, FEV(1) was correlated with IC (r = 0.83; P < 0.01) and residual volume/total lung capacity (r = -0.91, P < 0.01). CONCLUSIONS: Adolescent and adult patients with PBO had reduced peak V˙O(2) compared to healthy controls. Peak V˙O(2) was correlated with parameters of airflow limitation and rest hyperinflation. The greater the air flow limitation (lower FEV(1)) the greater the hyperinflation, air trapping, and aerobic capacity reduction.

Interferential electrical stimulation improves peripheral vasodilatation in healthy individuals.

BACKGROUND: Interferential electrical stimulation (IES), which may be linked to greater penetration of deep tissue, may restore blood flow by sympathetic nervous modulation; however, studies have found no association between the frequency and duration of the application and blood flow. We hypothesized that 30 min of IES applied to the ganglion stellate region might improve blood flow redistribution. OBJECTIVES: The purpose of this study was to determine the effect of IES on metaboreflex activation in healthy individuals. METHOD: Interferential electrical stimulation or a placebo stimulus (same protocol without electrical output) was applied to the stellate ganglion region in eleven healthy subjects (age 25±1.3 years) prior to exercise. Mean blood pressure (MBP), heart rate (HR), calf blood flow (CBF) and calf vascular resistance (CVR) were measured throughout exercise protocols (submaximal static handgrip exercise) and with recovery periods with or without postexercise circulatory occlusion (PECO+ and PECO -, respectively). Muscle metaboreflex control of calf vascular resistance was estimated by subtracting the area under the curve when circulation was occluded from the area under the curve from the AUC without circulatory occlusion. RESULTS: At peak exercise, increases in mean blood pressure were attenuated by IES (p<0.05), and the effect persisted under both the PECO+ and PECO- treatments. IES promoted higher CBF and lower CVR during exercise and recovery. Likewise, IES induced a reduction in the estimated muscle metaboreflex control (placebo, 21±5 units vs. IES, 6±3, p<0.01). CONCLUSION: Acute application of IES prior to exercise attenuates the increase in blood pressure and vasoconstriction during exercise and metaboreflex activation in healthy subjects.

Factors associated with inspiratory muscle weakness in patients with HIV-1

Background: the impact of human immunodeficiency virus type 1 (HIV-1) on lung function is well known and associated with a reduction in pulmonary ventilation. Moreover, the use of highly active antiretroviral therapy has been associated with mitochondrial dysfunction and decreased muscle strength. However, there is scarce information about the factors associated with inspiratory muscle weakness in these patients. Objective: the purpose of the present study was to investigate the factors associated with inspiratory muscle weakness in patients with HIV-1. Methods: two-hundred fifty seven patients with HIV-1 were screened and categorized into two groups: (1) IMW+ (n = 142) and (2) IMW-(n = 115). Lung function (FEV1, FVC and FEV1 /FVC), maximum inspiratory pressure, distance on the six-minute walk test and CD4 cell count were assessed. Results: the mean duration of HIV infection was similar in the two groups. The following variables were significantly different between groups: mean duration of highly active antiretroviral therapy (81 ± 12 in IMW+ versus 38 ± 13 months in IMW-; p = 0.01), and CD4 cell count (327 ± 88 in IMW+ versus 637 ± 97 cells/mm3 in IMW-; p = 0.02). IMW+ presented reduced lung function (FEV1, FVC, FEV1/FVC). Conclusion: patients with IMW+ had lower distance on the six-minute walk test in comparison to the IMW- group. The duration of highly active antiretroviral therapy, distance traveled on the 6MWT and CD4 count were determinants of IMW in patients with HIV. .

Interferential electrical stimulation improves peripheral vasodilatation in healthy individuals

BACKGROUND: Interferential electrical stimulation (IES), which may be linked to greater penetration of deep tissue, may restore blood flow by sympathetic nervous modulation; however, studies have found no association between the frequency and duration of the application and blood flow. We hypothesized that 30 min of IES applied to the ganglion stellate region might improve blood flow redistribution. OBJECTIVES: The purpose of this study was to determine the effect of IES on metaboreflex activation in healthy individuals. METHOD: Interferential electrical stimulation or a placebo stimulus (same protocol without electrical output) was applied to the stellate ganglion region in eleven healthy subjects (age 25±1.3 years) prior to exercise. Mean blood pressure (MBP), heart rate (HR), calf blood flow (CBF) and calf vascular resistance (CVR) were measured throughout exercise protocols (submaximal static handgrip exercise) and with recovery periods with or without postexercise circulatory occlusion (PECO+ and PECO -, respectively). Muscle metaboreflex control of calf vascular resistance was estimated by subtracting the area under the curve when circulation was occluded from the area under the curve from the AUC without circulatory occlusion. RESULTS: At peak exercise, increases in mean blood pressure were attenuated by IES (p<0.05), and the effect persisted under both the PECO+ and PECO- treatments. IES promoted higher CBF and lower CVR during exercise and recovery. Likewise, IES induced a reduction in the estimated muscle metaboreflex control (placebo, 21±5 units vs. IES, 6±3, p<0.01). CONCLUSION: Acute application of IES prior to exercise attenuates the increase in blood pressure and vasoconstriction during exercise and metaboreflex activation in healthy subjects. .

Inspiratory muscle training improves blood flow to resting and exercising limbs in patients with chronic heart failure.

OBJECTIVES: We tested the hypothesis that inspiratory muscle loading could result in exaggerated peripheral vasoconstriction in resting and exercising limbs and that inspiratory muscle training (IMT) could attenuate this effect in patients with chronic heart failure (CHF) and inspiratory muscle weakness. BACKGROUND: Inspiratory muscle training improves functional capacity of patients with CHF, but the mechanisms of this effect are unknown. METHODS: Eighteen patients with CHF and inspiratory muscle weakness (maximal inspiratory pressure <70% of predicted) and 10 healthy volunteers participated in the study. Inspiratory muscle loading was induced by the addition of inspiratory resistance of 60% of maximal inspiratory pressure, while blood flow to the resting calf (CBF) and exercising forearm (FBF) were measured by venous occlusion plethysmography. For the patients with CHF, blood flow measurements as well as ultrasound determination of diaphragm thickness were made before and after a 4-week program of IMT. RESULTS: With inspiratory muscle loading, CHF patients demonstrated a more marked reduction in resting CBF and showed an attenuated rise in exercising FBF when compared with control subjects. After 4 weeks of IMT, CHF patients presented hypertrophy of the diaphragm and improved resting CBF and exercise FBF with inspiratory muscle loading. CONCLUSIONS: In patients with CHF and inspiratory muscle weakness, inspiratory muscle loading results in marked reduction of blood flow to resting and exercising limbs. Inspiratory muscle training improves limb blood flow under inspiratory loading in these patients.