Sleep profile in a population of community-dwelling nonagenarians: data from the Mugello study.

BACKGROUND: Very few studies have investigated sleep characteristics in the oldest-old individuals (aged ≥85 years) and data collected often rely on self-reported information. This study had three aims: (i) to objectively assess, using a wearable device, the sleep characteristics of a large community of oldest-old subjects; (ii) to assess differences in sleep parameters between self-reported 'good sleepers' and 'bad sleepers'; (iii) to assess whether there was a relationship between sleep parameters and cognitive status in this community-dwelling population. METHODS: There were 178 subjects (74.2% women, median age 92 years) included in the 'Mugello study', who wore an armband 24 h/day for at least two consecutive nights to estimate sleep parameters. The perceived sleep quality was assessed using the Pittsburgh Sleep Quality Index (PSQI), the cognitive status through the Mini-Mental State Examination. Continuous variables were compared between men/women, and good/bad sleepers with the independent t-test or Mann-Whitney U-test, according to data distribution. Chi-square test was used for categorical/dichotomous variables. An ordinal logistic regression model was used to study the possible association between sleep parameters and cognitive function. RESULTS: Participants spent in bed nearly 9 h, with a total sleep time of 7 h, a sleep onset latency of 17 min, and a sleep efficiency of 83%. Sleep onset latency was significantly associated with different cognitive levels when age and education level were considered. No significant difference in sleep parameters estimated using the SenseWear armband were found between poor (n = 136, 76.4%) and good sleepers (n = 42, 23.6%), identified according to the PSQI. CONCLUSIONS: In this study, actigraphic measurements revealed that subjects with a cognitive decline were more prone to increased sleep onset latency. Sleep quality assessed using the PSQI was not coherent with actigraphic measurements in this sample, supporting the need for objective measures when investigating sleep quality in the oldest-old population.

Decannulation and improvement of responsiveness in patients with disorders of consciousness.

Decannulation is a rehabilitation milestone in patients with Disorders of Consciousness (DoC). investigate the relationship between decannulation and improvement of responsiveness (IR) in DoC. 236 tracheostomized patients with severe Acquired Brain Injury and DoC admitted in the Intensive Rehabilitation Unit were retrospectively included. They received personalized interdisciplinary rehabilitation. At discharge, IR was evaluated. The association between IR and demographic/clinical data was investigated using a logistic regression analysis, both in the Unresponsive Wakefulness Syndrome (UWS) and Minimal Consciousness State (MCS) group, divided according to their Coma Recovery Scale-Revised score at admission. In the UWS group (N = 107), only decannulation was associated with IR at discharge (OR: 5.94, CI: 2.08-16.91, p = .001). In the MCS group (N = 129) time post-injury (OR: 0.983, CI: 0.97-0.99, p = .012) and decannulation were associated with IR at discharge (OR: 17.9, CI: 6.39-50.13, p < .001). Decannulation and IR were found to be strongly related, independently from the initial clinical state. While the retrospective nature of the study could not exclude that decannulation may be a consequence of a spontaneous recovery, the obtained results may disclose its potential influence on the clinical history of patients with DoC.

Decannulation After a Severe Acquired Brain Injury.

OBJECTIVE: To identify the effect of some clinical characteristics of severe acquired brain injury (sABI) patients on decannulation success during their intensive rehabilitation unit (IRU) stay. DESIGN: Nonconcurrent cohort study. SETTING: Don Gnocchi Foundation Institute. PARTICIPANTS: Patients (N=351) with sABI and tracheostomy were retrospectively selected from the database of the IRU of the Don Gnocchi Foundation Institute. MAIN OUTCOME MEASURES: Potential predictors of decannulation were screened from variables collected at admission during clinical examination, conducted by trained and experienced examiners. The association between clinical characteristics and decannulation status was investigated through a Cox regression model. Kaplan-Meier curves were then created for time-event analysis. RESULTS: Among the patients (mean age, 64.1±15.5y), 54.1% were decannulated during their IRU stay. Absence of pulmonary infections (P<.001), sepsis (P=.001), tracheal alteration at the fibrobronchoscopy examination (P=.004) and a higher Coma Recovery Scale-Revised (CRS-R) score (P<.001) or a better state of consciousness at admission (P=.001) were associated with a higher probability of decannulation. CONCLUSIONS: Fibrobronchoscopy assessment of patency of airways and accurate evaluation of the state of consciousness using the CRS-R are relevant in this setting of care to better identify patients who are more likely to have the tracheostomy tube removed. These results may help clinicians choose the appropriate timing and intensity of rehabilitation interventions and plan for discharge.

Sleep-disordered breathing and effectiveness of cardiac resynchronization therapy in heart failure patients: gender differences?

OBJECTIVES: This study evaluated heart failure (HF) patients who underwent cardiac resynchronization therapy (CRT) and who had device-documented sleep-disordered breathing (SDB). We found gender differences in acute changes in SDB due to CRT impact. BACKGROUND: SDB typically occurs in HF patients. However, the role of SDB and its response to CRT in HF patients, as well as the relation with gender are currently not fully researched. METHODS: Among 63 consecutive patients who received CRT with an SDB algorithm, 23 patients documented SDB at one-month cardiac device interrogation and represented our population. We defined a Sleep apnoea Severity SCore(SSSC), and consequently, patients were categorized to have mild, moderate, and severe sleep apnoea syndrome divided into two groups: Group-1: 18 males (78%); Group-2: 5 females (22%). We evaluated the variation of apnoea burden and CRT response based on gender differences. RESULTS: A significantly higher proportion of patients in the male group were non-responders to CRT at 12-months follow-up (p = 0.076) while in the female population 5/5 patients (100%) were responders to CRT at the same follow-up time (p = 0.021). Among Group-2 subjects, we documented a significant linear decrease in SSSC(p > 0,01) while in Group-1 the CRT effect on SSSC was variable. At 12-months follow-up, the difference in SSSC between the two groups was statistically significant (p < 0.001). CONCLUSIONS: Our study reports a correlation between CRT response and sleep apnoea burden considering gender differences. In particular, HF-women responders to CRT demonstrate a significant linear decrease in sleep apnoea burden determined through a device algorithm, when compared to a similar male population. Further research is needed to confirm these findings.

Severe obstructive sleep apnea: first screening with an implanted pacemaker.

Sleep apnea syndrome (SAS) is a chronic condition associated with cardiovascular disease. In some pacemakers, an advanced algorithm using transthoracic impedance may be used to identify SAS. This algorithm may be also a useful tool for a long-term monitoring helping physicians to optimize therapy, reducing risk factors, and improving therapeutic compliance.

Dyspnea, chest wall hyperinflation, and rib cage distortion in exercising patients with chronic obstructive pulmonary disease.

PURPOSE: Whether dyspnea, chest wall dynamic hyperinflation, and abnormalities of rib cage motion are interrelated phenomena has not been systematically evaluated in patients with chronic obstructive pulmonary disease (COPD). Our hypothesis that they are not interrelated was based on the following observations: (i) externally imposed expiratory flow limitation is associated with no rib cage distortion during strenuous incremental exercise, with indexes of hyperinflation not being correlated with dyspnea, and (ii) end-expiratory chest wall volume may either increase or decrease during exercise in patients with COPD, with those who hyperinflate being as breathless as those who do not. METHODS: Sixteen patients breathed either room air or 50% supplemental O2 at 75% of peak exercise in randomized order. We evaluated the volume of chest wall (V(cw)) and its compartments: the upper rib cage (V(rcp)), lower rib cage (V(rca)), and abdomen (V(ab)) using optoelectronic plethysmography; rib cage distortion was assessed by measuring the phase angle shift between V(rcp) and V(rca). RESULTS: Ten patients increased end-expiratory V(cw) (V(cw,ee)) on air. In seven hyperinflators and three non-hyperinflators, the lower rib cage paradoxed inward during inspiration with a phase angle of 63.4° ± 30.7° compared with a normal phase angle of 16.1° ± 2.3° recorded in patients without rib cage distortion. Dyspnea (by Borg scale) averaged 8.2 and 9 at the end of exercise on air in patients with and without rib cage distortion, respectively. At iso-time during exercise with oxygen, decreased dyspnea was associated with a decrease in ventilation regardless of whether patients distorted the rib cage, dynamically hyperinflated, or deflated the chest wall. CONCLUSIONS: Dyspnea, chest wall dynamic hyperinflation, and rib cage distortion are not interrelated phenomena.

Chest wall kinematics and breathlessness during unsupported arm exercise in COPD patients.

We hypothesised that chest wall displacement inappropriate to increased ventilation contributes to dyspnoea more than dynamic hyperinflation or dyssynchronous breathing during unsupported arm exercise (UAE) in COPD patients. We used optoelectronic plethysmography to evaluate operational volumes of chest wall compartments, the upper rib cage, lower rib cage and abdomen, at 80% of peak incremental exercise in 13 patients. The phase shift between the volumes of upper and lower rib cage (RC) was taken as an index of RC distortion. With UAE, no chest wall dynamic hyperinflation was found; sometimes the lower RC paradoxed inward while in other patients it was the upper RC. Phase shift did not correlate with dyspnoea (by Borg scale) at any time, and chest wall displacement was in proportion to increased ventilation. In conclusions neither chest wall dynamic hyperinflation nor dyssynchronous breathing per se were major contributors to dyspnoea. Unlike our prediction, chest wall expansion and ventilation were adequately coupled with each other.

Dyspnea during speech in chronic obstructive pulmonary disease patients: effects of pulmonary rehabilitation.

BACKGROUND: For patients with limited physical activities who use oral communication for most social activities, the assessment of dyspnea during speech activities (DS) may provide relevant measurement criteria. Although speech production is altered by lung disease it has not been included in current dyspnea assessment tools. OBJECTIVES: We evaluated DS in patients with chronic obstructive pulmonary disease (COPD) with the aim of assessing: (i) the responsiveness to treatment of this newly developed evaluative dyspnea tool and (ii) whether DS is an independent measurement of other traditional outcomes. METHODS: We assessed lung function, the 6-min walking test (6'WT), chronic exertional dyspnea (MRC and BDI/TDI), and DS using the speech section of the University of Cincinnati Dyspnea Questionnaire (UCDQ) before and after a pulmonary rehabilitation program in 31 patients with COPD. RESULTS: The following items of the speech section of the UCDQ caused dyspnea: conversation, raising the voice, phoning, speaking to a group, talking in a noisy place, and singing. The mean overall DS score was 60 ± 23% of a maximal potential DS score. Pulmonary rehabilitation reduced each item of DS independently of change in lung function, chronic exertional dyspnea, and 6'WT. CONCLUSIONS: We concluded that DS is responsive to a respiratory rehabilitation program in patients with COPD. Evidence of independent objective measures supports the validity of a routine multivariable assessment including DS. We recommend assessment of DS particularly for patients who rely extensively on speech for communication.

Impact of a rehabilitation program on dyspnea intensity and quality in patients with chronic obstructive pulmonary disease.

BACKGROUND: It has yet to be determined whether the language of dyspnea responds to pulmonary rehabilitation programs (PRP). OBJECTIVE: We tested the hypothesis that PRP affect both the intensity and quality of exercise-induced dyspnea in patients with chronic obstructive pulmonary disease (COPD). METHODS: We studied 49 patients equipped with a portable telemetric spiroergometry device during the 6-min walking test before and 4 weeks after PRP. In a first screening visit, appropriate verbal descriptors of dyspnea were chosen that patients were familiar with during daily living activities. Tidal volume, respiratory frequency, inspiratory capacity, inspiratory reserve volume (IRV) and dyspnea intensity were evaluated by a modified Borg scale every minute during the test. RESULTS: Qualitative descriptors of dyspnea were defined by three different sets of cluster descriptors (a-c) at the end of the exercise test, before and after PRP: a - work/effort (W/E); b - inspiratory difficulty (ID) and chest tightness (CT), and c - W/E, ID and/or CT. The three language subgroups exhibited similar lung function at baseline, and similar rating of dyspnea and ventilatory changes during exercise. The rehabilitation program shifted the Borg-IRV relationship (less Borg at any given IRV) towards the right without modifying the set of descriptors in most patients. CONCLUSIONS: Rehabilitation programs allowed patients to tolerate a greater amount of restrictive dynamic ventilatory defect by modifying the intensity, but not necessarily the quality of dyspnea.

Chest wall kinematics during voluntary cough in neuromuscular patients.

Muscular diseases are characterized by progressive loss of muscle strength, resulting in cough ineffectiveness with its deleterious effects on the respiratory system. Assessment of cough effectiveness is therefore a prominent component of the clinical evaluation and respiratory care in these patients. Owing to uneven distribution of muscle weakness in neuromuscular patients, we hypothesized that forces acting on the chest wall may impact on the compartmental distribution of gas volume resulting in a decrease in cough effectiveness. Pulmonary volumes, respiratory muscle strength, peak cough flow and chest wall kinematics by optoelectronic plethysmography were studied in 8 patients and 12 healthy subjects as controls. Chest wall volume was modeled as the sum of volumes of the rib cage and abdomen. The plot of the volumes of upper to lower rib cage allowed assessment of rib cage distortion. Unlike controls, patients were unable to reduce end-expiratory chest wall volume, and exhibited greater rib cage distortion during cough. Peak cough flow was negatively correlated with rib cage distortion (the greater the former, the smaller the latter), but not with respiratory muscle strength. In conclusion, insufficient deflation of chest wall compartments and marked rib cage distortion resulted in cough ineffectiveness in these neuromuscular patients.

Chest wall kinematics and Hoover's sign.

BACKGROUND: No attempt has been made to quantify the observed rib cage distortion (Hoover's sign) in terms of volume displacement. We hypothesized that Hoover's sign and hyperinflation are independent quantities. METHODS: Twenty obstructed stable patients were divided into two groups according to whether or not they exhibited Hoover's sign during clinical examination while breathing quietly. We evaluated the volumes of chest wall and its compartments: the upper rib cage, the lower rib cage and the abdomen, using optoelectronic plethysmography. RESULTS: The volumes of upper rib cage, lower rib cage and abdomen as a percentage of absolute volume of the chest wall were similar in patients with and without Hoover's sign. In contrast, the tidal volume of the chest wall, upper rib cage, lower rib cage, their ratio and abdomen quantified Hoover's sign, but did not correlate with level of hyperinflation. CONCLUSIONS: Rib cage distortion and hyperinflation appear to define independently the functional condition of these patients.

Inhaled furosemide does not alleviate respiratory effort during flow-limited exercise in healthy subjects.

Expiratory muscle loading results in increased perception of respiratory effort; this response is mediated by non-vagal reflexes originating in the chest wall. Furosemide, due to its vagal effect, might not affect the perception of respiratory effort during expiratory flow-limited incremental exercise. In this study, we compared in nine healthy subjects the following determinants of exercise performance such as respiratory effort (Borg), workload (W'), ventilation (V'E), tidal volume (VT), respiratory frequency (f), and mean inspiratory flow (VT/TI), an index of central respiratory drive, during either standard incremental cycling exercise, or expiratory flow-limited incremental exercise. In addition we examined the effect of inhaled placebo, furosemide (40 or 80 mg) on the perception of respiratory effort following standard incremental cycling exercise and expiratory flow-limited incremental exercise. Compared with standard incremental cycling exercise, expiratory flow-limited incremental exercise increased the Borg score and VT/Ti, and decreased W',V'E ,VT, and f in all subjects at iso-workload. Neither placebo nor furosemide modified peak ventilatory variables, slopes, or intercepts of the relationships of the Borg score with W', V'E, VT/TI and VT during expiratory flow-limited incremental exercise. We conclude that (a) compared with standard incremental exercise, expiratory flow limited exercise increases central respiratory drive and perception of respiratory effort, and (b) furosemide does not affect the sensation of respiratory effort under the present conditions of increased drive to the respiratory muscles.

Optoelectronic Plethysmography has Improved our Knowledge of Respiratory Physiology and Pathophysiology.

It is well known that the methods actually used to track thoraco-abdominal volume displacement have several limitations. This review evaluates the clinical usefulness of measuring chest wall kinematics by optoelectronic plethysmography [OEP]. OEP provides direct measurements (both absolute and its variations) of the volume of the chest wall and its compartments, according to the model of Ward and Macklem, without requiring calibration or subject cooperation. The system is non invasive and does not require a mouthpiece or nose-clip which may modify the pattern of breathing, making the subject aware of his breathing. Also, the precise assessment of compartmental changes in chest wall volumes, combined with pressure measurements, provides a detailed description of the action and control of the different respiratory muscle groups and assessment of chest wall dynamics in a number of physiological and clinical experimental conditions.

Patterns of chest wall kinematics during volitional pursed-lip breathing in COPD at rest.

BACKGROUND: Analysis of chest wall kinematics can contribute to identifying the reasons why some patients benefit from pursed-lip breathing (PLB). MATERIAL AND METHODS: We evaluated the displacement of the chest wall and its compartments, the rib cage and abdomen, by optoelectronic plethysmography (OEP), during supervised PLB maneuver in 30 patients with mild to severe chronic obstructive pulmonary disease (COPD). RESULTS: OEP showed two different patterns. A first pattern characterized the 19 most severely obstructed and hyperinflated patients in whom PLB decreased end-expiratory volumes of the chest wall and abdomen, and increased end-inspiratory volumes of the chest wall and rib cage. Deflation of the abdomen and inflation of the rib cage contributed to increasing tidal volume of the chest wall. The second pattern characterized 11 patients in whom, compared to the former group, PLB resulted in the following: (i) increased end-expiratory volume of the rib cage and chest wall, (ii) greater increase in end-inspiratory volume of the rib cage and abdomen, and (iii) lower tidal volume of the chest wall. In the patients as a whole changes in end-expiratory chest wall volume were related to change in Borg score (r(2)=0.5, p<0.00002). CONCLUSIONS: OEP helps identifying the reason why patients with COPD may benefit from PLB at rest.

Exercise dyspnea in patients with COPD.

Dyspnea, a symptom limiting exercise capacity in patients with COPD, is associated with central perception of an overall increase in central respiratory motor output directed preferentially to the rib cage muscles. On the other hand, disparity between respiratory motor output, mechanical and ventilatory response of the system is also thought to play an important role on the increased perception of exercise in these patients. Both inspiratory and expiratory muscles and operational lung volumes are important contributors to exercise dyspnea. However, the potential link between dyspnea, abnormal mechanics of breathing and impaired exercise performance via the circulation rather than a malfunctioning ventilatory pump per se should not be disregarded. Change in arterial blood gas content may affect dyspnea via direct or indirect effects. An increase in carbon dioxide arterial tension seems to be the most important stimulus overriding all other inputs from dyspnea in hypercapnic COPD patients. Hypoxia may act indirectly by increasing ventilation and indirectly independent of changes in ventilation. A greater treatment effect is often achieved after the addition of pulmonary rehabilitation with pharmacological treatment.

Dyspnea during exercise in hyperbaric conditions.

INTRODUCTION: Length-tension and force-velocity characteristics of respiratory muscles and hyperinflation are the likely determinants of dyspnea in subjects exercising under hyperbaric conditions. We hypothesize that hyperinflation plays a minor role and that the reduced velocity of shortening of the respiratory muscles modulates dyspnea for any given pleural pressure. METHODS: We studied five normal subjects who performed an incremental exercise test on a cycloergometer in both normobaric (SL) and hyperbaric (4 ATA) conditions. We measured breathing pattern, inspiratory pleural pressure swing (Pessw), Delta Pes (i.e., the difference between the most and the less negative pleural pressures during tidal breathing), and dyspnea intensity (Borg score). End-expiratory lung volume (EELV) changes were evaluated by measuring changes in inspiratory capacity. Mean inspiratory flow (VT/TI) was used as an index of velocity of shortening of respiratory muscles. RESULTS: Compared with SL, at 4 ATA, peak exercise ventilation (VE) (84.5 vs 62.2 L x min(-1)) and VT/TI (2.99 vs 2.16 L x s)(-1) were lower, Pessw (30.9 vs 38.6 cm H2O) and Delta Pes (43.8 vs 62.2 cm H2O) were higher, and Borg score was not different (7.60 vs 8.20 au). EELV decreased progressively during exercise but remained higher than at SL. Borg score was greater for a same VE and lower for a same Delta Pes. VT/TI was lower for a same Pessw. The differences in EELV between SL and 4 ATA did not relate with the concurrent changes in Borg score. CONCLUSION: The results confirm our hypothesis that during exercise in hyperbaric conditions, decreased velocity of shortening of respiratory muscles modulates pressure-induced increases in dyspnea, with hyperinflation playing a minor role.

Is there a link between the qualitative descriptors and the quantitative perception of dyspnea in asthma?

BACKGROUND: There is no obvious link between qualitative descriptors and overall intensity of dyspnea during bronchoconstriction in patients with asthma. AIMS: To determine whether qualitative and quantitative perception of methacholine-induced bronchoconstriction independently contribute to characterizing clinically stable asthma. MATERIAL AND METHODS: We assessed changes in inspiratory capacity, and quantitative (by Borg scale) and qualitative (by a panel of eight dyspnea descriptors) sensations of dyspnea at 20 to 30% fall in FEV(1) during methacholine inhalation in 49 asthmatics. Furthermore, we calculated the level of perception of bronchoconstriction at 20% fall in FEV(1) (PB(20)). RESULTS: Descriptors selected by patients during methacholine inhalation allowed us to define three language subgroups: (1) chest tightness (subgroup A, n = 21); (2) work/effort (subgroup B, n = 7); and (3) both descriptors (subgroup C, n = 13). Eight of the 49 patients (subgroup D) were not able to make a clear-cut distinction among descriptors. The subgroups exhibited similar function at baseline and during methacholine inhalation. Most importantly, patients selected chest tightness to a greater extent (42.85%), and work/effort (14.3%) and both descriptors (26.5%) to a lesser extent at the lowest level of bronchoconstriction (FEV(1) fall < 10%) as at 20% fall in FEV(1). Thirty-two patients were normoperceivers (PB(20) > or = 1.4 to < 5 arbitrary units [au]), 7 patients were hyperperceivers (PB(20) > or = 5 au), and 10 patients were hypoperceivers (PB(20) < 1.4 au). Language subgroups were equally distributed across the perceiver subgroups. CONCLUSIONS: In patients with clinically stable asthma, PB(20) and language of dyspnea independently contribute to defining the condition of the disease. However, the possibility that this independence may be due to a beta-error should be taken into account.

Perception of airway obstruction and airway inflammation in asthma: a review.

Dyspnea has a multifactorial nature and the exact mechanism that causes breathlessness in asthma is not fully understood. There is compelling evidence that factors other than merely mechanical ones take part in the pathophysiology of breathlessness. Some recent reports attribute airway inflammation, which may contribute to the unexplained variability in the perception of dyspnea associated with bronchoconstriction. Eosinophil airway inflammation has been proposed as a determinant of breathlessness via mechanisms affecting either the mechanical pathways that control breathlessness or the afferent nerves involved in perception of dyspnea. In this review, data on the interrelation between inflammation and dyspnea sensation and the impact of treatment on dyspnea sensation are discussed. We conclude that regardless of whether mechanical or chemical inflammatory factors are involved, much variability in dyspnea scores remains unexplained.

Exercise training improves exertional dyspnea in patients with COPD: evidence of the role of mechanical factors.

BACKGROUND: To our knowledge, no data have been reported on the effects of exercise training (EXT) on central respiratory motor output or neuromuscular coupling (NMC) of the ventilatory pump, and their potential association with exertional dyspnea. Accurate assessment of these important clinical outcomes is integral to effective management of breathlessness of patients with COPD. MATERIAL AND METHODS: Twenty consecutive patients with stable moderate-to-severe COPD were tested at 6-week intervals at baseline, after a nonintervention control period (pre-EXT), and after EXT. Patients entered an outpatient pulmonary rehabilitation program involving regular exercise on a bicycle. Incremental symptom-limited exercise testing (1-min increments of 10 W) was performed on an electronically braked cycle ergometer. Oxygen uptake (O(2)), carbon dioxide output (CO(2)), minute ventilation (E), time, and volume components of the respiratory cycle and, in six patients, esophageal pressure swings (Pessw), both as actual values and as percentage of maximal (most negative in sign) esophageal pressure during sniff maneuver (Pessn), were measured continuously over the runs. Exertional dyspnea and leg effort were evaluated by administering a Borg scale. RESULTS: Measurements at baseline and pre-EXT were similar. Significant increase in exercise capacity was found in response to EXT: (1) peak work rate (WR), O(2), CO(2), E, tidal volume (VT), and heart rate increased, while peak exertional dyspnea and leg effort did not significantly change; (2) exertional dyspnea/O(2) and exertional dyspnea/CO(2) decreased while E/O(2) and E/CO(2) remained unchanged. The slope of both exertional dyspnea and leg effort relative to E fell significantly after EXT; (3) at standardized WR, E, and CO(2), exertional dyspnea and leg effort decreased while inspiratory capacity (IC) increased. Decrease in E was accomplished primarily by decrease in respiratory rate (RR) and increase in both inspiratory time (TI) and expiratory time; VT slightly increased, while inspiratory drive (VT/TI) and duty cycle (TI/total time of the respiratory cycle) remained unchanged. The decrease in Pessw and the increase in VT were associated with lower exertional dyspnea after EXT; (4) at standardized E, VT, RR, and IC, Pessw and Pessw(%Pessn)/VT remained unchanged while exertional dyspnea and leg effort decreased with EXT. CONCLUSION: In conclusion, increases in NMC, aerobic capacity, and tolerance to dyspnogenic stimuli and possibly breathing retraining are likely to contribute to the relief of both exertional dyspnea and leg effort after EXT.