Prevalence of limb muscle dysfunction in patients with chronic obstructive pulmonary disease admitted to a pulmonary rehabilitation centre.

OBJECTIVE: Assessment of needle electromyography (nEMG) may complement previous data on limb muscle dysfunction (LMD) in patients with chronic obstructive pulmonary disease (COPD). We attempted to quantify the prevalence of LMD and assess its impact on clinical outcomes in patients admitted to a rehabilitation programme. METHODS: One hundred and thirty-two clinically stable patients were consecutively enrolled. They underwent spirometry and the following primary outcomes were evaluated: St. George respiratory questionnaire (SGRQ), functional independence measure (FIM) questionnaire and a 6-min walking test (6MWT). One hundred and fourteen patients underwent nEMG. The frequency of LMD was related to COPD stage and chronic dyspnoea. RESULTS: nEMG detected myopathic signs in 36.8% of the patients. LMD was found even in early stages of COPD. FIM and 6MWT were significantly lower, and SGRQ tended to be higher at each COPD stage in patients with LMD. However, the 6MWT rate of decay across the COPD stages was similar in patients with and without LMD. CONCLUSIONS: LMD might not be restricted to patients with severe airway obstruction and regardless of COPD stage, contributes to functional limitation of these patients. SIGNIFICANCE: The putative role of LMD in motor limitations indicates the need to assess it early onto better organise a specific training programme as part of general pulmonary rehabilitation in COPD patients.

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.

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.

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.

Arm exercise and hyperinflation in patients with COPD: effect of arm training.

BACKGROUND: Unlike studies on leg exercise, reports on the regulation of dynamic hyperinflation during arm exercise are scanty. We ascertained the following in patients with COPD: (1) whether and to what extent upper-limb exercise results in dynamic hyperinflation, and (2) the mechanism whereby an arm-training program (ATP) reduces arm effort and dyspnea. PATIENTS: Twelve patients with moderate-to-severe COPD were tested during incremental, symptom-limited arm exercise after a non-intervention control period (pre-ATP) and after ATP. METHODS: Exercise testing (1-min increments of 5 W) was performed using an arm ergometer. Oxygen uptake (V(O2)), carbon dioxide output, minute ventilation (Ve), tidal volume, and respiratory rate (RR) were measured continuously during the tests. Inspiratory capacity (IC), exercise dyspnea, and arm effort using a Borg scale were assessed at each step of exercise. RESULTS: Arm exercise resulted in a significant decrease in IC and significant positive relationships of IC with an increase in V(O2) and exercise dyspnea and arm effort. The results of ATP were as follows: (1) a significant increase in exercise capacity (p < 0.001); (2) no change in the relationships of exercise dyspnea and arm effort with Ve and IC, and of IC with V(O2); (3) at a standardized work rate, Ve, exercise dyspnea, and arm effort significantly decreased, while the decrease in IC was significantly less (p < 0.01) than before the ATP; the decrease in Ve was accomplished primarily by a decrease in RR; and (4) at standardized Ve, exercise dyspnea and arm effort decreased significantly. CONCLUSIONS: Arm exercise results in the association of dynamic hyperinflation, exercise dyspnea, and arm effort in COPD patients. An ATP increases arm endurance, modulates dynamic hyperinflation, and reduces symptoms.

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.

Chest wall kinematics in patients with hemiplegia.

Owing to difficulties in measuring ventilation symmetry, good evidence of different right/left respiratory movements has not yet been provided. We investigated VT differences between paretic and healthy sides during quiet breathing, voluntary hyperventilation, and hypercapnic stimulation in patients with hemiparesis. We studied eight patients with hemiparesis and nine normal sex- and age-matched subjects. Right- and left-sided VT was reconstructed using optoelectronic plethysmography. In control subjects, no asymmetry was found in the study conditions. VTs of paretic and healthy sides were similar during quiet breathing, but paretic VT was lower during voluntary hyperventilation in six patients and higher during hypercapnic stimulation in eight patients (p = 0.02). The ventilatory response to hypercapnic stimulation was higher on the paretic than on the healthy side (p = 0.012). In conclusion, hemiparetic stroke produces asymmetric ventilation with an increase in carbon dioxide sensitivity and a decrease in voluntary ventilation on the paretic side.

Dissociation between respiratory effort and dyspnoea in a subset of patients with stroke.

Dyspnoea is not a prominent complaint of resting patients with recent hemispheric stroke (RHS). We hypothesized that, in patients with RHS presenting abnormalities in respiratory mechanics, increased respiratory motor output could translate into an increased perception of dyspnoea. We studied eight wheelchair-bound patients with RHS (mean age 62.4 years), previously evaluated by computerized tomography scanning, and a control group of normal subjects, matched for age and sex. We assessed routine spirometry, inspiratory and expiratory muscle pressures, breathing pattern and dyspnoea using a modified Borg scale. In six patients, we also measured oesophageal pressure during the maximal sniff manoeuvre and tidal inspiratory swing, and mechanical characteristics of the lung in terms of dynamic elastance during both quiet breathing and a hypercapnic/hyperoxic rebreathing test. During room air breathing, ventilation and tidal volume were similar in patients and controls, while tidal inspiratory swings of oesophageal pressure, an index of inspiratory motor output, were greater in patients ( P =0.005). Patients also exhibited a greater dynamic elastance ( P =0.013). During rebreathing, dynamic elastance remained higher ( P =0.01) and a greater than normal inspiratory motor output was found ( P =0.03). Responses of ventilation and tidal volume to carbon dioxide tension were normal, and in all patients but one a lower Borg score for the unit change in carbon dioxide tension and ventilation was found. In conclusion, a higher than normal inspiratory motor output was unexpectedly associated with a blunted perception of dyspnoea in this subset of RHS patients. This is likely to be due to the modulation of the integration process of respiratory sensation.