Purpose: To evaluate the concordance between the value of the actual maximum voluntary ventilation (MVV) and the estimated value by multiplying the forced expiratory volume in the first second (FEV₁) and a different value established in the literature. Methods: A retrospective study was conducted with healthy subjects and patients with stable chronic obstructive pulmonary disease (COPD). Five prediction formulas MVV were used for the comparison with the MVV values. Agreement between MVV measured and MVV obtained from five prediction equations were studied. FEV₁ values were used to estimate MVV. Correlation and agreement analysis of the values was performed in two groups using the Pearson test and the Bland–Altman method; these groups were one group with 207 healthy subjects and the second group with 83 patients diagnosed with COPD, respectively. Results: We recruited 207 healthy subjects (105 women, age 47 ± 17 years) and 83 COPD patients (age 66 ± 6 years; 29 GOLD II, 30 GOLD III, and 24 GOLD IV) for the study. All prediction equations presented a significant correlation with the MVV value (from 0.38 to 0.86, p < 0.05) except for the GOLD II subgroup, which had a poor agreement with measured MVV. In healthy subjects, the mean difference of the value of bias (and limits of agreement) varied between -3.9% (-32.8 to 24.9%), and 27% (-1.4 to 55.3%). In COPD patients, the mean difference of value of bias (and limits of agreement) varied between -4.4% (-49.4 to 40.6%), and 26.3% (-18.3 to 70.9%). The results were similar in the subgroup analysis. Conclusion: The equations to estimate the value of MVV present a good degree of correlation with the real value of MVV, but they also show a poor concordance. For this reason, we should not use the estimated results as a replacement for the real value of MVV.

The expansion of the rib cage and abdomen occurs in a synchronic way during a coordinated contraction of the diaphragm and the abdominal and intercostal muscles under normal conditions and healthy. The presence of restrictive respiratory disease may lead to uncoordinated action of the respiratory muscles which affects breathing pattern and chest wall volumes. The aim of this study was to evaluate chest wall volumes, chest wall asynchrony and inspiratory paradoxical movement of breathing, as well as the influence of the time of disease diagnosis in subjects with Parkinson’s disease and post-Stroke in comparison to healthy individuals. Total and compartmental chest wall volumes, chest wall asynchrony and paradoxical movement were measured at rest in a seated position by Optoelectronic Plethysmography in 76 individuals (29 healthy individuals, 20 post-Stroke and 27 Parkinson’s disease subjects). Post-stroke and Parkinson’s disease subjects were also grouped according to the length of diagnosis. In both groups with restrictive respiratory disease we observed that pulmonary rib cage compartment (V_RCp) volume is reduced when compared to healthy subjects (p <0.05). This same pattern was observed when analyzing post-stroke subjects with more than three years of diagnosis and Parkinson’s subjects with less than three years of diagnosis (p<0.05). Furthermore, post-stroke subjects with inspiratory paradoxical movement showed decreased total and compartmental chest wall volumes (p<0.05), while individuals with Parkinson’s disease with inspiratory paradoxical movement only presented a decrease in pulmonary rib cage compartment volume (p<0.05). Our study presents new findings for better understanding of chest wall volumes and chest wall asynchrony in post-stroke and Parkinson’s disease individuals. Half of the subjects with post-Stroke and Parkinson’s disease presented inspiratory paradox movement, but changes in breathing pattern was especially observed in post-stroke subjects with more than three years of diagnosis.

BACKGROUND: Air stacking (AS) is a lung insufflation method that requires the use of a manual insufflator to provide air volumes higher than inspiratory capacity. Neuromuscular patients benefit the most from the maneuver; however, the acute effects of AS in healthy subjects are still unclear. METHODS: Twenty healthy subjects (8 males) were studied by optoelectronic plethysmography to investigate the immediate effects of AS on cough peak flow, operational volume variations, distribution of these volumes in the chest wall compartments (pulmonary rib cage, abdominal rib cage, and abdominal), breathing pattern, and shortening velocity of the respiratory muscles during a protocol that included vital capacity maneuvers and spontaneous coughs before and after AS. RESULTS: Statistically significant increases in cough peak flow ( P < .03) and inspiratory capacity ( P < .001) were found immediately after AS. During its application, the pulmonary rib cage compartment was the largest contributor ( P = .002) to chest wall volume displacement. A significant increase in chest wall tidal volume ( P < .001), mainly in the pulmonary rib cage ( P < .001), was observed. Significant increases ( P < .001) in end-inspiratory chest wall volume were observed with main distribution in pulmonary ( P < .001) and abdominal rib cage ( P = .01). Significant increases in shortening velocity index of inspiratory muscles ( P < .001), expiratory muscles ( P < .001), and diaphragm ( P < .001) were also observed. In addition, significant decreases in expiratory time ( P < .001) and increases in duty cycle ( P = .02), breathing frequency ( P = .02), minute ventilation ( P < .001), maximum inspiratory ( P < .001), and expiratory flow ( P < .001) were observed. CONCLUSIONS: In healthy subjects, cough peak flow and chest wall volumes can be increased immediately after the application of the AS maneuver.

To evaluate sensitivity/specificity of the maximum relaxation rate (MRR) of inspiratory muscles, amplitude of electromyographic activity of the sternocleidomastoid (SCM), scalene (SCA), parasternal (2^ndIS) and rectus abdominis (RA) muscles; lung function and respiratory muscle strength in subjects with Myotonic dystrophy type 1 (DM₁) compared with healthy subjects. Quasi-experimental observational study with control group. MRR of inspiratory muscles, lung function and amplitude of the electromyographic activity of SCM, SCA, 2^ndIS and RA muscles during maximum inspiratory pressure (PImax), maximum expiratory pressure (PEmax) and sniff nasal inspiratory pressure (SNIP) tests were assessed in eighteen DM₁ subjects and eleven healthy. MRR was lower in DM₁ group compared to healthy (P = 0.001) and was considered sensitive and specific to identify disease in DM₁ and discard it in controls, as well as SNIP% (P = 0.0026), PImax% (P = 0.0077) and PEmax% (P = 0.0002). Contraction time of SCM and SCA was higher in DM₁ compared to controls, respectively, during PImax (P = 0.023 and P = 0.017) and SNIP (P = 0.015 and P = .0004). The DM₁ group showed lower PImax (P = .0006), PEmax (P = 0.0002), SNIP (P = 0.0014), and higher electromyographic activity of the SCM (P = 0.002) and SCA (P = 0.004) at rest; of 2^ndIS (P = 0.003) during PEmax and of SCM (P = 0.02) and SCA (P = 0.03) during SNIP test. MD₁ subjects presented restrictive pattern, reduced respiratory muscle strength, muscular electrical activity and MRR when compared to higher compared to controls. In addition, the lower MRR found in MD₁ subjects showed to be reliable to sensitivity and specificity in identifying the delayed relaxation of respiratory muscles.