Breathing pattern and chest wall kinematics during phonation in chronic obstructive pulmonary disease patients.

BACKGROUND: Breathing pattern description and chest wall kinematics during phonation have not been studied in male and female patients with chronic obstructive pulmonary disease. OBJECTIVES: We used optoelectronic plethysmography to provide a quantitative description of breathing pattern and chest wall kinematics. METHODS: Volumes of chest wall compartments (rib cage and abdomen) were assessed in 15 patients while reading aloud (R), singing (SI) and during high-effort whispering (HW). RESULTS: Relative to quiet breathing, tidal volume and expiratory time increased while inspiratory time decreased. The expiratory flow decreased during R and SI, but was unchanged during HW. In males, the end-expiratory volume decreased as a result of a decreased volume of rib cage during R, SI and HW and due to a decreased volume of abdomen during HW. In females, a decrease in end-expiratory volume was accomplished by a decrease in abdominal volume during R and HW. During R, the chest wall end-expiratory volume of the last expiration in females was to the left of the maximal expiratory flow volume curve (MEFV), with still substantial expiratory reserve volume available. In contrast, during SI and HW in females and during all types of phonation in males, chest wall end-expiratory volume of the last expiration was well to the right of the MEFV curve and associated with respiratory discomfort. Gender had a greater importance than physical characteristics in determining more costal breathing in females than in males under all conditions studied. CONCLUSIONS: Phonation imposes more abdominal breathing pattern changes in males and costal changes in females. Expiratory flow encroaches upon the MEFV curve with higher phonatory efforts and respiratory discomfort.

Effects of unsupported arm training on arm exercise-related perception in COPD patients.

We hypothesized that arm training might affect unsupported arm exercise-related perception by decreasing motor output to arm/torso muscles in patients with chronic obstructive pulmonary disease (COPD). Eleven patients were studied at 80% of peak incremental arm exercise, before and after unsupported arm training. Training increased endurance time, decreased respiratory effort and much more arm effort (by Borg scale) without affecting chest wall dynamic hyperinflation or configuration. Ventilatory response to carbon dioxide output was the same before and after training so that at isotime the reduction in ventilation correlated strongly with a simultaneous reduction in metabolic output. These changes reflect a reduced ventilatory drive. We conclude that: (i) a reduced level of ventilation, relative to a decrease in central motor output, is the contribution of arm training to symptom alleviation during unsupported arm exercise in COPD patients, and (ii) arm training improved patients' exercise-related perception without affecting chest wall operational volumes or configuration.

Effects of the Nuss procedure on chest wall kinematics in adolescents with pectus excavatum.

No data are available on the effects of the Nuss procedure on volumes of chest wall compartments (the upper rib cage, lower rib cage and abdomen) in adolescents with pectus excavatum. We used optoelectronic plethysmography to provide a quantitative description of chest wall kinematics before and 6 months after the Nuss procedure at rest and during maximal voluntary ventilation in 13 subjects with pectus excavatum. An average 11% increase in chest wall volume was accommodated within the upper rib cage (p=0.0001) and to a lesser extent within the abdomen and lower rib cage. Tidal volumes did not significantly change during the study. The repair effect on chest wall kinematics did not correlate with the Haller index of deformity at baseline. Six months of the Nuss procedure do increase chest wall volume without affecting chest wall displacement and rib cage configuration.

Chest wall kinematics in young subjects with Pectus excavatum.

Quantifying chest wall kinematics and rib cage distortion during ventilatory effort in subjects with Pectus excavatum (PE) has yet to be defined. We studied 24 patients: 19 during maximal voluntary ventilation (MVV) and 5 during MVV and cycling exercise (CE). By optoelectronic plethysmography (OEP) we assessed operational volumes in upper rib cage, lower rib cage and abdomen. Ten age-matched healthy subjects served as controls. Patients exhibited mild restrictive lung defect. During MVV end-inspiratory and end-expiratory volumes of chest wall compartments increased progressively in controls, whereas most patients avoided dynamic hyperinflation by setting operational volumes at values lower than controls. Mild rib cage distortion was found in three patients at rest, but neither in patients nor in controls did MVV or CE consistently affect coordinated motion of the rib cage. Rib cage displacement was not correlated with a CT-scan severity index. Conclusions, mild rib cage distortion rarely occurs in PE patients with mild restrictive defect. OEP contributes to clinical evaluation of PE patients.

Role of hyperinflation vs. deflation on dyspnoea in severely to extremely obese subjects.

AIM: To test the hypothesis that obese individuals may either hyperinflate or deflate the lung when exercising. In both cases breathlessness is an inescapable consequence. METHODS: Ventilatory variables, end-expiratory lung volume and end-inspiratory lung volume, and dyspnoea score (Borg scale) were studied in 20 class II-III obese subjects and 14 healthy controls during incremental symptom-limited cycle exercise. RESULTS: Ventilation increased with increasing work rate, in obese and in control subjects; most obese subjects had to increase end-expiratory lung volume to escape from flow limitation; in contrast, like controls, a few subjects deflated the lung on heavy-to-peak exercise. Dyspnoea was equal in degree at anaerobic threshold and peak exercise in obese as in control subjects, and in obese who hyperinflated as in those who deflated the lung. In particular, end-expiratory lung volume at baseline (r = -0.84, P = 0.04) was negatively correlated with changes in Borg score in obese who did not hyperinflate: the lower the former the higher the latter. On the other hand, tidal volume (r = 0.54, P = 0.045) and decrease in inspiratory reserve volume (r = 0.59, P = 0.028) were positively correlated with the Borg score in obese subjects who hyperinflated. No other independent variable correlated with the Borg score. CONCLUSIONS: We conclude that not all obese subjects had to increase end-expiratory lung volume on heavy-to-peak exercise. Changes in dyspnoea for unit changes in ventilation were similar in obese who did hyperinflate as well as in those who did not, suggesting that the increase in respiratory neural drive, associated with an increase in ventilation, is an important source of dyspnoea in obese as well as in control subjects.

Chest wall kinematics during cough in healthy subjects.

AIM: The study of kinematics of the chest wall (CW) could allow us to define the relative deflationary contribution of its compartments during fits of coughing. We hypothesized that if forces applied to the lung apposed rib cage are not commensurate with those applied to the abdomen-apposed rib cage, cough could result in rib cage distortion. METHODS: In 12 (five women) healthy subjects we evaluated the volumes of CW (Vcw) and its compartments: the lung apposed rib cage, the abdomen apposed rib cage and the abdomen, by optoelectronic plethysmography. The loop of volume of the lung apposed rib cage/volume of the abdomen apposed rib cage allowed the calculation of mean rib cage distortion, resulting in a dimensionless number which, when multiplied by 100, gives percentage distortion. Each subject performed voluntary single and prolonged coughing efforts at functional residual capacity (FRC) and after maximal inspiration (max). The normal level of mean distortion was set at <0.5%. RESULTS: The three compartments contributed to reducing end-expiratory Vcw during cough at FRC and prolonged maximum cough, with the latter resulting in the greatest CW deflation. Mean rib cage distortion did not differ between men and women (P > 0.1), but tended to significantly increase from single to prolonged Cough Max (1.3% +/- 1.0 vs. 2.3% +/- 1.6, respectively; P = 0.06). CONCLUSION: Rib cage distortion may ensue during coughing, probably as a result of uneven distribution of forces applied to the rib cage.

Chest wall kinematics, respiratory muscle action and dyspnoea during arm vs. leg exercise in humans.

AIM: We hypothesize that different patterns of chest wall (CW) kinematics and respiratory muscle coordination contribute to sensation of dyspnoea during unsupported arm exercise (UAE) and leg exercise (LE). METHODS: In six volunteer healthy subjects, we evaluated the volumes of chest wall (V(cw)) and its compartments, the pulmonary apposed rib cage (V(rc,p)), the diaphragm-abdomen apposed rib cage (V(rc,a)) and the abdomen (V(ab)), by optoelectronic plethysmography. Oesophageal, gastric and trans-diaphragmatic pressures were simultaneously measured. Chest wall relaxation line allowed the measure of peak rib cage inspiratory muscle, expiratory muscle and abdominal muscle pressures. The loop V(rc,p)/V(rc,a) allowed the calculation of rib cage distortion. Dyspnoea was assessed by a modified Borg scale. RESULTS: There were some differences and similarities between UAE and LE. Unlike LE with UAE: (i) V(cw) and V(rc,p) at end inspiration did not increase, whereas a decrease in V(rc,p) contributed to decreasing CW end expiratory volume; (ii) pressure production of inspiratory rib cage muscles did not significantly increase from quiet breathing. Not unlike LE, the diaphragm limited its inspiratory contribution to ventilation with UAE with no consistent difference in rib cage distortion between UAE and LE. Finally, changes in abdominal muscle pressure, and inspiratory rib cage muscle pressure predicted 62% and 41.4% of the variability in Borg score with UAE and LE, respectively (P < 0.01). CONCLUSION: Leg exercise and UAE are associated with different patterns of CW kinematics, respiratory muscle coordination, and production of dyspnoea.

Mechanisms of dyspnoea and its language in patients with asthma.

This study hypothesises that regardless of the global score of dyspnoea intensity, different descriptors may be selected by asthmatic patients during short cardiopulmonary exercise test (sCPET) and methacholine (Mch) inhalation. It also examines whether different qualitative dyspnoea sensations can help explain the underlying mechanisms of the symptom. Minute ventilation (V'E), tidal volume (VT) and inspiratory capacity (IC) were measured in 22 stable asthmatic patients, and the sensation of dyspnoea during Mch inhalation and sCPET was quantitatively (Borg scale) and qualitatively (descriptors) assessed. The work rate and oxygen uptake (V'O2) were also measured during sCPET. Airway obstruction and hyperinflation, as measured by IC reduction, were the best correlates for dyspnoea with Mch. During sCPET, changes in WR, V'O2, V'E and VT significantly correlated with Borg score, with V'E being the best predictor of dyspnoea; IC decreased in eight patients. Furthermore, chest tightness (68%) was the highest reported descriptor during Mch inhalation, whereas work/effort (72%) was the highest during sCPET. In conclusion, obstruction/hyperinflation and work rate are highly reliable predictors of Borg rating of dyspnoea during methacholine inhalation and short cardiopulmonary exercise testing, respectively. Regardless of the global score of intensity dyspnoea, different descriptors may be selected by patients during short cardiopulmonary exercise testing and methacholine inhalation. Various qualities of dyspnoea result from different pathophysiological abnormalities.

Breathing pattern and kinematics in normal subjects during speech, singing and loud whispering.

AIMS: We used for the first time a non-invasive optoelectronic plethysmography to assess breathing movements and to provide a quantitative description of chest wall kinematics during phonation. METHODS: Volumes of different chest wall compartments (abdomen and lung apposed to rib cage and abdomen) were assessed using optoelectronic plethysmography in 16 normal Italians (eight men) during reading, singing and high-effort whispering (HW). RESULTS: During phonation the breathing pattern was different from quiet breathing and exercise. (1) During phonation, tidal volume and expiratory time increased while inspiratory time decreased. The expiratory volume changes and flows during HW were considerably greater than during vocalization. During HW, the overall end-expiratory thoracic volume significantly decreased as a result of decreased volume of all compartments and essentially impinged on the maximal expiratory flow-volume curve. (2) While, as previously shown, during exercise the expired volume is due entirely to the abdomen, during phonation all three chest wall compartments contribute to it. Under all conditions studied breathing was, on average, more costal in females than in males but this was mainly related to different size rather than gender per se. CONCLUSIONS: Physical characteristics have a greater importance than gender in determining breathing pattern and chest wall kinematics during phonation. The activity of the control of expiration during phonation is more complex than during exercise.

COL1A2 (type I collagen) polymorphisms in the Colorado Indians of Ecuador.

BACKGROUND: EcoRI, MspI and RsaI restriction fragment length polymorphisms (RFLPs) of the COL1A2 (type I collagen) gene are proving to be extremely informative markers for describing human populations; therefore they hold considerable potential for anthropogenetic research. AIM: The objective of this study was to characterize at the DNA level the Colorado Indians from Ecuador, for whom only blood group frequency information is available, and to investigate their relationships with the Cayapa-another Ecuadoran Native American group belonging to the same linguistic affiliation-and other world populations. SUBJECTS AND METHODS: Colorado Indians (n = 80) were analysed for the three anthropologically informative RFLPs of the COL1A2 gene. To better define the genetic relationship between this group and other populations, principal component analysis (PCA) was performed and genetic distances were estimated. Population genetic structure was tested through analysis of molecular variance (AMOVA) by comparing haplotype frequencies. RESULTS: COL1A2 allele and haplotype frequencies showed a certain degree of heterogeneity between the two Chibchan populations of Ecuador. The AMOVA test detected a significant level of differentiation (Fst = 0.034, p = 0.0049) between Colorado and Cayapa Indians. PC and genetic distance analyses showed a clear-cut separation between African and non-African populations; within the latter, the two Native American groups were differentiated from each other. CONCLUSIONS: The present findings suggest the presence of a low level of genetic relatedness between the Colorado and the Cayapa, despite their supposed common ethnogenesis. This confirms what has been inferred from other genetic data about the high degree of heterogeneity among Native Americans, even within the same linguistic branch, thus supporting the existence of genetic sub-structure within the central and southern American populations.

Influence of expiratory flow-limitation during exercise on systemic oxygen delivery in humans.

To determine the effects of exercise with expiratory flow-limitation (EFL) on systemic O(2) delivery, seven normal subjects performed incremental exercise with and without EFL at approximately 0.8 l s(-1) (imposed by a Starling resistor in the expiratory line) to determine maximal power output under control (W'(max,c)) and EFL (W'(max,e)) conditions. W'(max,e) was 62.5% of W'(max,c), and EFL exercise caused a significant fall in the ventilatory threshold. In a third test, after exercising at W'(max,e) without EFL for 4 min, EFL was imposed; exercise continued for 4 more minutes or until exhaustion. O(2) consumption (V'(O)(2)) was measured breath-by-breath for the last 90 s of control, and for the first 90 s of EFL exercise. Assuming that the arterio-mixed venous O(2) content remained constant immediately after EFL imposition, we used V'(O)(2) as a measure of cardiac output (Q'(c)). Q'(c) was also calculated by the pulse contour method with blood pressure measured continuously by a photo-plethysmographic device. Both sets of data showed a decrease of Q'(c) due to a decrease in stroke volume by 10% (p < 0.001 for V'(O)(2)) with EFL and remained decreased for the full 90 s. Concurrently, arterial O(2) saturation decreased by 5%, abdominal, pleural and alveolar pressures increased, and duty cycle decreased by 43%. We conclude that this combination of events led to a decrease in venous return secondary to high expiratory pressures, and a decreased duty cycle which decreased O(2) delivery to working muscles by approximately 15%.

Understanding dyspnoea by its language.

Dyspnoea is a general term used to characterise a range of qualitatively distinct descriptors that vary in intensity. Based on the hypothesis that various qualities of respiratory discomfort result from different pathophysiological abnormalities, language could help to define one or more of the abnormalities responsible for breathing discomfort. The use of descriptors of dyspnoea may contribute to the understanding of the mechanisms of dyspnoea, and assist in identifying or predicting a specific diagnosis. Symptoms that can be reliably discriminated imply different pathophysiological mechanisms, whereas symptoms that cannot be reliably discriminated imply similar pathophysiological mechanisms. Since dyspnoea is a fundamental part of patient's clinical history, physicians should become more fluent in the language of dyspnoea.

Chest wall kinematics and respiratory muscle action in ankylosing spondylitis patients.

No direct measurements of the pressures produced by the ribcage muscles, the diaphragm and the abdominal muscles during hyperventilation have been reported in patients with ankylosing spondylitis. Based on recent evidence indicating that abdominal muscles are important contributors to stimulation of ventilation, it was hypothesised that, in ankylosing spondylitis patients with limited ribcage expansion, a respiratory centre strategy to help the diaphragm function may involve coordinated action of this muscle with abdominal muscles. In order to validate this hypothesis, the chest wall response to a hypercapnic/hyperoxic rebreathing test was assessed in six ankylosing spondylitis patients and seven controls by combined analysis of: 1) chest wall kinematics, using optoelectronic plethysmography, this system is accurate in partitioning chest wall expansion into the contributions of the ribcage and the abdomen; and 2) respiratory muscle pressures, oesophageal, gastric and transdiaphragmatic (Pdi); the pressure/volume relaxation characteristics of both the ribcage and the abdomen allowed assessment of the peak pressure of both inspiratory and expiratory ribcage muscles, and of the abdominal muscles. During rebreathing, chest wall expansion increased to a similar extent in patients to that in controls; however, the abdominal component increased more and the ribcage component less in patients. Peak inspiratory ribcage, but not abdominal, muscle pressure was significantly lower in patients than in controls. End-inspiratory Pdi increased similarly in both groups, whereas inspiratory swings in Pdi increased significantly only in patients. No pressure or volume signals correlated with disease severity. The diaphragm and abdominal muscles help to expand the chest wall in ankylosing spondylitis patients, regardless of the severity of their disease. This finding supports the starting hypothesis that a coordinated response of respiratory muscle activity optimises the efficiency of the thoracoabdominal compartment in conditions of limited ribcage expansion.

Assessing respiratory drive and central motor pathway in humans: clinical implications.

Feedback from sensory elements as well as projection from higher Central Nervous System structures modify the level and pattern of motor outflow to the respiratory muscles and hence ventilation. In this review we describe the different methods to evaluate the degree to which higher centers determine the level and pattern of ventilation and coordinate use of the respiratory muscles in healthy humans and in patients with a number of respiratory disorders.

Chest wall kinematics and respiratory muscle coordinated action during hypercapnia in healthy males.

The present study was designed to verify whether during hypercapnic stimulation, as we had previously found during exercise or walking, the partitioning of the respiratory motor output is equally distributed to the muscles of chest wall compartments to assist diaphragm function. We studied chest wall kinematics and respiratory muscle recruitment in seven healthy men during rebreathing of a hypercapnic-hyperoxic gas mixture (CO(2) RT). Data were compared with those previously obtained during either cycling exercise or walking. The chest wall volume ( Vcw), assessed by optoelectronic plethysmography (OEP), was modeled as the sum of the volumes of the lung-apposed rib cage ( Vrc,p), diaphragm-apposed rib cage ( Vrc,a) and abdomen ( Vab). Esophageal ( Pes), gastric ( Pga) and transdiaphragmatic ( Pdi= Pga- Pes) pressures were simultaneously recorded. Velocity of shortening ( V') and power ( W'= Px V') of the diaphragm ( W'di), rib cage muscles ( W'rcm) and abdominal muscles ( W'abm) were also calculated. During CO(2) RT the progressive increase in end-inspiratory Vcw resulted from an increase in both end-inspiratory Vrc,p and Vrc,a, while the progressive decrease in end-expiratory Vcw was entirely due to the decrease in end-expiratory Vab. The increase in Vrc,p was proportionally slightly greater than that in Vrc,a. The end-inspiratory increase and end-expiratory decrease in Vcw were accounted for by inspiratory rib cage (RCM,i) and abdominal (ABM) muscle recruitment, respectively. W'di, W'rcm and W'abm progressively increased. However, while most of W'di was expressed in terms of velocity of shortening, most of W'rcm and W'abm was expressed as force or pressure. A comparison of CO(2) results with data obtained during exercise revealed: (1). a gradual vs. an immediate response, (2). a similar decrease in Vab,e and Pabm, (3). an apparent lack of any difference in ABM recruitment, (4). less gradual ABM relaxation, (5). no drop in Pdi but a similar Wdi change and decrease in pressure-to-velocity ratio of the diaphragm. We have found that in healthy humans: (1). the increased motor output with hypercapnia is equally distributed between RCM and ABM to minimize transdiaphragmatic pressure and (2). data on chest wall kinematics and respiratory muscle recruitment are only partly in line with those obtained during walking or cycling exercise.

Breathing retraining and exercise conditioning in patients with chronic obstructive pulmonary disease (COPD): a physiological approach.

In this review we shall consider the commonest techniques to reduce dyspnea that are being applied to patients with chronic obstructive pulmonary disease (COPD) subjected to a pulmonary rehabilitation program (PRP). Pursed lip breathing (PLB) and diaphragmatic breathing (DB) are breathing retraining strategies employed by COPD patients in order to relieve and control dyspnea. However, the effectiveness of PLB in reducing dyspnoea is controversial. Moreover, DB may be associated with asynchronous and paradoxical breathing movements, reflecting a decrease in the efficiency ofthe diaphragm. Exercise training (EXT) is a mandatory component of PRP.EXT has been shown to improve exercise performances and peripheral muscle strength. Recent studies have focused on the effect of EXT on breathlessness. However, concerns persist as to whether the decreased sensation of dyspnea for a given exercise stimulus is principally due to psychological benefits of rehabilitation or to improved physiological ability to perform exercise. The effect of EXT on breathlessness may be reinforced by inhaling oxygen. However, two studies have recently shown that breathing supplemental oxygen during training has either a marginal effect or no advantage over training. In a comprehensive PRP, strength training (ST) and arm endurance training (AET) could have a role in decreasing peripheral muscle weakness and metabolic and ventilatory requirements for AET. The role of unloading the respiratory muscles during EXT has to be

Measures of perception of bronchoconstriction and clinical and functional data are not interrelated in asthma.

BACKGROUND: Sensitivity and absolute perceptual magnitude characterize the perception of bronchoconstriction (PB). OBJECTIVES: To define whether clinical and functional characteristics and level of bronchial hyperresponsiveness (BHR) correlate with these two PB indexes during bronchial challenge in asthma. METHODS: PB on both the Borg scale and the visual-analogue scale (VAS) was assessed in 45 consecutive asthmatics during a methacholine-induced decrease in forced expiratory volume in 1 s (FEV(1)) and specifically quantified as Borg and VAS slope, as a measure of sensitivity, whereas scores at a 20% FEV(1) decrease (PB(20)) were assessed as a measure of absolute perceptual magnitude. Clinical score and BHR were also assessed. RESULTS: PB(20) related to slope on both the Borg scale and the VAS (p < 0.0001). PB(20) and slope related neither to clinical score nor to baseline functional data on both scales. The relationship between the level of BHR and PB(20) on either scale was of questionable clinical significance (r(2) = 7%). CONCLUSIONS: Irrespective of the scale employed, our data indicate the need for directly assessing PB rather than deriving it from clinical and functional data and level of BHR.

Dyspnea, respiratory function and sputum profile in asthmatic patients during exacerbations.

Dyspnea is often used as a marker of asthma severity although a wide variation in dyspnea perception associated with bronchoconstriction (PB) has been described in asthmatic patients. Our hypothesis is that changes of airway inflammation, airway narrowing and hyperinflation may account for a part of the variability of breathlessness in spontaneous asthma attack. In asthmatic patients with exacerbation of the disease, we evaluated respiratory function, dyspnea (using visual Analogue Scale--VAS) and peak expiratory flow (PEF) values and variability (amplitude % mean), and sputum cellular and biochemical profile before (day I) and after (day II) therapy with i.v. corticosteroids and inhaled beta2-agonists, as appropriate. By day II, forced expiratory volume in 1 s (FEV1), inspiratory capacity (IC), PEF or VAS values and variability, sputum eosinophils and eosinophilic cationic protein (ECP) had improved. Improvement of dyspnea expressed as a decrease in VAS and reduction in variability of dyspnea sensation significantly correlated with increase in FEV1 %predicted value (%pv) (P=0.03; p=0.72 and P=0.02; p=0.74, respectively). No significant correlation was found between IC and VAS either in absolute values or as changes from days I and II, nor between sputum outcomes and PEF or VAS, regardless of how they were measured. We conclude that in acute asthmatic patients, dyspnea measurement, functional measurements and sputum analysis may be useful in monitoring disease activity, response to therapy and can provide different information on the state of the disease.