Patterns of Chest Wall Kinematics During Volitional Pursed-Lip Breathing in COPD at Rest
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ARTICLE IN PRESS Respiratory Medicine (2007) 101, 1412–1418 Patterns of chest wall kinematics during volitional pursed-lip breathing in COPD at rest Roberto Bianchi, Francesco Gigliotti, Isabella Romagnoli, Barbara Lanini, Carla Castellani, Barbara Binazzi, Loredana Stendardi, Michela Grazzini, Giorgio Scanoà Fondazione Don C. Gnocchi (IRCCS), Via Imprunetana, 124, 50020 Pozzolatico, Firenze, Italy Received 23 November 2006; accepted 29 January 2007 Available online 12 March 2007 KEYWORDS Summary Chronic obstructive Background: Analysis of chest wall kinematics can contribute to identifying the reasons pulmonary disease why some patients benefit from pursed-lip breathing (PLB). (COPD); Material and methods: We evaluated the displacement of the chest wall and its Rehabilitation; compartments, the rib cage and abdomen, by optoelectronic plethysmography (OEP), Chest wall; during supervised PLB maneuver in 30 patients with mild to severe chronic obstructive Dyspnea; pulmonary disease (COPD). Breathing exercises 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 (r2 ¼ 0.5, po0.00002). Conclusions: OEP helps identifying the reason why patients with COPD may benefit from PLB at rest. & 2007 Elsevier Ltd. All rights reserved. ÃCorresponding author. Tel.: +39 055 260 11; fax: +39 055 260 1272. E-mail address: [email protected] (G. Scano). 0954-6111/$ - see front matter & 2007 Elsevier Ltd. All rights reserved. doi:10.1016/j.rmed.2007.01.021 breathing. PLB is related tohas its been ability reported to that promotereasons the a relief why slower from PLB and dyspnea relieves deeper on provided dyspnea by in whether patients withtheir changes COPD. breathing It pattern in may chest provide additional volume information patients help do not identify useSome it the even apply when this theypatients, are however, employ technique taught. PLB, or spontaneously, report whereas benefiting from other it. the dyspnea. fractional pressure; this, conceivably,is would not the attenuate abdominal result contribution, the of tidal volume a of the higher chest wall rib cage inspiratory muscle volume. alter the pattern ofthrough breathing, a primarily mouthpiece by with increasingbased a tidal nose on clip wearing induring a place is mouthpiece natural known andend-expiratory to breathing nose and clip. while Breathing end-inspiratory avoiding chest measurements wall volumes it unmodified. dyspnea during exerciseunchanged either by end-expiratory-lung-volume enhancing it variably or leaving affects and moderate tosatisfied severe each chronic of dyspnea threeselected score criteria: from (i) (MRC a longhypoxemia pulmonary history participated rehabilitation of in program smoking obstruction the if study they and ( Thirty mild COPD to patients with moderatePatients moderate hyperinflation to and severe airway Methods chronic obstructivea pulmonary breathing disease retrainingfollowed strategy (COPD). by employed expiratory blowing by against partiallyPursed-lip patients closed lips breathing with is (PLB) performed as nasalIntroduction inspiration Thoracic kinematics and pursed lip breathing symptomatic patients capacity, therefore, attenuating the sensationto of dyspnea a in smallpressure production fraction of of ribvolume cage their of muscles both maximal and the theof rib pressure-generating diaphragm the cage abdomen and and abdomen.two limiting This different the would ways: increase limit (i) in by end-inspiratory decreasing end-expiratory volume compartments. which allows the evaluation oftechnique volume changes based of on chestwhile wall optoelectronic others plethysmography do (OEP) not,help identify we the applied reason a why some recently patients well-developed benefit from PLB relief in COPD patients. volume of the rib cage wouldchest not wall be promoted associated by with PLB dyspnea at the exclusive expense ofPLB tidal in patients withwall COPD? volumes help identify the reason for dyspnea relief with Studies on patients who naturally incorporate PLB into An increased tidal volume, however, may be obtained in To assess whether the volume changes of chest wall can We hypothesized that an increase in tidal volume of the Thus, the question arises: do changes in operational chest 10,11 2,3 5,6 In contrast, an increase in tidal volume with 4 7 – 9 We performed direct measurements of 3,5,6 ; (ii) in contrast, without the Table 1 ). They were ARTICLE IN PRESS 1 Not all 4 II), Table 1 Anthropometric, clinical, and functional data. Age BMI Smoke VC FEV1 FEV1/VC FRC TLC RV PaCO2 PaO2 MRC (years) (kg mÀ2) (py) (%p.v.) (%p.v.) (%) (%p.v.) (%p.v.) (%p.v.) (Torr) (Torr) (a.u.) Group (30 subj.) 7177267346715 87721 45716 38711 138738 111720 156756 41.777.2 73.2710.5 2.970.8 Subgroup 1 (19 subj.) 7277257351712 84722 38713 3479 152738 118719 177754 42.677.7 71.0710.5 2.970.8 Subgroup 2 (11 subj.) 7178287338717 92719 56714 45712 115727 100716 119736 40.276.4 76.979.9 2.970.7 po0.009 po0.05 po0.002 po0.005 po0.009 po0.02 po0.004 Values are mean 7SD. VC: vital capacity; FEV1: forced expiratory volume in 1 s; FEV1/VC: Tiffeneau ratio; FRC: functional residual capacity; RV: residual volume; MRC: Medical Research Council Dyspnea Scale; p.v.: predicted value; a.u.: arbitrary units. 1413 ARTICLE IN PRESS 1414 R. Bianchi et al. (ii) clinically stable condition, with no exacerbation, or each compartment was measured at the beginning and end hospital admission in the preceding four weeks, (iii) free from of inspiratory flow (zero-flow points). The difference other significant disease potentially contributing to dyspnea. between the end-inspiratory and end-expiratory volume of each compartment was calculated as the tidal volume (VT) Protocol contribution by each compartment. Thus, VCW ¼ VRC+VAb, and changes in VCW can be calculated as Routine lung function was measured first and then patients DVCW ¼ DVRC þ DVAb, were familiarized with procedures and scales for rating assuming that the only factor causing chest wall volume symptom intensity. Compartmental lung volumes were changes is gas movement. OEP calculates absolute volumes evaluated with subjects in a seated position at rest during and the absolute volume of each compartment at FRC in both quiet breathing (QB) defined as a patient’s habitual control conditions was considered as the reference volume. comfortable breathing, and PLB. A physiotherapist gave Volumes are reported either in absolute values or as changes every patient the same instructions about PLB execution. from the volume at FRC in control conditions. Patients were instructed to make a nasal inspiration followed by expiratory blowing against partially closed lips, avoiding forceful exhalation.1 Dyspnea No patient had difficulty in learning this technique. Three trials of both QB and PLB maneuvers, performed correctly Subjects were asked to quantify the following: (i) chronic 15 and with care in random order, were recorded for at least exertional dyspnea by MRC questionnaire and, (ii) the 6 min with the exclusion of sighing and coughing, and then sensation of nonspecific discomfort associated with the act averaged. Dyspnea sensation was measured before, during of breathing by pointing to a score on a modified Borg scale 16 and after QB and PLB. The study was approved by the Ethics from 0 (none) to 10 (maximal) arbitrary units (a.u.). Committee of the Institution and informed consent was obtained from subjects. Data analysis Lung function Values are means 7SD. Statistical procedure was used to test differences for paired and unpaired samples. Simple Routine spirometry obtained with subjects in a seated regression analysis was performed using Pearson’s correla- position was measured as previously reported.12 FRC tion coefficient. The level of significance was set at po0.05. (functional residual capacity) was measured by a constant All statistical procedures were carried out using the Statgraphics Plus 5.1 statistical package (Manugistics, volume whole-body plethysmograph (Autobox DL 6200 Sensor Medics; Yorba Linda, CA, USA.). The normal values Rockville, MD, USA). for lung volumes are those proposed by the European Respiratory Society.13 Results Chest wall kinematics and compartmental volumes Chest wall kinematics The volume of the chest wall (VCW) was modeled as the sum The analysis of the time course of volume changes in chest of the volumes of the rib cage (VRC), and abdomen (VAb). The wall compartments allowed us to identify two different PLB volumes of the chest wall and its compartments were patterns. The first pattern (left panels of Fig. 1 and Table 2) assessed by applying a noninvasive OEP technique, used as characterized 19 patients we called euvolumics in whom the previously described.14 Briefly, 89 reflecting markers were PLB maneuver decreased end-expiratory volumes of both placed front and