RT Journal Article SR Electronic T1 Thixotropic effects on operational chest wall volumes in healthy subjects JF European Respiratory Journal JO Eur Respir J FD European Respiratory Society SP P3980 VO 42 IS Suppl 57 A1 Guilherme Fregonezi A1 Fernando Henrique Fernandes Macedo A1 Maria Clara Goes A1 Rencio Bento Florencio A1 Vanessa Resqueti A1 Andrea Aliverti YR 2013 UL http://erj.ersjournals.com/content/42/Suppl_57/P3980.abstract AB Inspiratory muscle thixotropy can be achieved by muscle contraction at an inflated or deflated lung volume,causing muscle stiffness or slackness (Homma et al.). Here we aimed to assess the effects of thixotropy maneuver on operating volumes in healthy subjects.Ten subjects (5 f), age 24 yrs (IQR:22-27.5),BMI:24 Kg/m2(IQR:21.9-27.2),FVC% pred:97(IQR:89.2-104.2) and FEV1/FVC: 0.84 (IQR:0.82-0.86) were studied. End-inspiratory (EIV) and end-expiratory (EEV) volumes of Chest Wall [CW] were measured by Opto-Electronic Plethysmography before, during and immediately after inspiration at TLC and expiration at RV with occluded airways for 8 secs (apnea, AP). In addition,TLC and RV maneuvers were performed at occluded airways with inspiratory (INS) or expiratory (EXP) efforts sustained for 5 sec followed by 3 sec of relaxation. EEV and EIV variations were measured during the first 4 breaths immediately after each maneuver.Results are shown in figure 1a and 1b. After RV,maneuvers, chest wall EEV decrease significantly after INS and AP (p=0,0061 and p=0,0122, respectively); chest wall EIV decrease significantly during after INS (p=0,010).After TLC maneuvers, EIV increase significantly during INS,EX and AP maneuvers (p=0,0189, p=0,012 and p=0,0002, respectively).Our results suggest that a thixotropic effect determines an increase of chest wall operational volumes after sustaining lung volumes at TLC and a decrease after sustaining lung volumes at RV.