NORMAL THORACOABDOMINAL MOTIONS - INFLUENCE OF SEX, AGE, POSTURE, ANDBREATH SIZE

The purpose of this study was to assess normal values of thoracoabdomi nal motions (TAM) during spontaneous breathing and vital capacity (VC) maneuvers in relation to sex, age, and body position. For this, 120 h ealthy subjects from 10 to > 60 yr old were studied using the respirat ory inductive plethysmograph (Respitrace (R)). The volume-motion coeff icients obtained during quiet breathing for the rib cage (RC) were alm ost twice those for the abdomen (ABD) and were not influenced by sex o r age and also not by posture, except for the increased ABD coefficien ts in the supine posture (p < 0.05). Under most conditions RC motion p redominated over ABD motion, except quiet breathing in the supine posi tion. Sex-related differences in TAM were not found during quiet breat hing, yet during VC maneuvers the women were slightly more RC breathin g (p < 0.01). Age-related differences were also only significant durin g VC maneuvers: men of more than 50 yr old especially became less RC b reathing. Posture had a very significant effect (p < 0.001) during qui et breathing as well as during VC maneuvers: the RC predominance was g reatest in the standing posture and least in the supine posture. Durin g VC maneuvers the subjects became more RC breathers than during quiet breathing (p < 0.001). The X-Y coordinates of RC motion (on the Y axi s) versus ABD motion (on the X axis) showed under all conditions a cou nterclockwise looping during the breathing cycle: the looping was elli ptic during quiet breathing but was more irregular and variable during VC maneuvers, and this also depended on body position. in conclusion, in ''naive'' healthy subjects, TAMs present characteristic patterns t hat are markedly influenced by posture and, only during VC maneuvers, also by sex and age.