Duranti Roberto, Sanna Antonio, Romagnoli Isabella, Nerini Massimiliano, Gigliotti Francesco, Ambrosino Nicolino, Scano Giorgio
Department of Internal Medicine, Section of Clinical Immunology, Allergology and Respiratory Diseases, University of Florence, Viale Morgagni 85, 50134, Florence, Italy.
Pflugers Arch. 2004 May;448(2):222-30. doi: 10.1007/s00424-003-1231-8. Epub 2004 Jan 31.
We hypothesized that walking at increased speed or increasing gradient might have different effects on chest wall kinematics and respiratory muscle power components, and contribute differently to respiratory effort sensation. We measured the volumes of chest wall compartments by optoelectronic plethysmography, esophageal, gastric and transdiaphragmatic ( P(di)) pressures, and the sensation of the respiratory effort by a Borg scale in five normal subjects walking both at ascending gradient with constant speed (AG) and at ascending speed with constant gradient (AS). Chest wall kinematics, evaluated by displacement of chest wall compartments, did not show any significant difference between AS and AG. Muscle power, calculated as the product of mean flow and mean pressure, increased similarly, but its partitioning into pressure and velocity of shortening differed in the two modes. A greater increase in the pressure developed by the abdominal muscles ( P(abm)) (4.06-fold), and in the velocity of shortening of both rib cage inspiratory muscles ( v(rcm,i)) (2.01-fold) and the diaphragm ( v(di)) (1.90-fold) was associated with a lower increase in the pressure developed by the rib cage inspiratory muscles ( P(rcm,i)) (1.24-fold) and P(di) (0.99-fold) with AG. Instead, with AS, a lower increase in P(abm) (2.12-fold), v(rcm,i) (1.66-fold) and v(di) (1.54-fold) was associated with a greater increase in P(rcm,i) (1.56-fold) and P(di) (1.97-fold). A combination of P(abm) and v(di) during AG (Wald chi(2)=23.19, P<0.0000), with the addition of P(rcm,i) during AS (Wald chi(2)=29.46, P<0.0000), was the best predictor of Borg score. In conclusion, the general strategy adopted by respiratory centers during different walking modes does not differ in terms of ventilation, chest wall kinematics, and respiratory muscle power production, whereas it does in terms of partitioning of power into pressure and velocity of shortening, and respiratory muscle contribution to respiratory effort sensation. Combinations of different patterns of flow and pressure generation made the respiratory effort sensation similar during AS and AG modes.
我们推测，加快步行速度或增加坡度可能对胸壁运动学和呼吸肌力量成分产生不同影响，并对呼吸用力感觉有不同贡献。我们通过光电体积描记法测量胸壁腔室容积、食管、胃和跨膈压（P(di)），并在五名正常受试者以恒定速度上坡行走（AG）和以恒定坡度加快速度行走（AS）时，用Borg量表测量呼吸用力感觉。通过胸壁腔室位移评估的胸壁运动学在AS和AG之间未显示出任何显著差异。以平均流量与平均压力的乘积计算的肌肉力量同样增加，但其在压力和缩短速度方面的分配在两种模式下有所不同。腹部肌肉产生的压力（P(abm)）增加幅度更大（4.06倍），胸廓吸气肌缩短速度（v(rcm,i)）（2.01倍）和膈肌缩短速度（v(di)）（1.90倍）增加幅度更大，而AG时胸廓吸气肌产生的压力（P(rcm,i)）（1.24倍）和P(di)（0.99倍）增加幅度较小。相反，在AS时，P(abm)（2.12倍）、v(rcm,i)（1.66倍）和v(di)（1.54倍）增加幅度较小，而P(rcm,i)（1.56倍）和P(di)（1.97倍）增加幅度较大。AG期间P(abm)和v(di)的组合（Wald chi(2)=23.19，P<0.0000），加上AS期间的P(rcm,i)（Wald chi(2)=29.46，P<0.0000），是Borg评分的最佳预测指标。总之，呼吸中枢在不同步行模式下采用的总体策略在通气、胸壁运动学和呼吸肌力量产生方面没有差异，而在力量在压力和缩短速度方面的分配以及呼吸肌对呼吸用力感觉的贡献方面存在差异。不同流量和压力产生模式的组合使得AS和AG模式下的呼吸用力感觉相似。
