Goti P, Duranti R, Spinelli A, Gorini M, Gigliotti F, Misuri G, Rosi E, Iandelli I, Scano G
Dept of Internal Medicine, University of Firenze, Italy.
Monaldi Arch Chest Dis. 1995 Dec;50(6):427-32.
Whether or not short-term negative pressure ventilation (NPV) improves respiratory function by decreasing the drive to the respiratory muscles in hypercapnic chronic obstructive pulmonary disease (COPD) patients remains to be defined. In six severely obstructed hypercapnic COPD patients (Group A) with grade IV dyspnoea (modified Medical Research Council (MRC) dyspnoea scale), we evaluated pulmonary volumes, arterial blood gases, the pattern of breathing (tidal volume (VT) and respiratory frequency (Rf)) and the neuromuscular respiratory drive (NMRD), before and immediately after a 7 day period with the iron lung (IL). NMRD was assessed by expressing mouth occlusion pressure (P0.1) recorded during quiet breathing as a percentage of maximal P0.1 recorded during exogenous CO2 stimulation (P0.1 max,CO2). A group of six hypercapnic, less dyspnoeic (grade II to III) COPD patients (Group B), with similar mechanical characteristics, and another less obstructed historically normocapnic control group (Group C) were also considered. Before IL, in Group A VT was lower than in C, and P0.1 (%P0.1 max,CO2) was greater than in Group B and C. After a 7 day period with IL, VT increased, Rf decreased, and arterial blood gases and dyspnoea grade improved; P0.1 (%P0.1 max,CO2) significantly decreased remaining, however, greater than in Group C. In Group A the time course of arterial carbon dioxide tension (Pa,CO2) and P0.1 (%P0.1 max,CO2) were significantly related to each other. These data seem to indicate that IL is effective in improving respiratory function and symptoms in chronic hypercapnic severely dyspnoeic COPD patients. The observation that these effects were associated with a decrease in NMRD reflects an improved efficiency of the respiratory system. After IL, respiratory function in Group A was similar or even better than that in Group B. This study also considers the possibility of putting severely dyspnoeic hypercapnic COPD patients into an IL trial before starting a traditional rehabilitation programme.
短期负压通气（NPV）是否通过降低高碳酸血症慢性阻塞性肺疾病（COPD）患者呼吸肌的驱动力来改善呼吸功能仍有待确定。在6例患有IV级呼吸困难（改良医学研究委员会（MRC）呼吸困难量表）的重度阻塞性高碳酸血症COPD患者（A组）中，我们评估了使用铁肺（IL）7天前后的肺容量、动脉血气、呼吸模式（潮气量（VT）和呼吸频率（Rf））以及神经肌肉呼吸驱动力（NMRD）。NMRD通过将安静呼吸时记录的口腔闭塞压（P0.1）表示为外源性二氧化碳刺激期间记录的最大P0.1（P0.1 max,CO2）的百分比来评估。还考虑了一组6例高碳酸血症、呼吸困难较轻（II至III级）的COPD患者（B组），其具有相似的机械特征，以及另一个历史上为正常碳酸血症的阻塞较轻的对照组（C组）。在使用IL之前，A组的VT低于C组，且P0.1（%P0.1 max,CO2）高于B组和C组。在使用IL 7天后，VT增加，Rf降低，动脉血气和呼吸困难分级改善；P0.1（%P0.1 max,CO2）显著降低，但仍高于C组。在A组中，动脉二氧化碳分压（Pa,CO2）和P0.1（%P0.1 max,CO2）的时间进程彼此显著相关。这些数据似乎表明IL对改善慢性高碳酸血症重度呼吸困难COPD患者的呼吸功能和症状有效。这些作用与NMRD降低相关的观察结果反映了呼吸系统效率的提高。使用IL后，A组的呼吸功能与B组相似甚至更好。本研究还考虑了在开始传统康复计划之前，将重度呼吸困难的高碳酸血症COPD患者纳入IL试验的可能性。
