Respiration; international review of thoracic diseases
-
A patient with severe chronic obstructive pulmonary disease was studied during acute respiratory failure. On the day of intubation his respiratory rate was 42, the tidal volume 295 ml, and the maximal inspiratory pressure 8 cm H2O. These parameters improved with rest by mechanical ventilation to 16, 620 ml, and 30 cm H2O, respectively, on the day of successful weaning. ⋯ These physiological changes were associated with weaning difficulty. We conclude that respiratory failure and weaning are complex physiologic events under the influence of muscle strength, lung mechanics, gas exchange, and control of breathing. Therefore, prediction of weaning success based upon one or two measured parameters as has been done is probably inadequate in difficult patients.
-
Thirty years have passed since the International Conference on Sarcoidosis, held in Washington, D. C., in 1960. ⋯ On the other hand, no information on the causative agents has been obtained, and no advances have been made in the treatment of sarcoidosis. We expect steady advances in both in the 1990s and hope that the 12th World Congress on Sarcoidosis in September 1991 in Kyoto will mark the first step toward these objectives.
-
Comparative Study
Reexamination of the elastic properties of emphysematous lungs.
We calculated specific lung elastance (Es,L) as the change of lung elastic recoil pressure (Pel,L) required to produce a given fractional change in lung volume (delta VL/VL,0) as a function of transpulmonary pressure (PL) from published data in normal lungs, and in patients with chronic obstructive pulmonary disease (COPD) or alpha 1-antitrypsin deficiency (alpha 1-AD). Es,L, in normal lungs, is the bulk modulus, and was systematically greater than PL.dEs,L/dPL increased with VL. PL at Es,L = 30 cm H2O decreased with age in normal lungs, but Es,L at PL = 8 cm H2O showed no age relationship. ⋯ Thus abnormalities in lung elastic properties in emphysema do not account for chronic expiratory flow limitation in emphysema. Furthermore, the increased values of Es,L in emphysema suggest that emphysematous airspaces are poorly ventilated. As they are presumably poorly perfused, emphysema per se may not disturb ventilation perfusion ratios seriously.
-
Unfiltered breath sounds (NF) from the apical area of the heart, lung volume and ECG signals were recorded in 5 normal subjects. The signals were digitized and subjected to three methods of heart sound cancellation: 75-Hz high-pass filtering (75 HF), ECG-triggered blanking (BL) and adaptive filtering (AF). The sound signals were then subjected to the fast Fourier transform algorithm to obtain power spectra. ⋯ The inspiratory and expiratory sound power spectra were very similar and skewed slightly to the right, and therefore characterized by median frequencies. The differences between inspiratory and expiratory median frequencies were insignificant for NF: 42.90 +/- 2.03 (mean +/- SD) vs. 46.64 +/- 2.53 Hz (p greater than 0.1); for 75 HF: 106.43 +/- 10.27 vs. 118.22 +/- 6.30 Hz (p greater than 0.5); for BL: 44.46 +/- 3.33 vs. 66.73 +/- 2.93 Hz (p greater than 0.1), for AF: 49.72 +/- 5.68 vs. 79.20 +/- 13.07 Hz (p greater than 0.1). We conclude that the lack of significant differences suggests similar mechanisms and sites of production of inspiratory and expiratory vesicular breath sounds.