Chest wall stiffness in patients with chronic respiratory muscle weakness.

Using the weighted spirometer technique we studied chest wall compliance (Cw) in 16 nonobese patients with chronic weakness of the respiratory muscles and 20 healthy control subjects. In order to evaluate the validity of the technique, while Cw was being measured, we monitored thoracoabdominal configuration with 2 pairs of linearized magnetometers and electrical activity of the external oblique with a concentric needle electrode in 3 healthy subjects and 4 patients; in addition, we recorded in 3 subjects the electrical activity from the intercostal muscles and diaphragm throughout the procedure. The method was reproducible within 5.

Function of respiratory muscles during partial curarization in humans.

The effects of submaximal neuromuscular blockade (SMNB) on the recruitment (or derecruitment) of the respiratory muscles during different types of respiratory maneuvers were studied in four healthy males infused slowly with pancuronium. The effects on lung mechanics were similar to those observed previously in that lung recoil pressure during inspiration did not change while the chest wall pressure-volume (PV) curve was shifted to the right (Rahn diagram). In each subject, SMNB produced a large increase in abdominal (gastric) and transdiaphragmatic pressures at any given lung volume during inspiration, reflecting greater diaphragmatic contribution to respiratory pressure swings.

The interaction between the diaphragm, intercostal/accessory muscles of inspiration and the rib cage.

During Mueller maneuvers (MM), the volume change of rib cage, delta Vrc, and abdomen, delta Vab, are equal and opposite. Thus delta Vrc = -delta Vab. Substituting delta Prc.

[Significance of electromyography of the diaphragm in respiratory physiopathology].

Adequate electromyographic method are available in order to record the electrical activity of the vertebral (oesophageal surface electrodes) and the right or left costal (concentric needle electrodes) parts of the diaphragm and in order to stabilize the EMG's base line (rejection of the electrical movement's artefacts by means of RC filters). The electromyographic patterns of the agonistic and antagonistic activity of the diaphragm in normal subjects have been clearly defined in different circumstances such as quiet ventilation and hyperventilation. Disturbances of the ventilatory diaphragmatic activity have been demonstrated by electromyography in different diseases: broncho-pneumopathies; supraspinal disorders, myopathies.