| Popis: |
A novel optical system was used to map the inspiratory movement of the anterior chest wall in patients anaesthetized with isoflurane and nitrous oxide. Flow in the airway, and pressures in the airway, oesophagus and stomach were also measured, during mechanical ventilation and spontaneous ventilation, with and without the effects of opioid. In addition, breathing was stimulated with carbon dioxide. Both normal breathing, and occlusion of either inspiration or expiration for single breath cycles were studied. In some patients, electromyograms of diaphragm and external oblique muscles were recorded, to test whether inspiratory or expiratory occlusion affected either the timing of the respiratory cycle, or the activation of these muscles. The effects of airway occlusion on timing and muscle activity, compared with an unoccluded breath, were small. Occlusion decreased the amplitude of the EMG activity by 7.5%. During carbon dioxide stimulation, diaphragm activity was prolonged. There were no discernible effects on the external oblique activity. Passive inflation inflated the ribcage more than the abdomen, as shown by previous investigators. However during spontaneous ventilation, expansion during inspiration was predominantly abdominal. Stimulation with carbon dioxide increased the movement, and opioid reversal increased ventilation, but neither affected the pattern of movement, which was always closely proportional to the overall amplitude. Airway occlusion pressure indicated that expiration was active, and the movement during occlusion of expiration was inversely proportional to inspiratory movement. |
