Chest
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Comparative Study
Jet flow-regulated expiratory resistance to maintain constant CPAP during the entire respiratory phase.
We have developed a new continuous positive airway pressure (CPAP) device that consists of a microcomputer, a pressure transducer, and a pair of electronic interface valves. One of these valves creates the inspiratory demand flow, and the other creates the opposing jet flow by acting as an expiratory valve to maintain a constant CPAP. By controlling the two electronic interface valves, the airway pressure can be kept constant during the entire respiratory cycle. ⋯ The WWIt of our apparatus and demand-flow ventilators was much smaller than that of the CV 2000. In our device, WE was also much smaller than those of the others. These results indicate that our device can be used for CPAP without causing airway pressure fluctuation, and therefore, without imposing an extra workload on the patient.
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Suctioning of secretions from the left endobronchial tree is frequently necessary but often difficult in intubated patients. We examined the effectiveness of a catheter designed expressly for this purpose. Special curved tip (Bronchitrac-L) suction catheters were fitted with thin, radiopaque tubing to facilitate x-ray visualization. ⋯ There were no catheter-induced complications in this study. The curved tip catheter is an effective means of suctioning the left bronchial tree in patients with tracheostomy tubes. Its reliability in patients with oral endotracheal tubes is reduced but more effective than current methods.
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We wished to assess the role of increased vagal tone and arterial oxygen saturation (SaO2) as determinants of HR response to voluntary respiratory maneuvers in OSAS. The changes in HR and SaO2 during breath-hold (B), Valsalva (V) and Mueller (M) maneuvers were determined in nine male subjects with OSAS while breathing RA or O2. Oxygen saturation was significantly lower breathing RA than O2 at the end of B (92.6 +/- 1.6 vs 97.2 +/- 0.8 percent), V (92.9 +/- 1.3 vs 95.2 +/- 1.7 percent), and M (92.7 +/- 1.2 vs 95.3 +/- 1.9 percent). ⋯ In order to determine if awake HR response to the maneuvers reflected HR response to obstructive apnea, we examined the relationship between the HR response to B, V, and M during wakefulness and the response to obstructive apnea of similar duration while asleep. A significant correlation was found between the HR response to obstructive sleep apnea during sleep and the response to awake B (r = 0.67, p less than 0.001), V (r = 0.51, p less than 0.05), and M (r = 0.75, p less than 0.001). We conclude that in OSAS, increased vagal tone is a major determinant of HR response to voluntary respiratory maneuvers, that bradycardia can occur in the absence of hypoxemia, and that HR response to these maneuvers, especially to M, during wakefulness predicts HR response to obstructive apnea while asleep.