Pressure Support Compensation and Demand Continuous Positive Airway Pressure: Conclusion
Although we performed these studies using only one ventilator manufacturers pressure-support system, we nevertheless believe that the principles we have discussed will apply to other available ventilator pressure-support systems as well; however, variability in factors such as the effectiveness in achieving and maintaining the set level of pressure support and the mechanism by which pressure support is terminated at the end of inspiration will affect the particular relationship between optimal pressure support and Vt/Ti as derived in this study. For instance, a ventilator circuit with higher resistance would require higher levels of pressure support at a given Vt/Ti and endotracheal tube diameter. Therefore, the specific regressions derived in this study for selecting the optimal level of pressure support may not apply to other ventilator systems.
Positive airway pressure is often used during weaning trials to maintain arterial oxygen pressure and functional residual capacity. This study was carried out at ambient airway pressure (CPAP = 0), and the effect of varying levels of positive airway pressures on the requirement for pressure support was not evaluated; however, there are minor changes in airway pressure-volume relationships when the level of CPAP is increased on the Puritan-Bennett 7200 ventilator. If pressure support functions consistently at various levels of CPAP as well, the relationship of pressure support to Vt/Ti reported in this study should apply. diabet glucotror
In summary, pressure support can be used to overcome the resistances of endotracheal tubes and ventilator circuits and compensate selectively for the added inspiratory work due to these resistances. The level of pressure support must be adjusted according to the endotracheal tubes size and inspiratory flow rate. By using pressure support in this way, a patient s ability to maintain spontaneous breathing may be better assessed, and successful weaning may be facilitated.