| Popis: |
This study determined the effects of a 5-second inspiratory hold during ventilatory maneuvers on cardiopulmonary status before, during, and after endotracheal suctioning in an acute lung-injured model. Eight mongrel dogs were anesthetized, paralyzed, mechanically ventilated, and given intravenous oleic acid to produce pulmonary edema. Four protocols were tested in alternate order in which either tidal volume inflations or hyperinflations at an FiO2 of 0.6 were given with and without an inspiratory hold of 5 seconds before and after each of three sequential suctioning passes. In those protocols in which an inspiratory hold was used, statistically significant changes occurred in right atrial, pulmonary arterial, and aortic systolic and diastolic pressures (p less than 0.04). The use of an inspiratory hold with hyperinflation maintained PaO2 during suctioning (range of 81 to 91 mm Hg), but had the greatest decrease in PaO2 (8%) after return to the ventilator. In all protocols, with the exception of the one in which hyperinflations without an inspiratory hold were used, there was a cumulative increase in PaCO2 with tidal volume inflation protocols reaching peak PaCO2 values of 49 (+/- 7.5) mm Hg. In protocol 4 in which hyperinflation without inspiratory hold was used, PaO2 ranged from 75 (+/- 16) to 92 (+/- 34) mm Hg, and PaCO2 ranged from 37 (+/- 7) to 42 (+/- 6) mm Hg. In conclusion, the use of hyperinflation without an inspiratory hold resulted in the least undesirable changes in the variables studied. However, this protocol needs to be replicated in an acutely ill clinical population before recommended for practice. |
