High-Frequency Oscillatory Ventilation in Adults: Hemodynamics
The 30-day mortality rate in the current study was 61.7%, which is higher than those in the studies by Fort et al and Derdak et al, despite similar APACHE II scores. The higher mortality rate in the current study may relate to patient parameters that are not captured in the APACHE II score, such as burn injury or organ/bone marrow transplantation.
The higher mPaw applied during HFOV therapy was associated with an early and nonpersistent increase in PAOP, a small persistent increase in CVP, and a small decrease in CO. The increase in PAOP and CVP likely is related to changes in cardiac transmural pressure during HFOV therapy, however, without direct measurements of intrathoracic pressure, we cannot confirm this. These findings are very similar to those of three previous studies, which also reported an early rise in CVP and/or PAOP, while Mehta and colleagues observed a significant reduction in CO with the application of HFOV. Two pediatric studies also found significant reductions in CO measured noninvasively in infants converted from CV to HFOV.
The clinical significance of these hemodynamic effects is not known, as we do not have data on fluid or vasopressor administration at the time of HFOV initiation. However, the CO remained within a normal range throughout the study period, and the HFOV-induced reduction in CO was not associated with a drop in BP or a rise in heart rate. In addition, although lactate levels were not measured, patients did not develop worsening acidosis. http://www.cheap-asthma-inhalers.com/
Overall, 26% of patients did not tolerate HFOV therapy and were returned to CV because of difficulties with oxygenation, ventilation, or hemodynamics. Twelve percent of patients had HFOV therapy discontinued within 4 h. These patients had lower pH values, higher OI values, and higher mortality rates than those patients who had no difficulties tolerating HFOV therapy. There are many possible explanations for the lack of response to HFOV, including hypovolemia, poor cardiac function, or the presence of a poorly recruitable lung.