Combined Pressure Control/High Frequency Ventilation in Adult Respiratory Distress Syndrome and Sickle Cell Anemia: Recommendation
After 5 days of treatment with the PVDV, our patient was much improved, though not quite ready for extubation; he was converted to more conventional volume-limited ventilation because of the extreme variability in delivered tidal volumes as the patient moved in bed, ie, small changes in head position, amount of endotracheal tube leak, relative positional compression of one lung.
Patients with both airway and severe alveolar injury, ie, those with both increased airway resistance and decreased pulmonary compliance, may be the best candidates for this type of combined mode ventilation. generic for doxycycline
The pathophysiology of acute chest syndrome in sickle cell anemia is multifactorial: sludging and partial occlusion of the pulmonary microvasculature by sickled erythrocytes, marrow emboli, or altered erythrocyte-endothelium interactions damage the distal alveoli as in ARDS; airway injury secondary to infection and volutrauma is coupled with atelectasis and inflammation associated with ARDS. It is possible that the PVDV is particularly effective in the setting of ARDS in sickle cell anemia for several reasons: (1) improved alveolar recruitment leads to decreased ongoing volutrauma and should improve regional microvascular blood flow; (2) a decrease in the background respiratory rate is associated with decreased air trapping, as small airways and alveoli with longer time constants are given more time to empty; (3) cardiac output may increase due to cycling of lung volumes as noted above and as clinical improvement permits a lower intrathoracic pressure; and (4) improved oxygenation contributes to decreased sickling while the pulmonary vasculature recovers. Combined mode ventilation with the PVDV is particularly well suited to the patient with altered blood flow characteristics, stiff lungs, and increased airway resistance; it also minimizes iatrogenic injury and facilitates healing during the acute injury phase.
Category: Respiratory Symptoms
Tags: barotrauma, high frequency ventilation, sickle cell anemia