Early short-term application of high-frequency percussive ventilation improves gas exchange in hypoxemic patients.
BACKGROUND
Hypoxemia in acute lung injury/acute respiratory distress syndrome (ALI/ARDS) patients represents a common finding in the intensive care unit (ICU) and frequently does not respond to standard ventilatory techniques.


OBJECTIVE
To study whether the early short-term application of high-frequency percussive ventilation (HFPV) can improve gas exchange in hypoxemic patients with ALI/ARDS or many other conditions in comparison to conventional ventilation (CV) using the same mean airway pressure (P(aw)), representing the main determinant of oxygenation and hemodynamics, irrespective of the mode of ventilation.


METHODS
Thirty-five patients not responding to CV were studied. During the first 12 h after admission to the ICU the patients underwent CV. Thereafter HFPV was applied for 12 h with P(aw) kept constant. They were then returned to CV. Gas exchange was measured at: 12 h after admission, every 4 h during the HFPV trial, 1 h after the end of HFPV, and 12 h after HFPV. Thirty-five matched patients ventilated with CV served as the control group (CTRL).


RESULTS
PaO(2)/FiO(2) and the arterial alveolar ratio (a/A PO(2)) increased during HFPV treatment and a PaO(2)/FiO(2) steady state was reached during the last 12 h of CV, whereas both did not change in CTRL. PaCO(2) decreased during the first 4 h of HFPV, but thereafter it remained unaltered; PaCO(2) did not vary in CTRL. Respiratory system compliance increased after HFPV.


CONCLUSIONS
HFPV improved gas exchange in patients who did not respond to conventional treatment. This improvement remained unaltered until 12 h after the end of HFPV.
Carlos Chagas Filho Institute of Biophysics, Federal University of Rio de Janeiro, Rio de Janeiro, Brazil. u.lucangelo@fmc.units.it
Umberto
U
Lucangelo
Walter A
WA
Zin
Luca
L
Fontanesi
Vittorio
V
Antonaglia
Alberto
A
Peratoner
Massimo
M
Ferluga
Emanuele
E
Marras
Massimo
M
Borelli
Matteo
M
Ciccolini
Giorgio
G
Berlot
D055371:Acute Lung Injury / Q000150:complications*; D000328:Adult; D000368:Aged; D001784:Blood Gas Analysis; D061345:Early Medical Intervention; D005260:Female; D006612:High-Frequency Ventilation / Q000379:methods*; D006801:Humans; D000860:Hypoxia / Q000209:etiology / Q000628:therapy*; D008297:Male; D008875:Middle Aged; D011446:Prospective Studies; D011659:Pulmonary Gas Exchange; D012121:Respiration, Artificial / Q000379:methods*; D012128:Respiratory Distress Syndrome / Q000150:complications*; D013997:Time Factors