High-frequency oscillatory ventilation for adult respiratory distress syndrome--a pilot study.
OBJECTIVE
To evaluate the safety and effectiveness of high-frequency oscillatory ventilation using a protocol designed to recruit and maintain optimal lung volume in patients with severe adult respiratory distress syndrome (ARDS).


METHODS
Surgical and medical intensive care units in a tertiary care, military teaching hospital.


METHODS
A prospective, clinical study.


METHODS
Seventeen patients, 17 yrs to 83 yrs of age, with severe ARDS (Lung Injury Score of 3.81 +/- 0.23) failing inverse ratio mechanical conventional ventilation (PaO2/FiO2 ratio of 68.6 +/- 21.6, peak inspiratory pressure of 54.3 +/- 12.7 cm H2O, positive end-expiratory pressure of 18.2 +/- 6.9 cm H2O).


METHODS
High-frequency oscillatory ventilation was instituted after varying periods of conventional ventilation (5.12 +/- 4.3 days). We employed lung volume recruitment strategy that consisted of incremental increases in mean airway pressure to achieve a PaO2 of > or = 60 torr (> or = 8.0 kPa), with an FiO2 of < or = 0.6.


RESULTS
High-frequency oscillator ventilator settings (FiO2, mean airway pressure, pressure amplitude of oscillation [delta P] frequency) and hemodynamic parameters (cardiac output, oxygen delivery [DO2]), mean systemic and pulmonary arterial pressures, and the oxygenation index (oxygenation index = [FiO2 x mean airway pressure x 100]/PaO2) were monitored during the transition to high-frequency oscillatory ventilation and throughout the course of the high-frequency protocol. Thirteen patients demonstrated improved gas exchange and an overall improvement in PaO2/FiO2 ratio (p < .02). Reductions in the oxygenation index (p < .01) and FiO2 (p < .02) at 12, 24, and 48 hrs after starting high-frequency oscillatory ventilation were observed. No significant compromise in cardiac output or DO2 was observed, despite a significant increase in mean airway pressure (31.2 +/- 10.3 to 34.0 +/- 6.7 cm H2O, p < .05) on high-frequency oscillatory ventilation. The overall survival rate at 30 days was 47%. A greater number of pretreatment days on conventional ventilation (p < .009) and an entry oxygenation index of > 47 (sensitivity 100%, specificity 100%) were associated with mortality.


CONCLUSIONS
High-frequency oscillatory ventilation is both safe and effective in adult patients with severe ARDS failing conventional ventilation. A lung volume recruitment strategy during high-frequency oscillatory ventilation produced improved gas exchange without a compromise in DO2. These results are encouraging and support the need for a prospective, randomized trial of algorithm-controlled conventional ventilation vs. high-frequency oscillatory ventilation for adults with severe ARDS.
Fort
P
P
Department of Pulmonary/Critical Care Medieine, Wilford Hall Medical Center, Lackland AFB, San Antonio, TX 78236-5300, USA.
Farmer
C
C
Westerman
J
J
Johannigman
J
J
Beninati
W
W
Dolan
S
S
Derdak
S
S
D000293:Adolescent; D000328:Adult; D000368:Aged; D000369:Aged, 80 and over; D005260:Female; D006439:Hemodynamics; D006612:High-Frequency Ventilation; D006801:Humans; D008297:Male; D008875:Middle Aged; D010865:Pilot Projects; D011446:Prospective Studies; D011659:Pulmonary Gas Exchange; D012128:Respiratory Distress Syndrome / Q000503:physiopathology / Q000628:therapy*