P. Fort et al., HIGH-FREQUENCY OSCILLATORY VENTILATION FOR ADULT-RESPIRATORY-DISTRESS-SYNDROME - A PILOT-STUDY, Critical care medicine, 25(6), 1997, pp. 937-947
Objective: To evaluate the safety and effectiveness of high-frequency
oscillatory ventilation using a protocol designed to recruit and maint
ain optimal lung volume in patients with severe adult respiratory dist
ress syndrome (ARDS). Setting: Surgical and medical intensive care uni
ts in a tertiary care, military teaching hospital. Design: A prospecti
ve, clinical study. Patients: Seventeen patients, 17 yrs to 83 yrs of
age, with severe ARDS (Lung Injury Score of 3.81 +/- 0.23) failing inv
erse ratio mechanical conventional ventilation (Pao(2)/Fio(2) ratio of
68.6 +/- 21.6, peak inspiratory pressure of 54.3 +/- 12.7 cm H2O, pos
itive end- expiratory pressure of 18.2 +/- 6.9 cm H2O). Interventions:
High-frequency oscillatory ventilation was instituted after varying p
eriods of conventional ventilation (5.12 +/- 4.3 days). We employed a
lung volume recruitment strategy that consisted of incremental increas
es in mean airway pressure to achieve a Pao(2) of >60 torr (>8.0 kPa),
with an Fio(2) of <0.6. Measurements and Main Results: High frequency
oscillator ventilator settings (Fio(2), mean airway pressure, pressur
e amplitude of oscillation [Delta P] frequency) and hemodynamic parame
ters (cardiac output, oxygen delivery [Do(2)]), mean systemic and pulm
onary arterial pressures, and the oxygenation index (oxygenation index
= [Fio(2) x mean airway pressure x 100]/Pao(2)) were monitored during
the transition to high-frequency oscillatory ventilation and througho
ut the course of the high-frequency protocol. Thirteen patients demons
trated improved gas exchange and an overall improvement in Pao(2)/Fio(
2) ratio (p < .02). Reductions in the oxygenation index (p < .01) and
Fio(2) (p < .02) at 12, 24, and 48 hrs after starting high frequency o
scillatory ventilation were observed. No significant compromise in car
diac output or Do(2) was observed, despite a significant increase in m
ean 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 (sensiti
vity 100%, specificity 100%) were associated with mortality. Conclusio
ns: 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 ve
ntilation produced improved gas exchange without a compromise in Do(2)
. 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.