S. Mehta et al., Prospective trial of high-frequency oscillation in adults with acute respiratory distress syndrome, CRIT CARE M, 29(7), 2001, pp. 1360-1369
Objective: To evaluate the safety and efficacy of high-frequency oscillator
y ventilation (HFOV) in adult patients with the acute respiratory distress
syndrome (ARDS) and oxygenation failure.
Design: Prospective, clinical study.
Setting: Intensive care and burn units of two university teaching hospitals
.
Patients: Twenty-four adults (10 females, 14 males, aged 48.5 +/- 15.2 yrs,
Acute Physiology and Chronic Health Evaluation II score 21.5 +/- 6.9) with
ARDS (lung injury score 3.4 +/- 0.6, Pa-02/Fio(2) 98.8 +/- 39.0 mm Hg, and
oxygenation index 32.5 +/- 19.6) who met one of the following criteria: Pa
o(2) less than or equal to 65 mm Hg with Fio(2) greater than or equal to 0.
6, or plateau pressure greater than or equal to 35 cm H2O.
Interventions: HFOV was initiated in patients with ARDS after varying perio
ds of conventional ventilation (CV). Mean airway pressure (Pa-w) was initia
lly set 5 cm H2O greater than P-aw during CV, and was subsequently titrated
to maintain oxygen saturation between 88% and 93% and F-io less than or eq
ual to 0.60.
Measurements and Main Results: Fio(2), P-aw, pressure amplitude of oscillat
ion, frequency, blood pressure, heart rate, and arterial blood gases were m
onitored during the transition from CV to HFOV, and every 8 hrs thereafter
for 72 hrs. In 16 patients who had pulmonary artery catheters in place, car
diac hemodynamics were recorded at the same time intervals. Throughout the
HFOV trial, P-aw was significantly higher than that applied during CV. With
in 8 hrs of HFOV application, and for the duration of the trial, Ro, and Pa
ce, were lower, and Pao(2)/Fio(2) was higher than baseline values during CV
. Significant changes in hemodynamic variables following HFOV initiation in
cluded an increase in pulmonary artery occlusion pressure (at 8 and 40 hrs)
and central venous pressure (at 16 and 40 hrs), and a reduction in cardiac
output throughout the course of the study. There were no significant chang
es in systemic or pulmonary pressure associated with initiation and mainten
ance of HFOV. Complications occurring during HFOV included pneumothorax in
two patients and desiccation of secretions in one patient. Survival at 30 d
ays was 33%, with survivors having been mechanically ventilated for fewer d
ays before institution of HFOV compared with nonsurvivors (1.6 +/- 1.2 vs.
7.8 +/- 5.8 days; p = .001).
Conclusions: These findings suggest that HFOV has beneficial effects on oxy
genation and ventilation, and may be a safe and effective rescue therapy fo
r patients with severe oxygenation failure. In addition, early institution
of HFOV may be advantageous.