Early application of high-frequency oscillatory ventilation in H1N1 influenza-related severe ARDS is associated with better outcome

Introduction

High-frequency oscillatory ventilation (HFOV) is a promising rescue modality for refractory hypoxia and was used extensively in H1N1 influenza-related ARDS in 2009 and 2010. The aim of this study was to find predictors of successful outcome of HFOV in H1N1 influenza-related severe ARDS [1].

Methods

Patients with H1N1 influenza-related severe ARDS by the new Berlin definition (applied retrospectively) receiving volume-controlled ventilation (VCV) as per the ARDSnet protocol with PO₂/FiO₂ ≤100 at PEEP ≥12 cmH₂O and FiO₂ ≥0.7 were connected to HFOV as a rescue therapy for refractory hypoxia. All patients were followed until discharge from the hospital (survivors) or death (nonsurvivors).

Results

About 80 parameters were evaluated as outcome predictors of HFOV like demographics, comorbidities, clinical features, laboratory parameters, X-rays, ventilatory and blood gas parameters and therapy-related complications. Previously collected data of 19 patients were analysed applying the new Berlin definition. Demographic, clinical, comorbidity, laboratory and radiological parameters were comparable in survivors and nonsurvivors. Table 1 shows comparison of survivors and nonsurvivors with respect mainly to ventilatory and gas exchange parameters before application of HFOV. Duration of conventional mechanical ventilation before HFOV, 1.4 ± 0.69 versus 3.66 ± 3.53 days (P = 0.03), was the only discriminating parameter between survivors and nonsurvivors.

Table 1.

Comparison of survivors and nonsurvivors

Variable	Survivors	Nonsurvivors	P value
APACHE	13.3 ± 1.7	13.2 ± 2.2	0.14
Time VCV	1.4 ± 0.69	3.66 ± 3.5	0.03
PIP	35.6 ± 7.1	35.2 ± 5.1	0.44
PEEP	13.4 ± 2.0	13.4 ± 2.8	0.48
P/F	82.6 ± 31	68.8 ± 34	0.37
OI	36.08 ± 24	25.32 ± 7	0.1

Conclusion

In H1N1 influenza-related severe ARDS, early application of HFOV is a significant predictor of successful outcome.