High-frequency oscillatory ventilation and prone position as early alternative therapy in adults with severe acute respiratory distress syndrome

Background

In the past few years there has been a resurgence of interest in high-frequency oscillatory ventilation (HFOV), as part of the search for lung-protective ventilation in acute respiratory distress syndrome (ARDS). The prone position has been used increasingly as a simple and safe method to improve oxygenation in conventional mechanical ventilation (CMV), but only occasionally as adjunctive therapy in HFOV.

Objective

To evaluate safety and results when using both HFOV and the prone position in adult patients in the early phase of severe ARDS as integrated therapy for alternative lung-protective ventilation.

Methods

Adult patients diagnosed with ARDS resulting from a pulmonary cause (ARDSp) and from an extrapulmonary cause (ARDSe) receiving mechanical ventilation for less than 72 hours, when it is not possible for a conventional lung-protective strategy of low tidal volumes (≤ 6 ml/kg PBW) and limited inspiratory plateau pressures (≤ 30 cmH₂O), requiring FiO₂ ≥ 0.6 to keep PaO₂ ≥ 60 mmHg or SpO₂ ≥ 90% with moderate-high levels of mmHg PEEP in CMV and the prone position. Data are presented as the mean ± SD.

Results

We included in the study seven consecutive critically ill patients with early ARDS, four men and three women (five ARDSp/two ARDSe), aged 46.3 ± 20 years. APACHE-II score: 28.1 ± 4.8. LIS: 3.7 ± 0.2. OI: 35.6 ± 18.1. PaO₂/FiO₂: 88.6 ± 39.2. Patients were ventilated in the prone position and CMV with FiO₂: 0.84 ± 0.2. Tidal volume: 6 ± 0.3 ml/kg PBW. Plateau pressure: 34.3 ± 2.1 cmH₂O. Mean airway pressure: 25.9 ± 3.8 and PEEP: 17.1 ± 3.6 cmH₂O.

The patients were switched to HFOV in the prone position as alternative lung-protective ventilation. It was possible to apply higher mean airway pressures than in CMV and the prone position, to achieve significant and sustained improvements in gas exchange (PaO₂/FiO₂) and reductions in FiO₂ requirements in the first 24 hours of HFOV without hemodynamic instability or barotrauma. Patients were turned back to the supine position in HFOV (mean time in prone position: 3.1 ± 1.5 days) before transition to CMV (mean time in HFOV: 5.6 ± 3.2 days).

Two patients died in the first 2 days after being switched to HFOV, due to fulminant sepsis in Gram-negative bacteraemia and to massive alveolar haemorrhage in lupus, respectively. The other five patients were discharged alive from the ICU without ventilatory support. They are alive 3 months after diagnosis and treatment of ARDS.

Conclusions

It is possible to use lung-protective ventilation using HFOV and the prone position as adjunctive therapy, with good outcomes in adult patients in the early phase of severe ARDS without significant complications. In our experience, it would be interesting to evaluate in future studies whether HFOV and the prone position is a better approach to lung protective ventilation than CMV for the most severe ARDS adult patients.