OSCAR study
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Clinical Question
In patients with the acute respiratory distress syndrome (ARDS) require mechanical ventilation to maintain arterial oxygenation, dose high-frequency oscillatory ventilation (HFOV) reduce mortality as well as secondary lung injury associated with mechanical ventilation?
Bottom Line
The use of HFOV had no significant effect on 30-day mortality in patients undergoing mechanical ventilation for ARDS.
Major Points
Although mechanical ventilation can initially be lifesaving in patients with ARDS, it can also further injure the patients' lungs and contribute to death. High-frequency oscillatory ventilation (HFOV) is thought to minimize the repeated process of opening and collapsing of lung units that causes the secondary lung damage during mechanical ventilation. Many clinicians use HFOV for patients who have hypoxemia despite the use of standard approaches for improving arterial oxygenation. However, effectiveness of HFOV as a treatment for ARDS is not determined yet.
Guidelines
Design
- Multicenter, parallel-group, randomized, controlled trial
- N=795
- HFOV (n=398)
- Conventional (n=397)
- Setting: adult general ICUs in 12 university hospitals, 4 university-affiliated hospitals, and 13 district general hospitals in England, Wales, and Scotland
- Enrollment: Patients were recruited from December 7, 2007, until the end of July 2012.
- Mean follow-up: 30 days
- Analysis: Intention-to-treat
- Primary outcome: mortality up to 30 days after randomization
Population
Inclusion Criteria
- Undergoing mechanical ventilation
- A ratio of the partial pressure of arterial oxygen to the fraction of inspired oxygen of 200 mm Hg (26.7 kPa) or less
- Receiving a positive end-expiratory pressure of 5 cm of water or greater,
- Without evidence of left atrial hypertension
- Expected to require at least 2 more days of mechanical ventilation.
Exclusion Criteria
- Undergoing mechanical ventilation for 7 or more days
- Under the age of 16 years
- Weighed less than 35 kg
- Participating in other interventional studies
- Lung disease characterized by airway narrowing or air trapping
- Undergone recent lung surgery.
Baseline Characteristics
- Mean age: 55.4+/- 16.2 years
- Mean APACHE II score: 21.8
- Pao2: FiO2 ratio: 113
Interventions
- Randomized to HFOV or standard therapy
- Patients in the HFOV group were treated with the use of a Novalung R100 ventilator (Metran)7 until the start of weaning.
- Patients in the conventional-ventilation group were treated according to local practice in the participating ICUs.
Outcomes
Comparisons are HFOV therapy vs. conventional therapy.
Primary Outcomes
- mortality up to 30 days after randomization
- 41.7% in the HFOV group vs.s 41.1% in the conventional-ventilation group (95% CI, −6.1 to 7.5, P=0.85)