OSCAR
High-Frequency Oscillation for ARDS
- Included 795 patients within 7 days of undergoing mechanical ventilation with ARDS (Fi02:Pa02 < 200 and bilateral pulmonary infiltrates) and an expectation of at least 2 more days of mechanical ventilation
- Randomized patients to high- frequency oscillation ventilation (HFOV – Novalung R100) or conventional low tidal volume mechanical ventilation
- Primary endpoint (30-day mortality) was not different between HOV and conventional groups (41.7% vs. 41.1%, 95% CI -6.1 to 7.5)
- There was no difference between HFOV and conventional patients in ventilator-free days (17.6 vs. 17_1, P=0-42), ICU length of stay (17.6 vs: 16.1 days, p=0.18), or hospital stay (33.9 vs. 33.1 days, p=0.79)
- Neuromuscular-blocking drugs were used for a longer duration with HFOV (2.5 vs. 2 days, p=0.02), likely due to the fact that the HFOV mode has no facility to allow for spontaneous patient breaths
- There was no difference in days with inotropic or vasopressor agents between HFOV and conventional ventilation (2.9 vs. 2.8 days, p=0.74)
- It is unclear why a difference in mortality was not seen (as it was with the OSCILLATE trial).
- OSCILLATE used a different HFOV ventilator, mandated (not suggested) lunq protection strategies, and had a significantly lower control group mortality rate
TBL
High-frequency oscillation ventilation in patients with ARDS did not improve mortality or length of stay compared to conventional, low tidal volume mechanical ventilation.
OSCILLATE
High-frequency oscillation for ARDS
- Included 548 patients within 14 days of pulmonary symptoms, were undergoing mechanical ventilation with ARDS (Fi02:Pa02 < 200 and bilateral pulmonary infiltrates), and had an expectation of at least 2 more days of mechanical ventilation.
- Patients needed to be enrolled within 72 hours of meeting criteria.
- Randomized patients to high- frequency oscillation ventilation (HFOV – SensorMedics 3100B) or conventional low tidal volume mechanical ventilation.
- Both groups; had specific, protocolized titration and weaning procedures.
- Primary endpoint (in-hospital mortality) was higher with HFOV (47% vs. 35%, NNH 9, p=0-005)
- HFOV patients were more likely to require vasopressor therapy (91% vs. 84%, p=0.01) and neuromuscular blockers (83% vs. 68%, p<0.001).
- This effect was seen as early as 4 hours after the initiation of HFOV.
- Conventional ventilation was associated with more refractory hypoxemia (7% vs. 14%, p=0.007), but this did not translate to a greater mortality rate due to hypoxemia (79% vs. 66%, p=0.31)
- Of note, the steering committee terminated the study early despite the fact that the threshold P value had not been reached. Stopping early tends to overestimate the magnitude of effect (harm or benefit)
- It is unclear why a difference in mortality was seen (given that the OSCAR trial showed no difference in mortality).
- OSCILLATE used a different HFOV ventilator, mandated (not suggested) lung protection strategies, and had a significantly lower control group mortality rate-
- Finally, because OSCILLATE was stopped early, the magnitude of harm may be overestimated.
TBL
High-frequency oscillation ventilation in patients with early ARDS increased mortality compared to conventional, low tidal volume mechanical ventilation.
