ARDSnet: Ventilation with Lower Tidal Volumes as Compared with Traditional Tidal Volumes for Acute Lung Injury and the Acute Respiratory Distress Syndrome (ARMA)
The ARDSnet Investigators. N Engl J Med 2000; 342:1301-1308.
- In patients with Acute Lung Injury (ALI) or Acute Respiratory Distress Syndrome (ARDS), does ventilation with lower tidal volumes compared with traditional higher tidal volumes reduce death or ventilator-free days?
- Randomised, controlled trial
- 2×2 study combined with ketoconazole treatment (published separately)
- Original study was called KARMA and was designed to investigate the efficacy and safety of Ketoconazole and Respiratory Management in the treatment of ALI and ARDS
- The Ketoconazole arm of the study was later stopped due to an inability to show efficacy
- 10 university-associated hospitals across the USA
- March 1996 to March 1999
- Inclusion: mechanically ventilated adult patients with ALI or ARDS
- Definition: PaO2/FiO2 < 300mmHg; bilateral pulmonary infiltrates; no clinical evidence of left atrial hypertension or (if measured) a PCWP 18mmH or less
- Exclusion: pregnancy; neuropathies; chronic lung disease; severe burns
- 861 participants
- Low tidal volume ventilation with protocol for limiting plateau pressures and respiratory acidaemia
- Volume-assist-control ventilation with 6 ml/kg/breath (ideal body weight)
- Plateau pressure < 30 cm water
- Traditional, higher, tidal volume ventilation with similar protocol
- Volume-assist-control ventilation with 12ml/kg/breath (ideal body weight)
- Plateau pressure < 50 cm water
- 1st Primary outcome: reduced mortality favoured lower volume ventilation
- 39.8% vs 31.0% (p=0.007)
- 2nd Primary outcome: increased ventilator-free days favoured lower volume ventilation
- 12+/-11 days vs 10 +/-11 days (p=0.007)
- This lower-tidal-volume protocol should be used in patients with acute lung injury and the acute respiratory distress syndrome.
- Well designed methodology for the clinical question
- Adequately powered to detect small difference in primary outcome
- As a group sequential clinical trial, it will statistically favour a positive outcome.
- Only single-blinded: clinician aware of allocation, but no apparent difference in care provided with exception of PEEP level.
- The small between group difference in PEEP level may favour the intervention group.
The Bottom Line
- Adult patients with acute lung injury or acute respiratory distress syndrome should be ventilated with tidal volumes of 6 ml/kg, limiting plateau pressures to 30 cm water.