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.

Clinical Question

  • 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)

Authors’ Conclusion

  • 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.


Full text pdf / abstract / doi: 10.1056/NEJM200005043421801

Editorials, Commentaries or Blogs


Summary author: @DuncanChambler
Summary date: May 2014
Peer-review editor: @stevemathieu75


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