07. Advanced Strategies in ARDS

These interventions are standard of care for severe ARDS, though generally require notification of your attending/fellow given they are reserved for severe disease. If your institution does not routinely perform these then consider transferring the patient to an institution experienced in these strategies. Some of these interventions should only be implemented with supervision by your attending/fellow and well trained nurses and respiratory therapists. 

Neuromuscular Blockade 

  • Recommended for patients with P/F <150, better when used within 48 hours of ARDS onset. 
  • Temporary or continuous infusions to stabilize a patient and preserve oxygen delivery to vital organs. (See section Critical Care: Paralytics.) 
  • Improves hypoxia by limiting O2 consumption by respiratory muscles, improves hypercapnia by decreasing CO2 production and eliminating vent dyssynchrony. 

Prone Ventilation 

  • Recommended for patients with P/F <150 and for at least 16 hours per session.  
  • Improves oxygenation by better ventilation of dorsal lung segments, improved V/Q matching, and potential decrease in shunt. 
  • Evidence, including the PROSEVA trial, shows that prone positioning improves oxygenation, reduces ventilator-induced lung injury, and shows a mortality benefit. Sessions for 16+ hours with repeated sessions if P/F remains <150. 

Recruitment Maneuver 

  • Also known as “intermittent PEEP”. 
  • Goal is to recruit collapsed alveoli by using a higher PEEP level for a short period of time, e.g. 25-30cmH2O for 30-60 seconds. Consider hemodynamics of prolonged, elevated PEEP before initiating. 

Inhaled Nitric Oxide 

  • Selective pulmonary vasodilator improves V/Q mismatch, oxygenation, and P/F ratio. 
  • Works best if there is pulmonary arterial hypertension. 
  • Trials have failed to demonstrate improvement in clinical outcomes, though they were generally not well powered and some did not use low tidal ventilation strategies.  
  • Experts agree that it is reasonable to trial iNO for severe hypoxemia (P/F <80) when patients are otherwise optimized (neuromuscular blockade, prone positioning) prior to considering ECMO. 
  • May increase risk of renal failure, especially in higher doses.  

ECMO (Extracorporeal Membrane Oxygenation) 

  • A supportive measure in patients who have reversible causes of acute respiratory failure. 
  • Consider when P/F <80 and/or plateau pressures >30 in spite of optimized low tidal ventilation on low and high PEEP grids in the presence of neuromuscular blockade and prone positioning. 
  • Requires cardiothoracic surgeons, specialized equipment and trained personnel. If starting to consider this option, initiate contact with an ECMO center early as it may not be immediately available. 
  • While the EOLIA study itself only showed a trend towards improved mortality with ECMO, post-hoc analysis suggested a very high likelihood of improved survival for ECMO.  

APRV (Airway Pressure Release Ventilation) 

  • A high continuous positive airway pressure (P high) is delivered for a long duration (T high) then drops to a lower pressure (P low) for a short duration (T low). Spontaneous breathing can occur throughout cycle, i.e. nonsynchronous ventilation. 
  • APRV maintains higher mean airway pressures for a longer period of time, thereby improving alveolar recruitment and oxygenation. 
  • Transition between P high and P low facilitates ventilation. 
  • Physiologically appealing mode but only limited evidence in ARDS (small study showing shorter duration of mechanical ventilation). Results from the BiRDS trial may help clarify the role of this mode. 
  • This mode reduces work of breathing much less than synchronous ventilation, and is contraindicated in patients with severe obstructive airways disease.  

High Frequency Oscillatory Ventilation (HFOV) 

  • Theory: 
    • Maintain relatively constant mean airway pressure by using very high respiratory rates (measured in Hz) and very low tidal volumes (amplitude). 
    • High mean airway pressure assists with alveolar recruitment. 
  • Reality:  
    • Experts recommend against using HFOV based on trials showing no evidence of benefit relative to standard lung protective ventilation.  
    • Use is limited to clinical trials or as a salvage mode for persistent hypoxemia if there is provider experience at the institution. 

 

Diaz JV, Matthay MA, et al. Therapeutic strategies for severe acute lung injury. Crit Care Med. 2010; 38(8):1644-50. 

Guerin, C, Reignier J, Richard J, et al. Prone positioning in severe acute respiratory distress syndrome. NEJM. 2013; 368:2159-2168.  

Mora-Arteaga JA, Bernal-Ramírez OJ, Rodríguez SJ. The effects of prone position ventilation in patients with acute respiratory distress syndrome. A systematic review and metaanalysis. Med Intensiva. 2015 Jan 16. 

Papazian, L., Aubron, C., Brochard, L. et al. Formal guidelines: management of acute respiratory distress syndrome. Ann. Intensive Care 9, 69 (2019). 

Papazian L, Roch A, et al. Neuromuscular blockers in early acute respiratory distress syndrome. NEJM. 2010; 363(12); 1107-16 

Peek GJ, Elbourne D, et al. Efficacy and economic assessment of conventional ventilatory support versus extracorporeal membrane oxygenation for severe adult respiratory failure (CESAR): a multicentre randomised controlled trial. Lancet. 2009;374(9698):1351-63. 

Shekar K, Davies AR, Mullany DV et al. To ventilate, oscillate, or cannulate? J Crit Care. 2013 Oct;28(5):655-62. 

Taccone P Gattinoni L, et al. Prone positioning in patients with moderate and severe acute respiratory distress syndrome: a randomized controlled trial. JAMA. 2009; 302(18): 1977-84.