The Role of Steroids in ARDS
A review of the evidence
Alex Yartsev 11/2010
Briefly, on the definition of ARDS
• Acute severe hypoxic
respiratory failure with bilateral
diffuse alveolar damage
• Lots of different criteria:
1994 AECC consensus, the LIS
score, the Delphi definition…
-
It has to be acute
PaO2 to FiO2 ratio of <200
PEEP > 10
bilaterality
• ABSENCE of left
ventricular failure
Bersen A.D, the Acute Respiratory Distress Syndrome (ARDS) Ch 29 in Ohs Intensive Care Manual, 6th ed.
Briefly, on the pathology of ARDS
There is diffuse alveolar damage;
• Alveolar-capillary barrier is damaged
– Thus, there is pulmonary oedema
• There is a complex inflammatory infiltrate
– Neutrophils play some role? a major role?...
– but neutropenic patients gets ARDS as well…
• There is surfactant dysfunction
– Surfactant keep alveoli from collapsing
• Sequence of events depends on what is
causing the ARDS: is the cause
pulmonary or extrapulmonary?
Bersen A.D, the Acute Respiratory Distress Syndrome (ARDS) Ch 29 in Ohs Intensive Care Manual, 6th ed.
Briefly, on the pathogenesis of ARDS
-
The lung is a filter for the whole body’s blood
Circulating or local inflammatory mediators
Either way, something damages the endothelium first
The endothelium becomes leaky when it is inflamed
The endothelium expresses adhesion molecules, attracts neutrophils
Neutrophils / macrophages amplify lung damage
They also secrete mediators which cause pulmonary vasoconstriction
and thus worsening hypoxia
-
Leaky inflamed endothelium ceases to produce surfactant, and surfactant is also
lost because the leak through the capillary wall is bi-directional
Orfanos SE et al, Pulmonary endothelium in acute lung injury: from basic science to the critically ill Applied Physiology in
Intensive Care Medicine 2009, Part 2, 215-227,
Resolution of ARDS
• Pulmonary oedema resolves (type 2 cells
pump Na+ back into the vessels)
• About 5 days after onset, some repair takes
place
• There is a balance between repair and fibrosis
• Occasionally, fibrosis dominates
• This is fibrosing alveolitis
In summary
• The causes of ARDS are inflammatory
• The immune system does most of the damage
• Recovery of alveolar function is impaired by the
inappropriate fibrosis process
Why would steroids work?
– Inhibit the extravasation of leucocytes
(inhibit leucocyte adhesion molecules from interacting with endothelial
cell adhesion molecules; this raises the WCC )
– Increase the migration of lymphocytes to the
lymphoid tissues (and out of the bloodstream)
– Inhibit the function of macrophages and antigenpresenting cells
– Inhibit phagocytosis by macrophages
– Inhibit production of TNF-alpha and interleukin-1
– Inhibit expression of cyclooxygenase-2: Thus, inhibit
the synthesis of prostaglandins
– Inhibit synthesis of antibodies (in large doses)
What harm could they do?
• More risk of neuromuscular weakness
• When yoused together with neuromuscular blocking
agents, LOTS more risk of neuromuscular weakness
• Blunted febrile response = iatrogenic sepsis goes
unrecognised
Meduri GU, (1998) Effect of prolonged methylprednisolone therapy in unresolving
acute respiratory distress syndrome. A randomized controlled trial. JAMA 280:159–165
Meduri GU, (2007) Methylprednisolone infusion in early severe ARDS: results of a randomized
controlled trial. Chest 131:954–963
Steinberg KP, (2006) Efficacy and safety of corticosteroids for persistent acute respiratory
distress syndrome. N Engl J Med 354:1671–1684
Evidence for steroids in ARDS
• Meduri et al published a metaanalysis (2008)
– n = 518; all trials retrieved from
Cochrane
– Reduction in RR of death: 0.84
(0.78 if treated before day 14)
- Reduced length of ICU stay and
decreased number of ventilated days
Gianfranco Umberto Meduri
Meduri G.U et al Steroid treatment in ARDS: a critical appraisal of the ARDS network trial and
the recent literature 2008 Intensive Care Medicine Volume 34, Number 1, 61-69
ARDS network trial
Steinberg KP, (2006) Efficacy and safety of corticosteroids for persistent acute respiratory
distress syndrome. N Engl J Med 354:1671–1684
Evidence for benefit
Evidence for minimal benefit
And even if there was some benefit…
• When would you administer the steroids?
• How long is an effective course?
• Is there a difference in pulmonary vs
extrapulmonary causes of ARDS?
• Is there an improvement in long term lung
function?
And even if there was some benefit…
• When would you administer the steroids?
• How long is an effective course?
• Is there a difference in pulmonary vs
extrapulmonary causes of ARDS?
• Is there an improvement in long term lung
function?
No Further Questions, Please
References
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Bersen A.D, the Acute Respiratory Distress Syndrome (ARDS) Ch 29 in Ohs Intensive Care Manual, 6th ed.
Orfanos SE et al, Pulmonary endothelium in acute lung injury: from basic science to the critically ill
Applied Physiology in Intensive Care Medicine 2009, Part 2, 215-227,
Meduri G.U et al Steroid treatment in ARDS: a critical appraisal of the ARDS network trial and the recent
literature 2008 Intensive Care Medicine Volume 34, Number 1, 61-69
Steinberg KP, (2006) Efficacy and safety of corticosteroids for persistent acute respiratory distress
syndrome. N Engl J Med 354:1671–1684