Can ARDS Occur in Sepsis?
Yes, ARDS is a well-recognized and common complication of sepsis, occurring in approximately 25-42% of septic patients, with the risk increasing substantially in those with persistent arterial hypotension. 1, 2
Epidemiology and Incidence
Sepsis is the single most common cause of ARDS, accounting for approximately 40% of all ARDS cases. 1
The incidence of ARDS in septic patients varies by severity: 6.2% in general severe sepsis cohorts, but rises to 8.9% in those requiring ICU admission. 3
ARDS typically develops rapidly in septic patients, with a median onset of 1 day after hospital admission. 3
Pulmonary and intra-abdominal infections are the most commonly associated sites of infection in patients who develop sepsis-related ARDS. 1
Clinical Characteristics and Outcomes
Sepsis-related ARDS has distinct characteristics and worse outcomes compared to non-sepsis-related ARDS:
Patients with sepsis-related ARDS have significantly lower PaO₂/FiO₂ ratios on ARDS day 3,7, and 14 compared to non-sepsis-related ARDS. 4
Recovery from lung injury is prolonged, with less successful weaning from mechanical ventilation and slower extubation rates (53.6% vs 72.6% successful extubation). 4
Mortality is substantially higher: 28-day mortality of 31.1% vs 16.3%, and 60-day mortality of 38.2% vs 22.6% compared to non-sepsis-related ARDS. 2, 4
The development of ARDS in severe sepsis is associated with a 4-fold higher risk of in-hospital mortality (60% vs 14%). 3
Risk Factors for ARDS Development in Sepsis
Early identification of high-risk septic patients is critical:
Higher APACHE II or APACHE III scores are independently associated with ARDS development. 4, 5
Elevated serum lactate levels in the emergency department (particularly ≥4 mmol/L) independently predict ARDS development. 3
Specific infection sites carry higher risk: pneumonia (OR 2.31), pancreatitis (OR 3.86), and acute abdomen (OR 3.77). 5
Presence of shock increases ARDS risk (OR 2.57). 5
In septic patients without shock, the amount of fluid administered in the first 6 hours is independently associated with ARDS development (OR 1.21 per liter), but this association does not hold in patients with shock. 5
Management Implications
The Surviving Sepsis Campaign guidelines explicitly recognize "sepsis-induced ARDS" as a distinct entity requiring specific ventilator management:
Target tidal volume of 6 mL/kg predicted body weight (strong recommendation, high quality evidence). 1
Maintain plateau pressures ≤30 cm H₂O (strong recommendation, moderate quality evidence). 1
Use higher PEEP strategies for moderate to severe sepsis-induced ARDS (weak recommendation, moderate quality evidence). 1
Prone positioning for patients with PaO₂/FiO₂ ratio <150 (strong recommendation, moderate quality evidence). 1
Conservative fluid strategy once tissue hypoperfusion is resolved (strong recommendation, moderate quality evidence). 1
Consider neuromuscular blockade for ≤48 hours if PaO₂/FiO₂ <150 mm Hg (weak recommendation, moderate quality evidence). 1
Common Pitfalls
Do not assume that all respiratory failure in sepsis is ARDS—ensure patients meet Berlin criteria (bilateral infiltrates, PaO₂/FiO₂ ratio ≤300, absence of cardiac dysfunction). 1
Do not overlook the importance of early fluid management in non-shock septic patients, as excessive early fluid administration is independently associated with ARDS development in this subgroup. 5
Do not delay implementation of lung-protective ventilation once ARDS is identified, as this is the intervention with the strongest mortality benefit. 2