Critical Alerts

• ARDS mortality remains 30-40% even with optimal management
• Lung protective ventilation is the cornerstone of treatment
• Low tidal volume (6 mL/kg IBW) reduces mortality - this is non-negotiable
• Prone positioning for 16+ hours improves survival in moderate-severe ARDS
• Identify and treat the underlying cause - ARDS is a syndrome, not a diagnosis

Key Diagnostics

• Berlin Criteria for diagnosis
• P/F ratio (PaO2/FiO2) on PEEP ≥5 cmH2O
• Chest X-ray or CT (bilateral opacities)
• Echocardiogram (exclude cardiogenic edema)
• Labs to identify underlying cause

Emergency Treatments

• Intubation and mechanical ventilation with lung protective settings
• Tidal volume 6 mL/kg ideal body weight (calculate IBW!)
• Plateau pressure ≤30 cmH2O
• PEEP titration (use PEEP/FiO2 table or driving pressure)
• Prone positioning for P/F <150 (16+ hours/day)
• Conservative fluid strategy after initial resuscitation

Acute Respiratory Distress Syndrome (ARDS) is a form of acute, diffuse, inflammatory lung injury leading to increased pulmonary vascular permeability, increased lung weight, and loss of aerated lung tissue. It is characterized by acute onset of hypoxemia and bilateral pulmonary infiltrates not fully explained by cardiac failure.

Berlin Definition (2012)

Severity Classification

Epidemiology

• Incidence: 10-80 per 100,000 person-years
• ICU frequency: 10-15% of ICU admissions; 23% of mechanically ventilated patients
• Mortality: 30-40% overall; higher in severe ARDS
• Long-term: Survivors often have persistent functional limitations

Critical Findings

Poor Prognostic Indicators

• Age >65 years
• Pre-existing organ dysfunction
• Higher APACHE II/III scores
• Failure to improve P/F ratio by day 7
• Underlying cause (sepsis > trauma)
• Immunocompromised status

Conditions Mimicking ARDS

Distinguishing ARDS from Cardiogenic Pulmonary Edema

Establishing Diagnosis

Step 1: Clinical Assessment

• Identify acute respiratory symptoms (<1 week)
• Known or suspected trigger (infection, aspiration, etc.)
• Progressive hypoxemia despite oxygen

Step 2: Oxygenation Assessment

Calculate P/F Ratio:
P/F = PaO2 (from ABG) ÷ FiO2 (as decimal)

Example: PaO2 60 mmHg on FiO2 0.60 → P/F = 100

Must be on PEEP ≥5 cmH2O for Berlin criteria

Step 3: Imaging

• Chest X-ray showing bilateral opacities
• Not fully explained by effusion, atelectasis, nodules

Step 4: Exclude Cardiogenic Cause

• Echocardiogram to assess LV function
• BNP/NT-proBNP
• Clinical context (no history of heart failure, volume overload)

Identify Underlying Cause

ICU Admission

• All patients with ARDS require ICU admission
• Invasive mechanical ventilation required in majority
• Continuous monitoring essential
• Prone positioning requires experienced team

Considerations for Transfer

Transfer to ARDS/ECMO Center If:

• Refractory hypoxemia despite optimal management
• ECMO may be indicated
• Lack of expertise in lung protective ventilation or proning

Prognosis Discussions

• Prepare family for prolonged ICU course
• Mortality 30-40% (higher in severe)
• Survivors may have long-term disability
• Goals of care discussions early

Understanding ARDS

• ARDS is severe lung inflammation causing very low oxygen levels
• It requires a breathing machine (ventilator) to support breathing
• Treatment focuses on allowing lungs to heal while preventing further damage
• Recovery takes weeks to months

What to Expect

• Patient will be sedated and on ventilator
• May need to lie on stomach (prone position) to help oxygen
• Multiple lines and monitors
• Daily updates from ICU team
• Prolonged ICU and hospital stay likely

Questions Families Should Ask

• What caused the ARDS?
• How severe is it (P/F ratio category)?
• What treatments are being used?
• Are there signs of improvement?
• What are the potential complications?

COVID-19 ARDS

Differences from Classic ARDS

• May have preserved lung compliance initially ("L-type")
• High thrombotic risk
• Prolonged course
• Dexamethasone proven beneficial (RECOVERY trial)

Management Modifications

• Awake proning if not intubated
• Anticoagulation (at least prophylactic, some use therapeutic)
• Tocilizumab/baricitinib in select patients
• Avoid delayed intubation

Immunocompromised Patients

• Higher mortality
• Consider atypical pathogens (PCP, CMV, Aspergillus)
• Bronchoscopy with BAL may be needed
• Empiric coverage may need to be broader

Pregnancy

• Prone positioning can be done with appropriate support
• ECMO used in severe refractory cases
• Delivery decisions based on gestational age and maternal status
• Multi-disciplinary approach essential

Trauma

• Pulmonary contusion may progress to ARDS
• Hemorrhage complicates fluid management
• Fat embolism syndrome in long bone fractures
• Aggressive pain control to prevent splinting

Performance Indicators

Documentation Requirements

• P/F ratio with calculation
• IBW calculation
• Ventilator settings with rationale
• Response to interventions
• Underlying cause identified or workup ongoing
• Family discussions documented

Diagnostic Pearls

1. Always calculate P/F ratio - defines severity and guides treatment
2. Bilateral infiltrates alone are not ARDS - need acute onset and hypoxemia
3. Echo to exclude cardiogenic edema - especially if no clear ARDS trigger
4. Find the underlying cause - ARDS is a syndrome, not a diagnosis
5. P/F ratio requires PEEP ≥5 for Berlin criteria

Treatment Pearls

1. 6 mL/kg IBW is non-negotiable - this saves lives
2. Calculate IBW using height, NOT actual weight
3. Prone early if P/F <150 - mortality benefit proven
4. Accept permissive hypercapnia (pH >7.20) to maintain low Vt
5. Conservative fluids after initial resuscitation

Disposition Pearls

1. All ARDS goes to ICU - no exceptions
2. Consider ECMO center transfer early - before patient is too sick to transport
3. Prolonged course expected - prepare family
4. Survivors need rehabilitation - functional impairment common
5. Goals of care discussions should happen early