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Diagnosing and Managing ARDS

Jul 15, 2024

Diagnosing and Managing ARDS

Introduction

Welcome back to ICU Advantage, I'm Eddie Watson. My goal is to simplify complex critical care subjects for ICU success. If you find this helpful, please subscribe, hit the bell icon for notifications, and access exclusive notes via YouTube and Patreon memberships.

Diagnosis

Berlin Definition for ARDS

  1. Acute onset (less than 1 week)
  2. Bilateral diffuse pulmonary infiltrates
  3. Cardiogenic pulmonary edema ruled out
  4. PF ratio < 300 with > 5 cm PEEP or CPAP

Key Diagnostic Steps

  • History & Physical: Look for deteriorating respiratory status, symptoms like shortness of breath, dyspnea, tachypnea, hypoxemia, cyanosis, and crackles.
  • Chest X-Ray: Progressive lung deterioration, from normal to diffuse alveolar damage.
  • CT Scan: Less common but can differentiate between other issues and identify extrapulmonary causes.
  • Pulmonary Artery Occlusive Pressure: Less than 18 mmHg to rule out cardiogenic pulmonary edema (with PA cath).
  • Ultrasound: Useful for evaluating ARDS and cardiogenic pulmonary edema.
  • Lab Tests: ABGs for PF ratio, lactic acid, infectious workups (blood, sputum, urine cultures, nasopharyngeal PCRs), CBC, CRP, and procalcitonin.
  • Bronchoscopy: Low value unless alveolar hemorrhage is suspected.
  • Pseudo-ARDS: Distinguish from atelectasis; improve with high airway pressure within 12-24 hours.

Management Strategies

Primary Goals

  1. Reduce shunt fraction
  2. Increase oxygen delivery
  3. Decrease oxygen consumption
  4. Avoid further injury

Treat Underlying Cause

Fluid Management

  • Target euvolemia (neutral fluid balance).
  • Use diuretics or CRRT as needed.

Steroids

  • Controversial; benefit depends on the underlying cause.

Ventilatory Support

  • Non-Invasive: High flow nasal cannula, CPAP/BiPAP.
  • Intubation & Mechanical Ventilation: Intubate early for better control in moderate to severe ARDS.

Lung Protective Mechanical Ventilation (ARDSnet Protocols)

  • Low Tidal Volume: 6 ml/kg ideal body weight (range 4-8 ml/kg).
  • High PEEP: Minimum of 5 cm, spo2 ≧ 88%.
  • Monitor Plateau Pressure: Keep ≤ 30 cm H2O; adjust tidal volume as required.
  • Permissive Hypercapnia: Tolerate higher CO2 levels unless contraindicated (e.g., increased ICP or RV failure).
  • Inspiratory Time: Keep inspiratory time < expiratory time.

Ventilatory Asynchrony Solutions

  • Optimize settings (triggers, flows, cycle times).
  • Adequate sedation (Propofol, Fentanyl).
  • Consider paralysis if needed.

Proning

  • Consider if PF ratio < 150; possibly sooner.
  • Awake proning can be beneficial.

APRV/Bi-Level Ventilation

  • Advanced mode with inverse I/E ratio.
  • Needs good sedation.

Paralysis

  • Use deep sedation first.
  • Benefits: Compliance with vent, metabolic demand reduction.

Inhaled Vasodilators

  • Inhaled nitric oxide, EPO for pulmonary vasodilation.

ECMO

  • Consider if PF ratio < 150.

Nutrition

  • Enteral feedings to maintain nutrition and reduce VAP risk.

Damage Control (Salvage Therapy)

  • Temperature Control: Aim for normothermia (37°C).
  • Inotropes: Increase cardiac output.
  • Blood Transfusion Limits: Aim for Hb level increase to 8.0 if necessary.
  • Effusion Drainage: Drain effusions to aid in management.

Full transcript