Objective:

Reexamine the role of pulmonary circulation in ARDS using a heart–lung-centered framework.

Approach:

• Ventilation and hemodynamics: Review how positive-pressure ventilation, lung volume, and PEEP affect pulmonary vascular resistance (PVR), right ventricular (RV) load, and pulmonary blood flow.

Key Findings:

• Pulmonary vascular dysfunction contributes to ARDS morbidity and mortality through impaired RV function and reduced cardiac output.
• Positive airway pressure can reduce cardiac output and worsen ventilation–perfusion matching; lung volume has a U-shaped relationship with PVR.
• Optimal PEEP may recruit collapsed alveoli, improve oxygenation, reduce hypoxic pulmonary vasoconstriction, and lower PVR, whereas overdistention can increase PVR and RV afterload.
• In ARDS, increased PVR is associated with mortality and can impede RV ejection, causing RV dilation and increased right atrial pressure; ventricular interdependence may then restrict left ventricular filling.
• Acute cor pulmonale is defined echocardiographically by RV dilation with paradoxical septal motion. Reported risk factors in moderate-to-severe ARDS include pneumonia, driving pressure ≥18 mmHg, PaO2/FiO2 <150 mmHg, and PaCO2 ≥48 mmHg.
• Pulse-pressure variations are associated with worse outcomes in ARDS but are not sufficiently specific to assess volume responsiveness.

Interpretation:

The article presents pulmonary circulation as an interface linking respiratory failure with systemic hemodynamic compromise. Its effects depend on the balance between alveolar recruitment and overdistention; the context states that no single PEEP threshold necessarily predicts hemodynamic compromise.

Limitations:

• The provided context ends mid-sentence during discussion of assessing volume responsiveness, so the article’s subsequent content is unavailable.
• No study design, search methods, or evidence-grading details are provided in the supplied context.

Sources:

• Article context supplied in the prompt