Summary of Right Ventricular Function in Acute Respiratory Distress Syndrome: Impact on Outcome, Respiratory Strategy and Use of Veno-Venous Extracorporeal Membrane Oxygenation
Abstract Summary: Petit et al. explore the pathophysiology of right ventricular (RV) dysfunction in Acute Respiratory Distress Syndrome (ARDS), emphasizing its significant impact on patient outcomes. The authors propose an RV-protective management strategy that integrates optimized ventilatory settings, prone positioning, inhaled nitric oxide, and veno-venous extracorporeal membrane oxygenation (VV ECMO) to address severe RV impairment and improve survival.
Key Points:
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RV Dysfunction Pathophysiology: ARDS involves pulmonary vascular dysfunction and increased pulmonary vascular resistance (PVR), leading to RV dysfunction and potential acute cor pulmonale (ACP), significantly affecting patient prognosis.
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Pulmonary Hypertension in ARDS: Elevated PVR arises from endothelial dysfunction, vascular occlusion, increased tone, and remodeling, culminating in RV overload and subsequent failure.
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Mechanical Ventilation Impact: Mechanical ventilation, particularly when improperly managed (high tidal volumes and inappropriate PEEP), exacerbates pulmonary vascular pressures and RV afterload, worsening RV function.
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Incidence of Acute Cor Pulmonale: While earlier reports showed ACP in up to 60% of ARDS patients with traditional ventilation strategies, protective ventilation has reduced incidence to approximately 20-30%, though rates remain higher in severe ARDS cases.
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Risk Factors for RV Failure: Key factors contributing to RV dysfunction include high driving pressure (≥18 cmH2O), significant hypercapnia (PaCO₂ ≥48 mmHg), severe hypoxemia (PaO₂/FiO₂ <150 mmHg), and pneumonia as the underlying cause.
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Bedside RV Function Evaluation: Echocardiography is recommended as the primary non-invasive modality for monitoring RV function, supplemented by invasive hemodynamic assessments such as pulse pressure variation and right atrial pressures.
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Optimizing Ventilation Strategy: RV protection strategies include limiting plateau pressures (<27 cmH₂O), careful PEEP titration, minimizing hypercapnia, and maximizing oxygenation without causing pulmonary overdistension.
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Prone Positioning Benefits: Prone positioning significantly improves RV function by enhancing oxygenation, reducing hypercapnia, and distributing ventilation more evenly across the lungs without additional RV strain.
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Inhaled Nitric Oxide (INO): Although INO has not demonstrated survival benefits broadly in ARDS, it can specifically reduce RV afterload and provide hemodynamic stabilization in patients with refractory RV failure.
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Role of VV ECMO: VV ECMO is proposed for severe RV dysfunction unresponsive to conventional measures. It effectively reduces RV afterload through improved gas exchange and facilitates ultraprotective lung ventilation strategies.
Conclusion: Effective management of RV dysfunction through targeted respiratory strategies, prone positioning, selective use of INO, and timely initiation of VV ECMO could significantly enhance outcomes in severe ARDS patients by mitigating RV strain and circulatory failure.
Watch the following video on “TPES 2024: Dr. S Treschkatch “RV Function in ARDS and Respiratory failure” by TGH Advanced Perioperative Imaging Lab
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