22% of patients with moderate-to-severe ARDS develop acute cor pulmonale on protective ventilation. The right ventricle was never designed to handle pressure — and every PEEP increase, every hypercapnic minute, and every overdistended breath you deliver is loading a chamber that was built to fail. Here is how to recognize it, prevent it, and treat it before it is too late.
“We spend years learning about the left ventricle. We build our hemodynamic frameworks around it. We design our resuscitation strategies for it. And then we watch patients die of right ventricular failure — the thin-walled, crescent-shaped, pressure-intolerant chamber that we forgot to protect while we were busy protecting the lung.”
A Message From Javier Amador-Castaneda, BHS, RRT, FCCM
Founder & CEO, Interprofessional Critical Care Network (ICCN)
Last week, we discussed DanGer Shock, the 2025 ACC Expert Consensus on cardiogenic shock, and the SCAI staging system. That article was about the left ventricle — the pump that fails in AMI-CS and HF-CS, the pump that DanGer Shock addressed with the Impella.
Today we talk about the other ventricle. The one that does not make the headlines. The one that does not have a landmark device trial. The one that most hemodynamic discussions treat as an afterthought — until it fails, and the patient collapses.
The right ventricle.
Here is the number that should change how you think about every ventilated ARDS patient in your ICU: 22% of patients with moderate-to-severe ARDS develop acute cor pulmonale — right ventricular dilation with septal dyskinesia — even while receiving protective ventilation.
Not high-tidal-volume ventilation. Protective ventilation. The ventilator settings you are using right now, in your best patient, with your best protocols, are contributing to right ventricular failure in roughly one out of every five patients.
This is not a rare complication. This is a systematic, predictable consequence of the interaction between positive pressure ventilation and a ventricle that was never designed to handle pressure. And the interprofessional team that does not assess for it, does not prevent it, and does not treat it is losing patients who did not need to die.
Why the Right Ventricle Is Anatomically Destined to Fail Under Pressure
To understand why RV failure is so common in the ICU, you must understand why the RV is fundamentally different from the LV — and why that difference makes it exquisitely vulnerable.
The left ventricle is a thick-walled, ellipsoidal pressure chamber designed to pump blood against the high resistance of the systemic circulation. It generates pressures of 120 mm Hg or higher with every contraction. It is built for pressure work.
The right ventricle is a thin-walled, crescent-shaped volume chamber designed to pump blood through the low-resistance pulmonary circulation. Normal pulmonary artery systolic pressure is 20–25 mm Hg — roughly one-fifth of systemic pressure. The RV generates low pressures and moves the same stroke volume as the LV, but it does so by wrapping around the LV and contracting in a bellows-like motion rather than a concentric squeeze. The RV is optimized for compliance. It handles volume beautifully. It handles pressure catastrophically.
When pulmonary vascular resistance rises acutely — as it does in ARDS, pulmonary embolism, sepsis, or aggressive mechanical ventilation — the RV confronts an afterload it was never engineered to overcome. Unlike the LV, which can hypertrophy and adapt to chronic pressure loads over weeks and months, the RV has almost no capacity for acute adaptation. It dilates. As it dilates, the interventricular septum shifts leftward, compressing the LV and impairing LV filling. Cardiac output falls. Coronary perfusion to the RV free wall decreases (the RV is perfused during both systole and diastole, so hypotension directly reduces RV myocardial oxygen supply). A vicious cycle begins: RV dilation → septal shift → LV compression → decreased cardiac output → hypotension → decreased RV coronary perfusion → further RV dysfunction.
This is the spiral of acute cor pulmonale. And once it is established, it is extraordinarily difficult to reverse.
How the Ventilator Destroys the Right Ventricle
This is the section that connects everything ICCN has taught about VILI to the hemodynamic reality of the right heart. The ventilator does not just injure the lung parenchyma. It injures the pulmonary vasculature — and through the pulmonary vasculature, it injures the RV.
Mechanism 1: PEEP increases RV afterload.
PEEP increases intrathoracic pressure and compresses the pulmonary capillary bed. At moderate levels of PEEP in a recruitable lung, this effect is offset by the reduction in hypoxic pulmonary vasoconstriction (as recruited alveoli improve V/Q matching). But at excessive PEEP in a non-recruitable lung, the dominant effect is capillary compression → increased pulmonary vascular resistance → increased RV afterload.
The 2024 ESC Association for Acute CardioVascular Care (ACVC) consensus statement on acute cor pulmonale recommended an initial PEEP of less than 10 cm H₂O as reasonable in ARDS with RV concern — even acknowledging that the evidence base for this specific threshold is limited.
Medical Disclaimer: The content published in ICCN is intended solely for educational and informational purposes for healthcare professionals. It does not constitute medical advice, clinical guidelines, or a standard of care, and should not be used as a substitute for the independent professional judgment of a licensed clinician. All clinical decisions must be individualized to the patient and made by qualified healthcare providers. ICCN assumes no liability for any clinical outcomes arising from the information presented herein.
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