(200) Reduction in Right Ventricular Afterload With Nitric Oxide Predicts Survival in COVID-19 ARDS

Introduction: Increased right ventricular afterload is common in ARDS and can lead to right ventricular failure, a strong predictor of death in both COVID-19 and non-COVID-19 ARDS. Inhaled nitric oxide (iNO) is a selective pulmonary vasodilator that has been used to treat refractory hypoxemia in adult ARDS without clear benefit. However, previous trials have focused on its effects on oxygenation rather than hemodynamics.

In this study, we evaluated the effects of iNO on cardiac function among patients with COVID-19 ARDS. We hypothesized that iNO would reduce pulmonary artery pressures and improve right ventricular function, which could lead to improved outcomes independent of oxygenation.

Methods: We performed a post-hoc analysis of a randomized controlled trial. Intubated COVID-19 patients were treated with iNO at 80 ppm vs placebo. Transthoracic echocardiograms were performed on a subset of patients. Echocardiographic assessments included tricuspid annular plane systolic excursion (TAPSE), estimation of right ventricular systolic pressure (RVSP) based on the maximum velocity of the tricuspid regurgitant jet, mitral inflow and annular velocities to assess left ventricular diastolic function and left ventricular outflow tract velocity time integral as a correlate for cardiac output.

Results: Nineteen patients received echocardiograms before and after initiation of iNO. Treatment with iNO led to an increase in TAPSE (2.04 IQR 1.84-2.28 vs 2.44 IQR 2.24-2.71 cm, p=0.0005) and a reduction in RVSP (30.1±12.2 vs 25.9±10.7 mmHg, p< 0.0001) compared to baseline. There was no change in left ventricular function and no change in the PaO2/FiO2 (P/F) ratio before and after initiation of iNO.

Survivors (63%) demonstrated a greater reduction in RVSP with iNO compared to non-survivors (-7.59±4.82 vs -1.21±4.73 mmHg, p=0.016). There were no differences in the P/F ratio improvement or increase in TAPSE with iNO between survivors and non-survivors.

Conclusions: iNO reduces pulmonary artery pressures and improves right ventricular systolic function in COVID-19 ARDS. Improvement in pulmonary artery pressures, but not oxygenation, predicted survival to hospital discharge. Our data support the use of iNO to target improvement in right ventricular afterload rather than oxygenation alone in ARDS.