Use of inhaled nitric oxide in submassive intermediate-risk pulmonary embolism: a single-centre experience

<bold>Background:</bold> There is lack of universal consensus for management of submassive pulmonary embolism (PE) where thrombotic pulmonary arterial occlusion increases right ventricular (RV) afterload. We evaluated our experience in using inhaled nitric oxide (iNO) as a pulmonary vasodilator adjunct in such patients. <bold>Methods:</bold> This was a retrospective case series of adult patients with radiological and echocardiographic evidence of submassive PE from 1st January 2012 – 31st Dec 2023. Eligible patients had RV dysfunction with no haemodynamic instability nor contraindication to anticoagulation. <bold>Results:</bold> Twenty-two patients received iNO (10-20ppm) with oxygen via high-flow nasal cannula (HFNC). Median age was 67 years. Median BMI was 31.8 kg/m². 64% of patients required inotropes with dobutamine being used in the majority (median peak dose 3mcg/kg/min). Median duration of iNO use was 3.2 days with serial echocardiogram showing interval RV improvement in majority of the patients. Median duration of ICU admission was 4.8 days. Median FiO2 (fraction of inspired oxygen) requirements before iNO use was 0.4 (on HFNC) compared to 0.35 post iNO use. 55% of patients were discharged from ICU on low flow nasal prongs or room air. Two patients (with severe underlying lung disease) died after having reached ceilings of care. One patient progressed to thrombolysis and one patient progressed to veno-venous extracorporeal membranous oxygenation. <bold>Conclusion:</bold> iNO may be used as part of a multimodal RV support strategy in submassive intermediate risk PE whilst patients are being risk stratified for definitive treatment options. However appropriately powered randomised trials are needed to establish true efficacy.