P092 Dynamic echocardiography aids in managing NIV for myotonic dystrophy patient

Abstract Introduction Non-invasive ventilation (NIV) increases intrathoracic pressure (ITP), which may reduce venous return and cardiac output. However, the clinical implications of this physiological effect in patients with neuromuscular disorders, such as Myotonic Dystrophy (MD), remain poorly defined. Methods We report a 60-year-old male with MD and a permanent pacemaker on nocturnal NIV (S/T mode: IPAP 17 cm H₂O, EPAP 6 cm H₂O), who presented with worsening dyspnea and daytime ventilator dependency. On admission, he was in decompensated respiratory failure, prompting an increase in IPAP by 2 cm H₂O. While dyspnea improved, severe hypotension (systolic BP ~60 mm Hg) developed upon NIV initiation, requiring inotropes. Bedside dynamic echocardiography during NIV revealed significantly reduced venous return and near RV collapse at higher pressures. Corresponding declines in LVOT flow velocities and cardiac output were noted. Results Gradual downtitration of NIV pressures during echocardiographic monitoring, alongside arterial blood gas (ABG) evaluation, identified an optimal setting (IPAP 13 cm H₂O, EPAP 4 cm H₂O). At this level, RV filling improved, systolic BP stabilized at 110 mm Hg, and the patient reported symptomatic improvement. Mild compensated nocturnal hypercapnia (PCO₂ 49 mm Hg) was accepted as an outcome. Conclusion This case illustrates the potential for high NIV pressures to significantly impair cardiac output in patients with MD due to elevated ITP. Bedside dynamic echocardiography proved instrumental in titrating NIV settings to balance respiratory support with hemodynamic stability. Further studies are warranted to guide NIV management in similar neuromuscular populations.