Assessment of Stroke Volume in Shock Using Echocardiography Versus Bioreactive Impedance

Inclusion Criteria * Age ≥ 18 years * Clinical diagnosis of shock as determined by the treating ICU physician (e.g., hypotension requiring vasopressors or evidence of end-organ hypoperfusion) * Able to obtain informed consent from the patient or a legally authorized representative * Enrollment within 24 hours of ICU admission Exclusion Criteria: * Pregnancy * Known severe aortic valve disease or dynamic left ventricular outflow tract obstruction * Morbid obesity (BMI \> 40) that precludes accurate echocardiographic imaging Presence of cardiac arrhythmias (e.g., atrial fibrillation with rapid ventricular response) affecting stroke volume measurements * Implanted cardiac assist devices (e.g., LVAD, pacemaker dependency) * Imminent death or decision for comfort care only