Heart drug may unlock secrets of blood flow in sepsis

Copied word for word from the study's registry entry, so the wording is the study team's rather than ours.

Inclusion Criteria: Age 18-85 years. Diagnosis of septic shock according to Sepsis-3 criteria, requiring norepinephrine to maintain MAP ≥65 mmHg after adequate fluid resuscitation. Persistent tachycardia after initial hemodynamic optimization, adequate analgesia/sedation, and correction of reversible causes, defined as heart rate ≥95 beats/min. Continuous norepinephrine infusion for ≥6 hours, with norepinephrine dose ≥0.10 μg/kg/min at enrollment. Adequate volume status or absence of fluid responsiveness assessed by dynamic indices, echocardiography, or advanced hemodynamic monitoring; if PiCCO is used, GEDVI \>700 mL/m² and/or ITBVI \>850 mL/m² may be used as supportive criteria. Preserved or hyperdynamic cardiac function before esmolol initiation, defined as cardiac index \>3.0 L/min/m² or absence of severe septic cardiomyopathy. Ability to obtain sublingual microcirculatory images of acceptable quality at baseline. Written informed consent obtained from the patient or legally authorized representative. Exclusion Criteria: Shock mainly caused by non-septic etiologies, including cardiogenic, hypovolemic, obstructive, hemorrhagic, or anaphylactic shock. Severe cardiac dysfunction or severe septic cardiomyopathy, including cardiac index \<2.2 L/min/m² despite adequate preload, severe ventricular dysfunction, or need for inotropic agents at enrollment. Use of β-blockers before ICU admission or within 24 hours before enrollment. Contraindications to esmolol or β-blockade, including high-grade atrioventricular block without pacing, severe bradycardia, sick sinus syndrome, severe bronchospasm/asthma, or known allergy to esmolol. Severe structural heart disease or major pulmonary conditions affecting hemodynamics or safety, including severe valvular disease, significant congenital heart disease, cardiomyopathy, severe pulmonary bullae, or untreated pneumothorax. Acute coronary syndrome, life-threatening arrhythmia, or cardiac arrest before enrollment during the current ICU stay. Conditions interfering with sublingual microcirculatory assessment, including major oral/sublingual lesions, active oral bleeding, inability to access the sublingual area, or poor baseline image quality. Pregnancy or lactation, expected death or withdrawal of life-sustaining treatment within 24 hours, expected ICU stay \<48 hours, or inability to obtain informed consent.