A sigle-center, randomized controlled trial will be do to investigate the effects of esomol on heart rate, clinical parameters, mortality, and safety in septic shock patients with tachycardia at different stages, compared with patients who received conventional therapy.

The incidence of septic shock complicated with tachycardia is high and the prognosis is poor. Enough attention should be paid to and appropriate treatment should be given. High heart rate and high cardiac output are beneficial compensatory reactions of sepsis and septic shock. However, excessive sympathetic activation and high heart rate also have adverse effects on the cardiovascular system. Sustained tachycardia is harmful to patients with sepsis and septic shock and needs to be controlled. At present, it is widely used in the treatment of cardiovascular diseases and β Receptor blockers have the functions of preventing and reversing sympathetic effects, anti arrhythmia, anti-inflammatory and balancing myocardial oxygen supply and demand. Therefore, they are recommended to control arrhythmias in patients with septic shock. The 2014 guidelines for sepsis / septic shock in China suggest that if cardiac output is not low and the heart rate is fast after adequate fluid resuscitation, short acting drugs（β Receptor blockers）can be considered. However, there are some differences in the current clinical research results, and it suggests that the timing of treatment may affect the hemodynamic results and clinical outcomes of patients.

Therefore, this study intends to intervene with esmolol in patients with septic shock and tachycardia at different stages, and compare the hemodynamic parameters, clinical outcome, prognosis and adverse reactions with the conventional treatment group, in order to explore the appropriate time of esmolol in the treatment of patients with septic shock and tachycardia.

Inclusion Criteria:

" ≥ 18 years old; " New septic shock within 24 hours, meeting the diagnostic criteria in 2012; " Septic shock lasts for more than 6 hours, and after fluid optimization using dynamic parameters, vasoactive drugs are still needed to maintain blood pressure; " the heart rate is greater than 100 beats / min for ≥ 1 hour，not caused by agitation, fever, and other factors; " informed consents are signed.

Exclusion Criteria:

" Shock caused by sepsis; " Septic cardiomyopathy or decreased myocardial contractility, requiring the use of positive inotropic drugs or significant cardiac insufficiency, such as CI ≤ 2.2l/min m2, PAWP>18mmHg, EF<40%; " Severe bronchial asthma or COPD; " Pregnant or lactating women; " Sinus bradycardia, degree II and degree III heart block; " β-receptor blockers were used before enrollment or have the history of sinus tachycardia; " Severe valvular heart disease; " Allergic to esmolol; " Tachycardia due to elevated body temperature, agitation, insufficient capacity and other reasons; " Have participated in other clinical studies.