Acute kidney injury is major complication after open heart surgery. The cause of acute kidney injury following open heart surgery is related to activation of sympathetic nervous system, decrease of renal blood flow, ischemia-reperfusion injury and systemic inflammatory response.
Infective endocarditis patients undergoing open heart surgery have systemic inflammatory response associated with infective endocarditis. And the inflammatory response can be aggravated by cardiopulmonary bypass. The incidence of acute kidney injury following open heart surgery due to infective endocarditis was 50% in a previous report. And this acute kidney injury was related to the poor outcome and high mortality. Thus, the preventive method to protect kidney function will be needed in the patients with infective endocarditis undergoing open heart surgery.
Dexmedetomidine is a selective α2-agonist and has sedative, analgesic, and CNS depressive effect. And several experimental study demonstrated the renal protective effect. Intraoperative dexmedetomidine administration can reduce the amount of anesthetics needed and suppress the sympathetic response resulted by surgical stimulation. And dexmedetomidine was reported to reduce the level of serum cortisol, epinephrine and norepinephrine during the operation. Thus, these effects of dexmedetomidine can be expected to reduce the incidence of acute kidney injury.
Therefore, the investigators hypothesized that dexmedetomidine has renal protective effect and this effect might be related to the suppression of inflammatory response. Thus, the investigators will evaluate the incidence of acute kidney injury and the incidence of major adverse kidney events (MAKE) after open heart surgery due to infective endocarditis and the level of inflammatory mediators.
The primary end point of this study is the incidence of acute kidney injury after open heart surgery due to infective endocarditis. And secondary end point is the incidence of MAKE, the level of cystatin C which is related to the renal function, the level of inflammatory mediator and the postoperative morbidities.
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