After cardiopulmonary bypass heart surgery, with the rewarming of body temperature, the metabolic capacity of the body is enhanced, the microcirculation is opened, and tissue perfusion is increased. At the same time, the body pays off the oxygen debt formed by the low temperature and reduced blood flow in cardiopulmonary bypass, so that the tissue oxygen demand increases and oxygen consumption increases.Analgesia and sedation are important treatment measures for patients after cardiopulmonary bypass. S-isomer of ketamine and eselamine enhanced the sedation and enhanced the analgesic effect, but whether it can improve the imbalance of oxygen supply and oxygen consumption after cardiopulmonary bypass is unknown.

After cardiopulmonary bypass, the body usually appears in a state of hypermetabolism. In addition to anesthesia resuscitation and recovery of spontaneous respiration, chills, pain and anxiety can increase oxygen demand, increased oxygen consumption is also related to a series of neuroendocrine reactions.At the same time, the body needs to repay the oxygen debt formed by low temperature and reduced blood flow in extracorporeal circulation, so that the tissue oxygen demand increases, and the systemic oxygen consumption is significantly higher than the normal physiological state.

Sedation and analgesia treatment is one of the important early treatment measures for patients after heart surgery. Patients with heart disease are prone to anxiety and restlessness due to reduced cardiac function reserve, severe surgical trauma and extracorporeal circulation, which can lead to hemodilution, tissue edema, ischemia and reperfusion injury, etc. In addition, patients with high preoperative mental stress are prone to anxiety and restlessness.Appropriate sedation and analgesia treatment is very important to reduce stress response, reduce oxygen consumption and maintain the stability of hemodynamics.

The application of ketamine in sedation and analgesia has the characteristics of high controllability, and it does not inhibit respiration and mildly excites circulation, but whether it can improve the imbalance of oxygen supply and demand in patients after cardiopulmonary bypass is unknown.Therefore, it is of great significance to investigate the effect of ketamine on oxygen supply and oxygen consumption of patients after cardiopulmonary bypass surgery.

Inclusion Criteria:

• Consecutive adult (>18years)patients after heart surgery

Exclusion Criteria:

• Chronic kidney disease (CKD); ECMO or IABP assistance is required; Malignant tumor; Acquired immunodeficiency syndrome; receive psychiatric medication.