Application of CLCVP Technique in Early Intervention of CSA-AKI

Application of Controlled Low Central Venous Pressure Technique in Early Intervention of Cardiac Surgery-associated Acute Kidney Injury

The goal of this clinical trial is to learn about in postoperative acute kidney injury in cardiac surgery. The main questions it aims to answer are:

1. Controlled low central venous pressure (CLCVP) technique can reduce the occurrence of cardiac surgery-associated acute kidney injury (CSA-AKI) by reducing venous congestion and increasing renal perfusion pressure.
2. CLCVP technique does not increase the risk of postoperative cognitive dysfunction (POCD) during cardiac surgery.

Participants who are assigned to the intervention group will receive CLCVP technique. Specific methods are as follows: First,20min after the end of cardiopulmonary bypass, on the basis of ensuring that the mean arterial pressure (MAP) ≥ 60mmHg, the patients will accept dorsal elevated position. After that, if the patient's central venous pressure (CVP) is less than 10mmHg, nitroglycerin will be pumped at 0.2ug/ (kg * min). If the patient's CVP is still greater than or equal 10mmHg, we increase the dose by 0.2ug/ (kg * min) and pump again for 5min, and the like. Until the patient's CVP is less than 10mmHg or the dose of nitroglycerin increases to 1ug/ (kg * min), the current dose is maintained until the end of surgery.

If participants are assigned to the control group, no intervention measures will be taken.

The researchers will compare the intervention group with the control group to see the occurrence of CSA-AKI and POCD after cardiac surgery.

Acute kidney injury (AKI) is a common and serious complication after cardiac surgery, which is associated with worsen prognosis including longer hospitalization, elevated mortality and morbidity and greater healthcare costs.The pathophysiological mechanisms underlying the development of AKI after cardiac surgery are complex. Venous congestion during cardiac surgery rather than hypotension is independently associated with the postoperative adverse kidney events, for both AKI within 7 days postoperative and longer-term acute kidney disease (AKD) that develops between 8- and 90-day postoperative window.Central venous pressure (CVP) is used as an indicator to quantify the degree of venous congestion, and high CVP may reflect severe venous congestion, contributing to decreased organ perfusion pressure and negatively affect renal microcirculation.

Controlled low central venous pressure (CLCVP) technique is a common and safe technique in clinical surgery.CLCVP technology has been widely used in hepatectomy, but there are few studies on its application in cardiac surgery settings. Most scholars believe that it has no adverse effects on the kidneys, while some studies suggest that it has a certain protective effect on the kidneys, but the mechanism is unclear.Actively targeting lower CVP levels using fluid restriction, reverse Trendelenburg position, vasodilators and other methods by anesthetics, can significantly reduce major intraoperative bleeding events.CLCVP technique could potentially play a role in renal protection during cardiac surgery by easing venous congestion through reduced CVP levels.

We therefore carried out a controlled randomized clinical trial to study the effect of CLCVP technique on postoperative acute kidney complications after on-pump cardiac surgery. Specifically, we tested the hypothesis that CLCVP management reduces the incidence of postoperative AKI through lower intraoperative CVP levels.

Inclusion Criteria:

• Patients aged 18 years and older, who underwent cardiac surgery (coronary artery bypass grafting (CABG), heart valve surgery, heart transplant or surgical excision of intracardiac myxoma) were eligible for analyses.

Exclusion Criteria:

• pre-existing renal insufficiency defined by presence of abnormal preoperative serum creatinine ≥ 133 μmol/L and/or preoperative diagnosis of renal insufficiency within 6 months' preoperative period.
• patients with preoperative dialysis dependence within 60 days before surgery, off-pump heart surgery, prior kidney transplantation, pregnancy, as well as those under drug therapy with nitroglycerin were excluded.