Theoretically, aPRP is less exposure of coagulation factors and platelets to the extra-circulation system to achieve blood conservation from the deleterious effects of CPB. The centrifugation device and autologous transfusion system can be used to harvest and separate whole blood into red cell concentrate and aPRP fraction. The collected red cell is reinfused depended on hemoglobin concentration, and aPRP fraction is reinfusion after separation from CPB and reversal of anticoagulation.
Similar to prior reports8, 10, 15, we found the aPRP technique markedly reduced intraoperative allogeneic blood transfusion and shortened the duration of mechanical ventilation. For whole blood exposed to the CPB circuit, the patient’s platelets were activated, and coagulation factors were consumed during CPB. The use of aPRP can maintain normal platelet function, preserve plasma volume, and ultimately reduce transfusion. In previous studies, Zhou8 and Han15 presumed that the use of aPRP could ameliorate postoperative lung injury and shorten mechanical ventilation, possibly related to fewer allogeneic transfusions.
AKI is frequent as a severe complication following an operation for Type A AAD. According to KDIGO criteria, the reported incidence of post-AKI after thoracic aortic surgery is 53%16 and 77.6%17 in China. In this study, we found that there was a significantly lower incidence of post-AKI (45%) compared with the results reported previously. In the present study, we defined post-AKI as AKI occurred within 48 hours after surgery, which reduced the incidence of post-AKI and avoided other postoperative complications to confounding the effect of aRPR on renal function.
In this study, the use of aPRP was independently associated with an increased hazard of post-AKI. The main risk with aPRP harvest was hemodynamic fluctuation and hemodilution induced by acute hypovolemia and alternate fluid therapy. In the aPRP group, rapid fluid replacement therapy were required to maintain hemodynamic stability during aPRP collection. Total fluid volume for transfusion was higher in the aPRP group than in the non-aPRP group, which not related to post-AKI by Logistic analysis.
In this study, post-AKI development after type A acute aortic dissection repair was associated mainly with postoperative variables, such as postoperative serum creatinine and lactate. Although novel biomarkers, such as neutrophil gelatinase-associated lipocalin and cystatin C, have been identified as independent predictors of AKI and are superior to conventional biomarkers, sCr continues to be a more valuable and accepted tool for AKI diagnosis18. During surgery and CPB, the kidneys may suffer from an imbalance between oxygen supply and oxygen needs that is associated with lactate production 19. Higher serum lactate values, which are a surrogate marker of tissue hypoperfusion and imbalance of renal oxygen metabolism, were associated with the occurrence of postoperative AKI. In addition, lower hemoglobin induced by hemodilution during aPRP collection decreased oxygen delivery and was also associated with postoperative AKI20.
The precise mechanism of aPRP on post-AKI has not been clarified. Thus, careful monitoring and management of hemodynamic and maintaining fluid balance by experienced anesthesiologists during aPRP harvest play a vital role in improving postoperative kidney function. In addition, there still are some questions to be addressed for the application of aPRP in future studies
This retrospective study has several limitations. The most important limitation was the difference in preoperative variables between groups and the possibility of selection bias due to the nonrandomized design. The preoperative characteristics of patients in the aPRP group were younger age, higher BMI values, lower levels of preoperative SCr, and longer duration of surgery patients than those in the non-PRP group. The characteristics between the two groups could be adjusted to partially correct for these differences by propensity-adjusted matching analysis. Additionally, preoperative renal malperfusion is an independent predictor for postoperative AKI21. Preoperative renal malperfusion also induced an increase in preoperative SCr values, which possibly led to bias and adverse effects on the results. In this study, preoperative SCr values were higher in 160 (160/660, 24.2%) patients than after surgery, and only 25 (25/160, 15.6%) of these patients had post-AKI. Thus, instead of focusing on preoperative SCr, postoperative SCr was selected in our model of risk factors associated with post-AKI. Ultimately, most patients with severe ischemia or malperfusion were not enrolled in this study. The results were appropriate for patients classified as Penn class Aa but are not a guideline to those who are Penn class Ab and Ac22.