Reperfusion Syndrome and Vasoplegic Syndrome in Liver Transplant Surgery

Introduction:

At the time of the liver reperfusion, many inflammatory mediators coming from the liver graft to the systemic circulation produce a sudden load of cold and acidotic blood. At this stage of graft revascularization, it has been seen an increase of pulmonary vascular resistance index (PVRI) and pulmonary arterial pressure (PAP) and a reduction in systemic vascular resistance index (SVR), heart rate (HR), cardiac index (CI) and arterial blood pressure (ABP).

In this context, some patients suffer postreperfusion syndrome (PRS). This syndrome was first defined by Aggarwal et al as a decrease in the MAP greater than 30% of at least one minute duration and during the five minutes following the portal unclamping and was associated with several preoperative risk factors and postoperative complications. The variety of the risk factors presented in previous studies suggest that the PRS occurs in an unpredictable manner. These risk factors were described related to the organ of the donor; related to the recipient of the liver graft, and related to the surgical technique. The incidence varies largely among the considered studies, ranging from 12% to 77% and it can respond not only to preoperative and intraoperative factors associated with anesthetic-surgical practice, but also to the different criteria for definition of PRS as well as to the administration of vasoactive drugs to prevent or treat it.

On the other hand, the incidence of vasoplegic syndrome (VS) is not described and could be confused with PRS We studied the patients who received vasoactive support during liver transplant surgery and presented PRS considering the Aggarwal et al. definition, and VS considering the Ozal et al. criteria.

Methods:

Design: Retrospective observational study. Inclusion criteria: Patients undergoing liver transplantation who received vasoactive support and monitored with Swan Ganz catheter Exclusion criteria: liver transplantation for acute liver failure, combined liver and kidney transplantation, renal dysfunction (glomerular filtration \<60), moderate/severe vascular and valvular heart disease, moderate/severe hepatopulmonary syndrome, moderate/severe portopulmonary syndrome, and re-transplantation

• Study outcomes The primary objective of our study was to determine the incidence and risk factors of PRS and VS in norepinephrine/adrenaline patients according to the Aggarwal and Ozal criteria respectively. The second objective is to determine the postoperative complications.
• Data collection Preoperative variables related to recipient and donor were analyzed. Intraoperative variables were recorded at each stage of the surgery: pulmonary capillary wedge pressure (PCWP), mean pulmonary arterial pressure (mPAP), MAP, heart rate (HR), cardiac index (CI), systemic vascular resistance index (SVRI), central venous pressure (CVP), bleeding, need for transfusions, doses of vasoconstrictors, global requirements for bicarbonate and calcium chloride, presence of malignant arrhythmias (fibrilation, flutter, ventricular tachycardia) or ischemic electrocardiographic abnormalities. The times of each surgical phase, duration of cold ischemia and the weights of the liver (donor/recipient) were recorded too. Postoperative data collected included: graft rejection, a second surgery after liver transplant, the need for re-transplantation, renal dysfunction (glomerular filtration \<60), hospital stay, days of hospitalization and survival.

All items that could be used to identify the patient (clinical record ID number or name) were removed to protect personal data.

-Measurement of hemodynamic data The hemodynamic parameters (MAP, HR, SVR, CVP, CI, PCWP and mPAP) of each stage of the liver transplant surgery (dissection phase, anhepatic phase prior to unclamping of the IVC, at 1 and 5 min after graft reperfusion, and in the neohepatic phase after completion of the vascular anastomosis) were collected.

The PRS criteria were decrease in the mean arterial pressure ≥ 30% mmHg during the first 5 minutes after unclamping of the IPV, decrease in CI and SVR respect to baseline (anhepatic phase), and increase of the PCWP, CVP and mPAP respect to baseline.

Association between PRS and preoperative, intraoperative, and postoperative variables were analyzed and compared between the two groups (for PRS + and PRS - groups).