Cardoso, Nathalia Machado

Silva, Orlando de Castro e

Silva, Tiago

English

Cadernos Espinosanos (E-Journal)

Medicina (Ribeirão Preto) 2013;46(2): 115-7EDITORIALLooking for new prognostic indices inliver transplantation. Considerationsregarding a research projectBuscando novos índices prognósticos no transplante de fígado. Consi-derações a respeito de um projeto de pesquisaNathalia Machado Cardoso1, Tiago Silva2, Orlando de Castro e Silva31. Classical and pure MELD. The MELD for-mula does not fit all patients who arecandidates for OLTFirst of all it is important to remember that theMELD is nothing more than a score used worldwideto estimate the degree of systemic involvement  inpatients with end-stage liver disease. The score is basedon some variables such as creatinine, INR and totalbilirubin and permits to classify the patients by meansof a point system according to the severity of theirdisease. It is on the basis of the MELD score thatpatients who are candidates for a liver transplant areassigned to the waiting list in such a way that the morecritically ill ones will receive priority.This year we published a paper concerningliver transplantation1 with the objective ofdetermining the postoperative levels of classical or puremodel for end-stage liver disease (MELD), andchanges in lactate or base excess levels as possiblepredictive factors of the type of outcome for patientssubmitted to orthotopic liver trasplantation (OLT). Thisinvestigation motivated other studies focused on thesearch for sensitive predictive indices specific for thetype of outcome of invariably critically ill patientssubmitted to the most complex surgical procedurecurrently performed in human beings. We intend topresent here four comments that we consider pertinentwith the major objective of emphasizing importantaspects of the topic under study.1. Intern Student of the HCFMRP-USP and Monitor  of the division of digestive surgery, Department of  Surgery and anatomy, RibeirãoPreto Medical School, USP.2. MS Illinois Institute of Technology, Department of Applied Mathematics, Chicago, Illinois, USA.3. Full Professor, University of São Paulo. Head of the Department of Surgery and Anatomy, Ribeirão Preto Medical School, USP.MELD = 0.957 x Loge (Creatinine*) + 0.378 x Loge (Bilirubin *) + 1.12 x Loge (INR) + 0.643   * Creatinine and Bilirubin are expressed in mg/dL.Figure 1: MELD formula: Model for end-stage liver disease116Medicina (Ribeirão Preto) 2013;46(2): 115-7http://revista.fmrp.usp.br/Cardoso N.M., Silva T., Castro e Silva O. Looking for new prognostic indices inliver transplantation. Considerations regarding a research projectIn our study, we consider the classical MELDand pure MELD as synonyms, and stating that MELDis "pure" was based on the principle that no arbitraryscoring was added to it, as done in so-called specialsituations not contemplated by the classical MELD.Indeed, in our studies based on prognostic indices wesought to attach a new variable to the MELD in orderto improve it and make it more precise. Thus, theclassical, already known, MELD or the pure MELDas we called it in our study, by receiving a new variable,would become more elaborate and specific. This wasonly our way to differentiate the MELD popularlyknown in the area from the MELD that we tried tocreate in our studies.  And this search also deals with the fact thatthe MELD does not fit all patients in the same way.What occurs is that the model does not contemplateall the needs for organ allocation and cannot be usedin patients with hepatocellular carcinoma (HCC), fa-milial amyloid polyneuropathy  (FAP), and metabolicdiseases, among others. What occurs in these patientsis that the indicators that make up the MELD formula(INR, creatinine and total bilirubin) remain unchangedon a short-term basis, masking the real condition ofthe patient by assigning lower scores to him that donot reflect the severity of his situation. If we considerthe use of the MELD as a prognostic postoperativeindex - the central topic of our study - we can see thatit is even more inefficient since it does not contain inits formula indicators with the ability to discriminatebetween patients who will suffer complications andpatients who will immediately obtain a good postop-erative course.On this basis, it is common to question the factthat the MELD is used as a key element in the clinicalcourse of patients with liver disease, although it conti-nues to be a mathematical formula that provides anobjective value for the subjective clinical assessmentof the degree of systemic involvement, indicating tothe specialists a more exact direction of the course ofthe disease and greatly facilitating the decisions aboutthe conducts to be followed.Many studies have been published during thelast few years proposing to improve the MELD as aformula for organ allocation and also as a prognosticpostoperative index. Along this line, we started oursearch for new indicators, two of which proved to berelevant in the study mentioned above: base excessand serum lactate.2. Base excess in medical practiceDuring liver transplantation, which is a situationof stress, ischemia and hypermetabolism, serum lactatelevels increase due to the fall in hepatic function fortheir clearance from the organism caused by liverhypoxia and hypoperfusion.In addition, at this time lactate production isincreased, since lactate is the final product of glucoseutilization during anaerobiosis. This reaction, in turn,occurs with release of hydrogen ions that acidify themedium and cause a fall in blood pH (metabolicacidosis). The return of pH to normal values occursthrough the maintenance of acid-base equilibrium,which is mainly sustained by base consumption in orderto reach homeostasis. Thus, we talk about base excessas an index that estimates the quantity of basesnecessary for the restoration of physiological pH. Withthe increase in H+ ions during anaerobiosis, baseconsumption continues to increase, causing baseequilibrium to become increasingly negative3. Joint analysis of postoperative MELD, baseexcess and blood lactate as an index ofthe type of postoperative evolution of pa-tients submitted to orthotopic liver trans-plantationThe results were expected, since we do knowthat ischemia and reperfusion injury alters the functionof the organ and impairs lactate clearance. What wedid not know was at what specific time the lactateand base excess values would provide safe cluesregarding the prognosis of the patients.What we saw with the study was that, a littleafter liver reperfusion, the patients who showed afavorable immediate postoperative outcome had lowerlactate and base excess values than those who diedand that, in addition, this difference continued to bepresent until the end of the procedure.For an explanation, it is sufficient to return tothe previous item, which shows that lactate and baseexcess are intimately related and are part of the physi-ological mechanism of homeostasis in stress situations.117Cardoso NM, Silva T., Castro e Silva O. Looking for new prognostic indices inliver transplantation. Considerations regarding a research projectMedicina (Ribeirão Preto) 2013;46(2): 115-7http://revista.fmrp.usp.br/4. The findings of the present study and theiruse to guide the management of patientssubmitted to OLT during the postopera-tive periodThe importance of this result is based on thefact that, with the combination of these three param-eters, we can better direct the postoperative care ofmore seriously ill patients. On this basis, we can per-form a more expanded, constant and objective moni-toring of their status after the transplant procedure.However, this was one of the first studies conductedby our group in the search for new prognostic indices.We are currently involved in intensive andmultidisciplinary work that counts with the collabora-tion of the Illinois Institute of Technology in the US,and is developing new ways of calculating the MELD2.What we are studying is the incorporation in two dif-ferent ways of the lactate variable into the classicalMELD  by means of two equations. Both equationswere obtained through regression analysis using pa-tients data as independent variables and Boolean in-formation as a dependent variable.The difference between the two equations isthat we used the logarithm of bilirubin, INR, creatinineand blood lactate as independent variables for theregression analysis of the first equation  and only theMELD value and the logarithm of blood lactate forthe regression analysis of the second equation, animportant step that expresses the acute alteration ofhepatic function.This study has shown positive and more sensitiveand specific results compared to the MELD, knownand diffuse worldwide in the area of hepatology.Referências1. Cardoso N, Silva T, Cagnolati D, Freitas T, Mente ED, Basile-Filho A, Castro e Silva O. Can joint analysis of postoperativeMELD, base excess and blood lactate levels be used as anindex of postoperative outcome for patients submitted to livertransplantation? Acta Cir. Bras. 2013;28(1):54-60.2. Cardoso NM, Castro e Silva O, Silva T, Basile A, Mente ED. ANew Formula as a Predictive Score of Post-LiverTransplantation Outcome: Postoperative MELD Lactate. LiverTransp. 2013;19(6):S163.

Buscando novos índices prognósticos no transplante de fígado. Considerações a respeito de um projeto de pesquisa

https://www.revistas.usp.br/rmrp/article/download/62399/65200

Looking for new prognostic indices in liver transplantation. Considerations regarding a research project

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