Significance of postoperative changes in hemodynamics and biochemical indices in pediatric recipients of live-donor liver transplants

Modeling the hepatic arterial flow in living liver donor after left hepatectomy and postoperative boundary condition exploration

Preoperative and postoperative hepatic perfusion is modeled with one-dimensional (1-D) Navier-Stokes equations. Flow rates obtained from ultrasound (US) data and impedance resulted from structured trees are the inflow and outflow boundary condition (BC), respectively. Structured trees terminate at the size of the arterioles, which can enlarge their size after hepatectomy. In clinical studies, the resistance to pulsatile arterial flow caused by the microvascular bed can be reflected by the resistive index (RI), a frequently used index in assessing arterial resistance. This study uses the RI in a novel manner to conveniently obtain the postoperative outflow impedance from the preoperative impedance. The major emphasis of this study is to devise a model to capture the postoperative hepatic hemodynamics after left hepatectomy. To study this, we build a hepatic network model and analyze its behavior under four different outflow impedance: (a) the same as preoperative impedance; (b) evaluated using the RI and preoperative impedance; (c) computed from structured tree BC with increased radius of terminal vessels; and (d) evaluated using structured tree with both increased radius of root vessel, ie, the outlets of the postoperative hepatic artery, and increased radius of terminal vessels. Our results show that both impedance from (b) and (d) give a physiologically reasonable postoperative hepatic pressure range, while the RI in (b) allows for a fast approximation of postoperative impedance. Since hemodynamics after hepatectomy are not fully understood, the methods used in this study to explore postoperative outflow BC are informative for future models exploring hemodynamic effects of partial hepatectomy.

Hepatic and renal functions and blood cell counts in brain tumor patients during the perioperative period

We aimed to investigate the correlations between biochemical and hematological markers and the clinical conditions of brain tumor patients before and after craniotomy. A retrospective study was conducted in 90 brain tumor patients. Age, gender, underlying diseases, tumor size and intraoperative blood loss were recorded. Red blood cell counts and hepatic and renal markers were analyzed preoperatively and postoperatively. Albumin decreased by 5.6 g/L after surgery (p < 0.001). Older patients (>52 years) and females had lower albumin levels than younger patients and males did. Red blood cell counts and hemoglobin levels decreased significantly on the 1st and increased on the 3rd postoperative day. The blood glucose level increased on the 1st postoperative day and then decreased. Older patients had higher blood glucose levels than younger patients did (p < 0.05). The postoperative serum sodium, potassium and calcium levels were within the normal ranges; 37 patients had hypocalcemia (41.1%) and patients with hypokalemia and hyponatremia increased postoperatively. Albumin and hemoglobin levels were linearly correlated (correlation coefficient 0.559, p < 0.001). Intraoperative blood loss was correlated with tumor size (p < 0.05) but did not affect the decrease in hematological markers. In brain tumor patients, red blood cell counts and hemoglobin and serum albumin levels were significantly decreased after craniotomy; these effects were influenced by gender and age instead of intraoperative blood loss. The postoperative blood glucose level peaked and then decreased; it was affected by age and diabetes mellitus. Electrolytes remained relatively stable. These findings have implications for patient management and postoperative complication prevention.

Coagulopathy and transfusion therapy in pediatric liver transplantation

Bleeding and coagulopathy are critical issues complicating pediatric liver transplantation and contributing to morbidity and mortality in the cirrhotic child. The complexity of coagulopathy in the pediatric patient is illustrated by the interaction between three basic models. The first model, "developmental hemostasis", demonstrates how a different balance between pro- and anticoagulation factors leads to a normal hemostatic capacity in the pediatric patient at various ages. The second, the "cell based model of coagulation", takes into account the interaction between plasma proteins and cells. In the last, the concept of "rebalanced coagulation" highlights how the reduction of both pro- and anticoagulation factors leads to a normal, although unstable, coagulation profile. This new concept has led to the development of novel techniques used to analyze the coagulation capacity of whole blood for all patients. For example, viscoelastic methodologies are increasingly used on adult patients to test hemostatic capacity and to guide transfusion protocols. However, results are often confounding or have limited impact on morbidity and mortality. Moreover, data from pediatric patients remain inadequate. In addition, several interventions have been proposed to limit blood loss during transplantation, including the use of antifibrinolytic drugs and surgical techniques, such as the piggyback and lowering the central venous pressure during the hepatic dissection phase. The rationale for the use of these interventions is quite solid and has led to their incorporation into clinical practice; yet few of them have been rigorously tested in adults, let alone in children. Finally, the postoperative period in pediatric cohorts of patients has been characterized by an enhanced risk of hepatic vessel thrombosis. Thrombosis in fact remains the primary cause of early graft failure and re-transplantation within the first 30 d following surgery, and it occurs despite prolongation of standard coagulation assays. Data, however, are currently lacking regarding the use of anti-aggregation/anticoagulation therapies and how to best monitor for thrombosis in the early postoperative period in pediatric patients. Therefore, further studies are necessary to elucidate the interaction between the development of the coagulation system and cirrhosis in children. Moreover, strategies to optimize blood transfusion and anticoagulation must be tested specifically in pediatric patients. In conclusion, data from the adult world can be translated with difficulty into the pediatric field as indication for transplantation, baseline pathologies and levels of pro- and anticoagulation factors are not comparable between the two populations.