Bayesian network-based survival prediction model for patients having undergone post-transjugular intrahepatic portosystemic shunt for portal hypertension.

BACKGROUND: Portal hypertension (PHT), primarily induced by cirrhosis, manifests severe symptoms impacting patient survival. Although transjugular intrahepatic portosystemic shunt (TIPS) is a critical intervention for managing PHT, it carries risks like hepatic encephalopathy, thus affecting patient survival prognosis. To our knowledge, existing prognostic models for post-TIPS survival in patients with PHT fail to account for the interplay among and collective impact of various prognostic factors on outcomes. Consequently, the development of an innovative modeling approach is essential to address this limitation. AIM: To develop and validate a Bayesian network (BN)-based survival prediction model for patients with cirrhosis-induced PHT having undergone TIPS. METHODS: The clinical data of 393 patients with cirrhosis-induced PHT who underwent TIPS surgery at the Second Affiliated Hospital of Chongqing Medical University between January 2015 and May 2022 were retrospectively analyzed. Variables were selected using Cox and least absolute shrinkage and selection operator regression methods, and a BN-based model was established and evaluated to predict survival in patients having undergone TIPS surgery for PHT. RESULTS: Variable selection revealed the following as key factors impacting survival: age, ascites, hypertension, indications for TIPS, postoperative portal vein pressure (post-PVP), aspartate aminotransferase, alkaline phosphatase, total bilirubin, prealbumin, the Child-Pugh grade, and the model for end-stage liver disease (MELD) score. Based on the above-mentioned variables, a BN-based 2-year survival prognostic prediction model was constructed, which identified the following factors to be directly linked to the survival time: age, ascites, indications for TIPS, concurrent hypertension, post-PVP, the Child-Pugh grade, and the MELD score. The Bayesian information criterion was 3589.04, and 10-fold cross-validation indicated an average log-likelihood loss of 5.55 with a standard deviation of 0.16. The model's accuracy, precision, recall, and F1 score were 0.90, 0.92, 0.97, and 0.95 respectively, with the area under the receiver operating characteristic curve being 0.72. CONCLUSION: This study successfully developed a BN-based survival prediction model with good predictive capabilities. It offers valuable insights for treatment strategies and prognostic evaluations in patients having undergone TIPS surgery for PHT.

Cerebellar spongiform degeneration is accompanied by metabolic, cellular, and motor disruption in male rats with portacaval anastomosis.

The episodes of cerebral dysfunction, known as encephalopathy, are usually coincident with liver failure. The primary metabolic marker of liver diseases is the increase in blood ammonium, which promotes neuronal damage. In the present project, we used an experimental model of hepatic encephalopathy in male rats by portacaval anastomosis (PCA) surgery. Sham rats had a false operation. After 13 weeks of surgery, the most distinctive finding was vacuolar/spongiform neurodegeneration exclusively in the molecular layer of the cerebellum. This cerebellar damage was further characterized by metabolic, histopathological, and behavioral approaches. The results were as follows: (a) Cellular alterations, namely loss of Purkinje cells, morphological changes, such as swelling of astrocytes and Bergmann glia, and activation of microglia; (b) Cytotoxic edema, shown by an increase in aquaporin-4 and N-acetylaspartate and a reduction in taurine and choline-derivate osmolytes; (c) Metabolic adjustments, noted by the elevation of circulating ammonium, enhanced presence of glutamine synthetase, and increase in glutamine and creatine/phosphocreatine; (d) Inflammasome activation, detected by the elevation of the marker NLRP3 and microglial activation; (e) Locomotor deficits in PCA rats as assessed by the Rotarod and open field tests. These results lead us to suggest that metabolic disturbances associated with PCA can generate the cerebellar damage that is similar to morphophysiological modifications observed in amyloidogenic disorders. In conclusion, we have characterized a distinctive cerebellar multi-disruption accompanied by high levels of ammonium and associated with spongiform neurodegeneration in a model of hepatic hypofunctioning.

Transjugular intrahepatic portosystemic shunt and alfapump® system for refractory ascites in liver cirrhosis: Outcomes and complications.

BACKGROUND: Treatment of refractory ascites in liver cirrhosis is challenging. Transjugular intrahepatic portosystemic shunt and alfapump® have been proposed for the management, but few data comparing both exist. AIMS: The aim of this study was to evaluate the characteristics and outcomes of patients treated with transjugular intrahepatic portosystemic shunt and alfapump® for refractory ascites at our centre. METHODS: All consecutive patients were retrospectively reviewed for baseline characteristics, efficacy of treatment, complications and survival. RESULTS: In total, 19 patients with transjugular intrahepatic portosystemic shunt and 40 patients with alfapump® were included. Patients with transjugular intrahepatic portosystemic shunt had better liver function and less hepatic encephalopathy at baseline. Fifty-eight per cent of patients developed hepatic encephalopathy in the first six months after transjugular intrahepatic portosystemic shunt. In patients with alfapump®, renal function decreased and 58% developed prerenal impairment and 43% hepatorenal syndrome in the first six months. Alfapump® patients with new catheters required less reinterventions (26% versus 57% with old catheters, p = 0.049). Transplant-free survival at 1 year was 25% in alfapump® and 65% in transjugular intrahepatic portosystemic shunt. Hepatic encephalopathy predicted transplant-free survival in patients with alfapump® (hazard ratio 2.00, 95% confidence interval 0.99-4.02, p = 0.05). In a sensitivity analysis comparing patients with similar liver function, the rate of hepatorenal syndrome and prerenal impairment was higher in patients with alfapump® and these patients were hospitalised more frequently, whereas the rate of hepatic encephalopathy was similar in both treatment groups. CONCLUSIONS: Both transjugular intrahepatic portosystemic shunt and alfapump® were effective treatments for refractory ascites in cirrhosis. Patients treated with transjugular intrahepatic portosystemic shunt had a better one-year transplant-free survival but had less negative prognostic factors at baseline. Selecting patients without hepatic encephalopathy prior to implantation of an alfapump® might improve transplant-free survival.

Successful Surgical Intervention for Recurring Severe Hepatic Encephalopathy Caused by Portosystemic Collaterals After Living-Donor Liver Transplantation: A Case Report.

INTRODUCTION: Portosystemic collaterals (PsC) are a common finding in patients with cirrhosis who need liver transplantation (LT), and PsCs may cause several problems before and after LT. We report a case of successful surgical treatment of severe hepatic encephalopathy (HE) caused by PsC after living-donor LT (LDLT). CASE: A 71-year-old woman with hepatocellular carcinoma underwent LDLT for chronic hepatitis C virus infection at 64 years of age. The splenocaval collateral vein was ligated during LDLT to prevent portal flow steal. A recurrent episode of coma due to HE was triggered 7 years after LDLT and gradually became refractory to any drug treatments. Contrast-enhanced computed tomography revealed the development of the right gastroepiploic vein (RGEV), which flowed to the inferior vena cava via the inferior mesenteric vein (IMV). Owing to the chronic kidney disease (estimated glomerular filtration rate, 11-31 mL/min), interventional radiology (IVR) was not indicated, so surgical treatment was selected to treat the symptom. PsC was resected at the point of the RGEV and IMV, just before flowing into the IVC with vascular staplers. Antegrade portal blood flow was obtained by ultrasonography 2 days after surgery, and the patient was discharged from the hospital 26 days after the operation. After discharge, she has had no recurrent episode of HE. CONCLUSION: Surgical resection of the PsC was effective for treatment of HE caused by shunt flow after LDLT.

Management of Large, Spontaneous Portosystemic Shunts in Liver Transplantation: Case Report and Review of Literature.

BACKGROUND: The presence of collateral circulation in liver cirrhosis patients with portal hypertension is quite frequent due to re-permeabilization of closed embryonic channels. In some cases, these shunts could measure over 1 cm wide, therefore, containing a significative blood flow. Its management during liver transplantation could be challenging due to possible complications resulting from either ligation of the shunts or from ignoring them. We present the case of a patient with recurrent hepatic encephalopathy (HE) and a large spontaneous portosystemic shunt (SPSS) who submitted to liver transplant and review the literature identifying options, complications, and outcomes with the aim of facilitating decision making. MATERIAL AND METHODS: A 68-year-old, Spanish man diagnosed with liver cirrhosis with portal hypertension and recurrent episodes of HE is proposed for LT. The patient's Child-Pugh score was A6-B7, and the Model for End-stage Liver Disease score was 12. Preoperatively, a computed tomography scan showed a large SPSS running to the inferior cava vein. During the surgery, a small-sized portal vein and a large shunt measuring almost 3 cm wide were identified. After reperfusion, portal vein flow was 1000 to 1100 mL/min. Owing to the previous HE and the risk of low portal flow, the shunt was closed increasing the portal flow to 1800 mL/min. The patient was discharged without any complications. CONCLUSIONS: The presence of large SPSSs are frequent during LT. Decision making intraoperatively can be challenging due to possible complications derived from ligation of the SPSS or from ignoring it. Either preoperative assessment of a further HE risk or portal vein flow measurement after reperfusion are essential to achieve a correct resolution.

Transjugular Portosystemic Shunt Reductions: A Retrospective Single-Center Experience.

PURPOSE: To report the results of transjugular intrahepatic portosystemic shunt (TIPS) reductions for hepatic encephalopathy (HE), acute liver failure (ALF), and pulmonary hypertension (PH). MATERIALS AND METHODS: A single-institution retrospective review analysis was performed between 2007 and 2017 on patients undergoing TIPS reduction at single tertiary liver transplant center. A total of 27 patients (14 males and 13 females) underwent TIPS reduction for refractory HE (n = 18), ALF (n = 7), and PH (n = 2). The average age at time of reduction was 59 years (range, 23-73; standard deviation [SD], 8). Mean prereduction Model of End-State Liver Disease-Na and portosystemic pressure gradient were 19 (range, 11-29; SD, 6) and 9.4 mm Hg (range, -2 to 19; SD, 4.8), respectively. Comparison between responders and nonresponders was performed for multiple variables using a 2-tailed t test. Methods of reduction were compared in cases of HE. RESULTS: Technical success, defined as a decrease of at least 50% of the caliber of the shunt, was 100%. Clinical success rates in improving HE, ALF, and PH were calculated at 89%, 71%, and 100%, respectively. Eight patients had major and 10 had minor complications after the reductions. There were 3 shunt thrombosis. Pre- and postreduction Model of End-State Liver Disease-Na, portosystemic pressure gradient change, duration of indwelling TIPS, and reduction method were not significantly different between responders and nonresponders. Six-month survival rates were 80%, 20%, and 100% for HE, ALF, and PH, respectively. CONCLUSIONS: TIPS reduction is effective in reversing refractory HE, ALF, and PH after TIPS creation. TIPS reduction is associated with a high rate of complications and should be reserved for severe refractory overshunting complications.

Liver Transplant in a Patient With Hemophagocytic Lymphohistiocytosis.

Hemophagocytic lymphohistiocytosis is a rare and life-threatening systemic disease that can cause hepatic infiltration and present as acute liver failure. Here, we report a case of a 3-year-old pediatric patient who presented with acute liver failure and hepatic encephalopathy secondary to hemophagocytic lymphohistiocytosis. She had left lateral segment liver transplant from her father. After 27 months, she had bone marrow transplant from her sister. At the time of reporting (36 months after liver transplant), she showed normal liver function and blood peripheral counts. We found that liver transplant can be a curative treatment for this type of rare disorder, not only to improve the quality of life but also to prolong survival.

Pathological Features of Mitochondrial Ultrastructure Predict Susceptibility to Post-TIPS Hepatic Encephalopathy.

Background: Post-TIPS hepatic encephalopathy (PSE) is a complex process involving numerous risk factors; the root cause is unclear, but an elevation of blood ammonia due to portosystemic shunt and metabolic disorders in hepatocytes has been proposed as an important risk factor. Aims: The aim of this study was to investigate the impact of pathological features of mitochondrial ultrastructure on PSE via transjugular liver biopsy at TIPS implantation. Methods: We evaluated the pathological damage of mitochondrial ultrastructure on recruited patients by the Flameng classification system. A score ≤2 (no or low damage) was defined as group A, and a score >2 (high damage level) was defined as group B; routine follow-up was required at 1 and 2 years; the incidence of PSE and multiple clinical data were recorded. Results: A total of 78 cases in group A and 42 in group B completed the study. The incidence of PSE after 1 and 2 years in group B (35.7% and 45.2%, respectively) was significantly higher than that in group A (16.7% and 24.4%, respectively); the 1- and 2-year OR (95% CI) were 2.778 (1.166-6.615) and 2.565 (1.155-5.696), respectively, for groups A and B. Importantly, group B had worse incidence of PSE than group A [P=0.014, hazard ratio (95%CI): 2.172 (1.190-4.678)]. Conclusion: Aggressive damage to mitochondrial ultrastructure in liver shunt predicts susceptibility to PSE. The registration number is NCT02540382.

Living Donor Liver Transplantation in Acute Liver Failure Patients with Grade IV Encephalopathy: Is Deep Hepatic Coma Still an Absolute Contraindication? A Successful Single-Center Experience.

BACKGROUND The prognosis of the patients of acute liver failure (ALF) with onset of hepatic coma is often dismal. ALF is a well-accepted indication for liver transplantation (LT) and has markedly improved the prognosis of these patients. However, its role in ALF patients with onset of hepatic coma has never been elucidated before. The aim of our study was to analyze the outcome in patients of ALF with hepatic coma who underwent LT. MATERIAL AND METHODS From January 2002 to December 2015, a total of 726 liver transplantations were done at China Medical University Hospital, Taiwan. The hospital database of 59 recipients that underwent LT for ALF was analyzed. Eleven ALF patients with the onset of hepatic coma (grade IV encephalopathy) requiring mechanical ventilatory support were retrospectively analyzed. The patients were sub-grouped in 2 groups depending on the timing of LT after the onset of hepatic coma: Group A had LT within 48 h of onset of coma (n=7) and Group B had LT after 48 h of onset of coma (n=4). RESULTS The study cohort (group A and B) comprised 8 males and 3 females, with an average age of 39.63±13.95 years (range, 13 to 63). Ten patients received living donor liver transplantation (LDLT) and deceased donor liver transplantation (DDLT) was done in 1 recipient. All the patients in group A had complete neurological recovery and were extubated within 48 h after LT, whereas extubation was delayed for various reasons for group B patients. At a mean follow up of 36 months (range, 20 to 76 months), the overall survival of all the recipients (group A and B) was 72%. Three-year survival for Group A (n=7) was 85% and for Group B (n=4) it was 50%. There were no acute rejection episodes. CONCLUSIONS LT is an acceptable modality of treatment for patients of ALF with new onset of hepatic coma. Neurological recovery is expected in all patients if LT can be done within 48 h of onset of hepatic coma without increasing the risk of morbidity. Due to shortage of deceased donor organs in Asia, LDLT can be used proactively, with a success rate comparable to that of non-ALF patients undergoing LT.

Can Patients Who Develop Cerebral Death in Fulminant Liver Failure Despite Liver Transplantation Be Previously Forseen?

BACKGROUND: The outcome of medical treatment is worse in fulminant liver failure (FLF) developing on acute or chronic ground. Recently, liver transplantations with the use of living and cadaveric donors have been performed in these diseases and good results obtained. In this study, we aimed to present the factors affecting the recovery of cerebral functions after liver transplantation in hepatic encephalopathy (HE) developing in FLF, to identify irreversible patient groups and to prevent unnecessary liver transplantation. METHODS: In Inonu University's Liver Transplant Institute, 69 patients who made an emergency notice to the National Coordination Center for liver transplantation owing to FLF from January 2012 to December 2015 were included in the study. Patients were divided into 2 groups. Group 1 consisted of 52 patients who underwent liver transplantation and recovered normal brain function, and group 2 had 17 patients who underwent liver transplantation and did not recover normal brain function and had cerebral death. All patients were evaluated before surgery for clinical encephalopathy stage, light reflex, and convulsions. Groups were compared and assessed according to age (>40, 10-40 and <10 years), body mass index, etiologic factor, preoperative laboratory values, transplantation type, mortality, and encephalopathy level. Multivariate analysis was done for specific parameters. RESULTS: Prothrombin time (PT), international normalized ratio (INR), and total bilirubin values were significantly different between the groups. There was no significant difference between the groups regarding ammonia and lactate levels. There was a statistically significant difference between the groups regarding sodium and potassium levels from serum electrolytes. However, the averages of both groups were within normal limits. pH and total bilirubin levels were meaningful for multivariate analysis. CONCLUSIONS: HE reversibility, mortality, and morbidity are important in patients with HE who undergo liver transplantation. Therefore, West Haven clinical staging and serum INR, PT, and total bilirubin level may be helpful in predicting the reversibility of FLF patients with HE before liver transplantation. It was determined that West Haven encephalopathy grading is important in determining the reversibility of HE after transplantation in FLF; especially the probability of reversibility of stage 4 HE decreases significantly. High PT and INR levels, hyperbilirubinemia, and serum sodium and potassium concentrations were risk factors for the reversibility of HE in this study.

Hybrid Surgery for Portosystemic Encephalopathy in a Patient with Liver Cirrhosis: a case report.

Regarding the treatment for a portosystemic shunt, surgical or interventional radiological closure of the shunt was established. Interventional radiology including balloon-occluded retrograde transvenous obliteration can worsen portal hypertension and create a large thrombus close to the major venous system in the case of a huge portosystemic shunt. In contrast, it is also difficult to treat some cases through surgery alone when huge complicated shunts exist very deep in the body. Herein, we report a successful case of surgical shunt ligation for portosystemic encephalopathy in a hybrid operation room that enabled intraoperative angiography and computed tomography. A 62-year-old woman with chronic hepatitis C was referred to our hospital due to high levels of serum ammonia and hepatic encephalopathy. She had a massive, complicated portosystemic shunt from the inferior mesenteric vein to the left renal vein but did not have esophageal or gastric varices. It was difficult to occlude the portosystemic shunt by interventional radiologic techniques because the shunt had an extremely large amount of blood flow and many collateral routes. We performed the shunt ligation in the hybrid operation room. Intraoperative angiography provided detailed information about the portosystemic shunt, such as direction or volume of blood flow and collateral routes in real time. Her encephalopathy disappeared completely and she remains healthy with improved liver functional reserve to date. In conclusion, this is a successful case of a hybrid operation for an extremely large and complicated portosystemic shunt, providing for intraoperative angiography as a safe and reliable surgical treatment for portosystemic encephalopathy in patients with liver cirrhosis.

From Child-Pugh to Model for End-Stage Liver Disease: Deciding Who Needs a Liver Transplant.

This article reviews the historical evolution of the liver transplant organ allocation policy and the indications/contraindications for liver transplant, and provides an overview of the liver transplant evaluation process. The article is intended to help internists determine whether and when referral to a liver transplant center is indicated, and to help internists to counsel patients whose initial evaluation at a transplant center is pending.

Techniques for Transjugular Intrahepatic Portosystemic Shunt Reduction and Occlusion.

Transjugular intrahepatic portosystemic shunts (TIPS) effectively lower portal pressure and are commonly used to manage selected patients with variceal bleeding. Unfortunately, significant consequences are not infrequently encountered as a result of this diversion of portal venous flow. These consequences include disabling hepatic encephalopathy as well as hepatic decompensation. To manage these complications, therapeutic options include TIPS reduction and TIPS occlusion. TIPS reduction is the favored technique because of the potential for venous thrombosis and recurrent variceal hemorrhage after acute TIPS occlusion. Techniques and indications for TIPS reduction and TIPS occlusion are reviewed.

Long-term clinical and radiological improvement of chronic acquired hepatocerebral degeneration after obliteration of portosystemic shunt: Report of a case.

Neurological manifestations are common in patients with decompensated cirrhosis. The majority of these patients show hepatic encephalopathy or chronic acquired (non-Wilsonian) hepatocerebral degeneration (CAHD). They characteristically present with dysarthria, ataxia, involuntary movements, and altered mental status. Neuroradiological examination in patients with hepatic encephalopathy often shows abnormal signals in multiple regions of the brain, such as the pallidum, putamen, caudate nucleus, hemispheric white matter, and ventral midbrain. The pathogenesis of hepatic encephalopathy and CAHD is poorly understood and the response to conventional therapies is often poor. We report a male patient with cirrhosis of unknown cause, who developed slowly progressive cerebellar truncal and limb ataxia and slurred speech. Magnetic resonance imaging (MRI) showed focal T2 hyperintensity in bilateral dentate nuclei and middle cerebellar peduncles (MCPs). After treatment by obliteration of the portosystemic shunt, clinical manifestations and MRI abnormalities were dramatically improved. He was followed for six years until he died of uncontrollable bleeding due to hepatocellular carcinoma. At the last examination 9 months before death, he showed no apparent aggravation of neurological symptoms, and no abnormal signal intensities in the MCPs and supratentorial compartment. The clinical course and changes of brain MRI findings of this case are extremely rare, suggesting that obliteration of the portosystemic shunt may be effective for CAHD over long term.

TIPS improves liver transplantation-free survival in cirrhotic patients with refractory ascites: an updated meta-analysis.

AIM: To compare the liver transplantation-free (LTF) survival rates between patients who underwent transjugular intrahepatic portosystemic shunts (TIPS) and those who underwent paracentesis by an updated meta-analysis that pools the effects of both number of deaths and time to death. METHODS: MEDLINE, EMBASE, and the Cochrane Library were searched from the inception to October 2012. LTF survival, liver transplantation, liver disease-related death, non-liver disease-related death, recurrent ascites, hepatic encephalopathy (HE) and severe HE, and hepatorenal syndrome were assessed as outcomes. LTF survival was estimated using a HR with a 95%CI. Other outcomes were estimated using OR with 95%CIs. Sensitivity analyses were performed to assess the effects of potential outliers in the studies according to the risk of bias and the study characteristics. RESULTS: Six randomized controlled trials with 390 patients were included. In comparison to paracentesis, TIPS significantly improved LTF survival (HR = 0.61, 95%CI: 0.46-0.82, P < 0.001). TIPS also significantly decreased liver disease-related death (OR = 0.62, 95%CI: 0.39-0.98, P = 0.04), recurrent ascites (OR = 0.15, 95%CI: 0.09-0.24, P < 0.001) and hepatorenal syndrome (OR = 0.32, 95%CI: 0.12-0.86, P = 0.02). However, TIPS increased the risk of HE (OR = 2.95, 95%CI: 1.87-4.66, P = 0.02) and severe HE (OR = 2.18, 95%CI: 1.27-3.76, P = 0.005). CONCLUSION: TIPS significantly improved the LTF survival of cirrhotic patients with refractory ascites and decreased the risk of recurrent ascites and hepatorenal syndrome with the cost of increased risk of HE compared with paracentesis. Further studies are warranted to validate the survival benefit of TIPS in clinical practice settings.

Effective balloon-occluded retrograde transvenous obliteration of the superior mesenteric vein-inferior vena cava shunt in a patient with hepatic encephalopathy after living donor liver transplantation.

Balloon-occluded retrograde transvenous obliteration (BRTO) has become a common and effective procedure for treating hepatic encephalopathy due to a portosystemic shunt related to cirrhosis of the liver. However, this method of treatment has rarely been reported in patients after liver transplantation. Here, we report the case of a 52-year-old patient who underwent living donor liver transplantation (LDLT) due to hepatitis C virus-infected hepatocellular carcinoma that was complicated with portal vein thrombosis and a large portosystemic shunt between the superior mesenteric vein (SMV) and inferior vena cava (IVC). The SMV-IVC shunt was not obliterated during LDLT because there was sufficient portal flow into the graft after reperfusion. However, the patient was postoperatively complicated with encephalopathy due to the portosystemic shunt. BRTO was performed and was demonstrated to have effectively managed the encephalopathy due to the SMV-IVC shunt, while preserving the hepatic function after LDLT.

[Severe toxic acute liver failure: etiology and treatment]. / Insuffisances hépatiques aiguës sévères d'origine toxique : prise en charge étiologique et symptomatique.

Many substances, drugs or not, can be responsible for acute hepatitis. Nevertheless, toxic etiology, except when that is obvious like in acetaminophen overdose, is a diagnosis of elimination. Major causes, in particular viral etiologies, must be ruled out. Acetaminophen, antibiotics, antiepileptics and antituberculous drugs are the first causes of drug-induced liver injury. Severity assessment of the acute hepatitis is critical. Acute liver failure (ALF) is defined by the factor V, respectively more than 50% for the mild ALF and less than 50% for the severe ALF. Neurological examination must be extensive to the search for encephalopathy signs. According to the French classification, fulminant hepatitis is defined by the presence of an encephalopathy in the two first weeks and subfulminant between the second and 12th week after the advent of the jaundice. During acetaminophen overdose, with or without hepatitis or ALF, intravenous N-acetylcysteine must be administered as soon as possible. In the non-acetaminophen related ALF, N-acetylcysteine improves transplantation-free survival. Referral and assessment in a liver transplantation unit should be discussed as soon as possible.