Autonomic neuropathy is associated with hemodynamic instability during human liver transplantation

Cardiac autonomic modulation in children with severe liver disease, before and after liver transplantation

BACKGROUND

The cardiovascular system is directly influenced by the autonomic nervous system (ANS); its changes affect heart rate variability (HRV) and are sensitive indicators of physiological changes. Autonomic dysfunction (AD) is manifested in up to 60% of patients with cirrhosis. Therefore, we aim to analyze the indexes of HRV pre- and post-surgery of children submitted for liver transplantation (LT).

METHODS

HRV, in children of both genders from 6 months of age to 10 years, that attended at the pediatric surgery clinic in the queue for LT at the Children's Institute were analyzed. To access HRV we analyzed indexes such as standard deviation of the RR intervals (SDNN), root-mean-square of the successive normal sinus RR interval difference (RMSSD), low frequency (LF), high frequency (HF), and LF/HF.

RESULTS

The analysis of the behavior of cardiac autonomic modulation, in the period prior to LT and after surgery, showed an increase in HRV linear parameters SDNN, TINN (triangular interpolation of NN interval histogram), HFms². In the time domain, there was also an increase in the HFms² index.

CONCLUSIONS

The analysis of the period preceding LT and two months after surgery showed an increase in the HRV linear parameters representing a global HRV improvement. In the time domain, there was also an increase in the HFms² index, parasympathetic tone of the HRV.

Reduced neural baroreflex sensitivity is related to enhanced endothelial function in patients with end-stage liver disease

OBJECTIVES

Reduced baroreflex sensitivity (BRS) is a frequent complication in end-stage liver disease, but the underlying mechanism is unknown. We investigated the mechanical and neural components of BRS. Increased nitric oxide (NO) production has been reported in end-stage liver failure. Based on earlier experiments, we hypothesised that enhanced endothelial function might affect baroreflex function. Therefore, we explored the relation between endothelial function and the components of BRS.

MATERIALS AND METHODS

We enrolled 24 patients and 23 controls. BRS was determined by the spontaneous sequence method. Mechanical component was characterised by the distensibility coefficient (DC) of common carotid artery. Neural component was estimated as the ratio of integrated BRS and DC. Endothelial function was quantified by flow-mediated dilation (FMD) of the brachial artery.

RESULTS

Integrated BRS was reduced in patients [7.00 (5.80-9.25) vs. 11.1 (8.50-14.80) ms/mmHg]. The mechanical component was not different in the two groups, whereas neural component showed significant reduction in patients (3.54 ± 1.20 vs. 4.48 ± 1.43 ms/10^-3). FMD was higher in patients (9.81 ± 3.77 vs. 5.59 ± 1.36%). FMD and neural BRS were directly related in controls (r = 0.62), but inversely related in patients (r = -0.49).

CONCLUSIONS

Baroreflex impairment in end-stage liver disease might be explained by deterioration of the neural component, while the mechanical component appears to be preserved. Endothelial NO may enhance BRS in health; however, central endothelial overproduction of NO likely contributes to the reduction of neural component of BRS in patients awaiting liver transplantation.

The role of autonomic dysfunction in cirrhotic patients before and after liver transplantation. Review of the literature

In patients affected by hepatic cirrhosis, autonomic dysfunction is a common finding; usually it is asymptomatic but it may correlate with increased mortality and morbidity before, during and after liver transplant, due to hemodynamic instability in the course of stressful events like sepsis, gastrointestinal bleeding and reperfusion after transplantation surgery. Hyperdynamic circulation and hepatic dysfunction seem to play a role in the pathogenesis of autonomic dysfunction, even if pathophysiological mechanisms are not completely known. We present a revision of previous literature about prevalence, pathophysiological mechanisms, clinical features, and mortality and morbidity of autonomic dysfunction secondary to hepatic cirrhosis.

Atrioventricular conduction disturbances immediately after hepatic graft reperfusion and their outcomes in patients undergoing liver transplantation

Hemodynamic perturbation during hepatic graft reperfusion in patients undergoing liver transplantation (LT) is challenging and is frequently accompanied by bradyarrhythmia and even asystole. However, detailed data on electrocardiographic (ECG) changes during reperfusion are almost nonexistent, although the correct diagnosis by record is important for the treatment. We aimed to identify ECG rhythm disturbances during graft reperfusion and to investigate risk factors and outcomes. Data from 1065 consecutive patients who underwent adult LT were analyzed. The incidence, type, and detailed characteristics of ECG changes immediately after graft reperfusion were assessed using an electronically archived intraoperative ECG database. We analyzed risk factors, postoperative outcomes including major cardiovascular events, 30-day and 1-year mortalities of recipients based on the occurrence of atrioventricular (AV) block, and asystole during reperfusion. The typical pattern of postreperfusion bradyarrhythmia was progressive PR interval prolongation until a Mobitz type 1 AV block occurred. The overall incidence of AV block was 5.0% (53/1065), and 30.2% of them (16/53) had initiated as AV block and then progressed into ventricular asystole. Fulminant hepatic failure was a significant predictor for occurrence of AV block (odds ratio [OR], 7.20; 95% confidence interval, 3.38-15.32; P < 0.001). Patients with AV block showed significantly higher incidence of postoperative major cardiovascular events (P < 0.001) and 30-day mortality (P = 0.002) than those without AV block, whereas the 1-year mortality was not different between the 2 groups (P = 0.10). The postreperfusion asystole was consistently preceded by a Mobitz type 1 AV block. The occurrence of AV block and asystole appears to be an important prognosticator. Therefore, maintaining an optimal range of physiological status and gradual unclamping of the vena cava to avoid sudden atrial distension are recommended in high-risk patients during reperfusion period. Liver Transplantation 22 956-967 2016 AASLD.

Sympathetic withdrawal is associated with hypotension after hepatic reperfusion

OBJECTIVE

Post-reperfusion syndrome (PRS), severe hypotension after graft reperfusion during liver transplantation, is an adverse clinical event associated with poorer patient outcomes. The purpose of this study was to determine whether alterations in autonomic control in liver transplant recipients prior to graft reperfusion are associated with the subsequent development of PRS.

METHODS

Heart rate variability (HRV), systolic arterial blood pressure (SBP) variability, and baroreflex sensitivity of 218 liver transplant recipients were evaluated using 5 min of ECG and arterial blood pressure signals 10 min before graft reperfusion along with other clinical parameters. Logistic regression analyses were performed to assess predictors of PRS occurrence.

RESULTS

Seventy-seven patients (35 %) developed PRS while 141 did not. There were significant differences in SBP (110 ± 16 vs. 119 ± 16 mmHg, P < 0.001) and the ratio of low frequency power to high frequency power (LF/HF) of HRV (1.0 ± 1.4 vs. 2.1 ± 3.7, P = 0.003) between the PRS group and No-PRS group. In multivariate logistic regression analysis, predictors were LF/HF (odds ratio 0.817, P = 0.028) and SBP (odds ratio 0.966, P < 0.001).

INTERPRETATION

Low LF/HF and SBP measured before hepatic graft reperfusion were significantly correlated with subsequent PRS occurrence, suggesting that sympathovagal imbalance and depressed SBP may be key factors predisposing to reperfusion-related severe hypotension in liver transplant recipients.

Post-reperfusion syndrome during renal transplantation: a retrospective study

Post-reperfusion syndrome (PRS) is a serious, widely reported complication following the reperfusion of an ischemic tissue or organ. We sought to determine the prevalence, risk factors and short-term outcomes of PRS related renal transplantation. We conducted a retrospective, case-control study of patients undergoing renal transplantation between July 2006 and March 2008. Identification of PRS was based on a drop in mean arterial pressure by at least 15% within 5 minutes of donor kidney reperfusion. Of the 150 consecutive renal transplantations reviewed, 6 patients (4%) met criteria for post-reperfusion syndrome. Univariate analysis showed that an age over 60, diabetes mellitus, Asian race, and extended criteria donors increased the odds of developing PRS by 4.8 times (95% CI [1.2, 20]; P=.0338), 4.5 times (95% CI [1.11, 18.8]; P=.0378), 35.5 times (95% CI [3.94, 319.8]; P=0.0078) and 9.6 times (95% CI [1.19, 76.28] P=0.0115) respectively. Short term follow-up revealed increased graft failure rate within 6 months (6% vs. 16% P=0.0125) and almost twice the number of hospital days post-transplant in PRS cohorts (5.43 ± 2.29 vs. 10.8 ± 7.29 P=<0.0001). Despite limited reporting, PRS appears to be a relatively common complication of renal transplantation and is associated with increase morbidity.

Transient complete atrioventricular block during liver transplantation

Intraoperative dysrhythmias commonly occur in the surgical management of congenital heart diseases. It may also be seen in other surgical procedures. The initiating factors for an arrhythmia during surgery is usually a transient insult such as hypoxemia, cardiac ischemia, catecholamine excess, electrolyte abnormality and acidosis. CAVB is a life-threatening dysrhythmia in all ages. We herein report a case of transient CAVB in a 30-month-old boy during living-related liver transplantation for bile duct paucity-associated liver cirrhosis. Moreover, we discuss the probable etiology and treatment of CAVB in liver transplantation.

The effect of liver transplantation on autonomic dysfunction in patients with end-stage liver disease

Autonomic dysfunction is a recognized complication of end-stage liver disease (ESLD), but there is little information on how liver transplantation (LT) affects this problem. We sought to prospectively evaluate autonomic function in patients with ESLD before and after LT. Autonomic reflex screen (ARS) was performed on 30 patients with ESLD prior to transplantation. A 10-point composite autonomic score (CAS) was calculated from these data. ARS was repeated after LT, and these scores were compared with the pre-LT ARS. Thirty patients (25 male, 5 female) with cirrhosis that were listed for LT were enrolled in the study and underwent ARS prior to LT. The average age was 55.4 +/- 9.1 years. Indications for LT included hepatitis C virus (14), cryptogenic cirrhosis (5), alcoholic cirrhosis (4), and other (7). The mean native Model for End-Stage Liver Disease (MELD) score at ARS was 17.0 +/- 5.0. Prior to LT, 86.7% of patients had evidence of autonomic dysfunction. Mean CAS was 2.7 +/- 2.2. Sudomotor function was disturbed in 66%, parasympathetic function was disturbed in 57%, and adrenergic function was disturbed in 37%. There was no relationship between pre-LT CAS and age, gender, diabetes, etiology of liver disease, or MELD score. Twenty-one patients (17 male, 4 female) had repeat ARS a mean of 9 +/- 6.2 months after LT. The mean native MELD score at the time of ARS testing was 18.1 +/- 4.3. Mean pre-LT CAS in this group was 3.0 +/- 2.4. Pretransplant CAS was not related to age, gender, diabetes, or MELD score. Autonomic dysfunction improved after LT (CAS pre-LT, 3.0, versus CAS post-LT, 1.9, P = 0.02). There was no relationship between post-LT CAS and age, gender, diabetes, etiology of liver disease, immunosuppression, or type of transplant. In conclusion, autonomic dysfunction is common in patients with ESLD, with over 86% having abnormal testing. Sixty-three percent of patients with cirrhosis with autonomic dysfunction show improvement after LT.

Anesthetic management of a combined heart and liver transplantation in an amyloidotic patient: a case report

Few cases of combined heart and liver transplantation (CHLT) have been reported for familial amyloidosis. Our first CHLT was performed on a female patient with familial amyloidosis due to a genetic defect in transthyretin, characterized by deposition of amyloid in various organs and tissues. This disease produced autonomic heart dysfunction that preceded the development of clinical manifestations and may be an important factor in determining the optimal timing for liver transplantation. CHLT can be performed successfully, even in patients with advanced disease. However, the most compromised patients are more exposed to intraoperative risks, postoperative complications, and worsening of extracardiac and extrahepatic symptoms. Our patient presented severe cardiac dysfunction requiring CHLT. The operative technique is far from being consolidated, despite this, both organs were transplanted in the same day with 2 hours in the intensive care unit (ICU) between surgeries. The outcome of both organs has been favorable. The amyloidotic liver was transplanted to another patient, a sequential (domino) transplantation.

Hemodynamic changes during reperfusion of the graft in an animal model of liver xenotransplantation

Our goal was to determine the hemodynamic changes that are witnessed during the initial minutes of reperfusion of the graft in liver xenotransplantation from pig to baboon.

METHOD

We studied a group of 12 baboons undergoing transplantation of a pig liver via the classic technique with arterial anastomosis to the aorta. The anesthesia technique was similar to that used in humans. Hemodynamic monitoring, due to the size of the recipient, consisted of heart rate (HR), mean arterial pressure (MAP), and central venous pressure (CVP) recorded at the beginning and end of each of the three phases: preanhepatic (A1, A2), anhepatic (B1, B2), and neohepatic (C1 and C2). We aimed to maintain the following values by means of crystalloids, colloids, and blood derivates: HR >50 beats/minute; MAP >60 mm Hg; and CVP >10 mm Hg.

RESULTS

Both HR and CVP remained unchanged throughout the procedure. MAP droped briefly after vascular clamping (B1) but not on reperfusion (C1).

CONCLUSION

In cirrhotic patients there is an autonomic dysfunction, demonstrated as cardiovascular instability at times like the clamping of major vessels and reperfusion of the graft. On the other hand, the intact baboon has an intact nervous system. After vascular clamping, the sharp decrease in venous return lead to an adequate vasopressor response. Likewise, the extreme vasodilatation involved with reperfusion managed to maintain MAP above 70 mm Hg.

Radial to femoral arterial blood pressure differences during liver transplantation

This observational study compared femoral and radial arterial blood pressure in 72 patients undergoing liver transplant surgery. Simultaneous femoral and radial arterial blood pressures, cardiac index, core temperature and vasoconstrictor therapy were recorded at seven time points during the operation. No significant differences between radial and femoral pressures were found at the start of surgery. Femoral and radial systolic arterial blood pressures were statistically significantly different during liver reperfusion (mean (SD) arterial pressure = 92 (22) mmHg vs. 76 (22) mmHg, p < 0.01). Mean arterial blood pressures showed no statistically significant differences throughout the study. Vasoconstrictor drug administration was associated with a larger systolic pressure difference between femoral and radial arteries (28 (24) mmHg in patients being given vasoconstrictor drugs vs. 9 (19) mmHg in patients not needing vasoconstrictors during reperfusion, p < 0.001). In conclusion, differences in systolic arterial blood pressure occur between femoral and radial arterial monitoring sites during liver reperfusion, and in particular in patients being given vasoconstrictor therapy. Thus, if femoral arterial monitoring is not available, clinicians should rely on mean rather than systolic arterial pressure measurements from a radial artery catheter during liver transplantation.

Preoperative optimization of patients with liver disease

PURPOSE OF REVIEW

Recent papers relevant to the preoperative evaluation and optimization of patients with severe liver disease will be discussed. The emphasis will be placed on cardiovascular, pulmonary, and renal complications. Other aspects such as preoperative management of hepatitis B and C, other infectious issues, and liver cancer will not be discussed because this rarely involves the anesthesiologist.

RECENT FINDINGS

Dobutamine stress echocardiography has been the cornerstone of cardiac evaluation of liver transplant candidates. Combining liver transplantation with cardiac procedures has been shown to be feasible. While mild hepatopulmonary syndrome is well-tolerated, severe hepatopulmonary syndrome carries a fairly high mortality rate. New treatment modalities of severe portopulmonary hypertension have been introduced, and may have advantages over epoprostenol administration. Hepatic hydrothorax requires similar therapy to ascites [repeated thoracentesis or paracentesis, and transjugular intrahepatic portosystemic shunt (TIPS)], but refractory hydrothorax may require other interventions. Hepatorenal syndrome may improve by increasing renal blood flow through the use of vasoconstrictors (vasopressin, norepinephrine) in combination with albumin administration. Interventional radiologists can now change the flow through an established TIPS. Hepatic encephalopathy may result in some irreversible changes in the brain. It remains difficult to predict whether a patient with acute fulminant failure will recover spontaneously. Support devices that include hepatocytes show early promising results. The coagulation changes in living donors are incompletely understood. Finally, autonomic neuropathy as a complication of severe liver disease results in more hemodynamic instability.

SUMMARY

Recent advances in preoperative evaluation and optimization are presented and discussed.