Cerebral autoregulation in patients with cirrhosis and ascites. A transcranial Doppler study

Delay of cerebral autoregulation in traumatic brain injury patients

INTRODUCTION

Adequate cerebral perfusion prevents secondary insult after traumatic brain injury (TBI). Cerebral autoregulation (CAR) keeps cerebral blood flow (CBF) constant when arterial blood pressure (ABP) changes. Aim of the study was to evaluate the existence of delayed CAR in TBI patients and its possible association with outcome.

METHODS

We retrospectively analysed TBI patients. Flow velocity (FV) in middle cerebral artery, invasive intra-cranial pressure (ICP) and ABP were recorded. Cerebral perfusion pressure (CPP) was calculated as ABP - ICP. Mean flow index (Mx) > 0.3 defined altered CAR. Samples from patients with altered CAR were further analysed: FV signal was shifted backward relative to CPP; Mx was calculated after each shift (MxD). Mx > 0.3 plus MxD ≤ 0.3 defined delayed CAR. Favourable outcome (FO) at 6 months was defined as Glasgow Outcome Scale 4-5.

RESULTS

154 patients were included. GCS was 6 [4-9], ICP was 14 [9-20] mmHg. Data on 6 months outcome were available for 131 patients: 104/131 patients (79 %) were alive; GOS was 4 [3-5]; 70/131 (53 %) had FO. Mx was 0.07 [-0.19 to 0.28] overall. Mx was lower in patients with FO compared others (0.00 [-0.21 to 0.20] vs 0.17 [-0.12 to 0.37], p = 0.02). 118 (77 %) patients had intact CAR and 36 (23 %) patients had altered CAR; 23 patients - 15 % of the general cohort and 64 % of patients with altered CAR - had delayed CAR. Delay in the autoregulatory response was 2 [1-4] seconds. 80/98 (82 %) of patients with intact CAR survived, compared to 16/21 (76 %) with delayed and 8/12 (67 %) with altered CAR (p = 0.20). 80/98 (58 %) patients with intact, 10/21 (48 %) patients with delayed and 3/12 (25 %) patients with altered CAR had FO (p = 0.03).

CONCLUSION

A subgroup of TBI patients with delayed CAR was identified. Delayed CAR was associated with better neurological outcome than altered CAR.

The use of automated pupillometry to assess cerebral autoregulation: a retrospective study

BACKGROUND

Critically ill patients are at high risk of developing neurological complications. Among all the potential aetiologies, brain hypoperfusion has been advocated as one of the potential mechanisms. Impairment of cerebral autoregulation (CAR) can result in brain hypoperfusion. However, assessment of CAR is difficult at bedside. We aimed to evaluate whether the automated pupillometer might be able to detect impaired CAR in critically ill patients.

METHODS

We included 92 patients in this retrospective observational study; 52 were septic. CAR was assessed using the Mxa index, which is the correlation index between continuous recording of cerebral blood flow velocities using the transcranial Doppler and invasive arterial blood pressure over 8 ± 2 min. Impaired CAR was defined as an Mxa > 0.3. Automated pupillometer (Neuroptics, Irvine, CA, USA) was used to assess the pupillary light reflex concomitantly to the CAR assessment.

RESULTS

The median Mxa was 0.33 in the whole cohort (0.33 in septic patients and 0.31 in the non-septic patients; p = 0.77). A total of 51 (55%) patients showed impaired CAR, 28 (54%) in the septic group and 23 (58%) in the non-septic group. We found a statistically significant although weak correlation between Mxa and the Neurologic Pupil Index (r 2 = 0.04; p = 0.048) in the whole cohort as in septic patients (r 2 = 0.11; p = 0.026); no correlation was observed in non-septic patients and for other pupillometry-derived variables.

CONCLUSIONS

Automated pupillometry cannot predict CAR indices such as Mxa in a heterogeneous population of critically ill patients.

VALUE OF CLINICAL, LABORATORY PARAMETERS AND ANALYSIS OF RETINAL VASCULARIZATION IN PEDIATRIC PATIENTS WITH PORTAL HYPERTENSION

BACKGROUND

Portal hypertension is one of the complications of cirrhosis and is associated with numerous systemic manifestations, including renal, brain, pulmonary, cardiac and vascular changes. In routine ophthalmological examinations performed at our service, we observed that some children diagnosed with portal hypertension had increased retinal vascular tortuosity.

OBJECTIVE

1. To evaluate the presence of retinal vascular abnormalities (vascular tortuosity) in children diagnosed with portal hypertension; 2. To investigate the association between retinal vascular tortuosity and the presence of gastroesophageal varices in these children; 3. To evaluate the use of clinical and laboratory parameters to predict the presence of gastroesophageal varices in children with portal hypertension.

METHODS

This was a cross-sectional and observational study that included patients aged <18 years with a diagnosis of portal hypertension. The participants included were submitted to dilated fundus examination and fundus photography with Visucam (Carl Zeiss Meditec AG) device. Besides, clinical and laboratorial data were collected from the patients' medical records.

RESULTS

A total of 72 patients were included in this study, and 36% of them had an increase in retinal vascular tortuosity. Platelet count (P=0.001), bilirubin dosage (P=0.013) and aspartate transaminase dosage (AST) (P=0.042) were associated with the presence of gastroesophageal varices in digestive endoscopy. There was no association between retinal vascular tortuosity and the presence of gastroesophageal varices (P=0.498).

CONCLUSION

The results of this study suggest that platelet count, bilirubin dosage, and aspartate transaminase dosage were associated with the presence of gastroesophageal varices in digestive endoscopy. Regarding the retinal findings, we found that there was an increase in retinal vascular tortuosity in 36% of pediatric patients, but no association was found with the presence of gastroesophageal varices.

Incidence and Risk Factors of Intracranial Hemorrhage in Liver Transplant Recipients

BACKGROUND

Intracranial hemorrhage after liver transplantation is an infrequently reported complication but one which can have devastating consequences.

METHODS

We performed a retrospective cross-sectional analysis of all liver transplants performed between January 2010 and June 2015 at a single high-volume institution using a prospectively maintained electronic database and query of the electronic medical record. Cases of intracranial hemorrhage were adjudicated as either spontaneous intraparenchymal hemorrhage(IPH) or extra-axial hemorrhage (EAH). Patients with confirmed intracranial hemorrhage were compared with all other liver transplant recipients. Risk factors were identified by univariate analysis and logistic regression models for IPH and EAH.

RESULTS

Thirty-one (5.2%) of 595 liver transplant recipients developed an intracranial hemorrhage within 12 months of transplantation, 15 IPH and 16 EAH. The majority of intracranial hemorrhages were diagnosed within 1 month of transplantation. Eight (26%) intracranial hemorrhage patients died during hospitalization. Fourteen (45%) intracranial hemorrhage patients died within 1 year of transplantation and 1-year mortality was greater than in patients without intracranial hemorrhage (11.2%, P < 0.01). Female sex (adjusted odds ratio [OR], 3.291; 95% confidence interval [CI], 1.092-9.924; P = 0.034), higher pretransplant bilirubin (adjusted OR, 1.037; 95% CI, 1.006-1.070; P = 0.020), and greater increase in pretransplant to posttransplant systolic blood pressure (adjusted OR, 1.029; 95% CI, 1.006-1.052; P = 0.012) were associated with posttransplant IPH. Lower pretransplant serum fibrinogen level (adjusted OR, 0.988; 95% CI, 0.979-0.998; P = 0.017) was associated with posttransplant EAH.

CONCLUSIONS

Postoperative blood pressure control and pretransplant fibrinogen levels may be modifiable risk factors for preventing posttransplant intracranial hemorrhage.

Review article: the role of the microcirculation in liver cirrhosis

BACKGROUND

Intrahepatic microvascular derangements and microcirculatory dysfunction are key in the development of liver cirrhosis and its associated complications. While much has been documented relating to cirrhosis and the dysfunction of the microcirculation in the liver parenchyma, far less is known about the state of the extrahepatic microcirculation and the role this may have in the pathogenesis of multiple organ failure in end stage liver cirrhosis.

AIM

To provide an update on the role of the microcirculation in the pathophysiology of cirrhosis and its associated complications and briefly discuss some of the imaging techniques which may be used to directly investigate the microcirculation.

METHODS

A Medline literature search was conducted using the following search terms: 'cirrhosis', 'microcirculation', 'circulation', 'systemic', 'inflammation', 'peripheral', 'hepatorenal' and 'hepatopulmonary'.

RESULTS

Significant heterogeneous microvascular alterations exist in patients with cirrhosis. Data suggest that the systemic inflammation, associated with advanced cirrhosis, induces microcirculatory dysregulation and contributes to haemodynamic derangement. The resultant vasoconstriction and hypoperfusion in the systemic extrahepatic microvasculature, is likely to be instrumental in the pathophysiology of organ failure in decompensated cirrhosis, however the mechanistic action of vasoactive agents used to correct the circulatory disturbance of advanced cirrhosis is poorly understood.

CONCLUSIONS

Further research into the role of the microcirculation in patients with liver cirrhosis, will improve physicians understanding of the pathophysiology of cirrhosis, and may provide a platform for real time evaluation of an individual's microcirculatory response to vasoactive mediators, thus guiding their therapy.

Cirrhotic Multiorgan Syndrome

Patients with cirrhosis and portal hypertension are at an increased risk of the development of circulatory dysfunction that may potentially result in multiple organ failure. Apart from the liver, this may involve the heart, lungs, kidneys, the immune system, the adrenal glands, and other organ systems. As the disease progresses, the circulation becomes hyperdynamic, and signs of cardiac, pulmonary, and renal dysfunction are observed, in addition to reduced survival. Infections and an altered cardiac function known as cirrhotic cardiomyopathy may be precipitators for the development of other complications such as hepatorenal syndrome. In patients with chronic organ dysfunction, various precipitating events may induce an acute-on-chronic renal failure and acute-on-chronic liver failure that negatively affect the prognosis. Future research on the pathophysiologic mechanisms of the complications and the precipitating factors is essential to understand the basics of the treatment of these challenging conditions. The aim of the present review is to focus on the development and precipitating factors of various organ failures in patients with decompensated cirrhosis.

Vascular Doppler ultrasonographic indices in cirrhosis: a case-control study with emphasis on the common carotid arteries

PURPOSE

To compare vascular Doppler waveform indices, particularly in the common carotid arteries, between cirrhotic and healthy subjects.

MATERIALS AND METHODS

A total of 60 patients with Class-B cirrhosis and 60 healthy matched counterparts were enrolled in this prospective study. Vascular Doppler waveform parameters including resistance and/or pulsatility indices (RI and PI, respectively) were obtained from the common carotid, renal, celiac, superior mesenteric, femoral and brachial arteries.

RESULTS

Compared to patients, healthy subjects had significantly higher mean PI and RI obtained from the common carotid (1.53 ± 0.20 vs. 1.43 ± 0.14, p = 0.03; 0.75 ± 0.02 vs. 0.72 ± 0.02, p < 0.001, respectively) and celiac arteries (2.00 ± 0.36 vs. 1.81 ± 0.34, p = 0.03; 0.80 ± 0.03 vs. 0.78 ± 0.02, p < 0.001, respectively). Both the mean PI and RI derived from the renal arteries, in contrast, were significantly higher in patients compared to that in controls (1.05 ± 0.13 vs. 1.11 ± 0.07, p = 0.03; 0.59 ± 0.03 vs. 0.63 ± 0.03, p < 0.001, respectively). The mean vascular impedance values obtained from the remaining arteries were comparable between the two groups.

CONCLUSIONS

Blood flow increases in the common carotid and celiac arteries of Class-B cirrhotic patients with elevated renovascular impedance.

Cerebral haemodynamics in cirrhotic patients with hepatic encephalopathy

BACKGROUND & AIMS

Factors other than elevated levels of ammonia may be implicated in hepatic encephalopathy (HE) pathophysiology, including abnormal cerebral haemodynamics. Transcranial Doppler ultrasonography (TCD) evaluates cerebrovascular structural integrity and reactivity, through pulsatility index (PI) and breath-holding index (BHI) respectively. The aim of this study was to evaluate cerebral haemodynamics by TCD in patients with compensated and decompensated cirrhosis, and patients with and without HE.

METHODS

We studied 90 subjects by TCD measuring PI and BHI in the middle cerebral artery: 30 with cirrhosis and no HE, 30 with cirrhosis and low-grade HE and 30 healthy subjects. Critical flicker frequency, psychometric hepatic encephalopathy score and West-Haven criteria were performed to assess MHE and HE respectively.

RESULTS

Pulsatility index increased in decompensated cirrhotics (Child ≥ 7) when compared with compensated cirrhotics and healthy subjects [median (IQR) 1.07 (0.95-1.21) vs 0.90 (0.83-1.05) vs 0.87 (0.78-0.96); P < 0.001]. A reverse relationship was observed for BHI among the three groups [0.82 (0.45-1.11) vs 1.20 (0.82-1.52) vs 1.28 (1.06-1.68); P < 0.001]. Similar findings were observed in decompensation [model for end-stage liver disease (MELD) score ≥14]. Patients with HE showed higher PI and lower BHI [1.05 (1.00-1.16) and 0.89 (0.59-1.15)], when compared with patients without HE [0.96 (0.83-1.13) and 1.00 (0.60-1.53)] or controls [0.87 (0.78-0.96) and 1.28 (1.06-1.68)] (P < 0.001 for PI, and P = 0.007 for BHI). In multivariate regression models, only PI predicted HE, but it was outperformed by MELD-sodium and tumour necrosis factor-alpha.

CONCLUSIONS

These results indicate that cerebral haemodynamics are altered in patients with cirrhosis, in relation to severity of disease and HE. Findings on impaired PI and BHI suggest that structural vascular damage and loss of vascular autoregulation are implicated in the pathophysiology of HE.

Ammonia reduction with ornithine phenylacetate restores brain eNOS activity via the DDAH-ADMA pathway in bile duct-ligated cirrhotic rats

Ammonia is central in the pathogenesis of hepatic encephalopathy, which is associated with dysfunction of the nitric oxide (NO) signaling pathway. Ornithine phenylacetate (OP) reduces hyperammonemia and brain water in cirrhotic animals. This study aimed to determine whether endothelial NO synthase activity is altered in the brain of cirrhotic animals, whether this is associated with changes in the endogenous inhibitor, asymmetric-dimethylarginine (ADMA) and its regulating enzyme, dimethylarginine-dimethylaminohydrolase (DDAH-1), and whether these abnormalities are restored by ammonia reduction using OP. Sprague-Dawley rats were studied 4-wk after bile duct ligation (BDL) (n = 16) or sham operation (n = 8) and treated with placebo or OP (0.6 g/kg). Arterial ammonia, brain water, TNF-α, plasma, and brain ADMA were measured using standard techniques. NOS activity was measured radiometrically, and protein expression for NOS enzymes, ADMA, DDAH-1, 4-hydroxynonenol ((4)HNE), and NADPH oxidase (NOX)-1 were measured by Western blotting. BDL significantly increased arterial ammonia (P < 0.0001), brain water (P < 0.05), and brain TNF-α (P < 0.01). These were reduced significantly by OP treatment. The estimated eNOS component of constitutive NOS activity was significantly lower (P < 0.05) in BDL rat, and this was significantly attenuated in OP-treated animals. Brain ADMA levels were significantly higher and brain DDAH-1 significantly lower in BDL compared with sham (P < 0.01) and restored toward normal following treatment with OP. Brain (4)HNE and NOX-1 protein expression were significantly increased in BDL rat brain, which were significantly decreased following OP administration. We show a marked abnormality of NO regulation in cirrhotic rat brains, which can be restored by reduction in ammonia concentration using OP.

Non-alcoholic cirrhosis and the risk of stroke: a 5-year follow-up study

BACKGROUND/AIMS

As habitual heavy alcohol consumption is one of the major causes of cirrhosis in the western world, the majority of studies on the relationship between cirrhosis and stroke have focused on patients with alcohol-related liver diseases. Using a nationwide population-based dataset, this study therefore aimed to examine the risk of stroke among non-alcoholic cirrhosis patients over a 5-year period following their diagnosis with non-alcoholic cirrhosis, as compared with the general population during the same period.

METHODS

We used the 'Longitudinal Health Insurance Database', derived from the Taiwan National Health Insurance program. The study cohort comprised 2336 patients with cirrhosis and the comparison cohort consisted of 11,680 randomly selected subjects. Stratified Cox's proportional hazard regressions were performed to compare the 5-year stroke survival rate for the two cohorts.

RESULTS

In the total sample of 14,016 patients, 1187 patients (8.5%) experienced stroke during the 5-year follow-up period: 176 from the study cohort (7.5% of the patients with cirrhosis) and 1011 from the comparison cohort (8.7% of patients without cirrhosis) (P=0.076). After adjusting for the patients' geographical location, hypertension, diabetes, coronary heart disease, heart failure, atrial fibrillation and hyperlipidaemia, the regression analysis shows that patients with cirrhosis were less likely to experience stroke compared with those without cirrhosis during the 5-year period (hazard ratio=0.59, 95% confidence interval=0.52-0.67, P<0.001).

CONCLUSION

We conclude that patients with non-alcoholic cirrhosis were at a reduced risk for stroke compared with the general population.

Impaired cerebral autoregulation in primary biliary cirrhosis: implications for the pathogenesis of cognitive decline

BACKGROUND

Cognitive impairment is recognised in the early stages of primary biliary cirrhosis (PBC).

AIMS

To determine the mechanisms that underlie the cognitive dysfunction that can occur in early-stage PBC, with a particular focus on the role of autonomic dysfunction and altered cerebral autoregulation.

PATIENTS

Early-stage PBC patients, and age- and sex-matched controls.

INTERVENTIONS AND MAIN OUTCOME MEASURES

Brain magnetic resonance imaging to determine the relationship between structural brain abnormalities (T(2)) and cerebral vasculature responsiveness assessed using the Valsalva manoeuvre. Dynamic assessment of cerebral vascular flow using transcranial Doppler was also performed in PBC subjects to derive the pulsatility index (a marker of cerebral resistance) and the autoregulatory slope index [ASI; ratio between the cerebral blood flow velocity and blood pressure (BP)].

RESULTS

Cerebral resistance was increased (P=0.04), and cerebral autoregulation in response to the Valsalva was significantly impaired in the PBC group with markedly lower mean ASI values compared with the controls (7.8+/-7.0 vs -8.5+/-8.4; P=0.002). All controls had normal cerebral autoregulation compared with only 20% of the PBC group. Indicators of sympathetic failure (BP change between Valsalva phases III-IV and low-frequency heart rate variability) correlated with increasing globus pallidus (GP) T(2) values (P<0.05), beyond the effect of age.

CONCLUSION

This study demonstrates the presence of increased cerebral vascular resistance and abnormal cerebral autoregulation in PBC patients, and identifies a potentially important association between the degree of abnormality in structural changes in the GP. These findings suggest that organic brain injury in PBC is directly related to autonomic dysfunction.

Liver-kidney pathophysiological interrelationships in liver diseases

On the basis of several clinical and experimental researches, it is possible today to deepen the different mechanisms regarding kidney and liver relationships. However, the most studied field remains the renal function during liver disease. These alterations can be divided into: 1. Renal functional impairment is mainly considered due to hemodynamic derangement with a progressive decrease in peripheral vascular resistance (PVR) and an increase in cardiac output and rate, characteristic of hyperdynamic circulation, and outer cortex renal ischemia. Two principal forms of RFI characterize the hepatorenal syndrome (HRS) while in the first stage is based on the simple decrease in renal clearances with avid sodium retention. 2. Metabolic renal damage is principally due to abnormal serum levels of bile acids, bilirubin and perhaps toxic hepatic molecules which induce tubular dysfunction leading to RTA, of which type I, in the incomplete form, is the most common, varying between 30% and 50% of cases. It is mainly studied during cholestatic disease. 3. Organic renal impairment is principally based on immunological response to viral antigens and abnormal hepatic products which lead to the presence of immunocomplexes and cryoglobulins on the blood which tend to be deposited in the subendothelial and subepithelial glomerular areas, inducing complement activation, mesangial cell proliferation and monocyte-macrophage cell infiltration.

Splanchnic and systemic vasodilatation: the patient

Arterial vasodilatation is one of the most important characteristics of cirrrhosis and portal hyptertension. Nowadays, it has been known that progressive vasodilatation is an essential factor contributing to hyperdynamic circulation and multiple organ dysfunction in liver cirrhosis. Over the past decades, numerous investigations have originated from the clinical observations. Clinicians and investigators have learned and applied new concepts of the pathophysiology of portal hypertension. For example, we now have effective pharmacologic treatment for hepatorenal syndrome. This review summarizes the developement of progressive vasodilatation syndrome in liver cirrhosis and portal hypertension with focus on the patients.

Hemodynamic alterations in liver cirrhosis

In cirrhotic patients, portal hypertension is often associated with a hyperdynamic circulatory syndrome, with high cardiac output and reduced systemic vascular resistance and arterial pressure. The hyperdynamic circulatory syndrome is due to arterial vasodilation that mainly occurs in the splanchnic circulation, while vascular resistance in the other circulatory districts is normal or increased, accordingly with the degree of portal hypertension, liver impairment and activation of the renin-aldosterone and sympathetic nervous system. The mechanism(s) leading to splanchnic vasodilation is unclear. A favored hypothesis translocation of intestinal bacteria and/or some their products, such as endotoxin, into the interstitial space in the splanchnic organs results in the local release of vasodilating factors such as nitric oxide, carbon monoxide and others.

Autonomic dysfunction and impaired cerebral autoregulation in cirrhosis

Cerebral blood flow autoregulation is lost in patients with severe liver cirrhosis. The cause of this is unknown. We determined whether autonomic dysfunction was related to impaired cerebral autoregulation in patients with cirrhosis. Fourteen patients with liver cirrhosis and 11 healthy volunteers were recruited. Autonomic function was assessed in response to deep breathing, head-up tilt and during 24-h Holter monitoring. Cerebral autoregulation was assessed by determining the change in mean cerebral blood flow velocity (MCAVm, transcranial Doppler) during an increase in blood pressure induced by norepinephrine infusion (NE). The severity of liver disease was assessed using the Child-Pugh scale (class A, mild; class B, moderate; class C, severe liver dysfunction).NE increased blood pressure similarly in the controls (27 (24-32) mmHg) and patients with the most severe liver cirrhosis (Child-Pugh C, 31 (26-44) mmHg, p=0.405 Mann-Whitney). However, the increase in MCAVm was greater in cirrhosis patients compared to the controls (Child-Pugh C, 26 (24-39) %; controls, 3 (-1.3 to 3) %; respectively, p=0.016, Mann-Whitney). HRV during deep breathing was reduced in the cirrhosis patients (Child-Pugh C, 6.0+/-2.0 bpm) compared to the controls (21.7+/-2.2 bpm, p=0.001, Tukey' test). Systolic blood pressure fell during head-up tilt only in patients with severe cirrhosis. Our results imply that cerebral autoregulation was impaired in the most severe cases of liver cirrhosis, and that those with impaired cerebral autoregulation also had severe parasympathetic and sympathetic autonomic dysfunction. Furthermore, the degree of liver dysfunction was associated with increasing severity of autonomic dysfunction. Although this association is not necessarily causal, we postulate that the loss of sympathetic innervation to the cerebral resistance vessels may contribute to the impairment of cerebral autoregulation in patients with end-stage liver disease.

Dynamic cerebral autoregulation during exhaustive exercise in humans

We investigated whether dynamic cerebral autoregulation is affected by exhaustive exercise using transfer-function gain and phase shift between oscillations in mean arterial pressure (MAP) and middle cerebral artery (MCA) mean blood flow velocity (V(mean)). Seven subjects were instrumented with a brachial artery catheter for measurement of MAP and determination of arterial Pco(2) (Pa(CO(2))) while jugular venous oxygen saturation (Sv(O(2))) was determined to assess changes in whole brain blood flow. After a 10-min resting period, the subjects performed dynamic leg-cycle ergometry at 168 +/- 5 W (mean +/- SE) that was continued to exhaustion with a group average time of 26.8 +/- 5.8 min. Despite no significant change in MAP during exercise, MCA V(mean) decreased from 70.2 +/- 3.6 to 57.4 +/- 5.4 cm/s, Sv(O(2)) decreased from 68 +/- 1 to 58 +/- 2% at exhaustion, and both correlated to Pa(CO(2)) (5.5 +/- 0.2 to 3.9 +/- 0.2 kPa; r = 0.47; P = 0.04 and r = 0.74; P < 0.001, respectively). An effect on brain metabolism was indicated by a decrease in the cerebral metabolic ratio of O(2) to [glucose + one-half lactate] from 5.6 to 3.8 (P < 0.05). At the same time, the normalized low-frequency gain between MAP and MCA V(mean) was increased (P < 0.05), whereas the phase shift tended to decrease. These findings suggest that dynamic cerebral autoregulation was impaired by exhaustive exercise despite a hyperventilation-induced reduction in Pa(CO(2)).

Abnormally high resistive index of central retinal artery by ultrasound color Doppler in patients with viral chronic liver disease: correlation with worsening liver staging

Retrobulbar-ocular circulation provides an opportunity to assess the terminal circulation of the arterial cerebral tree. To evaluate whether retrobulbar circulation in patients with chronic liver disease is affected by adaptive mechanisms, we assessed by echo color Doppler, 1. The resistive-index of the central retinal artery, a terminal branch of the ophthalmic artery, and 2. the potential interrelationships with both liver staging and the most important splanchnic Doppler-parameters used to assess portal hypertension. The resistance index (RI) of the central retinal artery was obtained and compared with other classical Doppler parameters known to be affected by portal hypertension. The RI of the central retinal artery (CRA) was higher in cirrhotic patients than in controls or subjects with chronic hepatitis; it correlated with all the Doppler parameters of portal hypertension considered, with plasma renin-activity, and norepinephrine concentrations. Similarly to renal and splanchnic hemodynamics, retinal arterial circulation assessed by duplex Doppler seems to be affected by the histology of liver disease and by the overactivity of vasoconstrictor systems.

Vascular reserve in the lower limbs of cirrhotic patients: a duplex Doppler ultrasound study

AIM

To evaluate femoral artery impedance at rest and during reactive hyperaemia.

PATIENTS

Study population comprised 11 cirrhotic patients without ascites, 10 with ascites and 16 age- and sex-matched healthy subjects.

METHODS

Echocardiographic assessment of systemic haemodynamics; duplex Doppler ultrasound measurement of femoral artery pulsatility index and vascular reserve [pulsatility index rest/pulsatility index hyperaemia).

RESULTS

Cirrhotic patients had elevated cardiac index and low systemic vascular resistance. Pulsatility index (right femoral artery) was not statistically different either at rest or after reactive hyperaemia (controls: rest 10.6 +/- 0.4, hyperaemia 2.6 +/- 0.2; compensated cirrhosis: rest 10.1 +/- 0.8, hyperaemia 3.4 +/- 0.4; ascitic cirrhosis: rest 11.4 +/- 1.6, hyperaemia 2.9 +/- 0.4. Vascular reserve was 4.38 +/- 0.35 in controls, 3.33 +/- 0.39 in compensated and 4.70 +/- 0.89 in ascitic cirrhosis (p = not significant). No correlation was found between systemic haemodynamic parameters and either pulsatility index or vascular reserve.

CONCLUSIONS

The lower limb vascular reserve is preserved in cirrhosis.

Update on ascites and hepatorenal syndrome

Ascites is the most common complication occurring during liver cirrhosis. Even if a significant decrease in renal clearance may be observed in the first step of chronic active liver disease, renal impairment, at times complicated by the typical signs of hepatorenal syndrome, occurs only in patients with ascites, especially when tense and refractory. Experimental and clinical data seem to suggest a primary sodium and water retention in the pathogenesis of ascites, in the presence of an intrahepatic increase of hydrostatic pressure, which, by itself, physiologically occurs during digestion. Abnormal sodium and water handling leads to plasma volume expansion, followed by decreased peripheral vascular resistance and increased cardiac output. This second step is in agreement with the peripheral arterial vasodilation hypothesis, depicted by an increase in total blood volume, but with a decreased effective arterial blood volume. This discrepancy leads to the activation of the sympathetic nervous and renin-angiotensin-aldosterone systems associated with the progressive activation of the renal autacoid systems, especially, that of the arachidonic acid. During advanced cirrhosis, renal impairment becomes more sustained and renal autacoid vasodilating substances are less available, possibly due to a progressive exhaustion of these systems. At the same time ascites becomes refractory inasmuch as it is no longer responsive to diuretic treatment. Various pathogenetic mechanisms leading to refractory ascites are mentioned. Finally, several treatment approaches to overcome the reduced effectiveness of diuretic therapy are cited. Paracentesis, together with simultaneous administration of human albumin or other plasma expanders is the main common approach to treat refractory ascites and to avoid a further decrease in renal failure. Other effective tools are: administration of terlipressin together with albumin, implantation of the Le Veen shunt, surgical porto-systemic shunting or transjugular intrahepatic portosystemic stent-shunt, or orthotopic liver transplantation, according to the conditions of the individual patient.

Cerebral vascular resistance assessed by transcranial color Doppler ultrasonography in patients with chronic liver diseases

BACKGROUND AND AIM

Cerebral hemodynamic derangement is well known in patients with liver cirrhosis. The advent of transcranial Doppler enables a non-invasive observation of cerebral hemodynamics. To evaluate the clinical usefulness we examined cross-sectionally and longitudinally cerebral hemodynamic parameters in patients with cirrhosis.

METHODS

The subjects of the cross-sectional study were 117 patients with cirrhosis, 15 patients with chronic hepatitis and 25 healthy controls. The longitudinal study included 26 cirrhotic patients without encephalopathy, and 27 cirrhotic patients with encephalopathy. The pulsatility and resistive indices of the right middle cerebral artery were used as parameters of cerebral hemodynamics.

RESULTS

Cerebral pulsatility and resistive indices were significantly higher in patients with cirrhosis (1.05 +/- 0.23, P < 0.0001 and 0.63 +/- 0.07, P < 0.0001, respectively) than in the controls (0.75 +/- 0.11 and 0.55 +/- 0.05, respectively) and patients with chronic hepatitis (0.81 +/- 0.11 and 0.52 +/- 0.05, respectively). Cerebral pulsatility and resistive indices were significantly related with the severity of liver cirrhosis. Patients with encephalopathy had higher cerebral pulsatility and resistive indices than patients without encephalopathy. In the longitudinal studies, cerebral pulsatility and resistive indices were changed in parallel with the severity of cirrhosis and encephalopathy. Cerebral pulsatility and resistive indices were significantly correlated with the blood ammonia level and serum levels of bilirubin and albumin.

CONCLUSION

These cross-sectional and longitudinal studies showed that cerebral vascular resistance indices measured by using transcranial Doppler were increased in association with the severity of cirrhosis and encephalopathy. Cerebral pulsatility and resistive indices are real-time and useful parameters to assess and monitor cirrhotic patients.

Regional and systemic hemodynamic disturbances in cirrhosis

In cirrhosis of the liver there is an imbalance between factors mediating vasodilatation such as nitric oxide and factors mediating vasoconstriction such as endothelins. These imbalances result in portal hypertension, hepatorenal syndrome, portopulmonary hypertension, hepatopulmonary syndrome, as well as alterations in cerebral blood flow.

Increased cerebrovascular resistance in cirrhotic patients with ascites

Studies assessing regional hemodynamics in patients with cirrhosis and ascites have shown vasodilation in the splanchnic circulation and vasoconstriction in the renal circulation and in the brachial and femoral artery vascular territories. The aim of this study was to assess the cerebral vascular resistance in cirrhotic patients with ascites. The resistive index in the middle cerebral artery (an index of the cerebral vascular resistance) and in a renal interlobar artery were measured by Doppler ultrasonography in 7 healthy subjects: 13 patients with compensated cirrhosis and 24 patients with ascites (13 with renal failure). The arterial blood pressure and the activity of the renin-angiotensin and sympathetic nervous systems, as estimated by plasma renin activity and plasma norepinephrine concentration, respectively, were also measured. The resistive index in the middle cerebral artery was significantly increased in patients with ascites (0.68 +/- 0.05, mean +/- SD) as compared with patients without ascites (0.60 +/- 0.01, P < .05) and with healthy patients (0.52 +/- 0.01, P < .01). Renal resistive index was also increased in patients with ascites (0.77 +/- 0.01) compared with the other two groups (0.68 +/- 0.02 and 0.62 +/- 0.00, respectively; P < .001). The resistive index in the middle cerebral artery showed a direct correlation with renal resistive index (r = .73, P < .01), plasma renin activity (r = .61, P < .01), and norepinephrine (r = .53, P < .01). The resistive index in the middle cerebral artery showed an inverse correlation with mean arterial pressure (r = -.45, P < .01). These results indicate that in patients with cirrhosis and ascites there is a cerebral vasoconstriction which is probably related with the arterial hypotension and the overactivity of vasoconstrictor systems.