Reduced central blood volume in cirrhosis

Detection of early central circulatory transits in patients with cirrhosis by gamma variate fit of indicator dilution profiles

Patients with cirrhosis have hyperdynamic circulation with abnormally distributed blood volume and widespread arteriovenous communications. We aimed to detect possible very early (i.e., before 4 s) and early (i.e., after 4 s) central circulatory transits and their potential influence on determination of central and arterial blood volume (CBV). Thirty-six cirrhotic patients and nineteen controls without liver disease undergoing hemodynamic catheterization were given central bolus injections of albumin with different labels. Exponential and gamma variate fits were applied to the indicator dilution curves, and the relations between flow, circulation times, and volumes were established according to kinetic principles. No significant very early central circulatory transits were identified. In contrast, early (i.e., 4 s to maximal) transits corresponding to a mean of 5.1% (vs. 0.8% in controls; P < 0.005) of cardiac output (equivalent to 0.36 vs. 0.05 l/min; P < 0.01) were found in cirrhotic patients. These early transits averaged 7.7 vs. 12.7 and 17.2 s of ordinary central transits of cirrhotic patients and controls, respectively (P < 0.001). Early transits were directly correlated to the alveolar-arterial oxygen difference in the cirrhotic patients (r = 0.46, P < 0.01) but not in controls (r = 0.04; not significant). There was good agreement between the CBV determined by the conventional indicator dilution method and that determined by separation of early and ordinary transits by the gamma variate fit method (1.51 vs. 1.53 liter; not significant). In conclusion, no very early central circulatory transits were identified in cirrhotic patients. A significant part of the cardiac output undergoes an early transit, probably through pulmonary shunts or areas with low ventilation-perfusion ratios in cirrhotic patients. Composite determination of CBV by the gamma variate fit method is in close agreement with established kinetic methods. The study provides further evidence of abnormal central circulation in cirrhosis.

Quantitative treatment of the hyponatremia of cirrhosis

BACKGROUND

Hyponatremia represents a frequent complication of liver cirrhosis, associated with adverse events and death. It is caused either by excessive water retention or solute depletion, or a combination of both.

AIMS

To determine the cause of hyponatremia clinically and to examine the usefulness of quantitative calculations of water excess and Na deficit to guide treatment.

METHODS

We studied 23 patients with liver cirrhosis and PNa < or =131 meq/L to determine the cause of hyponatremia and results of quantitative treatment.

RESULTS

The most frequent cause of hyponatremia was diuretic-induced Na depletion, which occurred in 14 out of 23 instances, while four patients had water excess. Hyponatremia was corrected after a quantitative estimate of the Na deficit or relative water excess by algebraic formulas. The former was quantitatively replenished as 3% NaCl, the latter was excreted with the technique of furosemide-induced diuresis and re-infusion of solute, but not water, losses. After quantitative replacement, there was a significant correlation (R=0.98, P< 0.001) between the Na concentration predicted mathematically and that actually measured.

CONCLUSIONS

The hyponatremia of cirrhosis is frequently caused by diuretics. Its treatment can be effectively guided with the aid of quantitative estimates of Na deficit and/or water excess in all instances, although the methods of correction described are indicated in severe clinical conditions.

Hypertension and liver disease

Arterial hypertension is a common disorder with a frequency of 10% to 15% in subjects in the 40- to 60-year age group. Yet most reports find the prevalence of arterial hypertension in patients with chronic liver disease (cirrhosis) much lower. In this review, we consider the alterations in systemic hemodynamics in cirrhosis. The most characteristic findings in cirrhotic patients are vasodilatation with low systemic vascular resistance, increased cardiac output, high arterial compliance, secondary activation of counterregulatory systems (sympathetic nervous system, renin-angiotensin-aldosterone system, neuropituitary release of vasopressin), and resistance to vasopressors. The vasodilatory state is mediated through nitric oxide, calcitonin gene-related peptide, adrenomedullin, and other vasodilators, and is most pronounced in the splanchnic area. This constitutes an effective (although relative) counterbalance to increased arterial blood pressure. Subjects with established arterial hypertension (essential, secondary) may become normotensive during the development of cirrhosis, and arterial hypertension is rarely manifested in patients with cirrhosis, even in cases with renovascular disease and high circulating renin activity. There is much dispute as to the understanding of homeostatic regulation in cirrhotic patients with manifest arterial hypertension. This is a topic for future research.

Hyponatremia in liver cirrhosis: pathophysiological principles of management

Hyponatremia is common in cirrhosis, where it impairs encephalopathy. It could be either due to excess water, or reduced Na, or a combination of both. The diagnosis can be established with clinical skills aided by simple data like weight, blood pressure and plasma electrolytes. The quantitative estimates of the water surfeit or solute deficit, easily performed with simple formulas and measurements, guide accurate and programmed treatment procedures, avoiding the occurrence of the ominous central pontine myelinolysis.

Effects of tilting on central hemodynamics and homeostatic mechanisms in cirrhosis

Patients with cirrhosis have a hyperdynamic circulation and an abnormal blood volume distribution with central hypovolemia, an activated sympathetic nervous system (SNS) as well as the renin-angiotensin-aldosterone system (RAAS). As the hyperdynamic circulation in cirrhosis may be present only in the supine patient, we studied the humoral and central hemodynamic responses to changes with posture. Twenty-three patients with alcoholic cirrhosis (Child-Turcotte-Pugh classes A/B/C: 2/13/8) and 14 healthy controls were entered. Measurements of central hemodynamics and activation of SNS and RAAS were taken in the supine position, after 30 degrees head-down tilting, and after 60 degrees passive head-up tilting for a maximum of 20 minutes. After the head-up tilting, the central blood volume (CBV) decreased in both groups, but the decrease was significantly smaller in patients than in controls (-19% vs. -36%, P <.01). Central circulation time increased only in the patients (+30% vs. -1%, P <.01). The absolute increases in circulating norepinephrine and renin after head-up tilting were significantly higher in the patients than in the controls (P <.05 and P <.01, respectively). In patients with cirrhosis, changes in SNS and RAAS were related to changes in arterial blood pressure, systemic vascular resistance, heart rate, non-CBV, plasma volume, and arterial compliance. In conclusion, cardiovascular and humoral responses to changes in posture are clearly abnormal in patients with cirrhosis. Head-up tilting decreases the CBV less in patients with cirrhosis, and the results suggest a differential regulation of central hemodynamics in patients with cirrhosis.

Effects of tilting on central hemodynamics and homeostatic mechanisms in cirrhosis

Patients with cirrhosis have a hyperdynamic circulation and an abnormal blood volume distribution with central hypovolemia, an activated sympathetic nervous system (SNS) as well as the renin-angiotensin-aldosterone system (RAAS). As the hyperdynamic circulation in cirrhosis may be present only in the supine patient, we studied the humoral and central hemodynamic responses to changes with posture. Twenty-three patients with alcoholic cirrhosis (Child-Turcotte-Pugh classes A/B/C: 2/13/8) and 14 healthy controls were entered. Measurements of central hemodynamics and activation of SNS and RAAS were taken in the supine position, after 30 degrees head-down tilting, and after 60 degrees passive head-up tilting for a maximum of 20 minutes. After the head-up tilting, the central blood volume (CBV) decreased in both groups, but the decrease was significantly smaller in patients than in controls (-19% vs. -36%, P <.01). Central circulation time increased only in the patients (+30% vs. -1%, P <.01). The absolute increases in circulating norepinephrine and renin after head-up tilting were significantly higher in the patients than in the controls (P <.05 and P <.01, respectively). In patients with cirrhosis, changes in SNS and RAAS were related to changes in arterial blood pressure, systemic vascular resistance, heart rate, non-CBV, plasma volume, and arterial compliance. In conclusion, cardiovascular and humoral responses to changes in posture are clearly abnormal in patients with cirrhosis. Head-up tilting decreases the CBV less in patients with cirrhosis, and the results suggest a differential regulation of central hemodynamics in patients with cirrhosis.

Humoral and cardiac effects of TIPS in cirrhotic patients with different "effective" blood volume

The aim of this study was to evaluate the cardiac effects of transjugular intrahepatic portosystemic shunts (TIPS) in cirrhotic patients with different effective blood volume. Two-dimensional echocardiography was performed before and 7 and 28 days after TIPS insertion in 7 cirrhotic patients with PRA <4 ng/mL/h (group A, normal effective blood volume) and 15 with PRA >4 ng/mL/h (group B, reduced effective blood volume). Before TIPS, most cirrhotic patients showed diastolic dysfunction as indicated by reduced early maximal ventricular filling velocity (E)/late filling velocity (A) ratio. Patients of group B differed from patients of group A because of smaller left ventricular volumes and stroke volume, indicating central underfilling. After TIPS insertion, portal decompression was associated with a significant increase of cardiac output (CO) and a decrease of peripheral resistances. The most important changes were recorded in patients of group B, who showed a significant increase of both the end-diastolic left ventricular volumes and the E/A ratio and a significant decrease of PRA. In conclusion, these results show that the hemodynamic effects of TIPS differ according to the pre-TIPS effective blood volume. Furthermore, TIPS improves the diastolic cardiac function of cirrhotic patients with effective hypovolemia. This result is likely due to a TIPS-related improvement of the fullness of central blood volume.

Plasma volume expansion by albumin in cirrhosis. Relation to blood volume distribution, arterial compliance and severity of disease

BACKGROUND/AIMS

The aim of the study was to investigate the effect of a standard albumin load on blood volume distribution, arterial compliance, and the renin-angiotensin-aldosterone system in patients with different degrees of cirrhosis.

METHODS

31 patients with cirrhosis (Child classes A/B/C=8/14/9) received an intravenous infusion of 40 g human serum albumin during a haemodynamic investigation.

RESULTS

Whereas plasma- and blood volume increased by 23 and 15%, respectively (P<0.001), a significant increase in central blood volume was found only in class A patients (+8%, P<0.05), but not in class B or class C patients (+2.7%, not significant (n.s.)). In contrast, arterial compliance only increased significantly in class C patients (+18%, P<0.05), but not in class A or class B patients (+6%, n.s.). Plasma renin activity (PRA) decreased significantly in class C patients (-31%, P<0.05). When all patients were compared, the change in arterial compliance was inversely correlated to the change in PRA (r=-0.50, P<0.01).

CONCLUSIONS

Although infusion of albumin does not expand the central blood volume in patients with advanced cirrhosis, the results indicate a significant improvement in the low effective arterial blood volume of such patients, which may be important in the prevention of circulatory dysfunction.

Central and noncentral blood volumes in cirrhosis: relationship to anthropometrics and gender

The size of the central and arterial blood volume (CBV) is essential in the understanding of fluid retention in cirrhosis. Previously, it has been reported decreased, normal, or increased, but no reports have analyzed CBV with respect to gender and lean body mass. The aim of the present study was by means of an optimized technique to reassess it in a large group of patients with cirrhosis compared with healthy controls and matched controls in relationship to their body dimensions and gender. Eighty-three patients with cirrhosis (male/female, 60:23), 67 patients without liver disease (male/female, 22:45), and 14 young healthy controls (male/female, 6:8) underwent a hemodynamic investigation with determination of cardiac output, central circulation time, and CBV determined according to kinetic principles. Related to gender, CBV was lower in male cirrhotics (1.48 +/- 0.30 liter) than in matched and young controls (1.68 +/- 0.33 and 1.72 +/- 0.33 liter, respectively; P < 0.05-0.01). No significant differences in CBV were seen between female cirrhotics and controls. Absolute and adjusted CBVs were lower in the females than in men with cirrhosis (P < 0.001), and men with cirrhosis had lower absolute and body weight-adjusted CBVs than matched controls (P < 0.01). Normalized values of CBV (%total blood volume) were significantly lower in patients with cirrhosis (25 +/- 4%) than in matched controls (31 +/- 7%) and young controls (28 +/- 4%; P < 0.02). CBV correlated significantly with anthropometrics, including lean body mass (r = 0.68-0.82; P < 0.0001). In conclusion, the CBV of patients with cirrhosis was lower than that of controls when adjusted for body dimensions and gender. There are significant gender differences, and signs of underfilling are more pronounced in male than in female patients. The results emphasize the importance of adjustments of blood volumes for anthropometrics and gender.

Cardiac output determined by echocardiography in patients with cirrhosis: comparison with the indicator dilution technique

BACKGROUND/AIMS

Measurement of cardiac output in hyperkinetic patients with cirrhosis by Doppler echocardiography is increasingly reported, but has not been validated. We have compared simultaneous measurements of cardiac output by Doppler echocardiography (CO(d)) and by the indicator dilution technique (CO(I)).

METHODS

Twelve patients with cirrhosis were studied. CO(d) was measured as the spatial mean velocity of the left ventricular outflow tract, multiplied by the cross-sectional area and the heart rate. CO(I) was determined by the standard indicator dilution technique after injection of 125I albumin and 99mTc albumin into the right atrium and subsequent sampling from the femoral artery.

RESULTS

The mean CO(d) and CO(I) were similar (7.20 vs 7.15 l/min, NS). A highly significant correlation was present between CO(d) and CO(I) (r = 0.86, P < 0.0001; slope 0.91, Y(0) = 0.78 l/min). However, the mean squared difference between CO(d) and CO(I) was 2.3 (l/min)2. A Bland-Altman plot revealed no trend with the level of cardiac output. The standard deviation (0.79 vs 0.30 l/min, P < 0.01) and the coefficient of variation (10.5 vs 4.2%, P < 0.01) of duplicate measurements were significantly higher with the Doppler technique.

CONCLUSION

Doppler measurements of cardiac output in groups of patients with cirrhosis are accurate with respect to the group mean, but marked disagreements of over- and underestimation were seen in individual patients. The reproducibility of the Doppler technique is acceptable, although not as good as that of the indicator dilution technique.

Review article: volume expansion in patients with cirrhosis

Adequate size and distribution of the circulating medium are important for cardiovascular function, tissue oxygenation, and fluid homoeostasis. Patients with cirrhosis have cardiovascular dysfunction with a hyperkinetic systemic circulation, abnormal distribution of the blood volume, vasodilation with low systemic vascular resistance, increased whole-body vascular compliance, and increased arterial compliance. The effectiveness and temporal relations of plasma/blood volume expansion depend highly on the type of load (water, saline, oncotic material, red blood cells). Patients with cirrhosis respond in some aspects differently from healthy subjects, owing to their disturbed circulatory function and neurohormonal activation. Thus the increase in cardiac output and suppression of the renin-angiotensin-aldosterone system and sympathetic nervous system during volume expansion may be somewhat blunted, and in advanced cirrhosis, especially the non-central parts of the circulation, including the splanchnic blood volume, are expanded by a volume load. Infusion of oncotic material (preferably albumin) is important in the prevention of post-paracentesis circulatory dysfunction. In conclusion, volume expansion in advanced cirrhosis is qualitatively and quantitatively different from that of healthy subjects, and in those with early cirrhosis. Timely handling is essential, but difficult as it is a balance between the risks of excess extravascular volume loading and further circulatory dysfunction in these patients with a hyperdynamic, but hyporeactive, circulation.

Review article: albumin in the treatment of liver diseases--new features of a classical treatment

Albumin was introduced initially in the treatment of patients with cirrhosis and ascites to increase serum albumin concentration due to its oncotic effect. Although its administration declined some years later, at present it constitutes an essential treatment in clinical hepatology. Several studies have clearly demonstrated its efficacy in the prevention and treatment of circulatory dysfunction and hepatorenal syndrome in patients with cirrhosis. These effects can be due not only to its properties as a plasma expander but also to its capacity to bind numerous substances such as bile acids, nitric oxide and cytokines. Based on this capacity an albumin dialysis system (MARS) has recently been developed. The usefulness of this system in the management of patients with acute and chronic liver failure is, at present, under evaluation.

The mechanism of improved sodium homeostasis of low-dose losartan in preascitic cirrhosis

Renal sodium retention on standing is one aspect of the abnormal renal sodium handling in preascitic, well-compensated patients with cirrhosis. Recently, it has been shown that low doses (7.5 mg) of the angiotensin II (Ang II) receptor antagonist, losartan, can reverse renal sodium retention on high, 200-mmol sodium/d diet in these patients and restore them to sodium balance. Therefore, the effect of 7.5 mg of losartan on sodium excretion, when changing from supine to erect posture for 2 hours, was examined in 10 well-compensated patients with cirrhosis and 9 age- and sex-matched controls on the same sodium diet, under strictly controlled metabolic conditions. In contrast to control subjects, in whom sodium excretion was unaffected, single 7.5-mg doses of losartan again restored the preascitic patients with cirrhosis to sodium balance. In addition, it blunted the fall in erect posture- induced renal sodium excretion by a reduction in proximal and distal tubular reabsorption of sodium. These changes occurred without any significant changes in blood volumes, systemic and renal hemodynamics, or glomerular filtration rate (GFR) and filtered sodium load compared with controls, and despite activation of the systemic renin-angiotensin-aldosterone system, which was still within normal levels. In conclusion, the beneficial natriuretic effects of low-dose losartan on erect posture - induced sodium retention in preascitic cirrhosis supports the suggestion that the pathophysiology of sodium retention in preascites is in part caused by an intrarenal tubular effect of Ang II in that posture.

Evaluation of the splanchnic circulation with indocyanine green pharmacokinetics in liver transplant patients

Although indocyanine green (ICG) can be used to estimate cardiac output (CO) and blood volume independently, a recirculatory multicompartmental ICG model enables description of these and additional intravascular factors. This model was used to describe the effect of end-stage liver disease (ESLD) on systemic and splanchnic hemodynamics in patients undergoing orthotopic liver transplantation. ICG disposition was determined during the dissection phase in six patients with ESLD undergoing orthotopic liver transplantation and six healthy adult living liver donors. After injecting ICG, plasma concentrations were obtained for approximately 10 to 12 minutes by noninvasive pulse dye densitometry. The recirculatory model characterizes three distinct intravascular circuits: lumped parallel fast (presumably nonsplanchnic circulation) and slow peripheral (splanchnic) circuits and a central circuit (central blood volume). Mean transit time (MTT) in the fast peripheral circuit was not different in patients with ESLD and controls. However, ESLD resulted in a significant decrease in MTT in the central (0.11 +/- 0.028 [SD] v 0.24 +/- 0.094 minutes in controls; P <.001) and slow peripheral circuit (0.67 +/- 0.41 v 1.37 +/- 0.37 minutes in controls; P <.001) because of increased flows to the central and slow peripheral circuits. These findings are consistent with the described hyperdynamic systemic and splanchnic circulations in patients with ESLD. In conclusion, the ICG model is able to derive estimates of not only blood volume and CO, but also splanchnic hemodynamics under different physiological conditions. This model can be a useful tool to evaluate the effect of pharmacological manipulation of splanchnic hemodynamics.

Dyssynchronous electrical and mechanical systole in patients with cirrhosis

BACKGROUND/AIMS

Previous investigations have shown a prolonged QT interval in some patients with cirrhosis. The aim of this study was to investigate the relation between electrical and mechanical systole in patients with different degrees of severity of cirrhosis.

METHODS

Forty-eight patients with cirrhosis and portal hypertension, studied during a haemodynamic investigation, were compared to 17 controls.

RESULTS

A prolonged QTc (above 0.440 s(1/2)) was found in 37% of the cirrhotic patients vs. 5.9% in the controls (P=0.03), and there was a correlation to liver dysfunction (P<0.02). A direct relation between QT and time of mechanical systole (tS) was observed in controls (r=0.58, P<0.01), and cirrhotic patients (r=0.44, P<0.002). In patients with a prolonged QTc interval, the difference between electrical and mechanical systole time was substantially longer than in patients with a normal QTc interval (0.078 vs. 0.031 s, P<0.005). The QT values were related to markers of hyperdynamic circulation (r=-0.48 to 0.56, P<0.05-0.001). CONCLUSIONS; Prolonged repolarization, as evidenced by prolonged QTc, is related to both impaired liver function and systemic circulatory dysfunction. In addition these patients have alterations in the cardiac excitation-contraction relation with compromised association between electrical and mechanical function.

Total effective vascular compliance in patients with cirrhosis. Effects of propranolol

BACKGROUND

Total effective vascular compliance (TEVC), may be increased in cirrhosis. However, its significance is unclear.

AIMS

To investigate TEVC in patients with cirrhosis, and the effects of propranolol.

METHODS

Seven patients without liver disease and 44 cirrhotic patients were studied before and after double-blind administration of propranolol (n=33) or placebo (n=11).

MEASUREMENTS

TEVC (right atrial pressure response to rapid central volume expansion), hepatic venous pressure gradient (HVPG) and systemic hemodynamics.

RESULTS

TEVC (ml x mmHg(-1) x kg(-1)) was increased in cirrhotics (1.67 +/- 0.66 versus 1.33 +/- 0.32 in controls; P<0.05). TEVC was not modified by placebo, but was markedly reduced by propranolol (from 1.74 +/- 0.75 to 1.33 +/- 0.56; P<0.01). Propranolol decreased HVPG >10% in 20 patients ('responders': -20 +/- 9%) but <10% in 13 'non-responders'. TEVC was normalized by propranolol in HVPG 'responders' (from 1.76 +/- 0.88 to 1.21 +/- 0.51; P<0.01), but not in 'non-responders' (1.69 +/- 0.48 to 1.52 +/- 0.59; NS). Reduction of TEVC in responders was accompanied by increased free hepatic vein pressure (+21 +/- 20%, P=0.05; approximately 60% of the fall in HVPG), which was not observed in non-responders (+3 +/- 11%, NS).

CONCLUSIONS

TEVC is increased in cirrhosis. This abnormality is corrected by propranolol in patients exhibiting a >10% fall in HVPG, suggesting that changes in vascular compliance may influence the portal pressure response to propranolol.

Cirrhotic cardiomyopathy: a pathophysiological review of circulatory dysfunction in liver disease

The systemic circulation in patients with cirrhosis is hyperdynamic with an increased cardiac output and heart rate and a reduced systemic vascular resistance as the most pronounced alterations. The concomitant cardiac dysfunction has recently been termed "cirrhotic cardiomyopathy", which is an entity different from that seen in alcoholic heart muscle disease. Clinically, these patients present with sodium fluid retention and strain often unmasks the presence of latent heart failure. No specific treatment can yet be recommended but caution should be used with respect to procedures that may stress the heart such as shunt implantation and liver transplantation.

Blood volume distribution in patients with cirrhosis: aspects of the dual-head gamma-camera technique

BACKGROUND/AIMS

Patients with cirrhosis have increased total blood volume (TBV). The size of the "effective" blood volume has been closely investigated, whereas the distribution of the blood volume outside the thorax has not been examined. The aim was to estimate the blood volume distribution in patients with cirrhosis and portal hypertension, using a dual-head gamma-camera technique (DHGCT) and to validate this technique.

METHODS

Twenty-three patients with cirrhosis, 11 non-cirrhotic control patients, and six healthy controls had their blood volume distribution determined by the DHGCT.

RESULTS

The close relation between the estimated blood volume in the thorax region and the central and arterial blood volume, obtained by the dynamic indicator dilution technique (r=0.87, P<0.001), indicates validity of the DHGCT. Whole-body scintigraphy showed altered blood volume distribution in the cirrhotic patients with increased splanchnic blood volume (SpBV: 25.0 vs. 18.2% of TBV in controls, P<0.001), and all but one patient with hepatic venous pressure gradient above 12 mmHg had SpBV above 20% of TBV, but the blood volumes in the liver region were similar.

CONCLUSIONS

DHGCT is a valid method of estimating the blood volume distribution. Patients with cirrhosis and portal hypertension have grossly increased blood pooling in the splanchnic region, indicating splanchnic congestion.

The pathophysiologic basis for the treatment of cirrhotic ascites

Advances in the understanding of the pathophysiology of sodium retention and ascites formation in cirrhosis has helped improve the treatment of ascites in these patients. It is likely that further unraveling of these pathophysiologic changes will lead to the development of novel and better treatment options. For example, the development of aquaretic agents for the management of hyponatremia in cirrhosis may allow more effective use of diuretic therapy. The ultimate challenge is to use the understanding of the pathophysiology to develop new strategies to prevent the development of ascites in cirrhosis.

Pathogenesis of portal hypertension

Portal hypertension is defined by an elevation in portal pressure and is associated with haemodynamic alterations. Haemodynamic changes are characterized by a hyperdynamic circulation in the splanchnic and systemic territories and a reduced pressure effect of vasoconstrictive substances. They were observed in both patients and animals with different types of portal hypertension. In this review, the main results and their mechanisms of the splanchnic and systemic haemodynamic alterations in portal hypertension are discussed.

Arterial compliance in patients with cirrhosis: stroke volume-pulse pressure ratio as simplified index

Arterial function may be altered in patients with cirrhosis. We determined compliance of the arterial tree (C(1)) in relation to systemic and splanchnic hemodynamic derangement and clinical variables. C(1) and the stroke volume-pulse pressure index (SV/PP) were significantly higher (+62% and +40%, respectively; P < 0.001) in cirrhotic patients (n = 49) than in control subjects (n = 19), and a close correlation between C(1) and SV/PP was found in both cirrhotic patients (r = 0.86, P < 0.001) and control subjects (r = 0.96, P < 0.001). Univariate analysis showed significant relations between C(1) and SV/PP on one side and age, sex, body weight, portal pressure, systemic hemodynamics, biochemical variables, and severity of disease on the other. In the multiple-regression analysis, sex, age, mean arterial blood pressure, systemic vascular resistance, and biochemical variables were significant independent predictors of SV/PP (P < 0.005-0.00001). In conclusion, arterial compliance is elevated in cirrhosis. A simplified SV/PP index seems to reflect abnormalities in the arterial compliance of these patients.

The hyperdynamic circulation in cirrhosis: an overview

The hyperdynamic circulation begins in the portal venous bed as a consequence of portal hypertension due to the increased resistance to flow from altered hepatic vascular morphology of chronic liver disease. Dilatation of the portal vein is associated with increased blood flow, as well as the opening up or formation of veno-venous shunts and splenomegaly. At the same time, portal hypertension leads to subclinical sodium retention resulting in expansion of all body fluid compartments, including the systemic and central blood volumes. This blood volume expansion is associated with vasorelaxation, as manifested by suppression of the renin--angiotensin--aldosterone system, initially only when the patient is in the supine position. Acute volume depletion in such patients results in normalisation of the hyperdynamic circulation, whilst acute volume expansion results in exaggerated natriuresis. As liver disease progresses and liver function deteriorates, the systemic hyperdynamic circulation becomes more manifest with activation of the renin--angiotensin--aldosterone system. The presence of vasodilatation in the presence of highly elevated levels of circulating vasoconstrictors may be explained by vascular hyporesponsiveness due to increased levels of vasodilators such as nitric oxide, as well as the development of an autonomic neuropathy. However, vasodilatation is not generalised, but confined to certain vascular beds, such as the splanchnic and pulmonary beds. Even here, the status may change with the natural history of the disease, since even portal blood flow may decrease and become reversed with advanced disease. The failure of these changes to reverse following liver transplantation may be due to remodelling and angiogenesis.

Increased circulating calcitonin in cirrhosis. Relation to severity of disease and calcitonin gene-related peptide

Increased circulating levels of the neuropeptide calcitonin gene-related peptide (CGRP) have recently been described in cirrhosis. CGRP is formed by alternative transcription of the calcitonin/alpha-CGRP gene, which also gives rise to calcitonin (CT). This study was undertaken to determine circulating plasma concentrations of CT in patients with cirrhosis in relation to the severity of disease and the plasma level of CGRP. Moreover, the kinetics of CT was evaluated for different organ systems by determination of arteriovenous extraction. Thirty-nine patients with cirrhosis (Child-Turcotte classes A/B/C, n = 10/22/7) were studied under a hemodynamic investigation and compared with 13 control subjects without liver disease. CT and CGRP in arterial and organ venous plasma were determined by radioimmunoassays. In patients with cirrhosis, circulating CT was significantly increased versus control (12.1 v 6.9 pmol/L, P < .001) and a direct relation to the Child-Turcotte score was found (P < .005). The increased circulating CT was directly correlated with increased CGRP (r = .29, P < .05). No significant arteriovenous extraction of circulating CT was observed in the kidneys, hepatosplanchnic system, lower extremities, or peripheral circulation, but there was a substantial rate of pulmonary disposal and clearance (P < .005). It is concluded that in addition to thyroid production, increased circulating CT in cirrhosis is most likely due to overexpression of the calcitonin/alpha-CGRP gene, with relation to the severity of disease and possibly to an accompanying pulmonary dysfunction.

Intracerebroventricular infusion of hypertonic NaCl increases urinary CGMP in healthy and cirrhotic rats

Implication of serum atrial natriuretic peptide (ANP) and endothelin-1 (ET1) in the central nervous system (CNS)-induced natriuresis and hypertension respectively, was investigated in healthy and cirrhotic rats. Both healthy and nonascitic CCl(4)-induced cirrhotic rats under pentobarbital anesthesia received either normotonic (140 mmol/L) or hypertonic (320 mmol/L) NaCl artificial cerebrospinal fluid into the CNS lateral ventricle at a rate of 8.3 microl/min for 120 min. A sham operated group, but not centrally infused, served as matched control. Hypertonic NaCl solution significantly increased mean arterial pressure (MAP) similarly in both healthy (n = 5) ((MAP: 16 mm Hg, 13%) and cirrhotic rats (n = 6) ((MAP: 20 mm Hg, 15%) (ANOVA, p <.001) although the latter showed a slower increment. Under hypertonic NaCl infusion, natriuresis was also significantly increased in a similar manner in both healthy (U (Na) V: baseline: 0.38 +/- 0.22 micromol/min x 100 g; experiment: 2.36 +/- 0.90 micromol/min x 100 g; mean +/- SD) and cirrhotic rats (0.69 +/- 0.48 vs. 3.16 +/- 0.87; p <.001). By contrast, central hypertonic NaCl solutions did not show a significant modification of serum ANP in neither healthy (62 +/- 18 fmol/ml vs. 51 +/- 17 fmol/ml) nor cirrhotic rats (126 +/- 61 vs. 115 +/- 30). Likewise, ET-1 was not significantly modified under central hypertonic NaCl infusion in neither healthy (352 +/- 46 pg/ml vs. 344 +/- 39 pg/ml) nor cirrhotic rats (287 +/- 58 vs. 277 +/- 61). Despite no modification in serum ANP, there was a significant increment in urinary excretion of cGMP under central hypertonic NaCl infusions in bo th healthy (6.8 +/- 4.1 pmol/min x 100 g vs. 13.0 +/- 6.5 pmol/min x 100 g; p <.05) and cirrhotic rats (8.6 +/- 1.7 vs. 11.1 +/- 1.3; p <.05). Our data indicate the preservation of the mechanisms of central natriuresis in a model of non-ascitic CCl(4 )-induced cirrhosis in rats. An increment in urinary cGMP could potentially be implicated in the natriuretic response obtained by intracerebroventricular hypertonic NaCl stimulus in both healthy and cirrhotic rats. The lack of modification of serum ANP and ET-1 does not appear to support a systemic implication of these peptides in the natriuretic and hypertensive responses respectively induced by this manoeuvre.

Increased arterial compliance in decompensated cirrhosis

BACKGROUND/AIMS

In patients with cirrhosis, the systemic circulation is hyperdynamic with low arterial blood pressure and reduced systemic vascular resistance. The present study was undertaken to estimate the compliance of the arterial tree in relation to severity of cirrhosis, circulating level of the vasodilator, calcitonin gene-related peptide (CGRP) and mean arterial blood pressure (MAP).

METHODS

Arterial compliance (COMPart=deltaV/deltaP) was determined as the stroke volume relative to pulse pressure (i.e. systolic minus diastolic blood pressure) during a haemodynamic evaluation of portal hypertension in patients with biopsy-verified cirrhosis (Child-Turcotte classes A/B/C=10/15/6).

RESULTS

COMPart was significantly higher in cirrhotic patients (n=31) than in controls (n=10) (1.44 vs 1.00 x 10(-3) l/mmHg, p<0.01). It increased significantly through the Child-Turcotte classes A, B, and C (1.02, 1.47, and 2.1 x 10(-3) l/mmHg, respectively, p=0.03). The stroke volume did not change significantly with the severity of the disease, but pulse pressure decreased through class A, B, and C (79, 65, and 50 mmHg, respectively, p<0.01). COMPart was slightly, but significantly correlated to the circulating level of CGRP (r=0.34, p<0.05), and a substantial but inverse correlation was present to MAP (r= -0.63, p<0.002).

CONCLUSIONS

Elevated arterial compliance in cirrhosis is directly related to the severity of the disease and to the elevated level of circulating vasodilator peptide CGRP, and inversely related to the level of arterial blood pressure. The altered static and dynamic functions of the arterial wall in cirrhosis may have implications for the circulatory and homoeostatic derangement, and potentially for therapy with vasoactive drugs.

Increased circulating leptin in alcoholic cirrhosis: relation to release and disposal

Leptin is a cytokine peptide that decreases appetite and thereby food intake and increases energy expenditure. It is produced in fat cells, but recent animal experiments have shown expression of leptin in modified stellate hepatic cells. Because a change in circulating leptin in cirrhosis could be caused by an altered production rate, altered disposal rate, or both, the present study was undertaken to identify regions of leptin overflow into the blood stream and regions of leptin extraction. Patients with alcoholic cirrhosis (n = 16) and control patients without liver disease (n = 12) were studied during catheterization with elective blood sampling from different vascular beds. Blood samples for leptin determination (radioimmunoassay) were taken simultaneously from artery/hepatic vein, artery/renal vein, artery/iliac vein, and artery/cubital vein. Patients with cirrhosis had significantly increased circulating leptin (7.3 vs. control 2.6 ng/mL, P <.002) that correlated directly to ascitic-free body mass index (r = 0.71, P <.005). A significant renal extraction ratio of leptin was observed in control patients (0. 16) and in patients with cirrhosis (0.07), but the latter value was significantly lower than in the control patients (-44%, P <.05) and inversely correlated to serum creatinine (r = -0.60, P <.05). A significant, but equal, hepatosplanchnic extraction of leptin was observed in cirrhotic patients and control patients (0.08 vs. 0.07). In patients with cirrhosis a significant cubital venous-arterial difference in leptin was observed, but not in control patients. The iliac venous/arterial leptin ratio was significantly above 1.0 in both groups and of similar size (1.16 vs. 1.15), but a higher difference in concentration was found in the cirrhotic patients (+33%, P <.05). The spillover rates of leptin in cirrhotic patients may be even higher than estimated from the increased systemic veno-arterial gradients. In conclusion, the elevated circulating leptin in patients with cirrhosis is most likely caused by a combination of decreased renal extraction and increased release from subcutaneous abdominal, femoral, gluteal, retroperitoneal pelvic, and upper limb fat tissue areas. The hepatosplanchnic bed drained through hepatic veins could not be identified as a source of increased circulating leptin in cirrhosis, but a contribution by the portosystemic collateral flow cannot be excluded.

The renal sympathetic and renin-angiotensin response to lower body negative pressure in well-compensated cirrhosis

BACKGROUND & AIMS

Certain antinatriuretic hormonal systems may be involved in the subclinical sodium handling abnormality in preascitic cirrhosis. The aims of this study were to determine the following in preascitic cirrhosis: (1) basal activity of the renal sympathetic and renin-angiotensin systems and (2) the relationship between the response of these systems to lower body negative pressure and sodium excretion.

METHODS

Seven preascitic cirrhotic patients and 9 age- and sex-matched controls were studied on a 150 mmol sodium per day diet. Systemic and renal hemodynamics, renal neurohormonal secretion rates, and sodium excretion were assessed before, during increasing levels of, and after lower body negative pressure, each for 30 minutes.

RESULTS

Both groups responded with a significant decrease in central venous pressure (P < 0.01) that remained higher in the cirrhotics than in the controls throughout the study. Cirrhotics showed significant increases compared with controls in renal renin and angiotensin II secretion rates at -20 mm Hg of lower body negative pressure, which was associated with significant renal sodium retention (96 +/- 17 micromol/min vs. 218 +/- 21 micromol/min at baseline, P < 0.05), but there was no change in renal sympathetic activity.

CONCLUSIONS

In preascitic cirrhosis, sodium retention occurs in response to lower body negative pressure, which was associated with increased renal renin-angiotensin activity. Stimulation of the intrarenal renin-angiotensin system may be the initial renal pathophysiological change causing sodium retention in cirrhosis.

Recent advances in the pathophysiology of portal hypertension

Portal hypertension is a common complication of chronic liver disease. Increased resistance to portal blood flow through a cirrhotic liver initiates the development of portal hypertension. In addition, alteration of neural and humoral regulations, endothelins, and stellate cells all contribute to the increased intrahepatic resistance. Moreover, the collateral circulation represents an additional site of increased resistance to portal blood flow. Increased splanchnic blood flow appears to play an important role in the maintenance of chronic portal hypertension. Several mechanisms have been proposed to explain this haemodynamic derangement including increased circulating vasodilators, endothelial-derived vasodilators, and decreased vascular reactivity to vasoconstrictors. Finally, the development of portal hypertension induces peripheral arterial vasodilation. The arterial vasodilatation may result in an increase in vascular underfilling which in turn leads to sodium retention and plasma volume expansion. The increased plasma volume is necessary for the development of increased cardiac output and the full expression of hyperdynamic circulation in portal hypertension.

Effect of therapeutic paracentesis on plasma volume and transvascular escape rate of albumin in patients with cirrhosis

BACKGROUND/AIMS

Circulatory abnormalities with activation of vasoconstrictor systems after large-volume paracentesis are generally considered secondary to an increased extravasation of fluid from the intravascular compartment to the extravascular space with subsequent reduction in plasma volume. To test this hypothesis, plasma volume, the transvascular escape rate of albumin, the absolute escape rate of albumin and the activity of vasoconstrictor systems were measured in 25 cirrhotic patients with ascites in baseline conditions and 2 days after total paracentesis with plasma volume expansion.

METHODS

Plasma volume and the transvascular escape rate of albumin, the fraction of albumin passing from the intravascular to the extravascular space per unit of time, were assessed through the plasma disappearance curve of radioiodinated human albumin. The absolute escape rate of albumin, the total flux of albumin from intravascular to extravascular space per unit of time, was also calculated.

RESULTS

Eight of the 25 patients (32%) developed marked activation of vasoconstrictor systems after paracentesis. In these patients, plasma renin activity and plasma norepinephrine concentration increased from 6.6+/-2 to 23.4+/-11 ng x ml(-1) x h(-1) and 776+/-229 to 989+/-258 pg/ml, respectively (p<0.05). No significant changes in these parameters were found in the remaining 17 patients. The activation of vasoconstrictor systems occurred in the absence of changes in plasma volume (3456+/-276 vs 3476+/-264 ml, NS), transvascular escape rate of albumin (10.4+/-1 vs 10.9+/-2%/h, NS) and absolute escape rate of albumin (9.9+/-1.9 vs 10.5+/-0.7 g/h, NS).

CONCLUSIONS

These results do not support a contraction of plasma volume as the mechanism responsible for activation of vasoconstrictor systems after paracentesis. Rather, the activation of vasoconstrictor systems in the absence of changes in plasma volume suggests that paracentesis accentuates the impairment of "effective" blood volume present in cirrhotic patients with ascites.

Continuous blood pressure monitoring in cirrhosis. Relations to splanchnic and systemic haemodynamics

BACKGROUND/AIMS

Low arterial blood pressure is recognised as a distinctive factor in the hyperdynamic circulation in cirrhosis. 24-hour monitoring of the blood pressure and heart rate has recently revealed a reduced circadian variation with relation to liver function. However, associations with other clinical and haemodynamic characteristics have not been investigated and the aim of the present study was to identify splanchnic and systemic determinants of the 24-h blood pressure and heart rate in cirrhosis.

METHODS

The variables were measured by an automatic ambulant device for monitoring blood pressure and related to the results of an invasive haemodynamic investigation, including measurements of intra-arterial blood pressure (9.00-11.00 h) in 37 patients with cirrhosis.

RESULTS

The 24-h blood pressures were significantly lower and the heart rate was significantly higher in patients with cirrhosis than in matched controls (p < 0.05-0.001). To identify determinants of 24-h or intra-arterial blood pressures and heart rate, pertinent variables were included in a multivariate regression model. This model revealed that independent determinants of a low 24-h arterial blood pressure were a high post-sinusoidal resistance, a low plasma volume, a short central circulation time, and the presence of ascites. In contrast, a low intra-arterial blood pressure was determined by a low serum sodium, a low haemoglobin, and a high cardiac output. Diuretic treatment did not influence this model.

CONCLUSIONS

Although the 24-h blood pressure and the intra-arterial blood pressure were determined by different variables, the overall results indicate that abnormalities in both splanchnic and central haemodynamics and sodium-water retention are important in the pathophysiology of arterial hypotension in patients with portal hypertension.

Review: the controversy over the pathophysiology of ascites formation in cirrhosis

The pathogenesis of renal sodium retention and ascites formation in cirrhosis is a subject of much controversy. The generally accepted 'peripheral arterial vasodilatation hypothesis' seems to best explain the mechanism of sodium retention and other clinical findings, such as the hyperdynamic circulation of cirrhosis. However, recent data in pre-ascites and in early ascites do not seem to conform to the peripheral arterial vasodilatation hypothesis. Sodium handling abnormalities can be demonstrated in pre-ascitic cirrhosis when patients are challenged with a sodium load, in the absence of systemic vasodilatation or arterial underfilling. Therefore, an alternative hypothesis with a direct hepatorenal interaction, acting via sinusoidal portal hypertension and/or hepatic dysfunction as the affector mechanism, is proposed to be the initiating event in renal sodium retention in cirrhosis. The second and later process is the development of systemic arterial vasodilatation, possibly due to the presence of excess systemic vasodilators and/or decreased responsiveness of the vasculature to endogenous vasoconstrictors. This, in turn, will lead to a relatively underfilled circulation with consequent activation of neurohumoral systems, promoting further renal sodium retention as described by the peripheral arterial vasodilatation hypothesis and ultimately leading to ascites. When compensatory natriuretic mechanisms fail, refractory ascites develops and hepatorenal syndrome sets in. Thus, renal sodium retention in cirrhosis is the result of interplay of many factors, with direct hepatorenal interaction predominating in earlier stages of the cirrhotic process, while systemic vasodilatation becomes a more important pathogenetic factor as the disease progresses.

Effects of long-term administration of octreotide on sodium retention and atrial natriuretic peptide in carbon tetrachloride-induced cirrhotic rats

BACKGROUND/AIMS

To realize the roles of peripheral vasodilatation and atrial natriuretic peptide in the formation of cirrhotic ascites, the effects of long-term administration of octreotide on carbon tetrachloride-induced cirrhotic rats were evaluated.

METHODS

Urine sodium excretion, hemodynamics, plasma atrial natriuretic peptide levels, renin activities and aldosterone concentrations were compared between cirrhotic and control rats (protocol 1); and between octreotide- (65 micrograms/kg, twice daily for 10 days, subcutaneously) and placebo-treated (5% dextrose) cirrhotic rats (protocol 2). In an in vitro experiment, right atrial tissue of cirrhotic rats was incubated with different concentrations of octreotide to evaluate the release of atrial natriuretic peptide (protocol 3).

RESULTS

Cirrhotic rats had significantly lower urine sodium excretion and systemic vascular resistance, and significantly higher plasma atrial natriuretic peptide levels, renin activities and aldosterone concentrations than control rats. Compared with placebo-treated cirrhotic rats, octreotide caused increased urine sodium excretion (-10 +/- 4% vs. 13 +/- 8% from baseline values, p < 0.05) and systemic vascular resistance (2.6 +/- 0.1 vs. 3.3 +/- 0.3 mmHg.min.100 g.ml-1, p < 0.05); and decreased plasma atrial natriuretic peptide levels (166.7 +/- 24.8 vs. 234.0 +/- 19.2 pg/ ml, p < 0.05), renin activities (2.45 +/- 0.49 vs. 4.36 +/- 0.53 ng.ml-1.h-1, p < 0.01) and aldosterone concentrations (290.2 +/- 40.0 vs. 483.3 +/- 82.6 pg/ml, p < 0.05). In the in vitro experiment, right atrial release of atrial natriuretic peptide of cirrhotic rats was not significantly changed when incubated with different concentrations of octreotide.

CONCLUSIONS

Octreotide ameliorates renal sodium retention and suppresses plasma levels of atrial natriuretic peptide of ascitic cirrhotic rats with a novel mechanism via, at least partly, the modification of peripheral vascular resistance.

Effect of octreotide on systemic, central, and splanchnic haemodynamics in cirrhosis

BACKGROUND/AIMS

Cirrhosis with portal hypertension is associated with changes in the splanchnic and systemic haemodynamics, and subsequent complications, such as bleeding from oesophageal varices, have led to the introduction of long-acting somatostatin analogues in the treatment of portal hypertension. However, reports on the splanchnic and systemic effects of octreotide are contradictory and therefore the aim of the present study was to assess the effects of continuous infusion of octreotide on central and systemic haemodynamics, portal pressures, and hepatic blood flow.

METHODS

Thirteen patients with cirrhosis underwent liver vein catheterisation. Portal and arterial blood pressures were determined at baseline and 10, 30, and 50 min after a bolus injection of octreotide 100 micrograms, followed by continuous infusion of octreotide 100 micrograms/ h for 1 h. Hepatic blood flow, cardiac output, central and arterial blood volume, and central circulation time were determined at baseline and 50 min after the start of the octreotide infusion.

RESULTS

The mean arterial blood pressure increased during the first 10 min (p < 0.0005), but returned to baseline after 50 min. The central and arterial blood volume (-16%, p < 0.005) and the central circulation time (-8%, p < 0.05) were significantly decreased after 50 min, whereas the cardiac output did not change significantly. The hepatic venous pressure gradient and the hepatic blood flow did not change significantly at any time after infusion of octreotide.

CONCLUSIONS

Octreotide does not affect the portal pressure or hepatic blood flow, whereas it may further contract the central blood volume and thereby exert a potentially harmful effect on central hypovolaemia in patients with cirrhosis. However, these early effects do not exclude the possibility that administration of longacting somatostatin analogues over a longer period may have a beneficial effect.

Cardiovascular status after postural change in compensated cirrhosis: an argument for vasodilatory concept

It seems that hypervolemia and vasodilatation coincide in compensated cirrhosis, but neither rank nor importance of these factors has been fully clarified in adaptive response to postural change. We studied, with gated equilibrium radionuclide angiography and thoracic electrical bioimpedance the hemodynamic status of 19 patients with compensated cirrhosis and 18 healthy subjects in upright and supine positions. In the upright position, the cirrhotic patients were hypotensive and had decreased peripheral vascular resistance despite increased cardiac output. The transition to the supine position was accompanied by a significant fall in the heart rate and an increase in the stroke volume in both controls (92 +/- 22 to 63 +/- 10 beats/min, and 38 +/- 9 to 62 +/- 19 ml/m2, respectively) and cirrhotic patients (101 +/- 20 to 79 +/- 13 beats/min, and 44 +/- 15 to 63 +/- 19 ml/m2, respectively). Besides, the diastolic arterial pressure fell in controls from 89 +/- 9 mmHg to 81 +/- 11 mmHg; p < 0.01, while it remained unchanged in cirrhotic patients (77 +/- 17 vs 82 +/- 13 mmHg). In the supine position, the cirrhotic patients presented tachycardia and left ventricular hyperkinesy (increased velocity of left ventricular filling and emptying). In conclusion, these results show that in compensated cirrhosis the decreased arterial tone and peripheral blood pooling are important factors of adaptive hemodynamic reaction to postural change.

Alcohol abuse exaggerates autonomic dysfunction in chronic liver disease

BACKGROUND

Advanced chronic liver disease is characterized by peripheral arterial vasodilation and increased plasma catecholamine concentrations. These haemodynamic alterations may reflect impaired vascular responsiveness due to autonomic nerve dysfunction.

METHODS

Three established non-invasive tests based on the heart reactions to deep breathing (expiratory/inspiratory (E/I) ratio) and to tilt (acceleration and brake indices) were used to evaluate age-related autonomic nerve function in 27 patients with chronic alcoholic and non-alcoholic liver disease. Liver function was estimated by demethylating capacity. The results were compared with a control group consisting of 56 healthy individuals.

RESULTS

Overall, 12 patients (52%) had autonomic neuropathy (10 of 13 (77%) patients with alcoholic and 2 of 14 (14%) with non-alcoholic liver disease). Variance analysis showed that the age-corrected E/I ratio, but not the acceleration and brake indices, was significantly decreased compared with controls both in patients with alcoholic and non-alcoholic liver disease, indicating vagal nerve dysfunction (P < 0.0001 and 0.0133, respectively). The decrease in E/I ratio was also significantly more pronounced (-1.77 (0.62) (median (interquartile range)) versus 0.76 (0.70); P = 0.049) in patients with alcoholic compared with non-alcoholic liver disease. Furthermore, in contrast to non-alcoholics, patients with alcoholic liver disease were unable to increase their diastolic blood pressure after return to upright from a tilted position, indicating additional sympathetic neuropathy.

CONCLUSIONS

Autonomic, mainly vagal, nerve dysfunction is common in patients with liver diseases and is further exaggerated by alcohol abuse. Autonomic neuropathy may contribute to altered vascular responsiveness in patients with chronic liver diseases.

Endothelins in chronic liver disease

This review describes recent progress in the accumulation of knowledge about the endothelins (ETs), a family of vasoactive 21-amino acid polypeptides, in chronic liver disease. Particular prominence is given to the dynamics of ET-1 and ET-3 and their possible relation to the disturbed circulation and neurohumoral dysregulation found in cirrhosis. Recent studies have shown that the ET system is highly activated in most cirrhotic patients. Circulating ET-1 and ET-3 levels have a positive relation to the severity of the disease and fluid retention, with the highest values recorded in patients with functional renal failure. Studies on liver biopsies have revealed synthesis of ET-1 in hepatic endothelial and other cells, and recent investigations have identified the hepatosplanchnic system as a major source of ET-1 and ET-3 spillover into the circulation, with a direct relation to portal venous hypertension. In addition, marked associations with disturbance of systemic haemodynamics and with abnormal distribution of blood volume have been reported. Although the pathophysiological importance of the ET system in chronic liver disease is not completely understood, similarities to other vasopressive and antinatriuretic regulatory systems (i.e. the sympathetic nervous system, renin-angiotensin-aldosterone and vasopressin) are apparent, with respect to kinetics and haemodynamic dysregulation. Cirrhosis seems to be a pathophysiological condition with indications of the occurrence of ETs, not only as local modulators, but also as a system with potential importance for systemic regulation.

Platelet basal cytosolic calcium: the influence of plasma factors in cirrhosis

BACKGROUND

Platelet cytosolic calcium is necessary for normal platelet function, and may reflect intracellular signalling in vascular smooth muscle cells.

METHODS

The cytosolic calcium of platelets from patients with cirrhosis and control subjects was measured in contact with plasma from either source, using FURA 2AM.

RESULTS

The basal cytosolic calcium of patients with cirrhosis was found to be significantly lower than that of control subjects (95.7 +/- 10.0 cf. 128.0 +/- 7.8 nmol/l; p = 0.02). When platelets from control subjects were incubated for 45 min with freshly obtained plasma from patients with cirrhosis, the control platelet cytosolic calcium fell to concentrations similar to those of patient platelets (93.0 +/- 7.8 nmol/l; p < 0.005). Such an effect was not observed if patient serum or plasma that had previously been frozen was used. When patient platelets were incubated with fresh control subject plasma, the platelet cytosolic calcium increased (165.4 +/- 19.9 nmol/l; p = 0.01).

CONCLUSION

These results indicate that a plasma-borne factor, sensitive to freezing, is responsible for the abnormalities of platelet calcium signalling noted in cirrhosis.

Effect of oxygen inhalation on systemic, central, and splanchnic haemodynamics in cirrhosis

BACKGROUND/AIMS

Patients with cirrhosis exhibit a hyperdynamic circulation with increased cardiac output and low arterial blood pressure. The aim of the present study was to assess the effects of oxygen inhalation on systemic, central, and splanchnic haemodynamics and vasoactive systems in patients with cirrhosis (n = 19).

RESULTS

Spirometry was normal, but the carbon monoxide diffusing capacity (transfer factor) was significantly decreased, 18.8 ml.min-1.mmHg-1 (-32% of that predicted, p < 0.0001), and correlated significantly with the cardiac output (r = 0.78, p < 0.0005), plasma volume (r = 0.72, p < 0.001) and the central and arterial blood volume (r = 0.67, p < 0.005). After inhalation of 100% oxygen over a period of 20 min, the cardiac output decreased from 7.4 to 6.6 l/min (p < 0.0005), and the systemic vascular resistance increased from 980 to 1124 dyn.s.cm-5 (p < 0.005). The change in systemic vascular resistance was significantly greater in patients with mild liver dysfunction than in those with severe liver dysfunction (p < 0.02). In contrast, no significant changes were seen in the arterial or portal venous pressures during inhalation of oxygen. Arterial concentrations of catecholamines, renin, endothelin-1, and calcitonin gene-related peptide were all increased in patients with cirrhosis, but only the catecholamine concentrations decreased significantly (noradrenaline -13%, p < 0.02 and adrenaline -16%, p < 0.01) in response to oxygen.

CONCLUSION

During oxygen inhalation cardiac output decreases and systemic vascular resistance increases in association with a decrease in arterial concentrations of catecholamine, but oxygen supply in patients with cirrhosis does not normalise the hyperdynamic circulation or the low arterial blood pressure.

Relation of calcitonin gene-related peptide to systemic vasodilatation and central hypovolaemia in cirrhosis

BACKGROUND

The aetiology of the reduced systemic vascular resistance and abnormal 'filling' of the vascular bed in cirrhosis is still obscure. As increased concentrations of the potent vasodilator calcitonin gene-related peptide (CGRP) have recently been reported in cirrhosis, we related CGRP to central and peripheral haemodynamics in patients with cirrhosis.

METHODS

Thirty-one cirrhotic patients and six control subjects underwent an investigation with determination of systemic haemodynamics and circulating CGRP.

RESULTS

Circulating CGRP was significantly increased in patients with cirrhosis (P < 0.02) and covaried directly with the severity of cirrhosis (P < 0.02). The increased CGRP covaried negatively with the reduced systemic vascular resistance (P < 0.02), the reduced central blood volume (P < 0.01), and reduced central circulation time (P < 0.002) and positively with the non-central blood volume (P < 0.05).

CONCLUSIONS

These results suggest that increased CGRP may play a role in the systemic vasodilatation in cirrhosis and may contribute to the abnormal distribution of the blood volume, which may lead to abnormal sodium and water handling.