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C Merkel

Publications and source records attributed to C Merkel.

At least 55 records · Page 3Linked to original sources
PubMed1996

Interobserver and inter-equipment variability of echo-Doppler sonographic evaluation of the superior mesenteric artery.

The aim of this study was to assess the interobserver and inter-equipment variabilities of echo-Doppler sonographic measurement of superior mesenteric artery flow parameters. In the first part of the study the echo-Doppler sonographic parameters (maximum systolic velocity, minimum diastolic velocity, mean velocity, restrictive index, and pulsatility index) were measured independently in nine patients by four skilled operators using four different equipment models. In the second part of the study measurements were taken by the four operators in seven different patients, after one day of cooperative training; the purpose of this part was to define a strict and uniform protocol of Doppler sonographic examination. Significantly different values of maximum systolic velocity, minimum diastolic velocity, mean velocity, and pulsatility index were obtained by the different operators, whereas the inter-equipment variability was significant only for maximum systolic velocity, mean velocity, and pulsatility index. The analysis of the components of variance showed that a large part of this variance was nonsystematic. After training and definition of the protocol no significant differences were found among the operators for any of the parameters, and the 95% confidence limits and coefficients of variation showed a decrease as for maximum systolic velocity, mean velocity, and pulsatility index. This study demonstrates that a significant systematic variability exists among mesenteric Doppler measurements obtained by different operators using different commercially available equipment. Cooperative training can reduce the interobserver variability significantly and bring to an acceptable level the reproducibility of Doppler measurements of superior mesenteric artery flow parameters.

Analysis of Variance↗
PubMed1996

[Physiopathologic basis of medical therapy of portal hypertension in cirrhosis].

The in-depth study of the pathophysiology of portal hypertension is the basis for a correct medical treatment. The backward-flow theory of portal hypertension stresses the importance of increased hepatic vascular resistance, while the forward-flow theory of portal hypertension underscores generalized vasodilation, the hyperdynamic circulation and increased portal inflow. The role of expanded plasma volume has been emphasized in recent studies. The aim of drug therapy is to normalize each one of these components. Vasoconstrictor agents, i.e. vasopressin, triglycyl-lysin-vasopressin, non selective beta-blockers, somatostatin and octreotide, try to normalize the increased portal inflow and to decrease porto-collateral blood flow. Venous vasodilators, e.g. nitrates, mainly act by decreasing portal blood outflow resistance. Spironolactone has been proposed to decrease plasma volume. The use of a combination of a vasoconstrictor agent and a vasodilator or spironolactone has been proposed to increase the efficacy of medical treatment.

Humans↗
PubMed1995

Interobserver and interequipment variability of echo-Doppler examination of the portal vein: effect of a cooperative training program.

The aim of this study was to assess the interobserver, interequipment, and time-dependent variabilities of echo-Doppler measurements of portal blood flow velocity (PBV), portal vein diameters (PVDs) and their derived parameters, portal blood flow (PBF), and congestion index (CI) in cirrhotic patients. The influence of a cooperative training program of the operators on the reproductibility of the results was also investigated. The echo-Doppler parameters were independently measured in 15 patients by four skilled operators, using four echo-Doppler machines (Acuson, ATL, Hitachi-Esaote, Toshiba. Eight of the 15 patients were restudied after 15 days by the same operators using only one machine. Significantly different values of PBV, PBF, and CI were obtained. PBV variance was equipment-related (32%) and operator-related in a smaller portion (5%). No systematic effect related to the time of investigation was found. After training to define a precise protocol, new measurements were performed by four operators on 8 different patients. No significant differences were found among the operators for any of the parameters and the 95% confidence limits (CL) and coefficients of variation (CV) of PBV showed a marked decrease (CL from +/- 26.4% to +/- 15.6%). These results indicate that (1) a significant systematic variability exists between Doppler measurements with different equipment; (2) there is no significant time-dependent systematic variability of Doppler measurements; and (3) a cooperative training program reduces the interobserver variability for direct measurements, such as PBV.

Analysis of Variance↗
PubMed1995

Long-term effect of nadolol or nadolol plus isosorbide-5-mononitrate on renal function and ascites formation in patients with cirrhosis. GTIP Gruppo Triveneto per l'Ipertensione Portale.

The association beta-blockers plus nitrates has been reported to impair renal function and renal sodium handling, leading to increased risk of development of ascites, or worsening of a preexisting ascites, or increase in the requirements of diuretic agents. In 81 patients with cirrhosis and esophageal varices, participating in a multicenter controlled clinical trial of prophylaxis of variceal bleeding comparing nadolol (NAD) plus isosorbide-5-mononitrate (I5M) with NAD alone, renal function, presence of ascites, and diuretic requirements were assessed at inclusion and after 6 months of follow-up. No significant variation in s-urea or s-creatinine was observed in either group, Three patients in the nadolol group and two in the NAD plus I5M developed ascites at 6 months (P = .70), and a need to increase diuretic regimen was observed in four and three patients, respectively (P = .76). Decrease in heart rate and in mean arterial pressure was similar in the two groups. There was a significant correlation between increases in s-creatinine and decrease in mean arterial pressure in the whole series (P = .015). Only in patients treated with the association was there a significant larger proportion of patients ascitic who became anascitic, than of patients anascitic who became ascitic (P = .03). In patients treated with the association, there was a significantly larger decrease in hepatic venous pressure gradient (P = .05). It is concluded that patients treated with the association NAD plus I5M are not at increased risk of developing renal dysfunction or worsening of ascites compared with patients treated with NAD alone.(ABSTRACT TRUNCATED AT 250 WORDS)

Adolescent↗
PubMed1995

Relationship between portal blood flow measured by image-directed Doppler ultrasonography and hepatic blood flow measured by indocyanine green constant infusion in patients with cirrhosis.

The validity of portal blood flow measurement in image-directed Doppler ultrasound (PBF-IDU) is still under debate. In this study PBF-IDU has been compared with hepatic blood flow measured by the indocyanine green constant infusion technique (HBF-ICG), which is the reference invasive method with which to measure total hepatic blood flow in man (ie, the sum of hepatic artery and portal vein blood flow). In 27 cirrhotic patients with hepatopetal portal blood flow, PBF-IDU was measured by multiplying the portal vein cross-sectional area by the averaged mean velocity of blood in the vessel. About 1 hour later HBF-ICG was measured during hepatic vein catheterization performed to evaluate portal hypertension. In 19 of 27 patients, intrahepatic arterial resistance indices were also measured. PBF-IDU and HBF-ICG were 1.010 +/- 0.555 L/min (M +/- SD) and 1.496 +/- 0.731 L/min, respectively. Blood flow measured by the two methods showed a close correlation (r = 0.80, p < 0.001). The regression line showed that HBF-ICG was systematically higher than PBF-IDU (mean difference +29 +/- 30%). The hepatic artery component of HBF-ICG probably accounted for the difference. An inverse correlation was found between the differences between the two procedures and intrahepatic arterial resistance indices (r = -0.52, p = 0.04), which may be considered indirect parameters of arterial supply. It can be concluded that image-directed Doppler ultrasound is a sufficiently accurate method to measure portal blood flow in cirrhotics.

Adult↗
PubMed1995

Visual attention orienting in liver cirrhosis without overt hepatic encephalopathy.

The attention system in patients with liver cirrhosis has not yet been fully investigated. We therefore studied visual attention orienting in cirrhotic patients without overt hepatic encephalopathy. Seventy cirrhotic patients without overt hepatic encephalopathy (aged 57 +/- 10 yr., mean +/- s.d.) and 55 controls (aged 49 +/- 12 yr.) were enrolled. Visual attention orienting was evaluated by a computerized neuropsychological test. The Reitan A test, commonly used to detect subclinical hepatic encephalopathy, was used to evaluate mental performance. Psychometric test scores were reduced in cirrhotics compared to controls (attention test: neutral condition = 495 +/- 149 vs. 401 +/- 98 msec; valid condition = 434 +/- 110 vs. 398 +/- 84 msec; invalid condition = 485 +/- 146 vs. 392 +/- 110 msec; p < 0.001; Reitan A test = 52 +/- 20 vs. 35 +/- 11 sec., p < 0.001). The attention effect of the cue was found both in controls and cirrhotics; however, it was significantly higher in cirrhotics than in controls (61 +/- 111 vs. 33 +/- 41 msec; p < 0.002). The attention effect was directly correlated with Reitan A test (r = 0.23, p = 0.05) in cirrhotics. In conclusion, in cirrhotic patients without overt hepatic encephalopathy, visual attention orienting was present and focusing to an indexed location had a higher effect on reaction time compared to controls, possibly because of reduced basal arousal.

Aging↗
PubMed1995

Hepatic arterial resistance in cirrhosis with and without portal vein thrombosis: relationships with portal hemodynamics.

BACKGROUND/AIMS: Little information is available on hepatic arterial hemodynamics in cirrhosis because of the invasiveness of methods. Hepatic arterial resistance indexes were evaluated noninvasively by Doppler ultrasonography and were correlated with portal hemodynamics evaluated both noninvasively and invasively. METHODS: Hepatic arterial resistance indexes, portal blood flow velocity and volume, and portal vein congestion index were evaluated in 31 controls and 171 cirrhotic patients with (n = 13) or without (n = 158) portal vein thrombosis. Resistance to portal blood flow was also calculated in 15 patients from hepatic venous pressure gradient, measured by hepatic vein catheterization, and portal blood flow. RESULTS: Resistance indexes were significantly higher in cirrhotics without portal thrombosis than in controls (pulsatility index, 1.30 +/- 0.29 vs. 0.89 +/- 0.09; P < 0.001; resistive index, 0.71 +/- 0.07 vs. 0.59 +/- 0.04; P < 0.001). In patients with portal thrombosis, the pulsatility index (1.86 +/- 0.39) and resistive index (0.81 +/- 0.06) were significantly higher than in controls (P < 0.001) and in patients without thrombosis (P < 0.001). Resistance indexes directly correlated with portal resistance (P < 0.01), the congestion index (P < 0.01), and the degree of esophageal varices (P < 0.01). CONCLUSIONS: Hepatic arterial resistance indexes increase in cirrhosis, particularly with portal vein thrombosis. The pathophysiology of the increase in hepatic arterial resistance seems to be parallel to that of portal resistance.

Adult↗
PubMed1995

Effect of 8-day therapy with propionyl-L-carnitine on muscular and subcutaneous blood flow of the lower limbs in patients with peripheral arterial disease.

The efficacy of propionyl-L-carnitine in increasing walking capacity in patients with peripheral arterial disease is primarily due to the metabolic effect of the drug, but a direct vasoactive action is also hypothesized. Muscular and subcutaneous blood flow of lower limbs were separately evaluated using the 133-Xenon washout technique in 10 patients with peripheral arterial disease of moderate degree, before and after 8-days of treatment with propionyl-L-carnitine (1 g orally b.i.d.). After treatment, muscular blood flow slightly increased, from 10.7 +/- 13.4 to 14.1 +/- 14.0 ml kg-1 min-1. This increase was not statistically significant (T = -1.6568, P = 0.136). Subcutaneous blood flow was not affected by the treatment (from 26.2 +/- 16.9 to 26.1 +/- 12.5 ml kg-1 min-1, T = 0.0141, P = 0.95). In conclusion, in patients with peripheral arterial disease, short-term therapy with propionyl-L-carnitine had no clinical significant effect on muscular and subcutaneous blood flow of the lower limbs. Therefore, this study suggests that the beneficial effect of this drug on the walking capacity of patients with peripheral arterial disease is not due to a direct vasoactive action. Oral administration of propionyl-L-carnitine was found to be safe, as it did not cause any change in heptic, renal or metabolic functional parameters.

Administration, Oral↗
PubMed1995

Duplex Doppler ultrasonography allows a multiorgan noninvasive approach to splanchnic pharmacodynamics in patients with cirrhosis.

UNLABELLED: Duplex Doppler ultrasonography (DDU) is a suitable method to evaluate acute splanchnic hemodynamic effects of vasoactive drugs. It allows the contemporary evaluation of arterial and venous splanchnic parameters. Forty-six cirrhotic patients with esophageal varices were investigated by DDU. Portal blood flow mean velocity (PBV) (cm/s), portal blood flow volume (PBF) (ml/min), pulsatility index (PI) [(maximum-minimum)/mean velocity] in the superior mesenteric artery, in intrahepatic arteries (main branches), in an instrasplenic artery, and in interlobar arteries of the kidneys were measured before and 120-180 min after the administration of nadolol (80 mg p.o.) in 24 patients, and before and 120 min after placebo administration in 9 patients. In 13 patients who were chronically treated with nadolol, DDU parameters were evaluated before and 90 min after the administration of isosorbide-5-mononitrate (20 mg p.o.). RESULTS: placebo caused no hemodynamic change. After nadolol, heart rate decreased (-22 +/- 8%), and so did PBV and PBF (8.8 +/- 3.4 vs. 10.9 +/- 3.2, -20 +/- 17%, p < 0.0001; 660 +/- 347 vs. 852 +/- 371, -24 +/- 18%, p < 0.0001). Mesenteric PI increased (2.72 +/- 0.67 vs. 2.28 +/- 0.56, +21 +/- 25%, p = 0.005). Hepatic, splenic, and renal PIs showed slight, not significant changes (1.42 +/- 0.41 vs. 1.38 +/- 0.32, p = NS; 1.05 +/- 0.23 vs. 0.99 +/- 0.21, p = NS; 1.24 +/- 0.26 vs. 1.19 +/- 0.20, p = NS, respectively). After the administration of isosorbide-5-mononitrate, PBV decreased (8.2 +/- 2.0 vs. 9.4 +/- 2.3, -12 +/- 13%, p = 0.006), while PBF did not modify (648 +/- 189 vs. 711 +/- 209, p = NS).(ABSTRACT TRUNCATED AT 250 WORDS)

Administration, Oral↗
PubMed1994

Limitations of serum creatinine level and creatinine clearance as filtration markers in cirrhosis.

BACKGROUND: Several studies carried out in a limited number of patients demonstrated a wide range of overestimation of glomerular filtration rate (GFR) by serum creatinine level and creatinine clearance (Ccr) in liver disease. METHODS: We simultaneously evaluated Ccr, inulin clearance, and predicted GFR calculated from serum creatinine level in 56 cirrhotic patients. Inulin clearance was considered the gold standard for GFR evaluation. RESULTS: The sensitivity of serum creatinine level, predicted GFR, and Ccr in detecting renal failure was 18.5%, 51%, and 74%, respectively. On the basis of inulin clearance, patients were divided into two groups: those with normal GFR (mean, 106 +/- 34 mL/min per 1.73 m2) (group 1, 29 patients) and those with reduced GFR (mean, 56 +/- 19 mL/min per 1.73 m2) (group 2, 27 patients). Predicted GFR and Ccr were accurate markers of GFR in group 1 patients, while both overestimated GFR by about 50% in group 2 patients. An increased tubular secretion of creatinine accounted for the disparity between Ccr and inulin clearance in these patients. CONCLUSIONS: Our results indicate that renal failure is greatly underestimated on the basis of serum creatinine level and Ccr in cirrhotic patients. Clinical implications of this observation include excessive dosage of potentially nephrotoxic drugs and failure to recognize renal impairment induced by such medical treatments as diuretic therapy or paracentesis.

Adult↗
PubMed1994

Clinical significance of the evaluation of hepatic reticuloendothelial removal capacity in patients with cirrhosis.

The reticuloendothelial system plays an important role in the prevention of bacterial infection in patients with cirrhosis. Few data are available, however, on its activity in such patients. The aim of this study was to evaluate the maximum removal capacity of hepatic reticuloendothelial system in patients with cirrhosis on the basis of study of the removal kinetics of increasing amounts of 99mTc millimicrospheres and to verify its value as a prognostic factor for death and development of spontaneous bacterial peritonitis. Common clinical and biochemical parameters, Pugh score, maximum removal capacity, aminopyrine metabolic capacity and galactose elimination capacity were measured in 43 patients with cirrhosis (33 with alcoholic cirrhosis, 8 with posthepatitic cirrhosis and 2 with cryptogenic cirrhosis). Hepatic plasma flow and indocyanine green plasma clearance were also measured in 16 of these patients. Reference range of maximum removal capacity was determined in seven normal subjects. Maximal removal capacity below the normal range was found in 24 patients (56%). In the whole series maximum removal capacity averaged 16 +/- 12 micrograms/kg body wt/min (mean +/- S.D.). Maximal removal capacity was significantly correlated with serum albumin, prothrombin index, Pugh score, aminopyrine breath test, galactose elimination capacity and indocyanine green plasma clearance but not with hepatic plasma flow. During follow-up of up to 48 mo, spontaneous bacterial peritonitis developed in six patients, all with impaired maximum uptake capacity, and 11 patients died. Survival was significantly shorter in patients with impaired maximum removal capacity than in those with normal maximum removal capacity (log-rank test: p = 0.024).(ABSTRACT TRUNCATED AT 250 WORDS)

Adult↗
PubMed1994

Duplex Doppler sonographic evaluation of splanchnic and renal effects of single agent and combined therapy with nadolol and isosorbide-5-mononitrate in cirrhotic patients.

Thirty-eight cirrhotic patients with esophageal varices were investigated by duplex Doppler sonography. In every patient, the portal blood flow mean velocity (cm/sec) and portal blood flow volume (ml/min) were measured. In addition, the pulsatility index [(maximum-minimum)/mean velocity] was measured in the superior mesenteric artery, in the hepatic arteries, in an intrasplenic artery, and in intrarenal arteries. These parameters were measured again 120 to 180 minutes after administration of nadolol (80 mg orally) in 22 patients, 90 minutes after administration of isosorbide-5-mononitrate (20 mg orally) in nine patients, and subsequently after administration of isosorbide 5-mononitrate to 10 of the 22 patients treated earlier with nadolol. Duplex Doppler sonographic parameters also were evaluated in seven patients 120 minutes after administration of a placebo. In five of the 22 patients treated acutely with nadolol, the same parameters were measured again after 60 minutes without any additional drug administration. No hemodynamic changes occurred in response to the placebo. Portal blood flow mean velocity and portal blood flow volume decreased after nadolol and isosorbide-5-mononitrate; mesenteric pulsatility index increased after both nadolol and isosorbide-5-mononitrate. After combined therapy, we observed a further reduction in portal blood flow mean velocity and portal blood flow volume and a significant increase in hepatic, splenic, and mesenteric pulsatility indices. The addition of isosorbide-5-mononitrate to nadolol caused a decrease in portal blood flow mean velocity of more than 17% in all patients. Nadolol caused a slight increase in renal pulsatility index, which was amplified by the addition of isosorbide-5-mononitrate, suggesting a decrease in renal blood flow.

Adult↗
PubMed1994

Development and validation of a prognostic index predicting death after upper gastrointestinal bleeding in patients with liver cirrhosis: a multicenter study.

Prognostic factors of the outcome of upper gastrointestinal bleeding in patients with cirrhosis are insufficiently defined. Pertinent clinical, biochemical, and endoscopic data of 332 upper gastrointestinal bleedings in 268 patients with cirrhosis observed in the participating centers during 31 months were recorded. Clinical data were analyzed until 40 days after bleeding. A further set of 82 bleedings was used as a validation group. Ninety-two of the 268 patients died within the time of the study, and 28 of the 82 patients of the validation group died. According to a stepwise logistic regression analysis, s-creatinine, ascites on admission, previous diagnosis of hepatocellular carcinoma, s-bilirubin, prothrombin index, varices as definite or probable source of bleeding, gender, and presentation with hemathemesis were the best set of covariates for predicting outcome. From them a prognostic index was developed and validated in the 82 further bleedings. Sensitivity and specificity in the cumulated training and test sets were 75 and 80%, respectively. In the present material, the prognostic index was significantly more efficient than Child-Pugh score or the prognostic index proposed by Garden et al. These data show that it is possible to predict the outcome of upper gastrointestinal bleeding in cirrhosis on the basis of few easily available data. The prognostic index we proposed and validated may become useful to predict the outcome of a bleeding and to select or stratify patients in clinical trials.

Esophageal and Gastric Varices↗
PubMed1994

Randomized clinical study of the efficacy of amiloride and potassium canrenoate in nonazotemic cirrhotic patients with ascites.

Although some clinical studies seem to prove the efficacy of nonantialdosteronic potassium-sparing diuretics in the treatment of ascites, no controlled study has compared the efficacy of these drugs with that of antialdosteronic diuretics. Forty nonazotemic cirrhotic patients were randomized to receive amiloride (group A, n = 20) or potassium canrenoate (group B, n = 20). The initial doses of amiloride and potassium canrenoate were 20 mg and 150 mg, respectively. The doses were increased in stepwise fashion to 60 and 500 mg/day, respectively, if no response ensued. Nonresponders to the highest doses of each drug were later treated with potassium canrenoate and amiloride, respectively. Seven of 20 group A patients responded to amiloride, whereas 14 of 20 group B patients responded to potassium canrenoate (p < 0.025). Seven of 13 nonresponders to amiloride later responded to potassium canrenoate, whereas only two of the nonresponders to potassium canrenoate later responded to amiloride. The diuretic responses to amiloride and potassium canrenoate were related to the activity of the renin-aldosterone system. All responders to amiloride (n = 9) had normal values of plasma aldosterone. All nonresponders to amiloride who later responded to potassium canrenoate (n = 7) had increased levels of plasma aldosterone. Moreover, on comparison of all responders (n = 21) and nonresponders (n = 12) to potassium canrenoate, a higher degree of renal proximal sodium reabsorption (with consequent limitation of sodium delivery to the distal tubule) was found to be the main difference.(ABSTRACT TRUNCATED AT 250 WORDS)

Adult↗
PubMed1993

Prognostic significance of portal hemodynamics in patients with compensated cirrhosis.

The prognostic value of portal hemodynamics, measured by pulsed echo-Doppler, was prospectively evaluated, together with clinical, biochemical and endoscopic parameters, in a series of 50 consecutive patients with compensated cirrhosis. After a mean follow-up of 6 years, 25 patients had died, all from complications of liver disease. Among conventional variables, the step-wise Cox model showed that only the Child-Pugh score independently predicted death (chi 2 = 18.66; p < 0.001). When hemodynamic parameters were added to the Child-Pugh score in the same model, portal blood velocity was shown to add prognostic significance (improvement in chi 2 = 14.06; p = 0.0002; Wald test). The present study shows that a portal blood velocity below the lower limit of controls (10 cm/s) characterizes patients with shorter survival, and suggests that this non-invasive parameter should be associated to the Child-Pugh score in the evaluation of patients with cirrhosis.

Adult↗
PubMed1993

Renal vasoconstriction in cirrhosis evaluated by duplex Doppler ultrasonography.

Studies of renal perfusion when kidney function tests are still normal could be useful to understand the pathophysiology of functional kidney impairment in cirrhosis; currently, this requires invasive methodology. Duplex Doppler ultrasonography allows noninvasive evaluation of intrarenal arterial resistances. In 19 nonascitic and 35 ascitic cirrhotic patients with normal kidney function (normal serum creatinine and urea levels) and in 17 controls, we measured the intrarenal arterial pulsatility index (Pulsatility index = [Peak systolic velocity-Minimum diastolic velocity]/Mean velocity) and the resistive index (Resistive index = [Peak systolic velocity-Minimum diastolic velocity]/Peak systolic velocity) by duplex Doppler ultrasonography after visualization of interlobar, interlobular or arcuate arteries by color Doppler ultrasonography. The pulsatility index and resistive index (calculated as the mean of three to five consecutive determinations) were significantly higher in cirrhotic patients than in control patients (pulsatility index: 1.16 +/- 0.24 vs. 0.78 +/- 0.05 [mean +/- S.D.], p < 0.001; resistive index: 0.67 +/- 0.06 vs. 0.53 +/- 0.03, p < 0.001). The pulsatility index and resistive index were significantly higher in nonascitic cirrhotic patients than in control patients, in ascitic patients than in nonascitic patients, in ascitic patients not treated with diuretics than in nonascitic ones and in ascitic patients treated with diuretics than in those not treated. The pulsatility index and resistive index measured before and after treatment with diuretics (7 to 15 days) in seven patients were significantly increased by treatment. The pulsatility index and resistive index were significantly higher in Child-Turcotte-Pugh class B and C patients than in class A patients.(ABSTRACT TRUNCATED AT 250 WORDS)

Adult↗