Biomedical subjects

J D Donlan

Publications and source records attributed to J D Donlan.

7 recordsLinked to original sources

PubMed1996

A comparison of Doppler flowmetry with conventional assessment of acute changes in hepatic blood flow.

The validity and clinical relevance of Doppler flowmetry in measuring changes in regional blood flow are uncertain. In the present study we compared changes induced ketanserin in regional splanchnic blood flow as measured by Doppler flowmetry with changes in conventionally measured systemic and in hepatic haemodynamic indices estimated pharmacokinetically using indocyanine green. Fourteen patients with alcoholic cirrhosis and portal hypertension were evaluated. On multivariate analyses, significant associations were noted for only three indices: changes in estimated hepatic blood flow were predicted jointly by changes in flow in the main and right portal veins and hepatic artery (R2 = 0.80); changes in intrahepatic shunting (indocyanine green extraction) were predicted by changes in flow in the main and right portal veins (R2 = 0.55); and changes in sinusoidal perfusion (indocyanine green clearance) were significantly predicted by changes in main portal vein flow alone (R2 = 0.76). These data support the validity of Doppler flowmetry in quantifying change in regional blood flow, but highlight the limitations in its clinical application and interpretation. The association of changes in main portal vein flow with changes in sinusoidal perfusion has clinical potential but requires confirmation using other modulating drugs.

Coloring Agents↗

PubMed1993

Modified Doppler flowmetry in the splanchnic circulation.

BACKGROUND: Absolute measurements of blood flow by Doppler ultrasonography are subject to substantial error. A simplified method of Doppler flowmetry using conventional duplex Doppler equipment was studied to establish its validity in determining short-term changes in flow in the splanchnic circulation in portal hypertension. METHODS: Two simple indices were measured: peak velocity averaged over two cardiac cycles and vessel diameter. The relationship between peak and mean velocity was studied using a Doppler phantom. The feasibility of studying relevant vessels and the constancy of regional flow was determined by performing Doppler flowmetry in a basal state twice within 2 hours. RESULTS: Constancy of relationship between peak and mean velocities was confirmed (r > 0.98). Examination was successful in the majority of 28 consecutive patients with portal hypertension for superior mesenteric, main portal, right portal, and paraumbilical (when patent) veins, but was successful in only 54% for the hepatic artery. Constancy of basal flow was found in 11 selected patients when group data were considered, but in individuals, substantial and unpredictable variance was found. CONCLUSIONS: Modified Doppler flowmetry appears valid in the assessment of short-term changes in splanchnic blood flow of patients with portal hypertension. Individual variance in baseline flow is identified as a potential problem and is further reason for caution in the interpretation of measurements of Doppler flow.

Hepatic Artery↗

PubMed1992

Duplex Doppler ultrasound signs of portal hypertension: relative diagnostic value of examination of paraumbilical vein, portal vein and spleen.

The sonographic parameters in portal hypertension (PHT) were examined in a consecutive population of 118 patients who had PHT diagnosed using specific endoscopic, sonographic and Doppler signs. A patent or enlarged paraumbilical vein was found in 85.6% of patients overall and 82.5% of patients with varices indicating a relatively high sensitivity. A portal vein diameter greater than or equal to 13mm was found in only 41.1% and greater than or equal to 15mm in only 20% of patients. A thrombosed portal vein and reversed portal vein flow were present in 3.4% and 5.3% of patients respectively. These signs have only been reported in the context of PHT and are felt to be specific for PHT, but both have a very low sensitivity. Portal vein velocities were highly variable suggesting that this is not a useful predictor of PHT. Splenomegaly was found in only 53.5% of patients demonstrating its poor sensitivity as a sign of PHT. Varices were found in 73.3% of patients overall, and in 100% of patients with a patent or enlarged paraumbilical vein combined with ascites. No other statistically significant correlation between varices and sonographic findings was demonstrated. We conclude that the presence of a patent or enlarged paraumbilical vein is a practical, useful and sensitive ultrasound sign to look for in the diagnosis of PHT.

Esophageal and Gastric Varices↗

PubMed1992

A comparison of duplex Doppler sonography of the ligamentum teres and portal vein with endoscopic demonstration of gastroesophageal varices in patients with chronic liver disease or portal hypertension, or both.

The ability of duplex Doppler sonography of the ligamentum teres and portal vein to detect specific signs of portal hypertension was compared with the ability of endoscopy to demonstrate gastroesophageal varices in consecutive patients. Among 90 patients with parenchymal liver disease and a high probability of portal hypertension, 70 had varices, 72 had specific sonographic signs, and four had neither. Ultrasonography was comparable to endoscopy irrespective of the clinical severity of the underlying liver disease. Eleven patients had vascular occlusive diseases; nine had varices; and all had at least one sonographic sign. Duplex Doppler ultrasonography may have a clinical role in noninvasive detection of portal hypertension. Further studies correlating the findings with those of portal pressure are needed to define the place of duplex Doppler ultrasonography as a predictor of the presence of portal hypertension.

Adult↗

PubMed1990

Splenomegaly--an insensitive sign of portal hypertension.

The prevalence of splenomegaly associated with portal hypertension was examined in a consecutive population of 111 patients who had portal hypertension diagnosed using specific endoscopic, sonographic, and Doppler signs. Splenic size was measured objectively via its cranio-caudal length on coronal section using ultrasound and by clinical examination. Sonographically, 52% of patients had a definitely large spleen and 35% a spleen less than one standard deviation from the normal mean, while a further 13% had equivocal splenomegaly. Only 52% of patients had splenomegaly on clinical assessment. Splenomegaly was less common in patients with alcoholic (41% definite, 15% equivocal) than in those with non-alcoholic liver disease (66% definite, 17% equivocal, p = 0.02) and splenic length was significantly smaller in alcoholic patients (12.7 +/- 0.5 cm) compared to patients with either non-alcoholic liver disease (15.0 +/- 0.6 cm, p = 0.003) or portal hypertension due to vascular occlusive diseases (16.5 +/- 2.0 cm, p = 0.006). Splenomegaly, whether assessed sonographically or clinically, is an insensitive sign of portal hypertension and its absence cannot be used as a negative predictor of the presence of portal hypertension in patients with chronic liver disease.

Adult↗

PubMed1989

Identification of a patent paraumbilical vein by using Doppler sonography: importance in the diagnosis of portal hypertension.

The aim of this study was to determine if the addition of pulsed Doppler imaging to conventional sonography allows discrimination between true paraumbilical veins of portal hypertension and the apparent vein sometimes seen in the ligamentum teres in normal subjects. Conventional sonography and Doppler sonography of the ligamentum teres were performed in 33 normal subjects and in 39 patients with portal hypertension due to chronic liver disease. An apparent ligamentum teres vessel (i.e., hypoechoic channel) was identified on sonograms in 32 (97%) normal subjects (diameter 0.6-1.9 mm) and in 35 (90%) patients with portal hypertension (diameter 1.1-22 mm). In the portal hypertension group, the apparent vessel had a diameter of greater than 3 mm in only 20 patients (51%), but in 32 patients (82%) it was shown on Doppler examination to be a patent paraumbilical vein (i.e., hepatofugal venous signal). A patent paraumbilical vein on duplex Doppler sonography is therefore a specific sign of portal hypertension. The addition of Doppler imaging to conventional sonographic examination significantly increases the sensitivity for the diagnosis of portal hypertension by demonstration of a paraumbilical vein.

Adolescent↗

PubMedDate not supplied

Duplex Doppler ultrasound of the ligamentum teres and portal vein: a clinically useful adjunct in the evaluation of patients with known or suspected chronic liver disease or portal hypertension.

The prevalence and potential value of the detection of signs of portal hypertension by duplex Doppler ultrasound (DDU) of the ligamentum teres and portal vein in patients with known or suspected chronic liver disease and/or portal hypertension was studied in 136 consecutive patients undergoing clinical assessment including that of liver histopathology. Portal hypertension was considered to be present when any of the following DDU signs, previously demonstrated to be specific for portal hypertension, were present: an enlarged and/or patent para-umbilical vein, portal vein obstruction or hepatofugal flow in the portal vein. Of 123 patients with parenchymal liver disease, eighty-three had cirrhosis and, of these, portal hypertension was detected on DDU criteria in 86% of alcoholic cirrhotics and 67% of non-alcoholic cirrhotics. Of the 42 patients with non-cirrhotic liver disease, 1 of 7 patients with metastatic liver disease and 3 of 5 patients with alcoholic hepatitis had DDU signs of portal hypertension. Thus, in patients with parenchymal liver disease, DDU had a sensitivity of 73%, specificity of 90% and predictive values of 94 and 62% for positive and negative studies respectively for the detection of cirrhosis. In all 14 patients with portal hypertension secondary to vascular occlusive diseases, DDU examination of the ligamentum teres, portal vein and hepatic vein gave an accurate guide to the site of the occluding lesion. The high positive predictive value of DDU and its ability to aid in localizing the site of increased resistance to flow through the liver suggest that DDU of the ligamentum teres and portal vein is a potentially useful non-invasive adjunct in the assessment of patients with suspected or known liver disease or portal hypertension.

Humans↗