Flow Volume Index Research Articles

Comparison of the effects of polyethylenimine and maleated polypropylene coupling agents on the properties of cellulose‐reinforced polypropylene composites

AbstractThe desire to improve the properties of cellulose‐reinforced composites while producing them by methods as similar as possible to those used on an industrial scale is one of the driving forces in this field of research. In this work, extensive research for determining the mechanical, thermal, rheological, and physical properties of novel cellulose‐reinforced polypropylene composites containing a polyethylenimine (PEI) coupling agent was conducted. A comparison of their properties with those of reference composites without any coupling agent or containing a maleated polypropylene (MAPP) coupling agent was also carried out. The presence of the PEI coupling agent mainly gave rise to a substantial increase in the tensile and flexural strengths and elongations as well as the impact strength, heat deflection temperature (HDT), melt volume flow index, and water absorption of PEI‐containing composites in comparison with composites without any coupling agent added. However, the increases achieved in the tensile and flexural composite strengths and HDT were lower than those achieved with the MAPP coupling agent mainly for composites containing 50 wt % cellulose fibers. On the other hand, PEI‐containing composites exhibited, in most cases, larger elongations and energies required to break in tensile tests as well as larger impact strengths, melt volume flow indices, and water absorption percentages than MAPP‐containing composites. © 2008 Wiley Periodicals, Inc. J Appl Polym Sci, 2008

Relationships between ovarian blood flow and ovarian response to eCG-treatment of dairy cows

The goal of the present study was to investigate ovarian blood flow and ovarian response in cows undergoing a gonadotropin treatment to induce a superovulatory response, using transrectal colour Doppler sonography. Forty-two cows including 19 cross-bred, 14 German Holstein and 9 German Black Pied cows were examined sonographically before hormonal stimulation on Day 10 of the oestrous cycle, three days after administration of eCG (Day 13) and seven days after artificial insemination (Day 7 p.i.). After each Doppler examination, blood was collected for determination of total oestrogens (E) and progesterone (P 4) in peripheral plasma. The blood flow volume (BFV) and pulsatility index (PI), which is a measure for blood flow resistance, were determined in the ovarian artery, and B-mode sonography was used to count dominant follicles and corpora lutea. Important criteria to assess the ovarian response following the hormonal treatment were the number of follicles >5 mm in diameter on Day 13 and the number of corpora lutea on Day 7 p.i. per cow. The number of follicles ranged from 2 to 61 (mean ± S.E.M.: 17.5 ± 1.7) and corpora lutea from 0 to 50 (mean ± S.E.M.: 17.0 ± 1.6). The BFV increased from 28.4 to 45.0 ml/min between Days 10 and 13 and reached a maximum of 108.5 ml/min on Day 7 p.i. The PI decreased from 6.25 on Day 10 to 4.70 on Day 13 and to 2.10 on Day 7 p.i. The BFV and PI on Day 13 did not correlate with the number of follicles ( P > 0.05). However, on Day 7 p.i. the number of corpora lutea correlated positively with the BFV ( r = 0.64; P < 0.0001), and an inverse relationship was found for the PI ( r = −0.51; P = 0.0005). There were no correlations ( P > 0.05) between the BFV and PI on Day 10 and the number of follicles on Day 13 or the number of corpora lutea on Day 7 p.i. Results of the present study show that in cows, a hormonal treatment to induce a superovulatory response yielded a marked increase in BFV and a marked decrease in PI in the ovarian artery. However, there was no correlation between BFV and PI in the ovarian arteries before hormonal stimulation and the number of follicles and corpora lutea that developed after stimulation. Thus BFV and PI measured in the ovarian arteries have limited diagnostic value to predict the outcome of a gonadotropin treatment.

Correlation of Portal Venous Velocity and Portal Venous Flow With Short-Term Graft Regeneration in Recipients of Living Donor Liver Transplants

Background To evaluate the correlation of postoperative portal venous velocity (PVV) and portal venous flow (PVF) with the degree of short-term graft regeneration in recipients of living donor liver transplantation (LDLT). Materials and methods Between August 2005 and April 2006, we performed 44 adult-to-adult LDLTs with right-lobe grafts, of whom 31 recipients were included in this study. Doppler ultrasonography was used to measure PVV (cm/s) and PVF (mL/min) on postoperative days (POD) 1, 3, and 5 or 6. Portal venous velocity index (PVI) was defined as the ratio of PVV to graft weight (GW), and portal flow volume index (PFI) as the ratio of PVF to GW. Graft regeneration rate (GRR), defined as the ratio of the volume of regenerated graft to GW, was estimated by dividing computed tomography volumetry at POD 7 by GW measured after retrieval of the graft. We analyzed the relationship between GRR and PVV, PVF, PVI, and PFI. Results GW ranged between 528 g and 1040 g (mean = 735 g) and GRR ranged between 118% and 278% (mean = 172%). Although neither PVV nor PVF correlated with GRR, PVI and PFI at POD 1 ( P = .009) and PFI at POD 5 or 6 ( P = .012) significantly correlated with GRR at POD 7. Conclusion PVI and PFI at POD 1 are useful indicators to predict short-term graft regeneration in recipients of LDLT.

Impaired peripheral circulation in lower-leg arteries caused by higher arterial stiffness and greater vascular resistance associates with nephropathy in type 2 diabetic patients with normal ankle–brachial indices

Diabetic nephropathy is a major cause of lower-limb amputation. We enrolled 250 type 2 diabetic patients without apparent occlusive peripheral arterial disease (ankle–brachial indices >0.9) and 40 age-matched nondiabetic subjects consecutively admitted to our hospital. Flow volume and resistive index (RI), an index of vascular resistance, at the popliteal artery were evaluated using gated two-dimensional cine-mode phase-contrast magnetic resonance imaging. Brachial–ankle pulse wave velocity (baPWV) was measured as an index of arterial distensibility. Flow volume was negatively correlated with both baPWV ( p = 0.0009) and RI ( p < 0.0001) among the patients. When the patients were grouped into four subgroups with or without albuminuria and renal insufficiency according to the levels of urinary albumin excretion rate (≥20 or <20 μg/min) and estimated glomerular filtration rate (eGFR) (<60 or ≥60 ml/min/1.73 m 2), albuminuric patients with renal insufficiency ( n = 30) showed the lowest flow volume ( p = 0.0078) and the highest baPWV ( p = 0.0006) and RI ( p = 0.0274) among the groups. Simple linear regression analyses demonstrated that eGFR correlated positively with flow volume ( p = 0.0020) and negatively with baPWV ( p = 0.0258) and RI ( p = 0.0029) in patients with albuminuria ( n = 92), but not with normoalbuminuria ( n = 158). Impaired peripheral circulation in lower-leg arteries associates with nephropathy in diabetic patients even though they have normal ankle–brachial indices.

Testicular Blood Flow and Plasma Concentrations of Testosterone and Total Estrogen in the Stallion after the Administration of Human Chorionic Gonadotropin

The goal of this study was to investigate for the first time a possible association between plasma concentrations of testosterone and total estrogen and testicular blood flow in the stallion. Correlations between these variables were calculated before and after administration of human chorionic gonadotropin (hCG). Eight mature warmblood stallions received 5,000 IU hCG intravenously, and four stallions received solvent only. Testicular blood flow in the left and right testicular arteries was assessed using colour Doppler sonography by measuring blood flow volume (BFV) and pulsatility index (PI) immediately before (time 0) and 1, 3, 6, 12, 24, 72, 120 and 168 h after hCG administration. EDTA blood samples were collected after each examination from a jugular vein to measure plasma testosterone and total estrogen concentrations. After treatment, the BFV increased and was elevated at 1 h and between 12 and 24 h. The profile of the PI was contrary to that of the BFV throughout the study period. Following hCG, there was a biphasic increase in testosterone concentration with maxima between 1 and 3 h and between 24 and 72 h, and there was a monophasic increase in the total estrogen concentration with a maximum between 6 and 24 h. At time 0, the total estrogen concentration correlated significantly with BFV (r=0.90; P<0.05) but the testosterone concentration did not (P>0.05). The testosterone and total estrogen concentrations did not correlate with PI (P>0.05). The total estrogen concentration, but not testosterone, correlated well with BFV after injection of hCG (P<0.05). The results of this study indicated that the testicular blood flow volume of the stallion may be regulated by estrogens, but additional studies are necessary to investigate whether there is a causal relationship.

Insulin resistance functionally limits endothelium-dependent coronary vasodilation in nondiabetic patients

Insulin resistance (IR) is now considered to be a risk factor for coronary arterial atherosclerosis and is likely to be involved in a limited endothelium-dependent vasodilatory function in peripheral circulation. We investigated whether IR impairs endothelial vasodilator function in the noninfarcted coronary artery. In 14 nondiabetic patients (10 males, 66 +/- 6 years) who were selected from 214 patients underwent IR evaluation by glucose clamp, a Doppler flow wire was used to measure coronary flow changes (percent volume flow index, %VFI) during intracoronary administration of papaverin (10 mg) and stepwise administration of acetylcholine (Ach; 1, 3, 10 microg/ml per minute) into the non-infarcted left circumflex coronary artery. Insulin resistance was comparatively evaluated by an euglycemic hyperinsulinemic glucose clamp (M value, mg/m(2) per minute) or by a 75g-oral glucose tolerance test (120-min immunoreactive insulin; 120' IRI, pmol/l). Eight patients (57%) were defined as having IR on the basis of results obtained by both the glucose clamp method (M values <167 mg/m(2) per minute) and 120' IRI (>384 pmol/l). There was no difference between papaverin-induced %VFI increases in IR and non-IR subjects (328% +/- 43% vs. 361% +/- 87%). However, IR subjects showed significantly lower Ach-induced %VFI increases in a dose-dependent manner (P < 0.05), especially when low (1 microg/ml per minute) and moderate (3 microg/ml per minute) doses of Ach were used (165% +/- 18% or 248% +/- 29% in non-IR subjects vs. 130% +/- 20% or 183% +/- 41% in IR subjects, P < 0.001, respectively). Moreover, %VFI increase at a low dose of Ach infusion significantly correlated with M values or 120' IRI ([%VFI Ach 1 microg] = 85.9 + 0.35 [M values], r = 0.58, P = 0.038; [%VFI Ach 1 microg] = 176.8 - 0.47.[120' IRI], r = -0.57, P = 0.035). Insulin resistance limits endothelium-dependent coronary vasodilation in association with the severity of IR in non-diabetic patients.

Quantifying the Physiology of Laryngotracheal Stenosis: Changes in Pulmonary Dynamics in Response to Graded Extrathoracic Resistive Loading

A model of airway obstruction was developed to study the impact of changes in airway resistance on ventilatory mechanics. This was used to derive quantitative indices of airway obstruction to aid in the objective diagnosis and physiological monitoring of adult patients with laryngotracheal stenosis (LTS). Six airway resistors, the characteristics of which mirrored the selective impediment to inspiratory airflow that occurs in patients with LTS, were created and calibrated. Maximum-effort flow-volume loops were obtained from 15 volunteers with resistors placed in series with the spirometer. Diagnostic and monitoring performances of various flow-volume indices were assessed with receiver-operating characteristics (ROC) and analysis of variance (ANOVA), respectively. Promising indices were further evaluated in patients with LTS. Experimentally, the ratio of expiratory and inspiratory flows at midvital capacity (MEF50/MIF50) and peak expiratory to inspiratory flow ratio (PEF/PIF) had diagnostic sensitivities of 87% and 89%, respectively. The best index, both experimentally and clinically, was the ratio of area under the expiratory and inspiratory curves (ratio of integrals), with experimental and clinical sensitivities of 97% and 100%, respectively. A clinical specificity of 95%, and area under the curve of 0.965 were achieved for this index. Both PEF/PIF and the ratio of integrals could identify step changes in airway resistance greater than 10 cmH2O . sec . L (P < .05; ANOVA). Flow-volume testing is simple and noninvasive and can be used to quantify the diagnosis and physiological monitoring of patients with LTS. The ratio of areas under the expiratory and inspiratory curves appears to be the optimal index for this purpose.

Simultaneous evaluation of myocardial blood flow, cardiac function and lung water content using [15O]H2O and positron emission tomography

This study sought to evaluate an imaging approach using [15O]H2O and positron emission tomography (PET) for simultaneous assessment of myocardial perfusion, cardiac function and lung water content as a potential indicator of pulmonary oedema. Twenty-six subjects divided into two groups (group I, 13 patients with idiopathic dilated cardiomyopathy; group II, 13 healthy volunteers) underwent dynamic PET scanning after intravenous infusion of approximately 995 MBq [15O]H2O. In both groups, echocardiograms were performed after the PET studies. From the dynamic [15O]H2O data, lung water content (LWC) at equilibrium, myocardial blood flow (MBF), cardiac output (CO), stroke volume (SV) and stroke volume indexes (SVI) using the indicator dilution principle were determined. LWC was 18% (p = 0.038) higher in patients than in controls. Global MBF did not differ significantly between the groups, but regional MBF values were significantly lower (p < 0.05) in the anterior and septal walls in the patient group. The results of the Passing-Bablok regression indicated the absence of a systematic difference between the two techniques. Bland-Altman analysis performed for each group (patients vs healthy controls) showed a non-significant bias (p > 0.1) of -0.02 +/- 0.82 vs -0.05 +/- 0.54 l/min (CO), -1.44 +/- 14.31 vs 1.70 +/- 10.56 ml/beat (SV) and 0.47 +/- 6.21 vs 0.30 +/- 5.02 ml/beat/m2 (SVI). The 95% limits of agreement were -1.62 to 1.59 vs -1.11 to 1.01 l/min (CO), -26.61 to 29.49 vs -22.39 to 18.99 ml/beat (SV) and -11.69 to 12.88 vs -9.53 to 10.14 ml/beat/m2 (SVI). Right ventricular CO was increased by 33% (p = 0.014) in the patient group as compared with normal controls. Our results demonstrate that additional analysis of cardiac function and lung water content are feasible from the dynamic cardiac [15O]H2O PET studies acquired for myocardial perfusion. The parameters appear to work as expected. Further studies are warranted to elucidate the clinical value of these new parameters.

OP09.03: The 3D volume flow index is not an expression of volume blood flow

OP09.03: The 3D volume flow index is not an expression of volume blood flow

Low Blood Flow Estimates in Lower-Leg Arteries Predict Cardiovascular Events in Japanese Patients With Type 2 Diabetes With Normal Ankle-Brachial Indexes

To examine the association of baseline measures in lower-leg arteries and conventional cardiovascular risk factors with the incidence of cardiovascular disease (CVD) events in type 2 diabetic patients with normal ankle-brachial indexes (ABIs) (>0.9). We studied 129 type 2 diabetic patients and 35 age-matched nondiabetic subjects with no apparent CVD consecutively admitted to our hospital. At baseline, total flow volume and resistive index, as an index of vascular resistance, at the popliteal artery was evaluated using gated two-dimensional cine-mode phase-contrast magnetic resonance imaging. Patients were followed 4.8 +/- 1.5 years (range 3.0-8.2) or until their first event of CVD. On follow-up, 16 patients developed primary CVD events. Patients with CVD had lower blood flow (P < 0.01) and higher vascular resistance (P < 0.05) than patients without CVD. When the patients were grouped into tertiles according to their levels of total flow volume (129.6-85.5, 85.3-63.3, and 62.7-23.8 ml/min), Kaplan-Meier analysis showed a higher probability of developing CVD events in patients in the lowest than in patients in the highest (P = 0.0199, log-rank test) tertile. Multivariate Cox proportional hazards analysis revealed that the lowest tertile for flow volume (hazard ratio [HR] 8.60, 95% CI 1.61-45.97, P = 0.012), hypertension (3.99, 1.12-14.25, P = 0.033), and smoking status (12.01, 1.21-119.28, P = 0.034) were significant independent predictors of CVD events. We have demonstrated that low blood flow estimates in lower-leg arteries may be predictive for CVD events among Japanese patients with type 2 diabetes even though they have a normal ABI.

Farbkodierte Dopplersonographie: ein verlässliches Verfahren zur Erkennung des Risikos von Ösophagusvarizen-Blutung bei Patienten mit Leberzirrhose

The aim of the study was to examine the role of Doppler ultrasonography of the portal vein in predicting esophageal variceal bleeding in patients with liver cirrhosis and portal hypertension by comparing the ultrasound data to the endoscopic findings. 99 patients with liver cirrhosis and esophageal varices underwent color Doppler ultrasonography and esophagogastroduodenoscopy. The following portal hemodynamic parameters were analyzed: diameter and cross-sectional area, mean blood flow velocity, blood flow volume, perfusion pressure gradient, congestion index, and platelet count-to-spleen diameter ratio. Variceal characteristics, the size and the presence of red signs, were determined by endoscopic examination. Patients with variceal red signs had significantly higher values of portal diameter (1.538 +/- 0.246 vs. 1.243 +/- 0.167), cross-sectional area (1.286 +/- 0.448 vs. 0.945 +/- 0.256), blood flow volume (965.520 +/- 432.728 vs. 625.117 +/- 320.999) and congestion index (0.165 +/- 0.068 vs. 0.126 +/- 0.051) than patients without red signs, while the perfusion pressure gradient (0.260 +/- 0.087 vs. 0.447 +/- 0.271) and the platelet-to-spleen ratio (522.424 +/- 222.823 vs. 708.921 +/- 230.769) were lower. The same pattern of differences between the ultrasound parameters was found in patients with large varices comparing ones with red signs to the ones without them (diameter, 1.567 +/- 0.234 vs. 1.258 +/- 0.175; cross-section, 1.313 +/- 0.455 vs. 1.061 +/- 0.264; flow volume, 988.195 +/- 443.353 vs. 739.423 +/- 414.281; congestion index, 0.171 +/- 0.067 vs. 0.130 +/- 0.058; perfusion pressure gradient 0.247 +/- 0.078 vs. 0.501 +/- 0.379 and platelet-to-spleen ratio 479.930 +/- 184.302 vs. 699.094 +/- 316.171). Differences in values of ultrasonographic parameters were less obvious among groups of patients with different variceal sizes: only the diameter, cross-sectional area and blood flow volume were significantly different. The mean blood flow velocity did not depend on the variceal size or on the presence of red signs. The sensitivities and specificities of the analyzed parameters were 60-80% and 48.6-78.4%, respectively. Results suggest that color Doppler ultrasonography is a useful noninvasive method for evaluating the risk of esophageal variceal bleeding in patients with liver cirrhosis.

Abnormal peripheral circulation in type 2 diabetic patients with normal ankle-brachial index associates with coronary atherosclerosis, large artery stiffness, and peripheral vascular resistance

We tested the hypothesis that impaired peripheral circulation in diabetes arises from different aspects of vascular abnormalities even when accompanied by a normal ankle-brachial index (ABI > 0.9). One hundred fourteen type 2 diabetic patients with normal ABI and 33 age-matched non-diabetic subjects consecutively admitted to our hospital were enrolled. The Agatston coronary artery calcium score (CACS), as a marker of coronary atherosclerosis, was obtained using electron-beam computed tomography. An automatic device was used to measure brachial-ankle pulse wave velocity (baPWV) as an index of arterial distensibility. Total flow volume and resistive index (RI), as a marker of peripheral vascular resistance, at the popliteal artery were evaluated using gated two-dimensional cine-mode phase-contrast magnetic resonance imaging. Diabetic patients had baPWV ( P < 0.001) and RI ( P < 0.001) higher than those in the non-diabetic subjects, indicating that those parameters are characteristically altered in diabetic patients. When diabetic patients were grouped into three subgroups according to their levels of total flow volume, those with the lowest range showed the highest log-transformed CACS ( P < 0.001), baPWV ( P < 0.001), and RI ( P < 0.001) among the groups. Total flow volume was negatively correlated with log-transformed CACS ( P < 0.001), baPWV ( P < 0.001), and RI ( P < 0.001). Waveform at the popliteal artery could be clearly separated into systolic and early and late diastolic blood flows, which were negatively correlated with log-transformed CACS ( P < 0.001), RI ( P < 0.001), and baPWV ( P < 0.001), respectively. These results suggest that impaired peripheral circulation in diabetes is attributable to coronary atherosclerosis, large artery stiffness, and peripheral vascular resistance even when ABI is normal.

Canine awake head-out plethysmography (HOP): Characterization of external resistive loading and spontaneous laryngeal paralysis

We applied a novel head-out plethysmographic (HOP) method to study awake canine responses to external resistive loading and natural laryngeal paralysis. Measurements of inspiratory and expiratory specific airway resistance (sRaw(insp), sRaw(exp)) were obtained before and after uni- and bidirectional loading (R(add) = 5 cmH(2)O/L/s) in large-breed dogs (n = 9). Mean sRaw(insp) after inspiratory, and sRaw(exp) after expiratory loading were 31.4 and 33.3 cmH(2)Os, respectively. Bidirectional loads induced a significantly greater rise in both sRaw(insp) and sRaw(exp) (55.1 and 61.3 cmH(2)Os) compared to unidirectional loading (P < 0.001). Yet, type of loading did not affect flow-volume indices. The mean R(aw) of dogs was 4.81 cmH(2)O/L/s. Expiratory loading resulted in a significant 8.8% increase in functional-residual-capacity (FRC), compared to FRC(baseline) (76.7 ml/kg). Dogs (n = 5) with laryngeal paralysis demonstrated a significant increase in sR(aw) and R(aw) compared to controls without changes in FRC. In conclusion, HOP precisely characterized sR(aw) in response to external resistive loading. Hence, we could accurately quantify airway obstruction in awake dogs with laryngeal paralysis.

Portal and splenic hemodynamics in cirrhotic patients: relationship between esophageal variceal bleeding and the severity of hepatic failure.

The relationship between portal and splenic vein hemodynamics, liver function, and esophageal variceal bleeding in patients with cirrhosis remains unclear. The aim of the present study was to investigate quantitative Doppler parameters of splanchnic hemodynamics in cirrhotic patients and to determine the value of the Doppler parameters in predicting esophageal variceal bleeding. With the help of pulsed Doppler ultrasonography, we investigated portal and splenic hemodynamics in 18 healthy controls and in 45 patients with liver cirrhosis, in whom the relationship of splenic hemodynamics with esophageal variceal bleeding and the grade of cirrhosis was examined. Portal flow velocity was decreased in cirrhotic patients with Child's C cirrhosis, as compared to those with Child's A cirrhosis ( P < 0.001). The portal blood flow volume in Child's C cirrhosis were also significantly low compared to patients with Child's A and Child's B cirrhosis ( P < 0.001 and P < 0.05, respectively). There was a significant increase in the portal vein congestion index and splenic vein congestion index in patients with Child's C cirrhosis as compared to patients with Child's A cirrhosis ( P < 0.001). Among cirrhotic patients, the group with esophageal variceal bleeding had significantly greater splenic blood flow volume and splenic vein congestion index ( P < 0.001). Patients with ascites had significantly lower portal flow velocity ( P < 0.001) and higher portal vein congestion index and splenic vein congestion index ( P = 0.003 and P = 0.05, respectively) as compared to those without ascites. In this report we have shown that the decrease in blood flow and increased congestion indexes in the portal vein and splenic vein are related to the impairment of liver function in cirrhotic patients; these indexes may be valuable factors for predicting esophageal variceal bleeding.

Utility of color duplex sonography in the assessment of efficacy of the stellate ganglion blockade.

To assess the hemodynamic changes in the upper extremity arteries after sympathetic ganglion blockade (SGB) by using spectral Doppler parameters and to determine the applicability of these parameters for the evaluation of SGB efficacy. Spectral Doppler parameters (peak systolic velocity (PSV), end diastolic velocity (EDV), mean velocity (mean V), flow volume, resistive and pulsatility indices (RI, PI), inner arterial diameters (intima to intima) (D) with simultaneous recordings of heart rate (HR), systolic and diastolic blood pressures and upper extremity surface temperature changes) were recorded before and 5 min after during the first, fifth and tenth SGB procedures. SGB induced an increase in skin temperature in the ipsilateral hand and persistent dilatation of the radial diameter accompanied by reduction of RI and PI in the radial and third digital arteries in all patients. Hemodynamic changes assessed by spectral Doppler parameters could be used as sensitive and objective measurements of peripheral sympathetic nervous activity and vascular tonus, and may confirm a successfully performed SGB.

Increased intracranial blood flow volume in a preeclamptic woman with postpartum photophobia

Background Cerebral circulatory changes in preeclampsia are unclear. We studied the changes in intracranial blood flow volume using a new color Doppler ultrasonographic assessment in a preeclamptic woman with photophobia. Case A 39-year-old preeclamptic primigravida was admitted and delivered by cesarean at 36 weeks’ gestation. She developed bilateral photophobia with blood pressure elevation at 2 days postpartum. Blood flow volume index {mean velocity × π d 2/4} ( d = luminal diameter at systolic phase) was established. The sum of blood flow volume indexes of the bilateral internal carotid arteries and vertebral arteries increased at the onset of photophobia and blood pressure elevation. The blood flow volume index increased above 120 mm Hg of mean arterial blood pressure. Conclusion These data represent the increased cerebral hemodynamic changes in preeclampsia with photophobia.

The quantification of pulmonary valve haemodynamics using MRI.

The optimum slice location within the pulmonary root to quantify pulmonary valve haemodynamics was examined using magnetic resonance (MR) phase velocity mapping. MRI was carried out on 15 patients with congenital aortic valve disease. Although the patients had aortic valve disease, all measurements were made on the pulmonary valve. Systolic (Q(SYS)) and diastolic (Q(DIAS)) blood flow volume and cardiac index (CI) were determined at four pulmonary artery locations. The change in diastolic flow volume relative to slice 1, closest to the pulmonary valve, was also calculated. For a change in axial position of 1.5 cm, i.e. from 0.5 to 2 cm from the annulus, there was a change in diastolic flow volume of 4.4 ml. There was a significant increase in the mean diastolic flow from 3.4 to 7.7 ml (p = 0.01 between slice positions 0.5 and 2 cm. However, there was no significant change in CI, 3.4-3.7 l/min/m2 (p = 0.14) over the same distance. We believe that two factors are responsible for these results. The first is that of compliance, whose effects can be minimized by placing the MR slice close to the valve, however, this will not account for the second factor, being that of valve motion, and hence diastolic pulmonary valve flow or regurgitant volume will be underestimated. The degree of underestimation may only be important at mild and moderate levels of regurgitation or if changes in regurgitation are to be temporally measured.

Endoscopic ultrasonographic study of the azygos vein before and after endoscopic obliteration of esophagogastric varices by injection sclerotherapy.

The azygos vein plays an important role as a drainage system for the superior portosystemic collateral circulation in portal hypertensive patients. Endoscopic ultrasonography (EUS) and Doppler EUS allow the performance of hemodynamic studies of the azygos vein. In this study, we observed the changes in the azygos vein which occur with variceal obliteration by endoscopic injection sclerotherapy (EIS). We recruited patients with portal hypertension and bleeding varices who were not on portal pressure-lowering agents and who were scheduled for the EIS program. EUS was performed in these patients to study the azygos vein at the start of EIS. The azygos vein diameter, maximal velocity (Vmax), and blood flow volume index (BFVI) were measured. After variceal obliteration and within 1 week, another EUS study of the azygos vein was carried out. Out of 40 patients recruited into the study variceal obliteration and EUS assessment of the azygos vein, within 1 week of obliteration, was achieved in 33. We noticed a significant increase in azygos vein diameter (P<0.001) and BFVI (P=0.001) following variceal obliteration. No significant change was observed in Vmax (P>0.05). In one patient, marked caliber irregularities were observed in the azygos vein after variceal obliteration. Using EUS and Doppler EUS, hemodynamic studies of the azygos vein blood flow can be performed, allowing the monitoring of the effects of EIS and variceal obliteration on the superior portosystemic collateral circulation. The clinical significance of the observed changes in azygos blood flow that occur with variceal obliteration should be investigated in further studies and correlated with short-term and long-term outcome.

Value of Doppler Sonography in Revealing Transjugular Intrahepatic Portosystemic Shunt Malfunction

The purpose of the study was to evaluate the long-term clinical efficacy of Doppler sonography in revealing failure of transjugular intrahepatic portosystemic shunts (TIPS). During a 5-year period, 1192 Doppler examinations were performed in 216 patients with TIPS. No regular follow-up shunt venography was performed. Doppler examinations were retrospectively compared with the results of shunt revisions. Sonograms with negative findings were compared with the patients' clinical status so that the number of false-negative sonographic findings leading to an episode of shunt failure (recurrence of gastrointestinal bleeding or ascites) could be ascertained. Sonographic parameters assessed included diameter, velocity, flow volume, and congestion index of the portal vein; and shunt velocities. Doppler sonography revealed shunt occlusion in 25 of 26 angiographically proven cases (sensitivity, 96%). The combination of velocity criteria (peak intrashunt velocity > or =250 cm/sec, maximum velocity in the portal third of the shunt < or =50 cm/sec, or maximum portal vein velocity less than or equal to two thirds of the baseline value) revealed shunt stenosis in 103 of 110 cases (sensitivity, 94%). Doppler sonography missed a significant shunt stenosis that led to an episode of gastrointestinal bleeding or ascites recurrence in only seven cases. The congestion index of the portal vein showed significant differences between patent and malfunctioning shunts (p < 0.001). Doppler sonography is an effective primary imaging method for long-term follow-up of patients with TIPS.

Flow-volume curve changes in patients with obstructive sleep apnoea and brief upper airway dysfunction.

Patients with obstructive sleep apnoea (OSA) and those with brief upper airway dysfunction (BUAD) have been reported to have abnormalities of maximal flow-volume curves. This study was designed to assess the ability of flow-volume curves to predict the presence of OSA or BUAD. Four maximal flow-volume manoeuvres performed by 33 OSA patients and 16 BUAD patients were compared with those of 36 normal subjects. Flow-volume indices, their variability, saw-toothing in the curve and an algorithm based on the flow ratios and shape of the curves were assessed. When the confounding factors, body mass index (BMI), age, gender and smoking status were taken into account, there was no significant difference in a variety of indices derived from the flow-volume curves between OSA and normal subjects. No BUAD patient had normal flow-volume curves as determined with the algorithm. After BMI, age, gender and smoking status were accounted for, decreased forced expiratory volume in 1 s (FEV1), and increased variability of peak expiratory flow (PEF)/peak inspiratory flow (PIF) and FEV1/PEF remained significantly associated with BUAD. These findings suggest that flow-volume curve indices have no value in predicting OSA. Some abnormalities are found in patients with BUAD; a normal flow-volume curve makes the diagnosis of BUAD unlikely.