Changes In Resistance Index Research Articles

Reference values for fetal aortic isthmus blood flow parameters at 24 to 38 weeks' gestation

The goal of this study is to establish population-specific nomograms of fetal aortic isthmus (AoI) Doppler indices in the period of 24-38 weeks' gestation. This was a cross-sectional study of 240 Asian singleton pregnant women at 24-38 completed weeks' gestation. Fetal AoI blood flow was evaluated by Doppler study with automatic calculation of pulsatility index, resistance index, peak systolic velocity, end-diastolic velocity, and time-averaged maximum velocity. The relationship of these indices and gestational age was estimated by using regression analysis, and the best predictive models were determined to define mean, 5th, and 95th centile of each gestational age. The reproducibility was expressed by intraclass correlation coefficients and limits of agreement. The mean maternal age was 28 ± 5.7 years. A total of 97% of all attempts to obtain AoI Doppler waveforms were successful with high interobserver and intraobserver reproducibility. Pulsatility index and peak systolic velocity significantly correlated with gestational age (P = 0.03 and 0.001, respectively), whereas no significant change of resistance index, end-diastolic velocity, and time-averaged maximum velocity with advancing gestation was observed. This study offers normative values of fetal AoI Doppler indices, which may be useful in the difficult task of fetal surveillance in growth-restricted fetuses among our population.

AGE-RELATED CHANGES IN RENAL RESISTIVE INDEX AFTER ESWL

Objective: To determine relation between age and resistive index (RI) changes occurring after extracorporeal shock wave lithotripsy (ESWL). Material & Method: We performed a prospective study in Soetomo Hospital Surabaya. Using duplex ultrasonography, RI was determined in 20 patients with calyceal kidney calculi and pelvic kidney calculi. RI of the interlobar renal arteries were measured in the region near the calculi (distance, less than 2 cm), one hour before ESWL and RI was measured again at 1 hour, 3 days and 7 days after ESWL. Changes in RI values and relation with age (≤ 60 years old and > 60 years old) were evaluated. Results: The renal RI increased significantly 1 hour and 3 days after ESWL, but returned to before ESWL values 7 days after ESWL in the both groups. Although there was positive correlation between age and RI before ESWL, but there was no correlation between age and RI changes after ESWL. Conclusion: Renal RI is higher with age > 60 years, after ESWL renal RI showed transient increase which returned to baseline after 7 days.Key words: Color Doppler Ultrasonography, extracorporeal shock wave lithotripsy, renal resistive index, calyceal kidney calculi, pelvic kidney calculi.

English

The RI (Resistive Index) changes in renal inter lobar segmental arteries were studied in fifty diabetic patients and other 35 random cases. 98% of documented cases of diabetic nephropathy showed raised RI values, more than 0.7. The RI value of one diabetic nephropathy case (2% of cases) was only 0.68. Another one case showed raised RI values, even when the urine microalbuminuria level was only the upper normal value (30mg/L).This shows that renal interlobar segmental artery Doppler evaluation is as sensitive as the urine microalbuminuria study to detect the diabetic renal involvement, and rarely the Doppler study is seen to have an edge over the urine microalbuminuria assessment.

Diagnostic value of vascular endothelial growth factor determination in chronic pyelonephritis in children

Aim. This paper is devoted to the evaluation of clinical and diagnostic value of vascular endothelial growth factor detection in chronic pyelonephritis in children. Methods. The study included 62 patients with different compensation degrees of the disease. Patients were divided into 2 groups - subcompensation (37 patients), and decompensation (25 patients). Renal function was assessed by glomerular filtration rate. Vascular endothelial growth factor concentration was determined by the enzyme-linked immunosorbent assay. To assess the renal vasculature, triplex ultrasonography using pulsed Doppler was performed. The endothelial dysfunction was examined by postocclusion test with reactive hyperemia. Results. Vascular endothelial growth factor level had been significantly increasing in patients according to the severity of the disease. The vascular endothelial growth factor concentration exceeded 600 pg/ml all patients who has later developed chronic renal failure. The sensitivity of this indicator at the abovementioned critical point was assessed as 80%. The change of resistance index reflected renal vascularization disorders. The endothelial dysfunction in postocclusion test was also revealed in patients with pyelonephritis. The vascular endothelial growth factor level highly correlated with the glomerular filtration rate and resistance index. Conclusion. Detecting the vascular endothelial growth factor serum level is one of the tools for endothelial dysfunction laboratory monitoring and renal function assessment in in children with chronic pyelonephritis.

Does varicocele ligation affect inrtatesticular resistive indices?

The Resistive Index (RI), calculated from the spectral waveform during the scrotal ultrasound (US) examination, is an indicator of the integrity of testicular microcirculation. Prior investigations have shown correlations between elevated RI and impaired spermatogenesis. This study characterizes changes in RI after varicocele ligation (VL).

DIURETIC DOPPLER ULTRASOUND FOR EVALUATING OBSTRUCTED AND NON-OBSTRUCTED KIDNEY

Objective: The objective of this study was to evaluate the implementation of diuretic Doppler Ultrasound (DDU) to differentiate the obstructed and non-obstructed kidney. Material & Method: From 28 patients, we gathered data of 48 kidneys in accordance with the inclusion criteria. We evaluated the Doppler Ultrasound Resistive Index (RI) before and after administration of diuretic, using the renogram as the comparison. The result of renogram was categorized into total obstruction (n = 19), partial obstruction (n = 18), and non-obstructive dilatation (n = 3). The statistical analysis was performed using Anova test followed by Tukey HSD test. We also performed diagnostic test, the total and partial obstruction were categorized within obstructed group (n = 37) whereas normal and non-obstructed dilated kidney categorized as non-obstructed group (n = 11). Results: Average change of RI (ΔRI) was 0,542 ± 0,0457 for total obstruction, 0,0428 ± 0,0439 for partial obstruction, 0,0275 ± 0,0392 for normal kidney, -0,0300 ± 0,0361 for non obstructed dilated kidney. The result of normality and homogeneity test indicated the data were normally distributed. One-way Anova test revealed significant differences of ΔRI between groups. The subsequent Tukey HSD test indicated that there were significant differences in total and partial obstruction groups, compared to non-obstructive dilated kidney group. Based on ΔRI cut-off point (0,035) the diagnostic characteristics were 88,5% sensitivity and 72,3% specificity. Conclusion: RI of Diuretic Doppler Ultrasound is a valuable examination to evaluate obstructed and non-obstructed kidney. The cut-off point of 0,035 indicated probability of obstructive kidney. Keywords: Resistive index, renogram, obstructive kidney, non-obstructive kidney.

Renal Perfusion Assessment by Renal Doppler During Fluid Challenge in Sepsis

To assess renal resistive index variations in response to fluid challenge. Prospective cohort study. Three ICUs in French teaching hospitals. Consecutive patients receiving mechanical ventilation and requiring a fluid challenge. Resistive index measurement before and after fluid challenge. Renal Doppler was used to measure resistive index and esophageal Doppler to monitor aortic blood flow. Of the 35 included patients, 17 (49%) met our definition for fluid challenge responsiveness, that is, had at least a 10% increase in aortic blood flow. After fluid challenge, mean arterial pressure increased from 73 mm Hg (interquartile range 68-79) to 80 mm Hg (75-86; p < 0.0001) and stroke volume from 50 mL (30-77) to 55 mL (39-84; p < 0.0001). Stroke volume changes after fluid challenge were +28.6% (+18.8% to +38.8%) in fluid challenge responders and +3.1% (-1.6% to 7.4%) in fluid challenge nonresponders. Renal resistive index was unchanged after fluid challenge in both nonresponders (0.72 [0.67-0.75] before and 0.71 [0.67-0.75] after fluid challenge; p = 0.62) and responders (0.70 [0.65-0.75] before and 0.72 [0.68-0.74] after fluid challenge; p = 0.11). Stroke volume showed no correlations with resistive index changes after fluid challenge in the overall population (r² = 0.04, p = 0.25), in fluid challenge responders (r² = -0.02, p = 0.61), or in fluid challenge nonresponders (r² = 0.08, p = 0.27). Stroke volume did not correlate with resistive index changes after fluid challenge in the subgroups without acute kidney injury (AKIN definition), with transient acute kidney injury, or with persistent acute kidney injury. Systemic hemodynamic changes induced by fluid challenge do not translate into resistive index variations in patients without acute kidney injury, with transient acute kidney injury, or with persistent acute kidney injury.

Changes in Renal Doppler Ultrasonographic Parameters in Patients Managed with Rigid Ureteroscopy

There has been no study evaluating the intrarenal hemodynamic changes after ureteroscopy in the published literature. To determine preoperative and postoperative intrarenal vascular parameters such as resistive index (RI), pulsatility index (PI), peak systolic velocity (PSV), end-diastolic velocity (EDV), measure changes on these values (ΔRI, ΔPI, ΔPSV, ΔEDV) after ureteroscopy (URS) and compare the outcomes with the results of normal contralateral kidneys, and finally investigate possible parameters that would affect renal vascular resistance changes. We prospectively studied 47 patients who underwent rigid URS. Preoperative gray-scale and Doppler ultrasonography (CDUS) measurements were obtained 24 h before URS. Similarly, postoperative CDUS measurements were done 24 h after the operation. The degree of hydronephrosis and location of stones in the obstructed kidneys, diameters of both kidneys, and thickness of renal parenchyma were evaluated with gray-scale US followed by CDUS with calculation of the intrarenal RI, PI, PSV, and EDV values for each kidney. For the operated kidneys, statistically significant P values were noticed when RI and PI values were considered (P < 0.001). ΔRI and ΔPI of the operated kidneys were also significantly greater than the values for non-operated kidneys (P < 0.001). However, it was not the case for ΔPSV and ΔEDV values. In Spearman correlation coefficient analysis, ΔRI was found to be correlated with the parameters: "operative time" and "irrigation fluid volume". No significant relation was documented between ΔRI and the other parameters: age, gender, side of ureteroscopy, stone location, and degree of hydronephrosis. Significant changes in RI and PI values in patients treated with URS reveal that URS can cause a significant increase in renal vascular resistance. With the increase in operative time and irrigation fluid volume used during the operation, RI seems to be significantly increased.

Doppler Ultrasonographic Assessment of Early Changes in Kidney Graft Size and Resistive Index and Their Predictive Role on 1-Year Graft Function

IntroductionDoppler ultrasonography is a simple, noninvasive diagnostic tool for assessment and follow-up studies in renal transplantation. The aim of this study was to investigate the correlation between early changes in graft size and resistive index (RI) and 1-year graft function. MethodWe recorded graft size, RI, and serum creatinine level in 25 living kidney donors (before transplantation) as well as early (1-week), and 1-year after transplantation (in kidney recipients). Then we assessed the correlation between early changes in graft size and RI and 1-year Scr. ResultsRepeated measurement tests showed a significant increase in graft size including length (initial, 107.6 ± 5.8 mm; average increase, 8.48 ± 5.61 mm; P < 0.001), anterior-posterior diameter (initial, 46.3 ± 4.7 mm; average increase, 6.16 ± 4.08 mm; P < 0.001), and parenchymal thickness (initial, 14.96 ± 2.1 mm; average increase, 3.04 ± 1.98 mm; P < 0.001) 1 week after transplantation. However, during the 1-year follow-up examinations the increase in graft size was not significant in contrast with 1-week follow-up values (P > 0.47). Pearson correlations showed significant correlation between early changes in graft size (eg, anterior-posterior diameter, r = −0.492; P = 0.013); and 1-year Scr levels. There was no significant correlation between graft size changes and RI or RI and Scr early or 1-year after transplantation. ConclusionThere was a significant increase in kidney size (including length, anterior-posterior diameter, and cortical thickness) early after transplantation. The amount of increase in size significantly correlated with Scr level 1-year after transplantation. There was no correlation between RI and Scr.

The Effect of Diluted Penetration Enhancer in Nebulized Mist versus Liquid Drop Preparation Forms on Retrobulbar Blood Flow in Healthy Human Subjects

The aim of this study was to compare the effects of nebulized mist and liquid drop applications on retrobulbar blood flow. A prospective, non-randomized clinical trial was used to collect data from 40 healthy human eyes. Color Doppler Imaging determined peak systolic (PSV) and end diastolic (EDV) blood flow velocities and resistance index (RI) in the ophthalmic artery after both applications. Measurements were taken at baseline and at 1 min post-treatment in both eyes with 5 min measurements in the treatment eye only. p values ≤ 0.05 were considered statistically significant. Mist application to treatment eye produced an increase in 1 min and 5 min PSV and EDV (0.001 < p < 0.03) and a decrease in 5 min RI (p = 0.01), with no significant changes in PSV, EDV or RI of control eye or in treatment eye 1 min RI (p > 0.05). Drop application to treatment eye produced an increase in PSV (p < 0.001) and EDV (p = 0.01) at 1 min, with an increase in control eye 1 min PSV and EDV (p = 0.03). There were no statistically significant changes in treatment eye PSV, EDV and RI after 5 min (p > 0.05). The use of nebulized mist may provide an effective alternative to liquid drop medication application.

Transvaginal color Doppler sonography predicts ovarian interstitial fibrosis and microvascular injury in women with ovarian endometriotic cysts

To determine novel predictors of ovarian interstitial fibrosis and microvascular injury associated with ovarian endometriotic cysts (OECs). Case-control study. The gynecology unit of an affiliated hospital in China. Women <40 years of age with OECs or benign ovarian tumors (controls). Transvaginal color Doppler sonography was performed preoperatively to detect ovarian interstitial flow. Postoperatively, expressions of transforming growth factor-β1 (TGF-β1) and thrombospondin-1 (TSP-1), as well as microvessel density in ovarian interstitial, were analyzed using immunohistochemistry. Ovarian interstitial flow and expressions of TGF-β1, TSP-1, and microvessel density. Compared with controls, ovarian interstitial flow in the study group was decreased and arterial spectra indicated significantly higher resistance indices. Microvessel density was reduced, but TGF-β1 and TSP-1 were elevated in the study group. There was a positive correlation between TGF-β1 and TSP-1. There were negative correlations between TGF-β1 and microvessel density, and between TSP-1 and microvessel density. Microvessel density and resistance indices were negatively correlated, whereas the correlations of TGF-β1 and TSP-1 with resistance indices were positive. Resistance indices are consistent with pathological indices. Changes in resistance indices in ovaries with endometriosis are related to interstitial fibrosis and microvascular injury.

The Findings of a Retrospective Audit of Clinical Indications and Outcomes Related to Renal Artery Duplex Ultrasounds Performed during a 2-Year Period

Introduction In this retrospective audit of renal artery duplex ultrasounds (RADU), performed on 791 patients during a 2-year period, we analyze the clinical indications for testing, the patient cohort characteristics, and RADU results and outcomes. Results We found RADU to be sensitive and specific for the detection of renal artery stenosis with limitations in some instances attributable to physical interactions between ultrasound and body tissues and the variable presence of accessory renal arteries, even when performed by qualified experienced vascular sonographers. The results show the wide range of clinical indications for the performance of the test and document the multiple co morbidities of the patient population. Results show the majority of renal artery lesions are atherosclerotic in nature and that few patients go on to have renal artery intervention. The interventions do result in improvement of blood pressure but no change in resistive index. Conclusion The future role of RADU will be determined by medical research that provides evidence-based outcomes of the natural history of renal artery stenosis in the context of hypertension, allowing algorithms to be developed that best identify the medical versus interventional therapies for individual patients attempting to optimize renal function and blood pressure control while modifying associated risk factors. This will then allow more selective use of this diagnostic tool to answer more specified clinical questions on a case-by-case basis.

Cerebral blood flow during single lung ventilation

Our aim was to show the effect of one-lung ventilation (OLV) on cerebral blood flow (CBF) by measuring carotid blood flow. This technique has been the subject of experimental and clinical studies. Materials and methods: Carotid doppler flows were measured at 4 different times. Peak systolic velocity (PSV) and end diastolic velocity (EDV) were measured and pulsatility index (PI) and resistive index (RI) calculated. Results: There were no significant changes in PSV, PI, RI, or flow volume in the normal or diseased sides at repeated measures (P > 0.05).There was no significant difference between the flow velocities, PIs, RIs, or flow volumes measured in the supine and decubitus positions during OLV. In addition, there was no significant difference between the flow parameters of the upper and lower carotids measured in the lateral decubitus position before and after OLV. There was no correlation between any of the flow parameters and duration of OLV. Conclusion: OLV poses no additional risk in terms of CBF. However, further studies, supported by biochemical parameters and involving wider patient groups, are now needed.

Dynamic evaluation of renal resistive index in normoalbuminuric patients with newly diagnosed hypertension or type 2 diabetes

Renal resistive index is a useful measure for quantifying alterations in renal blood flow. In the present study we evaluated resistive index at baseline and after vasodilation induced by nitroglycerine in normoalbuminuric patients with type 2 diabetes or essential hypertension, relating the values to indices of systemic vascular dysfunction. Newly diagnosed treatment-naïve type 2 diabetic (n = 32) and hypertensive patients (n = 49) were compared with 27 age- and sex-matched healthy controls. Renal resistive index was obtained by duplex ultrasound at baseline and after 25 μg sublingual nitroglycerine. Endothelium-dependent (flow-mediated dilation) and -independent (response to nitroglycerine) vasodilation in the brachial artery was assessed by computerised edge detection system. Carotid-femoral pulse-wave velocity and augmentation index were assessed by applanation tonometry. Nitrotyrosine levels, an index of oxidative stress, were also measured. Resistive index was higher in diabetic than in hypertensive patients and controls (p < 0.001), while changes in resistive index induced by nitroglycerine were lower in hypertensive patients compared with controls (p < 0.01), and were further reduced in type 2 diabetic patients. Hypertensive and diabetic patients showed significantly increased arterial stiffness, nitrotyrosine levels and reduced endothelial function than controls (p < 0.05). Changes in resistive index induced by nitroglycerine were independently related to serum glucose, reactive hyperaemia and aortic pulse-wave velocity in the overall population. These results support the dynamic evaluation of renal resistive index as an early detector of renal vascular alterations in the presence of type 2 diabetes and hypertension, even before the onset of microalbuminuria.

운동 형태와 운동 강도에 따른 중대뇌동맥의 뇌혈류 속도의 비교 분석

The purpose of this research is to prepare exercise stability/safety by predicting possible dangerous situations during competitions in advance and presenting appropriate exercise intensity based on TCD(Transcranial Doppler ultrasound) analysis of Systolic, Diastolic and Mean Blood Flow Velocity, Pulsatility Index(PI) and Resistive Index(RI) from MCA according to exercise intensity as well as at rest. The subjects were 10(ten) Soccer and Judo players respectively from high school over 5 years in experience. To analyze Cerebral Blood Flow, PI and RI Changes according to exercise intensity, treadmill test was performed among single group at rest and with moderate, high and maximal intensity. In comparison with the velocities at rest, Systolic Velocity was increased at moderate and high intensity but it was decreased at maximal intensity for both groups(p0.05). Diastolic Blood Velocity and Mean Blood Velosity for the Soccer players were increased at moderate and high intensities but it was decreased at maximal intensity(p0.05). In case for the Judo players, they were increased at moderated intensity but they were decreased at high and maximal intensities (p0.05). On the other hand, Pulsatility and Resistive Index were increased at all the other intensities (p0.05). In a repeated measured 2-way ANOVA, there were not significant differences between the exercise types and intensities (p0.05). But there were significant differences between the each factors, Systolic Blood Velocity, Diastolic Blood Velocity, Mean Blood Velosity, Pulsatility Index and Resistive Index, and the various exercise intensities in a repeated measured 1-way ANOVA (p0.05).

Normal Doppler velocimetry of renal vasculature in Persian cats

Renal diseases are common in older cats. Decreased renal blood flow may be the first sign of dysfunction and can be evaluated by Doppler ultrasound. But previous studies suggest that the resistive index (RI) has a low sensitivity for detecting renal disease. Doppler waveforms of renal and intrarenal arteries demonstrate decreased blood flow before there are any changes in the RI. The purpose of this study was to evaluate the normal Doppler flowmetrics parameters of renal arteries (RAs), interlobar arteries (IAs) and abdominal aorta (AO) in adult healthy, Persian cats. Twenty-five Persian cats (13 females and 12 males with mean age of 30 months and an age range 12-60 months) with normal clinical examinations and biochemical tests and normal systemic blood pressure were given B-mode ultrasonographies in order to exclude all nephropathies, including polycystic kidney disease. All measurements were performed on both kidneys. Both kidneys (n=50) were examined by color mapping of the renal vasculature. Pulsed Doppler was used to examine both RAs, the IAs at cranial, middle and caudal sites, and the AO. The RI was calculated for all of the vessels. Early systolic acceleration (ESA) of RA and IA was obtained with Doppler spectral analysis. Furthermore, the ratio indices between RA/AO, and IA/RA velocities were calculated. The mean values of peak systolic velocity (PSV) and the diameter for AO were 53.17±13.46 cm/s and 0.38±0.08 cm, respectively. The mean RA diameter for all 50 kidneys was 0.15±0.02 cm. Considering the velocimetric values in both RAs, the mean PSV and RI that were obtained were 41.17±9.40 cm/s and 0.54±0.07. The RA had a mean ESA of 1.12±1.14 m/s(2) and the calculated upper limit of the reference value was 3.40 m/s(2). The mean renal-aortic ratio was 0.828±0.296. The IA showed PSV and RI values of 32.16±9.33 cm/s and 0.52±0.06, respectively. The mean ESA of all IAs was 0.73±0.61 m/s(2). The calculated upper limit of the reference value was 2.0m/s(2). The mean renal-interlobar artery ratio was 1.45±0.57. The RI values obtained in this study were similar to values reported in the literature. Some conditions that lead to a decrease in compliance and to an increase in vascular resistance can affect the Doppler spectral waveforms without changes in RI. To our knowledge, there are no studies that were directed toward to the normal ESA values of the renal vasculature in Persian cats. This study introduced a new ratio between the PSV of the RA and the IA. This index was developed based on the well-known effects of Doppler on the detection of stenosis, regardless of the cause. Further studies are necessary to verify the hemodynamic behavior of this index under pathological conditions in cats as well as the effect of aging, nephropathies and systemic pressure on Doppler velocimetric parameters.

안정시 및 운동 강도에 따른 고교축구선수의 뇌혈류 속도 및 저항지수의 변화

The purpose of this research is to prepare exercise stability/safety by predicting possible dangerous situations during competitions in advance and presenting appropriate exercise intensity based on TCD(Transcranial Doppler ultrasound) analysis of Systolic, Diastolic and Mean Blood Flow Velocity, Pulsatility Index(PI) and Resistive Index(RI) from MCA according to exercise intensity as well as at rest. The subjects were 10 soccer players from high school over 5 years in experience. To analyze Cerebral Blood Flow, PI and RI Changes according to exercise intensity, treadmill test was performed among single group at rest and with moderate, high and maximal intensity. In comparison with the velocities at rest, Systolic, Diastolic and Mean Blood Velocity were increased at moderate and high intensity but they were decreased at maximal intensity(p0.05). On the other hand, Pulsatility and Resistive Index were increased at all the other intensities(p0.05). In a repeated measured One-way ANOVA, there were significant differences between the each measured values-blood velocities and indexes-and the various exercise intensities (p0.05). In a post Hoc test, there were significant differences between rest and the other intensities in Systolic Blood Velocity ; rest and moderate/high intensity, moderate and maximal intensity, and high and maximal intensity in Diastolic Blood Velocity ; rest and moderate/high/maximal intensity, and high and maximal intensity in Mean Blood Velocity ; rest and moderate/maximal intensity, and moderate and high intensity in Pulsatility and Resistive Index (p0.05).

Prognostic Value of the Resistance Index in the Undescended Testis Relative to Patient's Age and Time-Point of Surgery

Purpose The undescended testis is one of the most common disease in paediatric urology. The aim of the present study was to analyse the testicular parenchymal blood flow as measured by the resistance index (RI) in relation to the patient's age and potential changes in RI following surgery. Material and Methods From 04/07 – 03/09 we prospectively studied 100 boys with uni- or bilateral undescended testes aged 1 to 14 using a high resolution linear ultrasound scanner. The RI was determined with simultaneous detection of B-mode and colour-flow Doppler before and 6 weeks after surgery. The obtained indices were compared with those of the descended contralateral testis. Results A total of 143 undescended testes (43 bilateral, 57 unilateral) and 57 descended contralateral testes were examined. In both groups the mean RI was 0,55 irrespecitve of the patient's age. Similarly, we did not observe any significant changes in RI following surgical correction of the undescended testis. Conclusions In contrast to progressive histo-pathological changes in untreated undescended testis over time, the time-point of surgery appears to have no relevant impact on the testicular parenchymal blood perfusion as measured by the RI. Therefore, the RI failed to show a predictive value with regard to both diagnosis and therapy of the undescended testis.

Colour Doppler ultrasound of the ocular circulation in patients with systemic lupus erythematosus identifies altered microcirculatory haemodynamics

We assessed whether quantitative analysis of Doppler flow velocity waveforms is able to identify subclinical microvascular abnormalities in SLE and whether eigenvector analysis can detect changes not detectable using the resistive index (RI). Fifty-four SLE patients with no conventional cardiovascular risk factors, major organ involvement or retinopathy were compared to 32 controls. Flow velocity waveforms were obtained from the ophthalmic artery (OA), central retinal artery (CRA) and common carotid artery (CA). The waveforms were analysed using eigenvector decomposition and compared between groups at each arterial site. The RI was also determined. The RI was comparable between groups. In the OA and CRA, there were significant differences in the lower frequency sinusoidal components (P < 0.05 for each component). No differences were apparent in the CA between groups. Eigenvector analysis of Doppler flow waveforms, recorded in proximity of the terminal vascular bed, identified altered ocular microvascular haemodynamics in SLE. Altered waveform structure could not be identified by changes in RI, the traditional measure of downstream vascular resistance. This analytical approach to waveform analysis is more sensitive in detecting preclinical microvascular abnormalities in SLE. It may hold potential as a useful tool for assessing disease activity, response to treatment, and predicting future vascular complications.

Glucagon-like peptide-2 increases mesenteric blood flow in humans

Objective. Mesenteric blood flow is believed to be influenced by digestion and absorption of ingested macronutrients. We hypothesized that the intestinotrophic hormone, GLP-2 (glucagons-like peptide 2), may be involved in the regulation of mesenteric blood flow. Changes in mesenteric blood flow were measured by Doppler ultrasound scanning of the superior mesenteric artery (SMA). The aim of the study was to demonstrate the influence of GLP-2 on this flow, expressed as changes in resistance index (RI). Material and methods. A homogeneous group of 10 fasting healthy volunteers completed a 2-day trial. On day 1, a standard meal was given, and RI measured in the SMA. On day 2, GLP-2 was infused intravenously (IV) at rates of 0.5, 1.0 and 2.0 pmol/kg/min over 3×45 min separated by a 15–20 min rest period. After a further 15–20 min of rest, 450 nmol synthetic GLP-2 was given subcutaneously (SC). RI in the SMA was measured before, during and after the meal and GLP-2 infusions. Results. After IV infusion of GLP-2, the following decreases in RI were observed: 0.5 pmol/kg/min: 2.7% (range 0–6.3%), 1.0 pmol/kg/min: 6.7% (range 0.4–15.9%), 2.0 pmol/kg/min: 15.3% (range 9.6–22.7%) p<0.00802. When given SC, GLP-2 elicited a maximum average change in RI of 15.6% (range 5.0–28.1%). The standard meal elicited a 14.7% (range 8.8–21.6%) change, p<0.020 There was a similar change in RI over time (0–90 min) after a standard meal and after subcutaneous GLP-2, p<0.005. Conclusions. Our study showed a significant association between IV and SC administration of synthetic GLP-2 and changes in mesenteric blood flow. An exponential dose–response relationship was observed after IV infusion. The meal-induced changes in mesenteric blood flow over time were similar to those obtained by SC GLP-2. Thus, our results support the hypothesis that GLP-2 is an important regulator of mesenteric blood flow.