Continuous-wave Doppler Sonography Research Articles

Implementation of continuous-wave Doppler ultrasound to detect the high-risk foetus in the low-risk mother: lessons from South Africa

IntroductionDetecting the risk of stillbirth during pregnancy remains a challenge. Continuous-wave Doppler ultrasound (CWDU) can be used to screen for placental insufficiency, which is a major cause of stillbirths in low-risk pregnant women. This paper describes the adaptation and implementation of screening with CWDU and shares critical lessons for further rollout. Screening of 7088 low-risk pregnant women with Umbiflow™ (a CWDU device) was conducted in 19 antenatal care clinics at nine study sites in South Africa. Each site comprised a catchment area with a regional referral hospital and primary healthcare antenatal clinics. Women with suspected placental insufficiency as detected by CWDU were referred for follow-up at the hospital. A 35–43% reduction in stillbirths was recorded.MethodsThe authors followed an iterative reflection process using the field and meeting notes to arrive at an interpretation of the important lessons for future implementation of new devices in resource-constrained settings.ResultsKey features of the implementation of CWDU screening in pregnancy combined with high-risk follow-up are described according to a six-stage change framework: create awareness; commit to implement; prepare to implement; implement; integrate into routine practice; and sustain practice. Differences and similarities in implementation between the different study sites are explored. Important lessons include stakeholder involvement and communication and identifying what would be needed to integrate screening with CWDU into routine antenatal care. A flexible implementation model with four components is proposed for the further rollout of CWDU screening.ConclusionsThis study demonstrated that the integration of CWDU screening into routine antenatal care, combined with standard treatment protocols at a higher-level referral hospital, can be achieved with the necessary resources and available maternal and neonatal facilities. Lessons from this study could contribute to future scale-up efforts and help to inform decisions on improving antenatal care and pregnancy outcomes in low- and middle-income countries.

Identifying the High-Risk Fetus in the Low-Risk Mother Using Fetal Doppler Screening.

Identifying the high-risk fetus in the low-risk pregnant mother (LRM) is a neglected area of research. Fetal growth restriction (FGR) is a major cause of stillbirths, especially in low- and middle-income countries (LMICs). FGR is very poorly detected particularly in healthy pregnant women classified as low risk. Umbiflow is an inexpensive continuous-wave Doppler ultrasound (CWDU) apparatus that is suitable for use by low-level health care providers for screening low-risk pregnant populations. It can easily detect umbilical artery blood flow in the cord, which correlates well with placental function, and poor placental function correlates well with FGR.Use of CWDU to screen an LMIC population of more than 7,000 LRMs has demonstrated a high prevalence of abnormal umbilical artery flow of 13%, and absent end-diastolic flow, which is associated with end-stage placental disease, was found in 1.2%. This is 10 times higher than previously reported in high-income countries. Screening with CWDU together with a standard protocol managing those pregnancies with abnormal placental blood flow resulted in a 43% reduction in stillbirths (risk ratio: 0.57; 95% confidence interval=0.29, 0.85) in this LRM population. Further, follow-up of infants who had abnormal umbilical artery blood flow showed that these infants had significantly less fat-free mass at ages 6 weeks, 10 weeks, 14 weeks, and 6 months, than those with normal umbilical artery blood flow (P<.015), confirming that CWDU was able to detect true FGR.Thus, screening with CWDU can detect the fetus at risk of stillbirth, and infants likely to have suboptimal growth and development postnatally. Screening with CWDU in LRMs opens the door to a step change in preventing stillbirths in LMICs.

Portable continuous wave Doppler ultrasound for primary healthcare in South Africa: can the EUnetHTA Core Model guide evaluation before technology adoption?

BackgroundThis study had a threefold aim: to test the value of stakeholder involvement in HTA to reduce evidence gaps and interpret findings; and to assess a medical device by applying the EUnetHTA Core Model (CM) in South Africa and thus ultimately provide a first overview of evidence for potential widespread adoption of the technology in a primary health care (PHC) setting. Used in primary healthcare setting for obstetric use, the technology under assessment is a low-cost continuous wave Doppler ultrasound (DUS).MethodsThe scoping of the assessment was defined by involving policy makers in selecting the domains and corresponding questions relevant to the ultrasound and its use. Additionally, hospital managers were invited to respond to dichotomous questions on the criteria for procurement. To substantiate evidence obtained from an initial literature review, different stakeholders were identified and consulted. The evidence generated fromall steps was used to populate the high-ranked assessment elements of the CM.ResultsThe HTA on continuous-wave DUS incorporated the evidence on organizational, ethical, and social value of its use together with effectiveness, safety, and cost-effectiveness of the technology. The domains on “health problem” and “safety” had a higher rank than the rest of the nine domains. Unexplained fetal mortality is the largest single contributor to perinatal deaths in South Africa. Pregnant women in PHC setting were examined using a continuous-wave DUS, after their routine antenatal visit. The healthcare professionals interviewed, indicated the benefit in the use of continuous-wave DUS in the PHC setting and the need for training.ConclusionsCollection and generation of evidence based on the HTA CM and the chosen decision criteria provided a generalized but structured guidance on the methodology. Several questions were not applicable for the technology and the context of its use and elimination of those that are inappropriate for the African context, resulted in a pragmatic solution. Engaging and consulting local stakeholders was imperative to understand the context, reduce evidence gaps, and address the uncertainties in the evidence, ultimately paving the way for technology adoption. Given the ongoing studies and the evolving evidence base, the potential of this technology should be reassessed.

Development of Gas-Liquid Slug Flow Measurement Using Continuous-Wave Doppler Ultrasound and Bandpass Power Spectral Density

This paper addresses the issues of slug detection and characterization in air-water two-phase flow in a vertical pipeline. A novel non-invasive measurement technique using continuous-wave Doppler ultrasound (CWDU) and bandpass power spectral density (BPSD) is proposed for multiphase flow applications and compared with the more established gamma-ray densitometry measurement. In this work, analysis using time-frequency analysis of the CWDU is performed to infer the applicability of the BPSD method for observing the slug front and trailing bubbles in a multiphase flow. The CWDU used a piezo transmitter/receiver pair with an ultrasonic frequency of 500 kHz. Signal processing on the demodulated signal of Doppler frequency was done using the Butterworth bandpass filter on the power spectral density which reveals slugs from background bubbles. The experiments were carried out in the 2” vertical pipeline-riser at the process system engineering laboratory at Cranfield University. The 2-inch test facility used in this experiment is made up of a 54.8 mm internal diameter and 10.5 m high vertical riser connected to a 40 m long horizontal pipeline. Taylor bubbles were generated using a quick-closing air valve placed at the bottom of the riser underwater flow, with rates of 0.5 litres/s, 2 litres/s, and 4 litres/s. The CWDU spectrum of the measured signal along with the BPSD method is shown to describe the distinctive nature of the slugs.

Windkessel Model-Based Cuffless Blood Pressure Estimation Using Continuous Wave Doppler Ultrasound System

Blood pressure (BP) measurement plays an essential role in the prevention of cardiovascular diseases. Studies have demonstrated Ultrasound (US) based BP analysis method combining with peripheral components of the circulatory system. In this paper, a cuffless BP measurement technique has been proposed using a portable continuous wave Doppler US system which consumes < 4 Watt of power. The US blood flow signal acquired utilizing 8 MHz pencil transducer probe from the brachial artery is denoised using soft thresholding method. The spectrogram envelope of maximum frequency is obtained by an adaptive signal noise slope intersection (SNSI) method to extract hemodynamic features. In the proposed method, 2-element Windkessel (WK) model consisting of peripheral resistance and arterial compliance is employed for BP estimation. Based on the extracted features, a machine learning algorithm determines the WK model parameters. From the experiments conducted on 85 subjects, it has been observed that both systolic and diastolic BP achieve Grade B and Grade C for British Hypertension Society (BHS) and IEEE Std. 1708 protocols, respectively. Regarding Association for the Advancement of Medical Instrumentation (AAMI) standard, diastolic BP estimation error is within an acceptable limit. The robustness of the approach is examined using pre-exercise and post-exercise performance of 10 subjects. Moreover, the effect on arterial compliance for increased BP and aging is observed to characterize the dynamic property of arterial system. The proposed method is non-invasive, non-occlusive, independent of any additional interfaces, operates with a small dataset and worthy of implementation as a portable system for point-of-care application.

Non-intrusive classification of gas-liquid flow regimes in an S-shaped pipeline riser using a Doppler ultrasonic sensor and deep neural networks

The problem of predicting the regime of a two-phase flow is considered. An approach is proposed that classifies the flow regime using Deep Neural Networks (DNNs) operating on features extracted from Doppler ultrasonic signals of the flow using the Fast Fourier Transform (FFT) is proposed. The features extracted are categorised into one of the four flow regime classes: the annular, churn, slug, and bubbly flow regimes. The scheme was tested on signals from an experimental facility. To increase the number of samples without losing key classification information, this paper proposes a Twin-window Feature Extraction (TFE) technique. To further distinguish the performance of the proposed approach, the classifier was compared to four conventional machine learning classifiers: namely, the AdaBoost classifier, bagging classifier, extra trees classifier, and decision tree classifier. Using the TFE features, the DNNs classifier achieved a higher recognition accuracy of 99.01% and greater robustness for the overfitting challenge, thereby showing the superiority of the DNNs in flow regime classification when compared to the four conventional machine-learning classifiers, which had classification accuracies of 55.35%, 86.21%, 82.41%, and 80.03%, respectively. This approach demonstrates the application of DNNs for flow regime classification in chemical and petroleum engineering fields, using a clamp-on Doppler ultrasonic sensor. This appears to be the first known successful attempt to identify gas–liquid flow regimes in an S-shaped riser using Continuous Wave Doppler Ultrasound (CWDU) and DNNs.

The Integration of Doppler Ultrasound With Two-Dimensional Echocardiography and the Noninvasive Cardiac Hemodynamic Revolution of the 1980s

In the 1970s, as cardiac imaging matured from M-mode to two-dimensional echocardiography, investigators in Norway showed that continuous-wave Doppler ultrasonography could be used to accurately measure the mean gradient and pressure half-time for stenotic mitral valves. In the 1980s, continuous-wave Doppler was validated for measurement of the pressure gradient across stenotic aortic valves, and pulsed-wave Doppler combined with two-dimensional echocardiographic imaging was validated for noninvasive measurement of stroke volume and cardiac output. The combination of stroke volume measurement and measurement of the time-velocity integral of flow through the aortic valve was then validated as a means to accurately calculate valve area for patients with stenotic aortic valves or aortic prostheses. This integration of cardiac Doppler ultrasonography with two-dimensional echocardiographic cardiac imaging led to a revolution in noninvasive hemodynamic evaluations, which have replaced invasive hemodynamic evaluations in surgical decision making for most patients with native or prosthetic valvular stenosis.

Differences in salivary secretory function between patients with erosive esophagitis and those with nonerosive reflux disease

It has been speculated that impaired salivary flow contributes to abnormal acid clearance in patients with erosive esophagitis (EE). For easy and objective assessment of salivary function, we developed a salivary gland blood flow measurement technique using continuous-wave Doppler sonography. In the present study, we evaluated the salivary secretory function in patients with EE and those with nonerosive reflux disease (NERD) using this method. Doppler waveform analysis was performed on the facial artery to assess blood inflow to the submandibular gland of 30 healthy subjects (HS). Blood flow was compared before and after secretory stimulation with 1mL of lemon juice. Saliva was simultaneously collected and weighed before and after stimulation. Continuous-wave Doppler sonography was also performed in patients with EE and NERD. The size of the submandibular gland was compared in 26 patients with EE, 41 patients with NERD, and 86 HS. The submandibular gland blood flow increased after stimulation in all HS. Both within-day and day-to-day reproducibility were good. There was a significant correlation between the percent increase in the maximum velocity and the percent increase in salivary secretion. Although the size of the submandibular gland was not significantly different among the three groups, the percent increase in the maximum velocity in patients with EE was significantly smaller than that in HS. We have established an easy method of assessing salivary function in daily practice. This study revealed that a decrease in salivary secretory function is involved in the pathology of EE.

Peak Systolic Velocity Measured by Continuous-Wave Doppler Ultrasonography without Angle Correction in Patients with Internal Carotid Artery Stenosis

Peak systolic velocity (PSV) is measured with pulse-wave (PW) Doppler with angle correction in patients with internal carotid artery stenosis (ICAS). However, the correlation between conventional angiography and PSV shows considerable scattering. We hypothesized that measuring PSV without angle correction would lead to better inter-rater reliability. This hypothesis was tested using a sector probe and continuous-wave (CW) Doppler without angle correction. Consecutive patients with more than 50% ICAS were enrolled from a prospective database. PSV was measured with PW Doppler with angle correction (PW PSV) and CW Doppler without angle correction (CW PSV) by 2 examiners. The inter-rater reliabilities of PW PSV and CW PSV were analyzed by Spearman's rank correlation test. A total of 37 ICAS sites (median 67 [interquartile range 57-78] % stenosis) were enrolled. Measuring PSV using a sector probe insonating nearly parallel to the flow was feasible in all cases. Inter-rater reproducibility of CW PSV (Spearman's ρ = .810) was similar to that of PW PSV (Spearman's ρ = .796). When limited to patients with a PSV greater than 200 cm/s with both PW Doppler examinations (25 ICAS sites), inter-rater reliability was relatively higher for CW PSV (Spearman's ρ = .674) than for PW PSV (Spearman's ρ = .423). Measuring PSV with CW Doppler using a sector probe was feasible. Inter-rater reliability was similar between PW Doppler with angle correction and CW Doppler without angle correction in evaluating PSV in patients with ICAS. CW Doppler appears to have better inter-rater reproducibility than PW Doppler in assessing high PSV.

Oil–water two-phase flow velocity measurement with continuous wave ultrasound Doppler

A flow velocity measurement method based on continuous wave ultrasound Doppler (CWUD) and flow profile modeling is presented. A theoretical model is proposed to relate the overall superficial velocity of oil–water two-phase flow with the mean velocity measured in the sensing volume of CWUD, by introducing velocity profile correlation. A CWUD measuring system was built to emit an ultrasonic wave of 1MHz and collect the frequency shift of the reflected waves. Dynamic experiments were carried out in a horizontal pipe of inner diameter of 50mm with the CWUD system. Six flow patterns of horizontal oil–water two-phase flow were observed including both the water continuous flow and the oil continuous flow. According to the results, the average frequency shift in oil–water two-phase flow varies with the flow pattern. The flow velocity correlations are separately established for the oil continuous dispersed flow, water continuous dispersed flow and stratified flow, based on the analysis of flow velocity profile correction. The average relative error of the overall superficial velocity is 3.63% with a maximum relative error of 12.22%.

Superiorin vivoCompatibility of Hydrophilic Polymer Coated Prosthetic Vascular Grafts

Protein adsorption, cell adhesion and graft patency was compared in hydrophilic versus hydrophobic polymer-coated prosthetic vascular grafts. We hypothesize that in vivo compatibility of hydrophilic polymer-coated prosthetic vascular grafts is superior to in vivo compatibility of hydrophobic grafts. A pairwise side-to-side common carotid artery interposition graft was placed eight female landrace goats (mean weight 55 kg). Protein adsorption was assessed using Western Blot in two hydrophilic and two hydrophobic grafts harvested after three days. Graft patency was monitored for 28 days in six goats with continuous wave Doppler ultrasonography. Adherence of endothelial cells, leukocytes and platelets was determined with ELISA and compared between the two graft types after 28 days. After three days, more ApoA-I, albumin and VEGF and less fibrin adsorbed to hydrophilic grafts. After 28 days, compared to hydrophobic grafts, higher numbers of endothelial cells were present on hydrophilic grafts (P=0.016), and less thrombocytes and leukocytes (P=0.012 and 0.024, respectively). Two out of eight hydrophobic grafts lost patency, while none of the hydrophilic grafts failed (P=0.157). Hydrophilic polymer-coated vascular grafts have superior in vivo compatibility when compared to hydrophobic grafts as characterized by reduced platelet and leukocyte adherence as well as higher endothelialization.

Peripheral Arterial Disease Assessment With Photoplethysmography and Continuous-Wave Doppler Ultrasound in Addition to Ankle-Brachial Index May Loss Time and Funds

Peripheral Arterial Disease Assessment With Photoplethysmography and Continuous-Wave Doppler Ultrasound in Addition to Ankle-Brachial Index May Loss Time and Funds

Peripheral Arterial Disease Assessment With Photoplethysmography and Continuous-Wave Doppler Ultrasound in Addition to Ankle-Brachial Index May Loss Time and Funds

Peripheral Arterial Disease Assessment With Photoplethysmography and Continuous-Wave Doppler Ultrasound in Addition to Ankle-Brachial Index May Loss Time and Funds

Photoplethysmography and Continuous-Wave Doppler Ultrasound as a Complementary Test to Ankle–Brachial Index in Detection of Stenotic Peripheral Arterial Disease

We evaluated the sensitivity and specificity of ankle-brachial index (ABI), photoplethysmography (PPG), and continuous-wave Doppler ultrasound (CWD) in the detection of anatomically stenotic peripheral arterial disease (PAD). Ninety-seven patients (194 legs) patients who had coincidentally undergone computed tomography angiography (CTA), ABI, PPG, and CWD for the evaluation of PAD were retrospectively reviewed. Sensitivity and specificity were measured. Among 194 legs, 163 (84%) legs had stenotic PAD on CTA. Overall sensitivity of ABI, PPG, and CWD was 69.3%, 81.6%, and 90.8% and specificity was 96.8%, 77.4%, and 64.5%, respectively. Ankle-brachial index showed a statistically significantly decreased sensitivity (14.8%) for below trifurcation level stenosis compared with CWD (92%) and PPG (67%). The sensitivity of ABI was also significantly decreased in single level and moderate stenosis (45.1% and 42.1%, respectively). In contrast, the sensitivity of CWD and PPG was not significantly decreased. The ABI showed significantly decreased sensitivity especially in stenosis below the trifurcation level. Both PPG and CWD were complementary to ABI in these groups of patients.

Continuous-Wave Doppler Ultrasound

Early noninvasive vascular diagnostic procedures relied heavily on continuous-wave (CW) Doppler ultrasound techniques. Development of CW Doppler instrumentation began in the mid 1950's in Japan with the work of physicist Shigeo Satomura. Donald Baker, an engineer at the University of Washington, working under the direction of pediatric cardiologist Robert F. Rushmer, lead a team that developed the first CW Doppler instrument in the United States in the early 1960's. CW Doppler instruments use two elements to continuously transmit ultrasound waves and to receive signals from moving reflectors within the ultrasound field. CW instruments are less costly and electronically less complex than pulsed Doppler systems. The major disadvantage of CW Doppler is the absence of depth discrimination. Display options include simple “audio” interpretation, analog recordings produced by a zero crossing detector, and spectral Doppler waveforms using fast Fourier analysis. Despite the limitations of CW Doppler techniques, they remain popular today in the assessment of patients in various clinical settings.

Change in blood flow velocity demonstrated by Doppler ultrasound in upper limb after axillary dissection surgery for the treatment of breast cancer

The aim of this study was to evaluate the arterial and venous blood flow in women who underwent upper limb axillary dissection surgery for the treatment of breast cancer. Sixty women were divided into two groups: group 1 (G1)--30 women who underwent breast surgery with axillary dissection level II or III (55.6 ± 8.6 years); group 2 (G2)--control, 30 women with no breast cancer (57.4 ± 7.0 years). Blood flow profile was evaluated by a continuous wave ultrasound Doppler device (Nicolet Vascular Versalab SE) with an 8 MHz probe. Axillary, brachial arteries and veins, arm circumference, volumes, and the ankle-brachial index (ABI) were examined. Wilcoxon test and Mann-Whitney tests were applied to analyze blood flow velocity intra-group and between G1 and G2, respectively. The G1 results showed no lymphedema and no peripheral arterial disease (ABI > 0.9). Moreover, the mean blood flow velocity of the vessels ipsilateral to the surgery was significantly higher than the contralateral ones for all vessels examined (P < 0.05). The mean velocity of blood flow of the vessels contralateral to surgery was significantly higher than the axillary artery in G2 (P < 0.05). It can be concluded that women who underwent axillary dissection due to breast cancer showed probable stenosis in the arterial and venous axillary and brachial vessels of the upper limb ipsilateral to the surgery, confirmed by the increase of blood flow velocity, and such obstruction might affect the limb contralateral to the operation site.

Limited Value of Temporal Artery Ultrasonography Examinations for Diagnosis of Giant Cell Arteritis: Analysis of 77 Subjects

Use of TA-US for diagnostic investigation of giant cell arteritis (GCA) has been proposed but remains a matter of debate because of the heterogeneous findings. We retrospectively evaluated operating characteristics of temporal artery ultrasonography (TA-US) in a single teaching hospital. All subjects with suspected GCA had been seen between 2002 and 2008 and had undergone TA-US with continuous-wave Doppler (until 2004) or color duplex ultrasonography (after 2004), followed within 30 days by a temporal artery biopsy (TAB). TA-US findings were compared with TAB-proven GCA and clinically diagnosed GCA. Results are expressed as sensitivities, specificities, and positive (LR+) and negative likelihood ratios (LR-) of stenoses, occlusions, and the halo sign; for the latter, only color duplex TA-US was considered. Seventy-seven patients fulfilled the selection criteria; 13 had TAB-proven and 19 had clinically defined GCA. Stenoses/occlusions were seen on 45.5% of TA-US and the halo sign was seen only once (3.2%) in 31 duplex TA-US. Respective sensitivities, specificities, LR+, and LR- for GCA diagnosis (using TAB-proven/clinically defined GCA as reference standards) were 69%/53%, 59%/57%, 1.7/1.2, and 0.5/0.8 for stenoses and/or occlusions, and 17%/10%, 100%/100%, infinite/infinite, and 0.8/0.9 for the halo sign. The halo sign showed 100% specificity for GCA but only 10%-17% sensitivity. Stenoses/occlusions were of low diagnostic value. These observations suggest that TA-US is neither an effective substitute for TAB nor a reliable screening test to decide which patients can be safely spared TAB.

411: Inter-Rater Reliability and False Positive Result Rates of Ankle Brachial Index Measurements Performed by Emergency Providers

411: Inter-Rater Reliability and False Positive Result Rates of Ankle Brachial Index Measurements Performed by Emergency Providers

Risk factors and underlying mechanisms for venous stasis syndrome: a population-based case–control study

Venous stasis syndrome may complicate deep vein thrombosis (DVT; i.e. post-phlebitic syndrome), but, in most cases, venous stasis syndrome is not post-phlebitic. The objective of this study was to determine the risk factors (including prior DVT) for venous stasis syndrome, and to assess venous outflow obstruction and venous valvular incompetence as possible mechanisms for venous stasis syndrome. This was a case-control study nested within a population-based inception cohort. The study population consisted of 232 Olmsted County, MN residents with a first lifetime venous thromboembolism (VTE) and 133 residents without VTE. Measurements included a questionnaire and physical examination for venous stasis syndrome; strain gauge outflow plethysmography, venous continuous wave Doppler ultrasonography and passive venous drainage and refill testing for venous outflow obstruction and venous valvular incompetence. Altogether, 161 (44%), 43 (12%), and 136 (38%) subjects respectively, had venous stasis syndrome, venous outflow obstruction and venous valvular incompetence. Independent risk factors for venous stasis syndrome included increasing patient age and body mass index (BMI), prior DVT, longer time interval since DVT, and varicose veins. Both venous outflow obstruction (p = 0.003) and venous valvular incompetence (p < 0.0001) were strongly associated with venous stasis syndrome. Increasing age and prior DVT were significantly associated with venous outflow obstruction, while prior DVT, varicose veins and venous stasis syndrome diagnosed prior to the incident DVT were significantly associated with venous valvular incompetence. The risks of venous outflow obstruction, venous valvular incompetence and venous stasis syndrome were higher with left leg DVT. In conclusion, increasing patient age and BMI, prior DVT (particularly left leg DVT), longer time interval since DVT and varicose veins are independent risk factors for venous stasis syndrome. Venous stasis syndrome related to DVT is due to venous outflow obstruction and venous valvular incompetence, while venous stasis syndrome related to older age and to varicose veins is due to venous outflow obstruction and to venous valvular incompetence, respectively.

Pathophysiology underlying irritable bowel syndrome -From the viewpoint of dysfunction of autonomic nervous system activity-

Although irritable bowel syndrome (IBS) is the most common gastrointestinal disease and is found in up to 50% of patients referred to gastroenterologists, its pathogenesis remains unexplained. Lately most attention has been focused on visceral hypersensitivity related to dysfunction of the autonomic nervous system. Although there have been many reports regarding the autonomic nervous system in IBS patients, the results have not always been consistent. In many studies, increased sympathetic nervous system activity and decreased parasympathetic nervous system activity have been the most frequently noted differences when IBS patients are compared with healthy controls. There are also some differences among IBS symptom subgroups and some differences between men and women. Data from previous studies have been inconsistent, with complicating factors resulting in difficulties in classification and the possibility of multiple physiological pathways for a similar symptom picture. Further studies based on the Rome III criteria are required to evaluate whether or not autonomic functions significantly differ from each other. However, although there are many methods of measurement for evaluation of the autonomic nervous system, there are few of these methods that are not only accurate but also cost-effective, non-invasive, and easy to perform. Recently, we developed a new method with the abovementioned advantages for measuring fingertip blood flow in evaluating the autonomic nervous system by continuous-wave Doppler sonography. Using this method, we found that abnormal fingertip blood flow responses suggested the presence of excess sympathetic activity.