Systematic Review of the Use of Power Doppler Ultrasound in the Imaging of Peripheral Nerve Compression Neuropathy.

BACKGROUND: Power Doppler ultrasonography has been used as an adjunct in the diagnosis of peripheral nerve compression neuropathy. To better characterize its sensitivity and specificity, the authors performed a systematic review of its use in carpal and cubital tunnel syndrome diagnosis. METHODS: The authors systematically reviewed published literature on the use of power Doppler ultrasound to diagnose peripheral compression neuropathy using Ovid MEDLINE, Embase.com, Scopus, Cochrane Database of Systematic Reviews, Cochrane Central Register of Controlled Trials, Database of Abstracts of Reviews of Effects, Health Technology Assessment Database, NHS Economic Evaluation Database, World Health Organization International Clinical Trial Repository Platform, and Clinicaltrials.gov. No filters for language, date, or publication type were used. RESULTS: After reviewing 1538 identified studies, 27 publications were included involving 1751 participants with compression neuropathy (2048 median and 172 ulnar). All but three studies examined patients with carpal tunnel syndrome. Heterogeneity between study design and methodology was a noted limitation. Sensitivity and specificity of power Doppler ultrasound in the diagnosis of carpal tunnel syndrome ranged from 2.2 to 93.4 percent, and 89 to 100 percent, respectively, whereas sensitivity for cubital tunnel syndrome was 15.3 to 78.9 percent. There was variability in power Doppler signal detection based on location, with higher sensitivities at the carpal tunnel inlet and in areas of increased nerve swelling. CONCLUSIONS: Power Doppler ultrasound is unreliable as a screening test but appears to increase diagnostic accuracy of ultrasonography in compression neuropathies. It is most beneficial in moderate to severe disease and may be valuable in detecting early cases and in disease surveillance.

Point-of-Care Ultrasound in the Evaluation of COVID-19.

BACKGROUND: The novel coronavirus SARS-CoV-2 has caused a pandemic, overwhelming health care systems around the world. Hospitals around the world, including the United States, have been struggling to adapt to the influx of patients with COVID-19, the illness caused by SARS-CoV2, given limited resources and high demand for medical care. OBJECTIVES: This article seeks to provide emergency physicians with a guide to sonographic findings in COVID-19 and an algorithm by which point-of-care lung ultrasound may assist emergency physicians caring for these patients during the SARS-CoV-2 pandemic. DISCUSSION: The studies currently being published have established a typical set of ultrasound findings in COVID-19. Point-of-care lung ultrasound is rapid and accessible in most emergency departments in the United States, and even in many resource-poor settings. CONCLUSION: Point-of-care ultrasound provides numerous benefits to emergency providers caring for patients with COVID-19, including decreasing resource utilization, assisting in diagnosis, guiding management of the critically ill patient, and aiding in rapid triage of patients under investigations for COVID-19.

Lower limb vascular assessment techniques of podiatrists in the United Kingdom: a national survey.

BACKGROUND: Podiatric vascular assessment practices in the United Kingdom (UK) are currently unknown. This study aimed to describe the current practices for performing lower limb vascular assessments by podiatrists in the UK, and, to investigate the effect of practitioner characteristics, including education level and practice setting, on the choice of tests used for these assessments. METHODS: A cross-sectional observational online survey of registered podiatrists in the UK was conducted using SurveyMonkey® between 1st of July and 5th of October 2018. Item content related to: practitioner characteristics, vascular testing methods, barriers to completing vascular assessment, interpretation of vascular assessment techniques, education provision and ongoing management and referral pathways. Descriptive statistics were performed, and multinomial logistic regression analyses were used to determine whether practitioner characteristics could predict the choice of vascular tests used. RESULTS: Five hundred and eighty five participants accessed the online survey. After drop-outs and exclusions, 307 participants were included in the analyses. Comprehensive vascular assessments had most commonly been performed once (15.8%) or twice (10.4%) in the past week. The most common indicators for performing vascular assessment were symptoms of suspected claudication (89.3%), suspected rest pain (86.0%) and history of diabetes (85.3%). The most common barrier to performing vascular assessment was time constraints (52.4%). Doppler examination (72.3%) was the most frequently reported assessment type, with ankle-brachial index (31.9%) and toe brachial index (5.9%) less frequently performed. There were variable interpretations of vascular test results. The most common topic for education was smoking cessation (69.5%). Most participants (72.2%) were confident in determining ongoing management, with the majority referring to the patient's general practitioner (67.6%). Practitioner characteristics did not predict the types of vascular tests performed. CONCLUSION: The majority of vascular assessments currently performed by podiatrists in the UK are inconsistent with UK or international vascular guidelines and recommendations. Despite this, most podiatrists felt confident in diagnosing, referring and managing patients with peripheral arterial disease (PAD), however many felt they needed more education to feel confident to assist patients with PAD to manage their cardiovascular risk factors.

Assessment of reproducibility and repeatability of cerebro-placental ratio.

INTRODUCTION: To test the reproducibility and repeatability of the cerebro-placental ratio. STUDY DESIGN: Pregnant women with a singleton pregnancy and secure dating were invited to participate after 24 weeks of pregnancy. Using recommended technique, umbilical artery PI was measured from the free loop of the umbilical cord and from the fetal end by one examiner in a state of fetal quiescence, generating four measurements per fetus. Fetal middle cerebral artery PI was also obtained. Cerebro-placental ratio (CPR) was calculated as MCA PI/Umbilical artery PI. Variability of the CPR on the two sampling occasions was tested using Pitman test of equality of variance for related samples. The difference between the two sets of CPR measurements was plotted against the mean to generate 95% limits of agreement. RESULTS: A total of 158 women were recruited. The mean CPR was significantly lower when the umbilical artery PI was obtained at the para-vesical site, than when it in obtained from a free loop (p < 0.001). No significant correlation was seen between gestational age and CPR, when the umbilical artery PI was measured from the para-vesical site (r = -0.079, p = 0.323) or the free loop (r = -0.103, p = 0.198). Total variance of the CPR using the umbilical artery free loop was 0.286, and that using the para-vesical site of the umbilical artery was 0.164. Pitman's test showed that the total variability of CPR at the two sites was significantly different (r = 0.254, p < 0.001). The variability of CPR was significantly lower if the umbilical artery PI measurement was taken at the fetal end than that in the free loop. CONCLUSION: The mean CPR site was significantly lower when the umbilical artery PI was obtained at the para-vesical than in the free loop. Measurement site for the umbilical artery PI contributes to a significant proportion to the total variability of the cerebro-placental ratio. CPR measurements should include umbilical artery PI measurements at the para-vesical site rather than the free loop of the umbilical cord in order to improve repeatability. Appropriate reference ranges for the interpretation of CPR will be needed.

Head and Neck Surgical Oncology Choosing Wisely Campaign: imaging for patients with hoarseness, fine needle aspiration for neck mass, and ultrasound for odynophagia.

Choosing Wisely Canada, is a campaign designed to raise awareness regarding inappropriate or unnecessary tests and treatments. The Canadian Society of Otolaryngology - Head & Neck Surgery and the Canadian Association of Head and Neck Surgical Oncologists developed a Choosing Wisely Canada list to help promote high quality care for patients presenting with disorders of the head and neck: (1) Don't order imaging - computer tomography (CT) or magnetic resonance imaging (MRI) - as the initial investigation for patients presenting with a chief complaint of hoarseness, (2) Don't perform an open biopsy or excision of a neck mass without having first considered a fine needle aspiration (FNA) biopsy and, (3) Don't order neck ultrasound to investigate odynophagia (discomfort or pain with swallowing) or globus sensation.

The effect of point-of-care ultrasonography on imaging studies in the medical ICU: a comparative study.

BACKGROUND: Point-of-care ultrasonography performed by frontline intensivists offers the possibility of reducing the use of traditional imaging in the medical ICU (MICU). We compared the use of traditional radiographic studies between two MICUs: one where point-of-care ultrasonography is used as a primary imaging modality, the other where it is used only for procedure guidance. METHODS: This study was a retrospective 3-month chart review comparing the use of chest radiographs, CT scans (chest and abdomen/pelvis), transthoracic echocardiography performed by the cardiology service, and DVT ultrasonography studies performed by the radiology service between two MICUs of similar size and acuity and staffing levels. RESULTS: Total number of admissions, patient demographics, and disease acuity were similar between MICUs. Comparing the non-point-of-care ultrasonography MICU with the point-of-care ultrasonography MICU, there were 3.75 ± 4.6 vs 0.82 ± 1.85 (P < .0001) chest radiographs per patient, 0.10 ± 0.31 vs 0.04 ± 0.20 (P = .0007) chest CT scans per patient, 0.17 ± 0.44 vs 0.05 ± 0.24 (P < .0001) abdomen/pelvis CT scans per patient, 0.20 ± 0.47 vs 0.02 ± 0.14 (P < .0001) radiology service-performed DVT studies per patient, and 0.18 ± 0.40 vs 0.07 ± 0.26 (P < .0001) cardiology service-performed transthoracic echocardiography studies per patient, respectively. CONCLUSIONS: The use of point-of-care ultrasonography in an MICU is associated with a significant reduction in the number of imaging studies performed by the radiology and cardiology services.

Older adults with heel ulcers in the acute care setting: frequency of noninvasive vascular assessment, surgical intervention, and 1-year mortality.

OBJECTIVES: To examine how often hospitalized older adults with a diagnosis of heel ulcers are evaluated with noninvasive vascular tests and to determine the impact of invasive vascular or surgical procedures on 1-year mortality. DESIGN: Retrospective review using an electronic database and chart review of all patients discharged with a diagnosis of heel ulcer between 2006 and 2009. SETTING: Urban teaching hospital. PARTICIPANTS: A total of 506 participants aged 65 years and older. MEASUREMENTS: Data collected included resident characteristics (demographics, medical history, and severity of illness using the Charlson comorbidity index), staging of heel ulcers, rates of noninvasive vascular assessments, vascular and surgical procedures, length of stay, and 1-year mortality. RESULTS: Thirty-one percent (155/506) of patients with a heel ulcer underwent noninvasive vascular testing and of these 83% (129/155) were found to have underlying ischemia. Twenty-six percent (130/506) of patients underwent at least 1 vascular or surgical procedure. The 1-year mortality rate for patients with stage 1 or 2 disease was 55%; this rose to 70% for patients with stage 3 or 4 ulcers (P = .01), and could not be explained by differences in the Charlson comorbidity index. Patients who underwent a vascular or surgical procedure had a significantly lower mortality compared with those who did not (59% vs 68% P = .04). CONCLUSION: Older adults with a heel ulcer in the acute care setting are frequently not assessed for underlying ischemia of the lower extremities. The diagnosis carries high 1-year mortality rates. Evidence-based protocols need to be developed to determine which older adults should have a vascular assessment and then undergo an invasive procedure.

Noncardiac point-of-care ultrasound by nonradiologist physicians: how widespread is it?

PURPOSE: The use of point-of-care (POC) ultrasound by nonradiologist physicians has recently been advocated. The aim of this study was to see how widespread this practice is. METHODS: The Medicare Part B databases for 2004 to 2009 were used. Global and professional component claims for noncardiac ultrasound were tabulated, and utilization rates per 1,000 beneficiaries were calculated. Provider specialty was determined. Utilization rates of ultrasound by radiologists and other specialists were compared, and changes over the years were studied. RESULTS: In 2009, 425.3 Medicare noncardiac ultrasound examinations per 1,000 beneficiaries were performed (+21% since 2004). Of these, radiologists performed 233.7 (55%), and another 15.6 (4%) were done at independent diagnostic testing facilities, for which provider specialty could not be determined. The remaining 175.7 (41%) constituted POC ultrasound by nonradiologists. Between 2004 and 2009, radiologists' utilization rate increased by 17%, compared with 28% for nonradiologists. Radiologists' market share of noncardiac ultrasound was 56.6% in 2004 and 54.9% in 2009. Other major specialties involved in POC ultrasound and their 2009 rates per 1,000 and percentage increases since 2004 were cardiology (39.7 [+60%]), vascular surgery (34.9 [+36%]), primary care (27.2 [+11%]), general surgery (24.2 [+8%]), and urology (22.3 [+12%]). CONCLUSIONS: Between 2004 and 2009, there was a 21% increase in the overall utilization rate of noncardiac ultrasound. Point-of-care ultrasound by nonradiologists amounted to 41% of all studies done in 2009. Multiple nonradiologic specialties are involved, but radiologists' involvement is far higher than any other single specialty. Radiologists' ultrasound market share remained relatively stable between 2004 and 2009.

Ultrasound imaging for the rheumatologist XXXV. Sonographic assessment of the foot in patients with osteoarthritis.

OBJECTIVES: The aims of our study were to investigate the prevalence of ultrasound (US) abnormalities in the foot of patients with osteoarthritis (OA) and to compare them with clinical findings. METHODS: Consecutive patients with foot OA were investigated by clinical and US examinations. Bilateral US of the midfoot and forefoot joints was performed by using a Logiq9 machine, equipped with a multi-frequency linear probe, operating at 14 MHz; in addition, power Doppler was applied (frequency 7.5 MHz; gain 50%; PRF 750 Hz). Clinical evaluation included the registration of demographic data, disease duration, current treatment undergone, joint swelling and tenderness. US study included the assessment of both inflammatory (joint effusion, synovial hypertrophy, local pathologic vascularisation at PD, big-toe bursitis) and structural (osteophytes, MTP joints subluxation) abnormalities. RESULTS: One hundred patients were studied. At midfoot level, clinical examination demonstrated signs suggestive for joint inflammation (tenderness and/or swelling) in at least one joint in 43/200 feet (21.5%) of 23 patients; US showed inflammatory abnormalities in 87/200 feet (43.5%) of 63 patients and structural lesions in 100/200 feet (50%) of 70 patients. At forefoot level, clinical examination found inflammatory signs in at least one joint in 128 feet (64%) of 64 patients; US showed inflammatory abnormalities in at least one joint in 176 feet (88%) of 88 patients and structural lesions in 189 feet (86%) of 86 patients. CONCLUSIONS: US is a useful imaging tool for analysing both inflammatory and structural damage lesions at foot joints level in OA. In addition, it demonstrated to be more sensitive than clinical examination in the detection of inflammatory abnormalities.

Trends in utilization rates of the various imaging modalities in emergency departments: nationwide Medicare data from 2000 to 2008.

PURPOSE: To study utilization trends in the various imaging modalities in emergency departments (EDs) over a recent multiyear period. METHODS: The nationwide Medicare Part B databases for 2000 to 2008 were queried. Medicare's location codes were used to identify imaging examinations done on ED patients. All diagnostic imaging Current Procedural Terminology(®) codes were grouped by modality. For each code, the database provides procedure volume; utilization rates per 1,000 beneficiaries were then calculated. Medicare's physician specialty codes were used to determine provider specialty. Utilization trends were studied between 2000 and 2008. RESULTS: The overall utilization rate per 1,000 beneficiaries for all imaging in EDs increased from 281.0 in 2000 to 450.4 in 2008 (+60%). The radiography utilization rate rose from 227.3 in 2000 to 294.3 in 2008 (+29%, 67 accrued new studies per 1,000). The CT rate rose from 40.0 in 2000 to 130.7 in 2008 (+227%, 90.7 accrued new studies per 1,000). The ultrasound rate rose from 9.6 in 2000 to 18.7 in 2008 (+95%, 9.1 accrued new studies per 1,000). Other modalities had much lower utilization. In 2000, CT constituted 14% of all ED imaging, but by 2008, it constituted 29%. In 2008, radiologists performed 96% of all ED imaging examinations. CONCLUSIONS: The rate of utilization of imaging is increasing in EDs. Growth is by far the most pronounced in CT, in terms of both the growth rate itself and the actual number of accrued new studies per 1,000 beneficiaries. Radiologists strongly predominate as the physicians of record for all ED imaging.

Early measurement of pulsatility and resistive indexes: correlation with long-term renal transplant function.

PURPOSE: To correlate pulsatility index (PI) and resistive index (RI) measured at early specific intervals after transplantation with 1-year estimated glomerular filtration rate (eGFR) and death-censored transplant survival to assess the long-term prognostic value of these Doppler indexes. MATERIALS AND METHODS: The local ethics committee was consulted, and no formal approval was required. This retrospective review included 178 consecutive patients (111 male, 67 female; mean age, 43.9 years ± 13.4 [standard deviation]; age range, 16-72 years) undergoing first deceased-donor renal transplantation between 1997 and 2000. All patients were identified from a prospectively maintained database. Spectral Doppler analysis was performed within 1 week after transplantation in all patients and between 1 week and 3 months after transplantation in 124 patients. Average PI and RI were determined from measurements obtained in the upper, lower, and interpolar regions. For statistical analysis, the χ(2) test, analysis of variance, the Student t test, Kaplan-Meier survival plots, and Cox proportional hazards models were used. RESULTS: Within 1 week after transplantation, there was a significant association between PI and 1-year eGFR when analyzed as tertiles (P = .02). Between 1 week and 3 months after transplantation, there was a significant relationship between 1-year eGFR and both PI and RI when comparing the lowest and highest tertiles (47.5 mL/min/1.73 m(2) for PI <1.26 vs 32.7 mL/min/1.73 m(2) for PI >1.49 [P = .01], 42.8 mL/min/1.73 m(2) for RI <0.69 vs 32.3 mL/min/1.73 m(2) for RI >0.74 [P = .03]). Both PI and RI were independent predictors of death-censored transplant survival (hazard ratio, 1.68 per unit [P < .001] and 260.4 per unit, respectively [P = .02]). CONCLUSION: PI and RI in the early posttransplantation period correlate with long-term transplant function and can potentially be used as prognostic markers to aid risk stratification for future transplant dysfunction.

Frequency and outcome of carotid atheromatous disease in patients with stroke in Pakistan.

BACKGROUND AND PURPOSE: Limited data exist on the frequency and outcome of carotid artery disease in Pakistan. Such information would help guide the usefulness of screening for the condition in this low-middle income health care setting. METHODS: A prospective, descriptive study was conducted among 3 large teaching hospitals in Karachi, Pakistan. Patients referred for carotid Doppler ultrasound examination were included if they had experienced a stroke or TIA within the previous month. The severity and morphology of carotid disease were characterized by trained technicians using standardized criteria. Demographic and risk factor data were collected at baseline, and the outcome of patients was assessed at least 6 months later. RESULTS: A total of 672 patients underwent bilateral carotid Doppler ultrasound (1344 carotid examinations). The findings revealed 0% to 50% stenosis in 526 (78%), 51% to 69% stenosis in 57 (8%), 70% to 99% stenosis in 82 (12%), and total occlusion in 7 patients (1%). Potentially surgically correctable disease, defined as 70% to 99% carotid artery stenosis, was present in only 79 (12%) patients, of whom 47 (60%) were ipsilateral symptomatic, 15 (20%) asymptomatic, and 17 (20%) had status unknown. Outcome information at >or=6 months follow-up was available for 36 of the 47 (76%) surgically correctable and only 4 of these patients (12%) had undergone surgical or radiological intervention (carotid endarterectomy in 3 patients and carotid stenting in 1 patient). CONCLUSIONS: The frequency of carotid artery disease of at least moderate severity is very low in patients with recent stroke or TIA and there is low utilization of high-cost, carotid intervention procedures in Pakistan. These data raise questions regarding the applicability and cost-effectiveness of routine carotid ultrasound screening in our country and similar population in Asia. The local socio-economic and clinical data do not support routine carotid Doppler ultrasound in every patient with stroke and TIA in Pakistan. Studies are warranted to determine predictors of significant carotid artery stenosis in stroke/TIA patients of our country to develop reliable stroke guidelines appropriate for local population.

Survey of Doppler use in lymphoedema practitioners in the UK.

Lymphoedema practitioners anecdotally don't use Doppler in the vascular assessment of their patients prior to the application of compression. The belief is that the results are inaccurate in the presence of oedema. The objective of this article is to gather information about the use of Doppler by lymphoedema specialists in the vascular assessment of lymphoedema patients in the UK. A questionnaire on the use of Doppler in lymphoedema patients was distributed to 250 delegates attending the British Lymphology Society Conference in Glasgow in Ocotber 2005. There appears to be no consensus in the method of vascular assessment of lymphoedema patients. More research is needed to ascertain the accuracy of Doppler in the assessment of lymphoedema patients. Guidelines are also required in the vascular assessment of lymphoedema patients based on scientifically valid evidence.

Micro-ultrasound imaging assessment of carotid plaque characteristics in apolipoprotein-E knockout mice.

This study was aimed to test the hypothesis that noninvasive assessment of carotid plaques can be achieved by high-resolution micro-ultrasound imaging in apolipoprotein-E knockout (apoE-KO) mice. Forty-two male apoE-KO mice were fed a high-fat diet and atherosclerotic lesions in the left common carotid artery were induced by perivascular placement of constrictive collars. Eight weeks after surgery, all mice were divided into interventional group (n=21) which received mental stress stimulation and intraperitoneal injection of lipopolysaccharide, and control group (n=21) which received only 0.9% sodium chloride solution for 4 weeks. Plaque morphology and flow velocities were evaluated by micro-ultrasonography. The results showed that micro-ultrasound imaging and corresponding cross-sectional histopathology data revealed positive correlations for plaque area, intima-medial thickness (IMT), eccentric index (EI) and remodeling index (RI) (all p<0.05). Ultrasound-derived IMT, EI and RI in the ruptured plaques were significantly greater than those in the nonruptured plaques (all p<0.05). Maximal flow velocity (Vmax) was higher in the ruptured plaque sites compared with nonruptured plaques sites (p<0.001). Multivariate logistic regression analysis revealed that IMT and Vmax were independent predictors of plaque rupture. In conclusion, micro-ultrasound imaging provides a reliable approach to the noninvasive and quantitative assessment of carotid plaques in apoE-KO mice.

Community nurse use of Doppler ultrasound in leg ulcer assessment.

Doppler ultrasound is used by community nurses to measure the ankle brachial pressure index (ABPI). This is required before applying compression therapy for patients with chronic venous insufficiency and venous leg ulcers.However, emphasis on the ABPI result has resulted in inappropriate referrals to the vascular department which led the author to survey current practice within one primary care trust. Results illustrated variations in how nurses obtain training and maintain their competency in using Doppler ultrasound. This has an impact on the accuracy of interpretation of the ABPImeasurement and subsequent management of the patient. Practical issues also explained the difficulties nurses encountered in using the correct procedure within the community, which may result in unreliable measurements. There is a need to standardize training for all community nurses, and to review the structure of current clinical guidelines to enable a wider analysis of arterial assessment, in order to reduce the emphasis purely on the ABPI measurement.

Power Doppler ultrasound assessment of ovarian perifollicular blood flow in women with polycystic ovaries and normal ovaries during in vitro fertilization treatment.

OBJECTIVE: To evaluate whether ovarian perifollicular blood flow (PFBF) varies by ultrasound among women with polycystic and normal ovaries undergoing in vitro fertilization (IVF). DESIGN: Prospective observational cohort study of women undergoing IVF treatment. SETTING: Department of reproductive medicine at a university teaching hospital. PATIENT(S): Thirty four women with regular spontaneous ovulatory menstrual cycles undergoing IVF divided into two groups according to findings on a baseline transvaginal ultrasound scan: group 1 consisted of 20 women with ultrasound-evident normal ovaries (USNO group), and group 2 consisted of 14 women with ultrasound-evident polycystic ovaries (USPCO group). INTERVENTION(S): Serial transvaginal power Doppler ultrasound assessments throughout the follicular phase of ovarian stimulation. MAIN OUTCOME MEASURE(S): Ovarian PFBF and ovarian stromal artery pulsatility index. RESULT(S): Women with USPCO had a significantly lower ovarian stromal artery pulsatility index at the time of the first ultrasound assessment before starting the FSH injections compared with USNO women. However, there was no difference in ovarian PFBF between women with USPCO and USNO during the follicular phase of ovarian stimulation for IVF. CONCLUSION(S): There is no difference in ovarian follicular vascularity between women with polycystic and normal ovaries during ovarian stimulation at IVF treatment.

Change in stroke volume in response to fluid challenge: assessment using esophageal Doppler.

OBJECTIVE: To compare two methods of assessing a change in stroke volume in response to fluid challenge: esophageal Doppler and thermodilution with the pulmonary artery catheter. DESIGN: Prospective study. SETTING: Department of Intensive Care of a university medical center. PATIENTS: 19 adult patients, intubated and sedated, with a pulmonary catheter and a clinical indication for a fluid challenge. INTERVENTIONS: Two examiners independently assessed the effect of a fluid challenge on stroke volume and cardiac output with esophageal Doppler. Thermodilution performed by an independent clinician was used as the reference. Between-method variation and interobserver variability of the Doppler method were assessed. MEASUREMENTS AND RESULTS: There were no differences in stroke volume and cardiac output before volume challenge when measured with either of the two methods or by the two examiners using the esophageal Doppler. Despite a small bias between the methods and the two examiners using the esophageal Doppler (overall bias for cardiac output 0.3 l/min), the precision was poor (1.8 l/min). CONCLUSIONS: The esophageal Doppler method is a non-invasive alternative to the pulmonary artery catheter for the assessment of stroke volume in critically ill patients. Measurement of stroke volume response to fluid challenge using esophageal Doppler shows substantial interobserver variability. Despite the poor precision between methods and investigators, similar directional changes in stroke volume can be measured.

Illustrative estimates of costs and effects of the use of Doppler ultrasonography in high-risk pregnancies.

OBJECTIVES: To examine the cost-effectiveness of Doppler ultrasonography in high-risk pregnancies. METHODS: An analysis was made of the cost-effectiveness of Doppler ultrasonography in high-risk pregnancies in relation to different organizational models. National costs of Doppler ultrasonography for singleton pregnancies with intrauterine growth retardation were estimated for three models. The cost-effectiveness analysis was based on results from a meta-analysis on clinical effects, patient costs, immediate health care costs, and costs per "saved" perinatal death. RESULTS: In the decentralized model (the current situation in Denmark), incremental health care costs were estimated to be 13.5 million DKK, with patient costs set at zero. In the regional and centralized models, the estimated costs were 9.3 million/0.9 million DKK and 3.4 million/2.6 million DKK, respectively. The incremental costs were more than outweighed by the savings made from significant reductions in obstetric interventions. The centralized model dominated the other two models in the cost-effective analysis. In the decentralized model, the costs of avoiding one perinatal death were estimated to be 1 million DKK. The sensitivity analysis suggested that the cost-effectiveness ratio differed considerably, depending on the assumptions used, although the rank order of the three models did not change. CONCLUSIONS: The cost-effectiveness analysis showed that a centralized model with five obstetric centers offering Doppler ultrasonography dominates the regional and decentralized models. However, even with the decentralized model (which reflects the current situation in Denmark), the costs of avoiding one perinatal death would seem to be reasonable. In view of the paucity of available cost and effects data and the sensitivity of the results to changes in the assumptions made, more reliable information is needed before a decision can be made regarding the organization of Doppler ultrasonography for high-risk pregnancies.

Doppler sonography for the assessment of central mandibular blood flow.

In this study we evaluated the role of Doppler sonography in the assessment of central mandibular blood flow. We assessed the characteristics of blood flow in the mental artery, the larger terminal branch of the inferior alveolar artery, in 30 healthy volunteers equally distributed in the age groups 20-39, 40-59 and over 60 years. We used a DWL Multi-Dop X4(R) Doppler sonography machine (DWL GmbH) with an 8 MHz probe applied intraorally. The variables analysed were patency, time averaged maximum velocity (TAMV), pulsatility index (PI), discomfort and the duration of the procedure. All the arteries analysed were patent. The TAMV and PI decreased as age increased and there were significant differences between the age groups: TAMV (P = 0.01), PI (P = 0.006). Pair-wise comparisons also showed significant differences (P< 0.05) between the 20-39 and the over 60 age group, 40-59 and the over 60 age group for TAMV, and between the 20-39 and over 60 age group for PI. The difference in measurements between the right and left sides in individual patients was not significant. The assessment took about 20 minutes and caused little discomfort. The technique is simple and could potentially be used to influence clinical decisions.

Assessment of coronary stenoses by Doppler wires: a validation study using in vitro modeling and computer simulations.

The present study evaluates the use of intracoronary velocity measurements by Doppler guidewires for assessing coronary obstructions. In vitro experiments were performed in a flow model using acrylic phantoms of coronary stenoses with different configurations (stenosis area: 56%, 75% and 89%; stenosis length: 1 and 5 mm; stenosis border: tapering or abrupt). Nonpulsatile laminar flow conditions of a test fluid were established at flow rates ranging from 0.5 to 2.0 mL/s to simulate baseline flow and flow after vasodilation. Peak Doppler velocity was measured proximal to, within and distal to the model stenoses. Computer simulations were employed to calculate radial flow profiles with and without a Doppler wire aligned with the vessel center. In 84 in vitro flow experiments, peak Doppler velocity correlated well with the average flow velocity as calculated from the actual flow rate and the vessel's cross-sectional area proximal to (r = 0.98, SEE = 1.4, p < 0.001) and within (r = 0.97, SEE = 16.4, p < 0.001) the stenosis. However, the ratio of calculated average velocity to Doppler-measured peak velocity was significantly different from 0.5, the expected value for a parabolic flow profile (0.76+/-0.08, 0.81+/-0.14; p < 0.001). Acceptable accuracy was found for the Doppler estimation of stenosis severity using the continuity equation (error: 0.9+/-1.2% and -4.6+/-3.5% for stenosis with a length of 5 mm and 1 mm, respectively). Doppler velocity reserve significantly underestimated the true flow reserve for the 56% and 75% stenoses (p < 0.01). Computer simulations demonstrated significant alterations of flow profiles by the wire, which explained the observed underestimation of the true flow reserve by the Doppler velocity reserve. Thus, Doppler guidewire measurements of intracoronary flow velocities are useful to assess the severity of coronary stenoses. However, the in vitro results and computer simulations indicate that guidewires alter the flow profile, so that Doppler velocity reserve may underestimate the true flow reserve.