Angle-dependence and reproducibility of dual-beam vector doppler ultrasound in the common carotid arteries of normal volunteers.

Dual-beam vector Doppler has the potential to improve peak systolic blood velocity measurement accuracy by automatically correcting for the beam-flow Doppler angle. Using a modified linear-array system with a split receive aperture, we have assessed the angle-dependence over Doppler angles of 40 degrees -70 degrees and the reproducibility of the dual-beam blood maximum velocity estimate measured in the common carotid arteries (CCA) 1 to 2 cm prior to the bifurcation of 9 presumed-healthy volunteers. The velocity magnitude estimate was reduced by approximately 7.9% as the angle between the transmit beam and the vessel axis was increased from 40 degrees to 70 degrees. With repeat measurements made, on average, approximately 6 weeks apart, the 95% velocity magnitude limits of agreement were as follows: Intraobserver -41.3 to +45.2 cm/s; interobserver -29.6 to +46.8 cm/s. There was an 8.6 cm/s interobserver bias in velocity magnitude. We conclude that the dual-beam vector Doppler system can measure blood velocity within its scan plane with low dependence on angle and with similar reproducibility to that of single-beam systems.

Moxifloxacin (Avelox) for the treatment of bacterial skin infections.

Moxifloxacin (Avelox, Bayer), which is available for oral administration, is a broad-spectrum synthetic antimicrobial agent with excellent Gram-positive activity and good Gram-negative activity. The US FDA recently approved this drug for the treatment of bacterial skin infections.

Moxifloxacin versus cephalexin in the treatment of uncomplicated skin infections.

The efficacy and safety of oral moxifloxacin (400 mg once daily, 7 days) versus cephalexin (500 mg three times daily, 7 days) were compared in a prospective, multicentre, randomised, double-blind trial in 401 adults with uncomplicated skin infections. Clinical outcome was evaluated in 351 patients. Moxifloxacin proved to be as effective as cephalexin both clinically (90% versus 91%, respectively) and bacteriologically in eradicating the most frequently isolated pathogen Staphylococcus aureus (92% and 93%, respectively). Moxifloxacin was more effective than cephalexin in eliminating Streptococcus spp. (90% and 82%, respectively). Drug-related adverse events were comparable in both treatment groups with the most frequently reported being nausea in the moxifloxacin-treated patients and headache in the cephalexin-treated patients. Medication was discontinued due to unwanted reactions in 3% of the moxifloxacin- and 4% of the cephalexin-treated patients. Moxifloxacin, 400 mg once daily for 7 days, is as safe and effective as cephalexin 500 mg three times daily for 7 days in the treatment of uncomplicated skin infections.

Doppler backscatter properties of a blood-mimicking fluid for Doppler performance assessment.

The Doppler backscatter properties of a blood-mimickig fluid (BMF) were studied to evaluate its suitability for use in a Doppler flow test object. Measurements were performed using a flow rig with C-flex tubing and BMF flow produced by a roller pump or a gear pump. A SciMed Doppler system was used to measure the backscattered Doppler power with a root-mean-square power meter connected to the audio output. Studies investigated the dependence of the backscattered Doppler power of the BMF with: circulation time; batch and operator preparations; storage; sieve size; flow speed; and pump type. A comparison was made with human red blood cells resuspended in saline. The backscatter properties are stable and within International Electrotechnical Commission requirements. The BMF is suitable for use in a test object for Doppler performance assessment.

A 2-year study of liquid nitrogen therapy in cutaneous leishmaniasis.

BACKGROUND: Among the different modalities for treatment of cutaneous leishmaniasis, liquid nitrogen is considered an effective therapy with very mild side-effects. METHODS: A study was conducted using liquid nitrogen topically for the treatment of cutaneous leishmaniasis in the King Hussain Medical Centre, Amman-Jordan. Among 468 patients of cutaneous leishmaniasis, 293 were treated with liquid nitrogen and the rest were treated with other known treatment modalities. RESULTS: Of the patients treated with cryo surgery liquid nitrogen, 215 of 293 permitted appropriate follow-up; the clinical response was significant and effective. No systemic adverse effects were noted. Mild cutaneous complications were infrequent, and included hypopigmentation, hyperpigmentation, and scar formation. CONCLUSIONS: From the results of this study, liquid nitrogen therapy may be considered an effective treatment for cutaneous leishmaniasis.

Ectoparasites as sexually transmitted diseases.

Although Sarcoptes scabii and Phthirus pubis infestations in humans are not always associated with the presence of other sexually transmitted diseases, usually they are. Therefore, patients presenting with scabies or P. pubis should be routinely tested for various sexually transmitted diseases. These very uncomfortable infestations are easily curable with proper therapy. Lindane 1% preparations effectively exterminate both vermin. We have not seen any resistant strains. Especially with P. pubis, all household contacts should be treated to avoid reinfestation.

Filariasis.

Filariasis is found in many tropical and subtropical countries. Approximately 10% of patients with filariasis enter the end stage of the disease known as elephantiasis. The obstruction of the lymphatic system leads to massive swelling and ulceration, especially of the legs, causing deformity and difficulty in movement and function. The condition is preventable with control of the vector and early drug therapy.

On the Doppler signal from a steady flow asymmetrical stenosis model: effects of turbulence.

A steady flow model with a 70% (by area) asymmetrical stenosis was used to examine how changing flow regimes (laminar to turbulent) affect the Doppler signal. Human red blood cells (RBCs) (Hct = 42%) in saline were employed at a flow rate corresponding to a Reynold's number of approximately 545. A dilute suspension of 4% fixed RBCs was also used for the purpose of backscattered power comparison. Measurements of the Doppler signal enabled the backscattered power, time domain statistics, frequency spectra, frequency domain statistics, various spectral indices, autocorrelation function and decorrelation time to be calculated as a function of distance from the stenosis. It is shown that the characteristics of the Doppler signal measured at each site provide information on the nature of the insonated flow field and these correlate well with those expected. The results demonstrate that the onset of turbulence not only affects the Doppler spectrum but also has a profound effect on the signal power, the decorrelation time and the signal statistics.

Weak reflection of ultrasound by elements arranged in the steps of a one-dimensional random walk, with reference to backscatter by blood.

Blood backscatters ultrasound primarily because the erythrocytes (red blood corpuscles) have a specific acoustic impedance slightly different from that of the surrounding plasma. In an attempt to explain some of the main results concerning such scatter, a one-dimensional model is set up and analysed. The results computed from it are in qualitative agreement with, and contribute a partial explanation of, the variation of reflection coefficient with erythrocyte concentration and the noise in the backscattered signal.

Role of models in understanding and interpreting clinical Doppler ultrasound.

Mathematical and physical models are essential tools in both fundamental and clinically applied Doppler ultrasound research. In this paper we illustrate a variety of models and show how they can be used to understand and interpret clinical Doppler ultrasound signals, particularly from stenosed arteries. The physical models discussed include both steady and pulsatile flow systems, and also a flow visualization technique that can be used to interpret the Doppler signals at a fundamental hemodynamic level. The mathematical models deal with three different aspects of the Doppler signal: models that describe the mechanism of ultrasound scattering by blood, a model to stimulate the returned Doppler signal and a model that may be used to aid in the analysis of clinical recordings. Each of these models provides a more complete understanding of blood flow through normal and stenosed vessels and contributes to the interpretation of clinical Doppler signals.

On the design and evaluation of a steady flow model for Doppler ultrasound studies.

For experimental studies of pulsed and continuous wave Doppler systems, a steady flow model has the important advantage of simplicity in interpreting the results. However, there are a number of important aspects of the design that require careful consideration before a satisfactory design can be achieved. This paper discusses these aspects and some of the difficulties that can arise. It also describes the design and evaluation of a steady flow model that uses a rigid tube with a suspension of glutaraldehyde hardened red blood cells in physiological saline as the scattering medium.

Weak reflection of a wave by a one-dimensional array of randomly spaced elements, with reference to the scattering of ultrasound by blood.

The mean reflection coefficient is deduced for a line of elements each of the same thickness, placed at random between two fixed ends, where the reflection coefficient of each element is very small. This theory is applied to the problem of the scattering of ultrasound by blood, and some qualitative agreement with experimental data is found. A simplified theory is also presented, from which the variance of the reflection coefficient is given.