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Biomedical subjects

J Farrah

Publications and source records attributed to J Farrah.

8 recordsLinked to original sources
PubMed1998

Variable venous anatomy of the popliteal fossa demonstrated by duplex scanning.

BACKGROUND: Location of the sapheno-popliteal junction (SPJ) is highly variable and therefore often difficult to identify correctly at operation. The anatomy is often complicated by associated pathology in the popliteal fossa, which makes clinical examination unreliable. OBJECTIVE: The purpose of our study was to quantify this variability and record other concomitant pathology in patients with sapheno-popliteal junction incompetence. METHODS: We retrospectively reviewed duplex scans of 544 patients with 638 legs showing SPJ incompetence, from a total of approximately 4000 patients attending our laboratory between August 1993 and August 1995. RESULTS: We found that 51% of sapheno-popliteal junctions were located within 2 cm above the popliteal skin crease and a further 36% within 4 cm, with the remaining situated anywhere between 4 and 10 cm above the popliteal skin crease. Additionally 18% of patients had either Giacomini or gastrocnemius vein incompetence in addition to SPJ incompetence, further complicating the clinical picture. CONCLUSION: When SPJ incompetence is suspected, duplex scanning identifies the exact location of the junction and other associated pathology in the popliteal fossa, and allows the position of the junction to be marked on the leg preoperatively.

Anatomy, Cross-Sectional↗
PubMed1994

Duplex ultrasonography for assessment of venous valvular function of the lower limb.

Both legs of 29 patients with venous disease and those of 15 controls without venous disease were assessed by duplex ultrasonography. The duration of reverse flow after release of manual calf compression was measured in the common femoral, long saphenous, popliteal and short saphenous veins. Before undertaking the study, the reproducibility of the technique was evaluated in six subjects by repeating the examination over 3 consecutive days; the coefficient of variation of the test was 7.3 per cent. The 95 per cent confidence interval (c.i.) of the median (0.16 s) of all measurements in the normal limbs was 0.12-0.18 s. The 95 per cent c.i. for the 95th percentile of all measurements in normal limbs was 0.32-0.52 s. In limbs with clinical evidence of venous disease at least one of the sites examined was found to have reverse flow lasting longer than 0.5 s. These data suggest that the measurement of reverse flow after release of manual calf compression is a reproducible technique. While the method records some reverse flow in normal veins, its duration is unlikely to exceed 0.5 s; significant reflux is therefore defined as reverse flow exceeding 0.5 s.

Adult↗
PubMed1994

Microangiopathy of the skin and the effect of leg compression in patients with chronic venous insufficiency.

PURPOSE: The reasons for the efficacy of leg compression in the treatment of chronic venous insufficiency are not clear. We have used laser Doppler fluxmetry to assess the effect of external compression on the skin microcirculation. METHODS: Fifteen patients with lipodermatosclerosis caused by chronic venous insufficiency and 15 control subjects were studied in the supine and sitting positions. The laser Doppler probe, incorporated in a polyethylene chamber, was applied to the lower leg underneath a blood pressure cuff. Pressures were applied from 10 to 100 mm Hg in increments of 10 mm Hg. A computer data logging system recorded laser Doppler flux blood cell velocity, and concentration of moving blood cells. RESULTS: In patients in the supine position, 20 mm Hg compression resulted in a median increase of 33% in laser Doppler flux, and a median increase of 79% in blood cell velocity, but higher pressures caused a progressive decrease in laser Doppler flux and blood cell velocity. With the patient in the sitting position, compression up to 60 mm Hg caused an increase in laser Doppler flux (median percentage increase at 20 mm Hg compression 84%) and blood cell velocity (median percentage increase at 20 mm Hg compression 22%). At 20 mm Hg compression, the concentration of moving blood cells decreased in the supine position (median percentage fall 27%) but did not change significantly in the dependent position. The effects of compression in control subjects were similar to those in patients, but to a lesser degree. CONCLUSION: Our study suggests that compression treatment may achieve part of its effect by causing an increase in the microcirculatory flow velocity.

Aged↗
PubMed1993

Peripheral nerve function in chronic venous insufficiency.

Abnormalities of vasomotion, impairment of the venoarteriolar reflex and increased skin blood flow reported in the liposclerotic skin of patients with chronic venous insufficiency (CVI) suggest altered nervous control of the skin microcirculation. The aim of this study was to determine whether patients with CVI have a peripheral neuropathy. Forty patients with CVI and lipodermatosclerosis (LDS) and 35 age and sex-matched controls were examined for neuropathy using three modalities of testing. Threshold to warming was used to assess unmyelinated fibres, and threshold to cooling and vibration to assess myelinated fibres. Warming and cooling thresholds were measured on the sole of the foot by a purpose built, computer controlled instrument. The threshold to vibration was measured on the big toe using the Ohio Bio-thesiometer. A significantly raised threshold to warming and vibration was found in the CVI group compared to the normal controls [median threshold to warming (interquartile range) in CVI group = 5.3 (0.1-9.1) median threshold to warming (interquartile range) in controls = 1.21 (0.17-3.5), p = 0.005 and median threshold to vibration (interquartile range) in CVI group = 22 (13-31) median threshold to vibration (interquartile range) in controls = 12 (8.5-27.5), p = 0.024]. The thresholds to cooling was not statistically different in the two groups. This study demonstrates the presence of a peripheral neuropathy in patients with chronic venous insufficiency, and this may be important in the pathogenesis of venous ulceration.

Aged↗
PubMed1993

Does venous function deteriorate in patients waiting for varicose vein surgery?

We have looked at the deterioration in the condition of the lower limbs in a group of 36 patients who were waiting for a median time of 20 months for varicose vein surgery, using clinical examination, colour Duplex scanning and photoplethysmograph (95% refilling times). We found a significant deterioration in this group of patients, with four limbs initially unaffected developing reflux on Duplex scanning, of which three had clinical varicose veins (all four were offered surgery), and of the initial 56 involved limbs, 10 further sources of reflux were found (18%), necessitating alteration of the initial planned surgical procedure. No patient developed deep venous insufficiency or ulceration while on the waiting list, although there was one new case of lipodermatosclerosis. However, had surgery been undertaken after the first assessment, 14 patients (25%) would potentially have required further surgery, although accepting this as justification for allowing patients to wait takes no account of patients suffering or quality of life while waiting for operation.

Adult↗
PubMed1990

Skin damage in chronic venous insufficiency: does an oxygen diffusion barrier really exist?

Eleven patients with lipodermatosclerosis (LDS) and 14 patients without venous or arterial disease underwent measurement of xenon-133 (133Xe) half-clearance times from the gaiter region of the leg. Xenon has similar diffusion characteristics to oxygen, and the investigation reflects the ability of the isotope to diffuse from the skin surface into capillary blood. Median skin half-clearance time for skin in the LDS group was 2.2 min and in the control group 2.1 min. From the subcutaneous tissues, the respective times were 14.1 and 17.4 minutes. These differences are not statistically significant. The study fails to yield evidence suggesting that an oxygen diffusion barrier exists in lipodermatosclerosis.

Chronic Disease↗