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Biomedical subjects

D R Bird

Publications and source records attributed to D R Bird.

13 recordsLinked to original sources
PubMed1992

Effect of high-flux hemodialysis on quality of life and neuropsychological function in chronic hemodialysis patients.

The objective was to evaluate the effect of high-flux hemodialysis on quality of life, intra- and interdialytic symptoms and neuropsychological function. The study was double-blind single cross-over with random allocation to order of treatment. The patients were stable adult hospital hemodialysis patients. Both the conventional and high-flux membranes were cellulose acetate, the dialysate was bicarbonate, and dialysate sodium was held constant. The high-flux membrane had an ultrafiltration rate of 15 ml/h/mm Hg transmembrane pressure, a B12 clearance of 88 ml/min and a beta 2-microglobulin clearance of 11.4 ml/min. The values of the conventional membrane were 3.5-5.0, 34-45 and negligible. Each treatment period was 4 months. Twenty-two patients completed both phases of the cross-over. The KT/V value was higher during high-flux than conventional treatment; 1.42 versus 1.27(p < 0.05). There were no differences between high-flux and conventional treatment with respect to quality of life. Symptoms during dialysis were less severe during high-flux than conventional treatment for 12/14 items. Only 3 items reached statistical significance (0.05 > p > 0.01) and none were clinically significant. Symptoms between dialyses were less severe during high-flux than conventional treatment for 18/20 items. No single item had a statistically significant improvement but 3 had clinically important improvement. Among the 23 neuropsychological variables, none demonstrated statistically significant changes.

Adolescent↗
PubMed1981

The role of pulsatility index in the clinical assessment of lower limb ischaemia.

The routine clinical use of pulsatility index (PI) in the quantitative assessment of Doppler blood velocity/time waveforms, was assessed in normals and in patients with leg ischaemia. Two thousand and five hundred common femoral artery waveforms were studied in 57 subjects (38 males, 19 females). PI values showed a mean variability of 17% in subjects in normal sinus rhythm (NSR) (range 4.1-13.2). In 17 patients in atrial fibrillation (AF) but with no clinical arterial disease, PI varied 26%. Variability was reduced, using a ten beat average, to 7.5% in NSR and 9% in AF. Rise in PI correlated well with increase in peripheral resistance (R = 0.82) but PI was poorly related to arterial stiffness (R = 0.50). Although PI was able to identify patients with proximal arterial narrowing it was unable to distinguish the severity of disease as assessed arteriographically minimum diameters (R = 0.30). From our observations we conclude that while PI has an established place in the assessment of peripheral arterial disease it must be applied with caution and averaging from ten heart beats is an essential manoeuvre. PI may prove to be a more reliable index for assessing distal rather than proximal disease.

Adult↗
PubMed1981

Long grafts in the treatment of critical ischaemia.

Forty-two woven 10-mm Dacron grafts were implanted from the common iliac artery to the distal popliteal artery in 38 patients with rest pain or gangrene. The long-term patency at 5 years was 50%, using life-table analysis. These results show that iliopopliteal Dacron grafts are effective in preventing major amputations of severely ischaemic limbs.

Blood Vessel Prosthesis↗
PubMed1980

Upstream stenosis. Its diagnosis by Doppler signals from the femoral artery.

Transcutaneous femoral artery Doppler signals were measured with a 10-MHz pencil probe in 263 lower limbs of 135 patients. The Doppler waveforms were compared with arteriograms in 125 limbs with lower-limb ischemia and in 138 controls in the detection of minor (< 50%) and major (> 50%) iliac-artery stenosis. Doppler maximum velocity-time waveforms were obtained using a maximum frequency follower, and the wave-form shape was analyzed using a Laplace transform (LT) to produce a coefficient, the LT damping. Pulsatility index (PI) was also calculated. In 62 limbs with minor artery disease, mean LT damping was significantly greater than normal (0.5 +/- 0.15 vs 0.33 +/- 0.06; P < .001). In 63 limbs with major iliac stenosis, mean LT damping was higher still (0.78 +/- 0.16; P < .02). The LT damping was not affected by increased distal impedance and there was a good correlation with iliac stenosis in 65 limbs with an occluded superficial femoral artery (r = -0.73). The results with PI were inferior at every grade of severity of iliac disease when assessed by receiver-operator characteristic curves. These results suggest that LT damping is a sensitive method of analyzing femoral Doppler signals in the noninvasive detection of iliac artery stenosis.

Arterial Occlusive Diseases↗
PubMed1979

Pulsed Doppler angiography in lower limb arterial ischemia.

A 30-channel pulsed Doppler vessel imaging system (MAVIS, GEC Medical, Middlesex, England), was used to obtain images and maximal Doppler velocity time waveforms in the diagnosis of stenosis of the origin of the profunda femoris artery (PFA) and in the detection of structural changes within Dacron arterial grafts. In PFA scans of 33 limbs in 22 patients (mean age, 52 years), PFA stenosis of more than 50% at operation was invariably associated with a damping factor of the maximal Doppler velocity-time waveform of greater than 1.5 (eight limbs). In 12 limbs with a normal PFA at operation, the damping factor was always less than 1.4, and in 13 limbs of normal patients without arterial disease, the damping factor was always less than 1.34. In studies of 10 mm arterial grafts, the internal diameter of 14 iliopopliteal grafts scanned just above the popliteal anastomosis was strikingly reduced as compared with the femoral anastomosis of 14 aortoiliofemoral grafts and seven axillobifemoral grafts. These preliminary results suggest that MAVIS studies can be used noninvasively to detect PFA stenosis and to identify luminal narrowing of iliopopliteal grafts.

Angiography↗