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Biomedical subjects

R N Baird

Publications and source records attributed to R N Baird.

At least 145 records · Page 8Linked to original sources
PubMed1983

Vascular surgical audit-arterial reconstructions and amputations for lower limb ischaemia.

There were 750 arterial reconstructions and 2134 major amputations in hospitals within the South West Regional Health Authority (SWRHA) from 1974-1978, according to a Hospital Activity Analysis (HAA) based survey of all patients undergoing these operations for atherosclerotic limb ischaemia. Those undergoing arterial reconstruction fared better than amputees in terms of hospital mortality (5.2% vs. 21%) and length of hospital stay (21.4 days vs. 47 days). Comparison of the HAA results with case records and operating theatre books at Bristol Royal Infirmary showed a failure-of-inclusion rate of 10% for arterial reconstructions and 9.3% for amputations. There was a difference in the proportion of arterial reconstructions to major amputations (2.5:1) at Bristol Royal Infirmary compared with SWRHA hospitals (1:3), but hospital stay and operative mortality were similar.

Amputation, Surgical↗
PubMed1982

Transient ischaemic attacks: the static and dynamic morphology of the carotid artery bifurcation.

Studies evaluating the static and dynamic characteristics of the common carotid bifurcation are described. Slow motion angiographic frames, real time B-mode images and time position M-mode tracings have demonstrated appreciable vessel wall motion with an increase in distensibility at the carotid bulb compared to the proximal common carotid artery. Histopathological studies suggest that changes in the carotid artery elastin and collagen structure may contribute to the increased distensibility at the carotid bulb. The presence or absence of a cervical bruit did not correlate with the ultrasonic demonstration of plaque or blood flow turbulence. Mechanical factors relating to the development of symptoms of cerebral ischaemia are discussed.

Auscultation↗
PubMed1982

Diagnosis and monitoring in arterial surgery: the use of ultrasound and related techniques.

Recent advances in ultrasound techniques have led to new pathophysiological measurements for patients with arterial diseases. They have identified arterial wall stiffening in early atherosclerosis and have shown an exaggerated vascular response to the inhalation of cigarette smoke. Femoral artery Doppler signals have been used to assess the haemodynamic effects of incomplete stenoses of the iliac arteries. Ultrasound imaging has been used to predict non-invasively atheroma at the carotid bifurcation as well as to identify changes in implanted grafts which are associated with late graft failure.

Arterial Occlusive Diseases↗
PubMed1981

Department of Surgery, Bristol Royal Infirmary, U.K.

Recent developments in ultrasound techniques have made it possible to investigate patients with arterial disease non-invasively by using Doppler blood velocity signal analysis. Since January 1979, 189 patients were pre-stroke syndromes have been investigated by using pulsed Doppler and real-time B-mode ultrasound imaging and waveform analysis. The results were that both imaging systems were highly (more than 92%) sensitive and specific when compared with conventional carotid arteriography. The ultrasound systems detected turbulence and could also be used to measure the distensibility of the arterial wall. The results show that varying grades of carotid stenosis can be demonstrated by two ultrasonic imaging systems, and that lateral scans are particularly helpful.

Blood Flow Velocity↗
PubMed1981

Cigarette smoking: acute main and small vessel hemodynamic responses in patients with arterial disease.

While cigarette smoking is a major risk factor in lower limb ischemia, not all smokers develop symptomatic lesions, which suggests an individual susceptibility. Using Doppler probes the acute main vessel response to smoking was quantified in terms of the pulse transit time delay. Patients with occlusive arterial disease had a significant shortening in the transit time delay, suggesting a stiffening in the main vessels in response to smoking not seen in control subjects without disease. In patients with occlusive disease the digital pulse volume recorder amplitude decreased significantly in response to both low and high nicotine cigarettes, and these patients tended to self-titrate their nicotine intake, suggesting that little is to be gained by switching from high to low nicotine cigarettes: rather, cessation of smoking should be considered. These preliminary results suggest that patients with atherosclerotic occlusive disease are more susceptible to cigarette smoking and that Doppler or pulse volume recorder testing may help identify those habitual smokers who are at risk.

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

Treatment of vasospastic disease with prostaglandin E1.

Prostaglandin E1, a vasodilator and potent inhibitor of platelet aggregation, was administered to 26 patients with severe vasospastic disease of the hands. Patients tolerated infusions well and reported appreciable symptomatic improvement. Five of eight ischaemic ulcers healed in six weeks. Non-invasive studies of blood flow were used to observe haemodynamic changes during and after infusions. The Doppler-derived radial artery pulsatility index fell from 8.8 +/- 0.6 to 4.6 +/0 0.5 (mean +/- SEM), indicating hand vasodilatation. This fall was maintained 24 hours after infusion (5.9 +/- 0.9), but the index had returned to normal values at two weeks. The amplitude of finger pulse volume recordings increased (5.6 +/- 0.7 mm to 23.8 +/- 3.4 mm) and was raised two and six weeks after infusion (13.5 +/- 2.1 mm). Hand temperature measured by infrared radiometry also increased (27.4 +/- 0.7 degrees C to 31.2 +/- 1.2 degrees C). Intensity of digital vasospasm induced by cold water challenge was not objectively affected by prostaglandin E1 despite an increased finger temperature after infusion. Nevertheless, patients reported less frequent and severe attacks. Prostaglandin E1 given by central venous infusion is a safe new vasoactive agent that can produce appreciable symptomatic improvement by increasing digital perfusion, which may last for several weeks after treatment. Further study will define its mode of action and its place in the management of peripheral vascular disease.

Adult↗
PubMed1980

Intermittent claudication: is a supervised exercise class worth while?

Twenty-one patients (19 men and two women) with disabling exercise-related leg pain attended a physiotherapy department on one afternoon each week for an exercise training programme lasting one month. The clinical diagnosis of intermittent claudication and localisation of the atherosclerotic occlusions were confirmed in all but one case by pulse volume recordings and segmental Doppler systolic pressure measurements. Two patients whose symptoms worsened underwent arterial reconstruction. Post-training assessment at six months showed that the remaining 18 patients walked 80% further and performed 75% more step-ups. They also felt much healthier, having unduly restricted their activities before because they had feared the onset of ischaemic leg pain. These results suggest that supervised exercise training is a simple and effective method of treating patients with intermittent claudication.

Blood Pressure↗
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↗