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Biomedical subjects

R G Gosling

Publications and source records attributed to R G Gosling.

At least 73 records · Page 4Linked to original sources
PubMed1986

Transcranial measurement of blood velocities in the basal cerebral arteries using pulsed Doppler ultrasound: a method of assessing the Circle of Willis.

Transcranial pulsed Doppler ultrasound and spectral analysis were used for detection of blood velocities in the basal cerebral arteries. The Doppler transducer was placed superior to the zygomatic arch and during insonation of the middle cerebral artery care was taken to obtain maximum Doppler-shift frequency signals since this allowed a small angle between the ultrasound beam and this artery. Doppler signals were obtained from the middle, anterior, and posterior cerebral arteries in 20 volunteers with the average depth of the Doppler gate at 4.9 (4.6-5.2 cm), 5.2 (4.9-5.4 cm), and 6.3 cm (6.0-6.9 cm), respectively. These measurements were in agreement with those obtained for 15 cadaver studies, in whom the distance from the proposed site of the Doppler transducer to each basal cerebral artery was measured as 4.7 +/- 0.6, 5.3 +/- 0.5, and 5.9 +/- 0.9 cm, respectively. The reproducibility of middle cerebral artery blood velocity values was tested in seven subjects and showed a variation of not more than 8% in any individual. The method was used in combination with common carotid compression to assess four patients who had occlusive extracranial carotid disease; in three the disease was more severe on one side and reversal of blood flow in the proximal ipsilateral anterior cerebral artery was demonstrated, consistent with cross flow from the contralateral side via the anterior communicating artery of the Circle of Willis. In the fourth patient augmentation of posterior cerebral artery blood velocities during common carotid compression indicated the major collateral source was from the vertebrobasilar system.

Adult↗
PubMed1986

Transcranial measurement of blood velocities in the basal cerebral arteries using pulsed Doppler ultrasound: velocity as an index of flow.

Blood velocities have been measured transcranially, at small Doppler angles, in the middle cerebral artery of normal volunteers. Cerebral blood flow was changed by varying carbon dioxide tension. In four volunteers, the relationships between arterial pCO2 and percentage change in intensity weighted mean, median, and maximum Doppler-shifted frequencies in the internal carotid and middle cerebral arteries were linear with slopes of 2.5 and 2.8% per mm Hg change in pCO2. In 38 volunteers, the relationship between end-expiratory pCO2 and time-averaged maximum Doppler frequency was linear over the range of pCO2 20-60 mm Hg with slopes of 2.5 and 2.9 percentage change per mm Hg, for internal carotid and middle cerebral, respectively. These results are very similar to those reported using direct methods of measuring cerebral blood flow. As the transcranial Doppler method is reproducible, this indicates that changes in middle cerebral blood velocity may be used to monitor changes in flow.

Adult↗
PubMed1986

Anatomical validation of middle cerebral artery position as identified by transcranial pulsed Doppler ultrasound.

The basal cerebral arteries were insonated using transcranial pulsed Doppler ultrasound (TPDU) at 2 MHz. The Doppler sample volume (SV) depths at which signals were obtained which could be attributed to the middle, anterior and posterior cerebral arteries (MCA, ACA and PCA) were compared with measurements in adult cadavers and with B-scan ultrasound studies in infants. The depth of the internal carotid artery (ICA) terminal division into ACA and MCA was closely correlated for both groups. In adults, it was found at 5.6 +/- 1.0 cm using TPDU while in cadavers it was found at 5.3 +/- 0.5 cm from the temporal bone. In infants, it was found at 3.2 +/- 0.3 cm for the right side, and 3.2 +/- 0.2 cm for the left side using TPDU, and at 3.4 +/- 0.4 cm and 3.4 +/- 0.5 cm for right and left sides respectively using B-scan ultrasound. The mean depth of the MCA mid-point in infants as defined by TPDU and B-scan was also closely correlated, with values of 2.8 +/- 0.3 cm and 2.7 +/- 0.3 cm for right and left sides respectively using TPDU and of 2.8 +/- 0.4 cm and 2.7 +/- 0.4 cm for right and left sides respectively using B-scan ultrasound. Values for the most lateral part of the MCA did not correlate. In adults, signals from the ACA and PCA were obtained at greater SV depth than the MCA, thus preventing confusion.

Adult↗
PubMed1985

Red blood cell velocity changes with age and sex in the common carotid and supra-orbital arteries.

Doppler-shifted ultrasound and spectral analysis were used to assess signals from the resting supra-orbital artery and the common carotid artery at the base of the neck of 658 (270 male, 388 female) asymptomatic subjects aged 5 to 90 years. The sonagrams obtained showed two peaks (A and B) during cardiac systole. The ratio of these peaks (A/B) decreased from 20 to 50 years and then levelled out. The male A/B ratios from both arteries were higher than those for the females between 20 and 50 years, and for the common carotid these differences were highly significant (P less than 0.001).

Adolescent↗
PubMed1985

Erythrocyte flow velocity changes with age and sex in augmented supraorbital, superficial temporal and common carotid pulses.

Doppler-shifted ultrasound and spectral analysis were used to assess signals from augmented supraorbital and superficial temporal pulses, and the common carotid pulse 4 cm above the base of the neck of 658 (270 male, 388 female) asymptomatic subjects aged 5-90 years. The sonagrams obtained showed two peaks (A and B) during cardiac systole and the ratio of these peaks (A/B) decreased between the ages of 20 and 50 years, and then levelled out. Mean male values of common carotid sonagrams were significantly higher than female values during this age range (p less than 0.001).

Adolescent↗
PubMed1984

Doppler ultrasound screening for arterial disease in elderly stroke patients.

Doppler-shifted ultrasound and spectral analysis were used to assess the carotid arteries of 77 elderly stroke patients, which represented 154 carotid bifurcations. Severe carotid disease was demonstrated at 19 of the 154 carotid bifurcations and in eight of these complete occlusion of the internal carotid artery was present. In 12 of the 19 instances the severe disease was in the internal carotid artery associated with the stroke. Localized carotid bruits were present in five patients and only three of these were associated with severe disease of the internal carotid artery. Minor disease was detected in 80 of the 154 carotid bifurcations and no disease was detected at the remaining 55 carotid bifurcations. An abnormally low ankle/arm systolic pressure ratio, which indicated occlusive arterial disease of the legs, was obtained in 19 of the 43 patients examined. No relationship was found between the severity of carotid artery disease and the presence of haemodynamically significant disease of the lower limbs. Ultrasound measurement of aortic compliance gave significantly lower values in elderly stroke patients compared to elderly asymptomatic volunteers. Comparison of flow-velocity transit times from the stroke-affected and non-affected limbs showed no consistent effect of the stroke on vascular tone in the patients assessed.

Aged↗
PubMed1983

Femoral artery flow and pain during lumbar aortography: comparison of ionic and non-ionic contrast media.

A method is described for non-invasively measuring the increase in lower limb blood flow during transfemoral lumbar aortography. Flow measurements were made using a continuous wave Doppler-shift ultrasound transducer placed over the contralateral femoral artery. The effect of the non-ionic contrast medium B15000 (Iopamidol), conventional contrast medium (Urografin 370) and Urografin 370 plus Lignocaine were compared in a double-blind trial. All three produced an increase in flow which reached a peak between 12 and 45 s after injection. The peak flow following Iopamidol was significantly lower than that from both Urografin 370 alone and with addition of Lignocaine. There was a difference of lesser degree between Urografin 370 plus Lignocaine and Urografin 370 alone; however, this was not statistically significant. The subjective assessments of pain and patient 'discomfort' paralleled these objective flow measurements.

Aged↗
PubMed1982

Detection of carotid bifurcation disease: comparison of ultrasound tests with angiography.

Doppler-shift ultrasound with spectral analysis permits the measurement of the relative heights of systolic peaks (the A/B ratio) in blood velocity sonograms from supra-orbital and common carotid arteries, the temporal artery occlusion test, the common carotid resistance index and transit times of flow-velocity waves in the internal carotid pathway. The results are compared with 201 carotid angiograms and expressed in terms of sensitivity (true positive) and specificity (true negative). Supra-orbital and common carotid A/B ratios, in combination with the temporal artery occlusion test, detected all grades of carotid artery disease with a sensitivity of 72 per cent and a specificity of 93 per cent. The corrected transit time gave a sensitivity of 57 per cent and a specificity of 89 per cent, whilst the Resistance Index gave a sensitivity of 60 per cent and a specificity of 80 per cent. The values of ultrasound parameters associated with severe disease, defined as reductions in lumen diameter of 75 per cent or more, of the internal carotid artery are examined. The temporal artery occlusion test gave a sensitivity of 91 per cent and a specificity of 94 per cent. These results were more accurate than those obtained for the corrected transit time (sensitivity 83 per cent, specificity 92 per cent) and for the Resistance Index (sensitivity 75 per cent and specificity 92 per cent). The results show that of the tests described the supra-orbital and common carotid artery A/B ratios, together with the temporal artery occlusion test, gave the best sensitivity and specificity for detection of both severe and minor carotid bifurcation disease.

Adolescent↗
PubMed1982

In vivo arterial compliance in man.

Six hundred 'normal' volunteers have been examined, ranging in age from neonates of three days to adults of 65 years. Average compliance was measured for the aortic, iliac, and leg arterial pathways using a non-invasive atraumatic Doppler ultrasound method in non-sedated subjects. No variation of compliance with mean blood pressure was found but there was a strong dependence on age and sex. At birth, leg arteries appear to be markedly more compliant than the aorta. Relative values are reversed in the first five years, after which the aorta remains more compliant, reaching a maximum value around 10 years and then decreasing sharply towards leg values until 20 years. Beyond this age aortic compliance very slowly, and aorta, iliac, and leg arteries appear to tend towards equal compliance in the sixth decade. An explanation for the significant differences between aortic compliance in males and females from menarchy to menopause is offered and implications of these compliance variations in atherogenesis are discussed.

Adolescent↗
PubMed1980

Diagnosis by ultrasound of severe carotid artery disease in patients undergoing cardiopulmonary bypass operations.

A non-invasive method using continuous wave Doppler shift ultrasound and spectral analysis was used as a screening test for severe carotid artery disease in patients undergoing cardiopulmonary bypass operations. One hundred and eighty-eight patients were examined before cardiac surgery (91 for ischaemic heart disease, 17 for ischaemic heart disease and valve replacement, 66 for valve replacement alone, and 14 for congenital abnormalities). The mean age of the 108 patients suffering from ischaemic heart disease was 54 years (+/- 8) and that of the 80 patients admitted either for valve replacement alone or for congenital abnormalities was 52 years (+/- 12). Five of the 108 patients suffering from ischaemic heart disease were found to have severe occlusive disease of the internal carotid artery by the ultrasound test, while the test was normal in the other two groups. Patients with severe carotid artery disease proceeded to carotid arteriography and endarterectomy before the planned heart operation.

Cardiac Surgical Procedures↗
PubMed1980

Detection of disease at the carotid bifurcation using ultrasound--including an imaging system.

A two-stage approach is described for the detection of occlusive arterial disease at the carotid bifurcation using continuous wave Doppler-shift ultrasound with spectral analysis of backscattered signals from erythrocytes. The first stage involves analysis of Doppler-shift signals from the supraorbital and common carotid arteries. Abnormal signals from these arteries are frequently caused by the presence of atheroma at the carotid bifurcation and are used to indicate the necessity for imaging the bifurcation. This latter technique produces a physiological image of the arteries, as it depends on detecting erythrocyte velocities beneath a transducer which is guided over the surface of the neck. The investigation has advantages over arteriography in that it is noninvasive, has no attendant risk and may be repeated as often as required.In order to evaluate the accuracy of these methods the results have been compared with x-ray findings in patients undergoing carotid arteriography. In 20 comparisons there were no false positives and one false negative in which the arteriogram showed a small lesion. These results indicate that the two noninvasive methods may be used in sequence to demonstrate operable disease around the carotid junction.

Adult↗
PubMed1979

Retrograde cerebral embolism.

Cerebral embolism may complicate lesions of the subclavian arteries or aortic isthmus distal to the origins of the vertebral or carotid arteries. This may be due to retrograde propagation of occlusive thrombus. In other cases the vessels are patent but there are periods of reverse blood flow, creating a potential for reflux of embolic material to the ostia of the neck vessels.

Adult↗