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Biomedical subjects

T G Lynch

Publications and source records attributed to T G Lynch.

60 records · Page 4Linked to original sources
PubMed1981

Oculopneumoplethysmography, Doppler examination, and supraorbital photoplethysmography: a comparison of hemodynamic techniques in assessing cerebrovascular occlusive disease.

There noninvasive techniques used in the evaluation of carotid occlusive disease were compared in the same population group. The cerebrovascular Doppler examination (CDE) had an accuracy rate of 89%, oculopneumoplethysmography (OPG-Gee) an accuracy rate of 94%, and supraorbital photoplethysmography (SOPPG) an accuracy rate of 86%. With the combined use of the CDE and the OPG-Gee, the accuracy rate increased to 96% when the results were concordant, and the false-negative rate dropped to 3%. The data would suggest that the combined use of the CDE and the OPG-Gee offers an advantage over either technique used individually.

Arterial Occlusive Diseases↗
PubMedDate not supplied

Evaluation of cerebrovascular Doppler examination and oculopneumoplethysmography in a clinical perspective.

The cerebrovascular Doppler examination (CDE) and oculopneumoplethysmography (OPG-Gee) were compared in a single population group with no statistically significant difference found between the 2 studies. There appeared to be an advantage to combinant testing, for when the results of the 2 studies were concordant there was an accuracy of 94% and a false negative rate of 8%. Clinical correlation was available in 96% of the patients, providing adequate evidence to support the adjuvant role of non-invasive screening in the evaluation of symptomatic individuals. The percentage of false negative studies and the incidence of ulcerative disease make a diagnostic role impractical at present. For the asymptomatic individual, the diagnostic role of non-invasive screening seems justified. The false negative studies in the present series were confined to those vessels with 50-70% stenoses, which are difficult to assess angiographically and may be better characterized by hemodynamic evaluations.

Cerebral Angiography↗
PubMedDate not supplied

Carotid restenosis: long-term noninvasive follow-up after carotid endarterectomy.

Recurrent stenosis has not been a primary consideration in the selection of patients for carotid endarterectomy. We have studied the incidence of postoperative restenosis retrospectively in 265 patients following 310 carotid endarterectomies. Two hundred fourteen patients (248 endarterectomies) were examined at 6-12 month intervals using ocular pneumoplethysmography, spectral analysis, and B-mode imaging. The absolute incidence of recurrent carotid disease was 28% (69 of 248), with a 13% (33 of 248) incidence of hemodynamically significant restenosis and a 15% (36 of 248) incidence of hemodynamically insignificant disease. Life table analysis of the data projected a 32% incidence of hemodynamically significant restenosis after 7 years and a 40% incidence of hemodynamically insignificant recurrence. These data demonstrate a progressively increasing rate of restenosis. The incidence of ipsilateral neurologic events was 8% (24 of 310); 12 occurred in association with noninvasively evident recurrent disease (12 of 69, 17%), whereas 11 occurred in noninvasively determined normal arteries (11 of 179, 6%). Noninvasive follow-up was not available in 1 patient. Of the 12 events associated with recurrent disease, 5 occurred in association with hemodynamically significant restenosis (5 of 33, 15%), whereas 7 occurred in association with hemodynamically insignificant disease (7 of 36, 19%). Carotid endarterectomy is a durable operative procedure with 92% (286 of 310) of arteries remaining asymptomatic over the period of clinical follow-up. However, absolute and life table projections of the incidence of asymptomatic restenosis are high, and this factor should be considered in the selection of patients for carotid endarterectomy, particularly in the absence of lateralizing symptoms.

Adult↗
PubMedDate not supplied

Acute ischemia-reperfusion injury in the canine hindlimb.

A canine arterial ligation preparation was used to produce whole limb ischemia-reperfusion injury. Alterations in the distribution of arterial blood flow as well as the morphology of skeletal muscle ischemia-reperfusion have not been investigated completely in this setting. Five anesthetized adult mongrel dogs underwent multiple infrarenal aortic branch ligations; one randomly selected hindlimb was subjected to six hours of ischemia and two hours of reperfusion, while the opposite limb served as control. Distribution of arterial blood flow was analyzed by injection of radiolabeled microspheres. Electromagnetically measured femoral arterial blood flow was 92 +/- 10 ml/min during control, and increased significantly (p less than 0.05) to 254 +/- 94 ml/min during reperfusion. Flow distribution to skin, muscle, and bone was 9 +/- 2%, 68 +/- 7%, and 8 +/- 1% during control, and 7 +/- 3%, 65 +/- 8%, and 9 +/- 4% after reperfusion, which did not represent significant changes. Arteriovenous shunting was 11 +/- 4% during control, and was 13 +/- 5% during reperfusion, which was not significantly different. Subcellular injury in the ischemic and reperfused hindlimb was demonstrated by light and electron microscopy. These findings further characterize whole limb ischemia-reperfusion injury in the canine hindlimb.

Acute Disease↗