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Biomedical subjects

W Gee

Publications and source records attributed to W Gee.

At least 55 records · Page 3Linked to original sources
PubMed1983

Ocular pneumoplethysmography in carotid-cavernous sinus fistulas.

Pulsatile exophthalmos in association with carotid-cavernous sinus fistulas has been well defined anatomically, by angiography. This paper presents the physiological assessment of this entity, as measured with ocular pneumoplethysmography (OPG-Gee). The abnormal arteriovenous communication lowers resistance to arterial flow. This is characterized by a lowered ophthalmic systolic pressure and an increased ocular blood flow. The OPG readily documents the physiological result of therapeutic intervention.

Arteriovenous Fistula↗
PubMed1983

Ocular pneumoplethysmography in head-injured patients.

Severe head injury is frequently associated with multiple trauma. In the comatose patient, endotracheal intubation and ventilator support are often required, if there is associated dyssynchronous spontaneous effort. The latter is managed with therapeutic (drug) paralysis. An elaborate life-support and monitoring system coupled with controlled paralysis limits the mobility of the patient for diagnostic procedures, and a continuing reevaluation of neurological status is difficult. Under these circumstances the ocular pneumoplethysmograph provides a simple rapid noninvasive assessment of ocular blood flow, and this reflects cerebral blood flow and alterations in brain compliance. Alterations in the therapeutic regimen can be based on these observations.

Brain Injuries↗
PubMed1981

Extracranial surgery for the low-flow-endangered brain.

Angiography documented severe (greater than 75%, cross-sectional area) bilateral carotid stenotic or occlusive disease in 60 patients. One third of these patients were thought to have transient ischemic symptoms of low-flow rather than embolic etiology. Preangiographic ocular pneumoplethysmography (OPG-Gee) was obtained in all patients. Postoperative OPG studies were obtained in the 39 patients who underwent unilateral carotid surgery. In seven of the 39 patients who were operated on, bilateral procedures were performed; OPG studies were obtained after the second procedure also. Comparison of the preoperative and postoperative OPG studies provided convincing evidence that the establishment of major carotid inflow should be the primary objective in patients with severe bilateral carotid disease, and that distal extracranial-intracranial reconstruction should be reserved for patients failing to respond to augmented inflow because of deficient collateral vessels.

Blood Pressure↗
PubMed1981

Postendarterectomy carotid occlusion.

In a prospective study of 300 carotid endarterectomies, ocular pneumoplethysmography (OPG-Gee) was performed in the recovery room after all procedures. Positive test findings, indicative of occlusion of the repaired vessels, were encountered after 16 (5%) of these procedures, and all 16 patients were completely asymptomatic. Serial test results, without angiographic confirmation, have remained positive in nine. Angiography confirmed the positive test results in three. Immediate reoperation, without angiography, confirmed the positive test findings in four, and normal flow was restored in all four cases. Success of carotid endarterectomy should not be measured by absence of symptoms. Objective documentation of persistent patency is essential. Present policy dictates that if recovery room test results are positive, the patient be returned to the operating room as soon as possible, with no delay for angiography.

Blood Pressure↗
PubMed1980

Carotid stenosis plus occlusion: endarterectomy or bypass?

In 15 patients with unilateral internal carotid artery occlusion and contralateral internal carotid artery stenosis of pressure significance (75% cross-sectional area or greater), the ocular pneumoplethysmograph (OPG-Gee) has documented bilateral improvement in the ophthalmic systolic pressure in 12/15 patients who underwent endarterectomy of the stenosed carotid artery as the sole operative procedure. External carotid to internal carotid shunt on the side of the internal carotid occlusion need be entertained only in those patients who remain symptomatic on the side of the internal carotid occlusion after contralateral stenosis endarterectomy.

Arterial Occlusive Diseases↗
PubMed1980

Spontaneous dissection of internal carotid arteries. Spontaneous resolution documented by serial ocular pneumoplethysmography and angiography.

Spontaneous dissection of the internal carotid artery can appear on an angiogram as a total occlusion of this vessel. This appearance differs from that typical of atherothrombotic occlusion. In four patients with spontaneous dissections of internal carotid arteries, serial ocular pneumoplethysmography demonstrated spontaneous restoration to functional patency. Repeated angiography confirmed the noninvasive testing in all four patients.

Carotid Artery Diseases↗
PubMed1979

Ophthalmoplethysmography in head and neck surgery.

Ophthalmoplethysmography (OPG) is a simple, noninvasive diagnostic test in which the cerebral hemispheric blood flow can be indirectly measured. Its use in head and neck surgery is invaluable because it enables the surgeon to predict preoperatively whether a patient will survive carotid artery resection. In a three-year period, nine patients have survived carotid resection on the basis of favorable OPGs, without a death or permanent neurologic complication. A comparison of the results of OPG testing with intraoperative measurement of internal carotid artery pressure showed close correlation in 14 of 20 patients who were tested. Lack of correlation in four patients can be explained by the circumstances of the intraoperative test. This study's findings demonstrate that this test has high clinical reliability.

Aged↗
PubMed1979

Restenosis or occlusion after carotid endarterectomy: a survey with ocular pneumoplethysmography.

One hundred seventy-three carotid endarterectomies in 141 patients operated on during a 12-year period were surveyed both clinically and by ocular pneumoplethysmography (OPG)-Gee. Seventeen (12%) patients had positive OPG examinations. Three arteries (1.7%) demonstrated symptomatic recurrent stenosis in accord with earlier reports. An additional 8.1% of the operated arteries had asymptomatic recurrent stenosis. A total recurrence rate of 9.8% was found. Because of the considerable silent recurrence rate we have found, we recommend annual screening by OPG. Angiography and repeated endarterectomy are then used when appropriate.

Air↗
PubMed1979

Carotid endarterectomy shunting. Effectiveness determined by operative ocular pneumoplethysmography.

The theoretical advantages and practical disadvantages of carotid endarterectomy shunting are well known. To assess shunt physiology, we performed operative ocular pneumoplethysmography on six patients before carotid clamping, during carotid clamping, during carotid shunting, and on completion of carotid repair. In each case the shunt functioned, at best, as a vessel with at least a 75% or greater cross-sectional area stenosis. However, in all cases it appreciably elevated the ipsilateral ophthalmic systolic pressure over that noted during carotid clamping. There is no question that carotid shunting provides a margin of safety during prolonged carotid clamping.

Blood Pressure↗
PubMed1977

The asymptomatic carotid bruit and the ocular pneumoplethysmography.

Patients with asymptomatic carotid bruits require some noninvasive method for detecting which would benefit from angiography and possible prophylactic operative repair of the suspected atherosclerotic lesion. This report describes the use of the ocular pneumoplethysmograph (OPG) in this regard. Data for establishing OPG criteria of significant carotid stenosis were derived from studies in symptomatic patients who had also undergone angiography. In this review, the OPG demonstrated an accuracy of 91.6% in detecting at least a 75% diameter stenosis. The OPG criteria were applied to 116 patients with asymptomatic carotid bruits. Forty two of the 116 patients fulfilled at least one of the four criteria for angiography. In 38 of the 40 patients who underwent angiography, the OPG findings were confirmed, for an accuracy of 95%. Twenty-two patients underwent 27 operations, without morbidity or mortality.

Arterial Occlusive Diseases↗
PubMed1977

An alternative approach to lesions in the proximal segments of the brachiocephalic arterial system.

Tolerance of a cerebral hemisphere to permanent interruption of the ipsilateral carotid artery or to prolonged operative clamping of this vessel, can be determined preoperatively by a noninvasive technique combining the use of the ocular pneumoplethysmograph with compression of the proximal part of the common carotid artery. This technique is essential for the management of proximal lesions of the brachiocephalic arterial system to avoid the use of bypass grafts and to permit a supraclavicular approach rather than thoracotomy or a median plane sternotomy.

Adult↗
PubMed1975

Elective carotid artery resection.

A retrospective study of carotid artery resection disclosed a 64% mortality when resection was performed on an emergency basis, as compared with 14% when the surgery was undertaken electively. This concurs with other studies that have demonstrated increased survival rates when elective carotid artery resection has superseded carotid artery rupture, and reemphasizes the need for a more accurate means of predicting individual tolerance for loss of the carotid artery. Use of the ocular plethysmograph (OPG) is proposed as a simple and accurate means of evaluating the adequacy of collateral hemispheric blood flow to compensate for a potentially resectable carotid artery. Eleven patients have been evaluated using this technique. Nine were predicted to successfully tolerate carotid artery resection, while intolerance was predicted for the remaining two. Four of the nine patients have undergone resection of the artery with no neurologic sequelae to date.

Aged↗