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Biomedical subjects

W Gee

Publications and source records attributed to W Gee.

At least 37 records · Page 2Linked to original sources
PubMed1989

Collateral compensation of severe carotid stenosis.

In 516 patients who had endarterectomies for unilateral severe carotid stenoses, arteriography demonstrated no contralateral severe stenoses or occlusions. Pre and postoperative ocular pneumoplethysmography (OPG-Gee) measured simultaneous bilateral ophthalmic systolic pressures (OSP). Immediately after each OPG test a brachial systolic pressure (BSP) was measured with a stethoscope, cuff and manometer. Bilateral ophthalmobrachial systolic pressure (OBSP) indices were calculated from the three pressures measured with the combined testing. Analysis of these OBSP data indicates that the severe stenoses were relatively well compensated in 314 of the 516 patients (61%) whereas there was limited collateral compensation in the remaining 202 patients (39%). The data also suggest that the latter group incurs a greater element of compensatory central hypertension, which is reversed by carotid endarterectomy.

Blood Pressure↗
PubMed1988

Ocular pneumoplethysmography after lens implantation.

A series of letters in this journal discussed the safety of ocular pneumoplethysmography (OPG-Gee) in pseudophakic patients. In the interval since these letters, experience with OPG-Gee tests performed on 115 pseudophakic eyes demonstrated no ocular morbidity associated with these procedures.

Blood Pressure↗
PubMed1987

Accessory nerve injury during carotid endarterectomy.

Injury to the accessory nerve (cranial nerve XI) during carotid endarterectomy is rare; to date only three cases have been reported in the literature. Traction on the sternocleido-mastoid muscle was the proposed mechanism of injury in all three cases. Four cases of accessory nerve palsy occurred in 850 carotid endarterectomies performed between 1978 and 1986 at this institution, an incidence of 0.47%. All four patients had classic signs and symptoms of accessory nerve injury, which developed between 20 and 60 days after operation. The three most recent cases were examined specifically for accessory nerve injury in the immediate postoperative period and exhibited normal trapezius function. None had any other central nervous system dysfunction. Two of these patients regained full accessory nerve function and the most recent case is showing signs of reinnervation with conservative therapy. Isolated central nervous system and spontaneous accessory nerve palsies are exceptionally rare, and since any traction injury or transection should have been detected by postoperative examinations in three of four patients, we propose surgical scar formation as a mechanism of accessory nerve palsy after carotid endarterectomy. If such a palsy develops in the postoperative period, we recommend conservative therapy.

Accessory Nerve Injuries↗
PubMed1986

Physiology of carotid endarterectomy with ocular pneumoplethysmography.

Objective documentation of the quantitative physiologic changes associated with the repair of carotid lesions of hemodynamic consequence was obtained in 701 procedures by a comparison of pre- and postoperative ocular pneumoplethysmographic tests (OPG-Gee). The results of repair of severe stenoses depended on the status of the carotid artery opposite the repaired vessel. If the vessel opposite the carotid artery repaired was functionally patent, severely stenosed, or totally occluded, the ocular blood flow improvement on the side of repair was 16%, 27%, and 47%, respectively. Only in the latter group was improvement in ocular blood flow observed on the side opposite the carotid repair (13%). Ocular blood flow, the bulk of which (choroid) is not autoregulated, is a much more sensitive indicator of carotid lesions of hemodynamic consequence than is the autoregulated cerebral blood flow. OPG-Gee is presented as a simple noninvasive test that reliably and reproducibly assesses the quantitative physiologic changes associated with the repair of carotid lesions of hemodynamic consequence. The latter represent 84% of all carotid endarterectomies at this institution.

Arterial Occlusive Diseases↗
PubMed1986

Assessment of intra-aortic balloon pumping by ocular pneumoplethysmography.

The ocular pneumoplethysmograph (OPG-Gee) has been used to screen for unsuspected carotid disease in candidates for cardiac operations. This article demonstrates that the validity of such screening is maintained, even if the patient is sustained by an intra-aortic balloon pump (IABP). An unexpected observation is the apparent reduction of ocular blood flow during IABP, which was reduced in this series of 56 patients by an average of 11.6 per cent.

Blood Circulation↗
PubMed1986

Reappraisal of ocular pneumoplethysmography after carotid endarterectomy.

An initial report documented a 3-year experience (1978 through 1980) with ocular pneumoplethysmography (OPG-Gee) done in the recovery room after carotid endarterectomy. The present report analyzes a similar 4-year experience (1981 through 1984) on 864 carotid endarterectomies performed by 20 surgeons in which the results of OPG tests done in the recovery room suggested carotid endarterectomy thromboses in 33 of the 864 patients (3.8%). All patients underwent immediate reoperation, and thromboses were confirmed in 26 of the 33 patients (79%). In the seven patients without thromboses, findings at reoperation accounted for the abnormal physiology in six of the seven patients. Overall, in 32 of the 33 patients (97%) the recovery room OPG tests accurately reflected a source of hemodynamic compromise. The application of the special OPG-Gee criteria in this report will minimize needless reoperation after carotid endarterectomy.

Anesthesia Recovery Period↗
PubMed1985

Primary structure and gene organization of human hepatitis A virus.

The RNA genome of human hepatitis A virus (HAV) was molecularly cloned. Recombinant DNA clones representing the entire HAV RNA were used to determine the primary structure of the viral genome. The length of the viral genome is 7478 nucleotides. An open reading frame starting at nucleotide 734 and terminating at nucleotide 7415 encodes a polyprotein of Mr 251,940. Comparison of the HAV nucleotide sequence with that of other picornaviruses has failed to reveal detectable areas of homology. However, a computer analysis of the putative amino acid sequence of HAV and poliovirus demonstrated the existence of short areas of homology in virion protein 3 (VP3) and throughout the carboxyl-terminal portion of the polyproteins. In addition, extensive protein structural homologies with poliovirus were detected.

Amino Acid Sequence↗
PubMed1983

The collateral hemispheric systolic pressure.

Satisfactory calibrated BP tracings were obtained during 385 (85%) of 455 carotid endarterectomies. The pressures were measured from the distal common carotid arteries while the external carotid arteries were clamp occluded. Continuous recordings were made with and without proximal common carotid clamp occlusion. The two systolic pressures resulting in each patient were plotted as a single point on a graph, with the direct carotid systolic pressure on the abscissa and the back carotid systolic pressure on the ordinate. Formulae of the mean values in 101 of the 385 procedures, in which the opposite carotid systems contained severe stenoses or total occlusions, and the other 284 procedures, in which the opposite carotid systems had no notable lesions, demonstrate that the collateral hemispheric systolic pressure depends on the status of the opposite carotid artery and on the central BP. We derived formulae for these two groups of patients to demarcate the lowest collateral hemispheric systolic pressure adequate for hemispheric integrity during and following prolonged operative carotid occlusion or following permanent interruption of carotid blood flow as a result of thrombosis, ligation, or resection without graft replacement.

Arterial Occlusive Diseases↗
PubMed1983

Ocular pneumoplethysmography in cardiac pacing.

Variations in ocular blood flow (OBF) reflect variations in cardiac stroke output very closely. The use of ocular pneumoplethysmography (OPG-Gee) for the measurement of OBF is a simple, noninvasive method of assessing the hemodynamics of ventricular versus atrioventricular sequential pacing.

Arrhythmias, Cardiac↗