Biomedical subjects

K Fitzgerald

Publications and source records attributed to K Fitzgerald.

39 records · Page 3Linked to original sources

PubMedDate not supplied

Hypermanganesemia in patients receiving total parenteral nutrition.

BACKGROUND: Manganese is one of the trace elements that is routinely administered to total parenteral nutrition (TPN) patients. The recommended daily IV dosage ranges from 100 to 800 MICROg. We have used 500 microg daily. Recent reports have suggested neurologic symptoms seen in some patients receiving home parenteral nutrition (HPN) may be due to hypermanganesemia. Therefore, HPN patients and some short-term inpatients receiving TPN were studied to ascertain the relationship between dose and blood levels. METHODS: Red blood cell manganese levels were obtained by atomic absorptiometry. RESULTS: The levels in 36 hospitalized, short-term patients obtained within 48 hours of initiating TPN were all normal. The 30 patients receiving TPN from 3 to 30 days had levels that ranged from 4.8 to 28 microg/L (normal, 11 to 23 microg/L). Two patients had abnormal levels, at days 14 and 18. Fifteen of the 21 patients receiving inpatient TPN or HPN for 36 to 5075 days had elevated Mn levels. Only one patient with hypermanganesemia, an inpatient, had abnormal biochemical liver tests (bilirubin and alkaline phosphatase). One of the patients with a high level had some vestibular symptoms attributed to aminoglycoside use and had increased signal density in the globus pallidus on T1-weighted images on magnetic resonance imaging (MRI). A second patient with Mn levels twice normal had no neurologic symptoms, but had similar MRI findings. A third had some basal ganglia symptoms, confirmed by a neurologic evaluation, seizures, and very high Mn levels. The MRI showed no signal enhancement, but motion artifacts limited the study technically. CONCLUSIONS: Hypermanganesemia is seen in HPN patients receiving 500 microg manganese daily and may have resulted in some neurologic damage in three patients. Hypermanganesemia is sometimes seen after a short course of TPN in inpatients, as early as 14 days. Patients should be monitored for hypermanganesemia if they receive Mn in their TPN for >30 days. A 500 microg/d dose of Mn is probably excessive, and 100 microg/d should probably never be exceeded. Mn should be eliminated from the solution if the Mn level is elevated and should not be readministered unless the level returns to normal or subnormal. Mn should not be supplemented if the patient has liver disease with an elevated bilirubin.

Adolescent↗

PubMedDate not supplied

The value of flash visual evoked potentials in albinism.

In albinism, the majority of temporal retinal fibers serving the nasal visual field cross at the chiasm and project to the contralateral hemisphere. This misrouting is seen in hemispheric asymmetries present in the visual evoked potential (VEP). Misrouting of retinal fibers was also thought to occur in dissociated vertical deviation, Prader-Willi syndrome, and perhaps carrier states of albinism. However, recent literature is reaching the conclusion we have drawn in our laboratory: only albinism shows VEP hemispheric asymmetries that reverse when the other eye is stimulated. Use of different stimuli, recording conditions, and response criteria among investigators has created some confusion in differentiating what constitutes asymmetry. We conclude that use of a diffuse flash stimulus and a bipolar electrode derivation that compares differences between the left and right occipital hemispheres will clearly differentiate albinism from all other conditions, making it especially useful in a pediatric population.

Adolescent↗

PubMedDate not supplied

Intra-operative and post-operative flow in the in-situ saphenous vein bypass.

We have attempted to further define the hemodynamic properties of the arterialized in-situ saphenous vein. The natural taper of the vein and the presence of arteriovenous fistulas are two unique factors associated with this conduit. Utilizing intra-operative electromagnetic flowmeter (EF) measurements and post-operative duplex ultrasound scanning (DUS), we have studied the natural history of these conduits from the time of their arterialization. The EF mean arterial blood flow in 71 in-situ bypasses was 100.8 cc/ml, range 25-200. No significant correlation was found between these measurements and angiographic runoff, vein diameter, pre- or post-operative Ankle/Brachial Index (ABI) and site of distal anastomosis. Three immediate failures requiring revisions were not predicted by EF flow measurements. Using the unique combination of Doppler ultrasound measurement and real time imaging, afforded by the DUS, fistula flow was determined. These studies showed that terminal bypass segment blood flow is not significantly affected by cutaneous fistula interruption. We found that duplex ultrasound scanning is a useful tool ideally suited to the study of the arterialized saphenous vein in-situ. One of its main advantages is the ability to accurately localize the site and hemodynamic significance of any arteriovenous fistulas.

Angiography↗