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Biomedical subjects

M L Young

Publications and source records attributed to M L Young.

At least 91 records · Page 5Linked to original sources
PubMed1986

Comparison of surgical and anesthetic complications in neurosurgical patients experiencing venous air embolism in the sitting position.

Because venous air embolism (VAE) has been considered to be a major deterrent to use of the sitting position, records of 255 patients undergoing neurosurgery in the sitting position from 1975 to 1982 were reviewed to determine the nature of morbidity and mortality in relation to the surgical procedure as well as to the occurrence of VAE. Complications were classified as surgical or anesthetic during joint review by a neurosurgeon and two neuroanesthesiologists. Outcome was classified on the basis of postoperative hospital course and discharge examination. The incidence of VAE was 30%. Although there was a variety of perioperative complications in patients with and without VAE, most of the complications were related to the operative procedure, not the sitting position or VAE. The episodes of VAE did not seem to be significant factors in the perioperative morbidity and mortality in our series of patients operated upon in the sitting position. Two case reports are discussed in detail.

Aged↗
PubMed1985

Rapid atrial pacing-induced infra-His conduction block in children.

High right atrial pacing (abrupt initiation and random coupling to the spontaneous rhythm) was performed in 285 pediatric cardiac patients for diagnostic purposes. Nine patients (3%) were found to have pacing-induced infra-His conduction block. In two patients this occurred following a preceding long cycle as well as a preceding short-to-long sequence cycle length change. In five patients block occurred with an abrupt shortening of the coupling H-H interval (in three patients the infra-His block initiated a series of 2:1 infra-His block). In two patients with type II second-degree atrioventricular block the initiating events were not recorded. In one of them, when the rapid atrial pacing was incremented to the same cycle length with infra-His block, the atrioventricular response became 1:1 with normal conduction. These findings of pacing-induced infra-His conduction block can be explained by the normal response of the His-Purkinje system to changes in the preceding cycle lengths, and to the abrupt shortening of the coupling interval.

Cardiac Pacing, Artificial↗
PubMed1985

Effects of fentanyl on local cerebral blood flow in the rat.

Fentanyl reduces the cortical cerebral blood flow and metabolic rate for oxygen in rats, though seizure activity occurs in some animals at high doses. However, the effects of fentanyl on blood flow and metabolism in subcortical structures have not been clearly delineated. The present study examines the effects of intravenous fentanyl (100 or 400 micrograms . kg-1) on local cerebral blood flow (1-CBF) in paralyzed, mechanically ventilated rats. Rats ventilated with 70% N2O in 30% O2 served as controls. Local CBF was measured using 14C-iodoantipyrine and autoradiography. Blood pressure, PaO2, PaCO2, pH, and temperature were comparable in all groups. The EEG showed slow wave activity in most animals given 100 micrograms . kg-1 fentanyl while seizure activity occurred in all animals given 400 micrograms . kg-1 fentanyl. With 100 micrograms . kg-1 fentanyl, CBF tended to be depressed in all cortical and subcortical areas, except the peri-aqueductal gray; and with 400 micrograms . kg-1 fentanyl, 1-CBF tended to be elevated (compared to 100 micrograms . kg-1 fentanyl) in most areas of the brain. The limbic system structures, however, were most affected by 400 micrograms . kg-1 fentanyl with statistically significant increases (compared to the 100 micrograms . kg-1 group) in 1-CBF of 86% and 67% respectively in the amygdala and septal nucleus. These results confirm that moderately high doses of fentanyl which cause slow wave activity on the EEG also depress 1-CBF in rats; moreover, doses of fentanyl that produce seizure activity produce increases in 1-CBF in most cerebral structures with greatest effects on limbic system 1-CBF.

Animals↗
PubMed1985

The use of subjective and objective audiologic test procedures in the diagnosis of multiple sclerosis.

The necessity of using a test battery approach in the diagnosis of the MS patient is described. The objective and subjective audiologic test procedures complement each other by implicating different CNS sites influenced by the demyelinating process. Since two or more central lesions must be demonstrated to confirm a diagnosis of MS, different audiometric test procedures, sensitive to dysfunction at various CNS levels, are vital. The multi-sensory evoked-response procedures have been particularly helpful in revealing subclinical abnormalities. Researchers do advocate, however, inclusion of other neuro-otologic test procedures, such as detailed auditory and vestibular testing, interaural time discrimination, and localization testing as part of the diagnostician's test battery.

Acoustic Impedance Tests↗
PubMed1984

Effects of sufentanil on regional cerebral glucose utilization in rats.

Sufentanil, a narcotic five to ten times more potent than fentanyl, reduces cortical cerebral blood flow and oxygen consumption in rats, with seizure activity occurring in some animals. However, the effects of sufentanil on blood flow and metabolism in subcortical structures have not been defined clearly. The present study examines the effects of intravenous sufentanil (40 or 160 micrograms/kg) on regional cerebral glucose utilization (r-CMRgl) in paralyzed, mechanically ventilated rats using 2-deoxy-D-[14C]glucose and autoradiography. Regional cerebral glucose utilization was decreased in all cortical areas examined in rats receiving either dose of sufentanil; the larger dose of sufentanil (160 micrograms/kg) decreased r-CMRgl in cortical structures 20-45% below control values. Two subcortical structures, the caudate nucleus and the ventral thalamic nucleus, manifested a 39-54% decrease in r-CMRgl at each dose of sufentanil. Limbic system structures responded differently. Sufentanil 40 micrograms/kg produced focal areas of markedly increased r-CMRgl in the amygdala of two of six rats; sufentanil 160 micrograms/kg produced marked increases in r-CMRgl in focal areas of hippocampus (four of eight rats) and amygdala (seven of eight rats). EEG activation suggestive of seizure activity was evident in the two low-dose sufentanil and six of the seven high-dose sufentanil rats that had focally increased r-CMRgl in the amygdala. Sufentanil causes a selective increase in r-CMRgl in subcortical limbic nuclei, particularly the amygdala, in the rat. EEG patterns of seizure activity may reflect subcortical, rather than cortical activation.

Anesthetics↗