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Biomedical subjects

N M Greene

Publications and source records attributed to N M Greene.

At least 19 recordsLinked to original sources
PubMed1992

An American anesthesia training program in East Africa.

A unique 5-year program designed to improve the quality and availability of anesthesia care in developing nations has been initiated in East Africa. Based upon North American anesthesiologists serving as volunteer teachers, the program emphasizes teaching to the exclusion of taking over anesthesia care. The teaching is practical and relevant to the clinical practice of anesthesia in developing countries. The volunteers teachers serve, one at a time, 12 months of the year for several years in two pre-existing structured East African anesthesia training programs, thereby providing the advantages of consistent, reliable teaching assistance for a period of years to programs of demonstrable interest and experience in anesthesia training.

Africa, Eastern↗
PubMed1991

Zones of differential sensory block during extradural anaesthesia.

We have measured spinal segmental levels of anaesthesia to light touch (LT), pinprick (PP) and cold temperature discrimination (TE) during 2% lignocaine extradural anaesthesia in 22 patients, to determine if zones of differential sensory block develop during extradural anaesthesia and, if so, the extent to which TE extends beyond PP or LT levels and how age affects differential block. The median thoracic dermatomal levels were 4.5 for LT, 2.0 for PP and 2.0 for TE. Zones of differential sensory block developed within 5 min of extradural injection of local anaesthetic, and persisted for the next 55 min. In all instances, PP extended more cephalad than LT, and TE extended above PP levels. There were no differences in the extent of zones between the two groups of patients with mean ages of 28 and 48 yr. Thus, during extradural anaesthesia, sympathetic denervation extended one to two spinal segments above the sensory levels of LT and PP anaesthesia, age (28 vs 48 yr) affected neither the cephalad extent nor the width of zones of differential block, and PP levels of anaesthesia were closer to presumed levels of sympathetic block than were LT levels.

Adult↗
PubMed1989

Time-courses of zones of differential sensory blockade during spinal anesthesia with hyperbaric tetracaine or bupivacaine.

The purposes of this study were twofold: to compare bupivacaine and tetracaine spinal anesthesia with regard to the zones of differential sensory blockade and to evaluate the time-courses of the widths of the zones of differential sensory blockade during spinal anesthesia. In 51 patients, the most rostral levels of sensory denervation to light touch, pinprick, and temperature discrimination were measured. There was no statistically significant difference in the height of sensory blockade in the 29 patients given bupivacaine and in the 22 patients given equipotent doses of tetracaine. The widths of the zones of differential blockade were also not statistically different between the two groups during onset, maintenance, and regression of anesthesia, except that the light touch-to-pinprick and light touch-to-temperature zones of differential blockade were greater with bupivacaine than with tetracaine 30 min after subarachnoid injection. The width of the zones of differential blockade also remained unchanged within each group during onset, maintenance, and regression of anesthesia. Changes in, and absolute levels of, blood pressure and heart rate were similar with both bupivacaine and tetracaine throughout. We conclude that zones of differential sensory blockade are essentially the same with tetracaine and bupivacaine, that the widths of the zones of differential sensory blockade remain constant during onset, maintenance, and offset of spinal anesthesia, and that bupivacaine and tetracaine are associated with similar changes in heart rate and blood pressure during spinal anesthesia.

Adult↗
PubMed1979

3-Methoxy-4-hydroxyphenethyleneglycol production by human brain in vivo.

A direct method has been employed to estimate the rate of production by human brain of 3-methoxy-4-hydroxyphenethyleneglycol, the major metabolite of brain norepinephrine, a brain neurotransmitter. Venous specimens were obtained from the internal jugular vein from ten awake human subjects at a puncture site above the common facial vein, the first major source of extracranial inflow. Arterial specimens were simultaneously obtained from the radial artery. Plasma samples were assayed and a highly significant difference was found in the concentration of the metabolite in plasma coming out of the brain (venous blood) as compared to plasma entering the brain (arterial blood). This venous-arterial difference was calculated to be 0.7 +/- 0.1 nanogram per milliliter of blood. Assuming an adult brain weight of 1400 grams and normal cerebral blood flow, it is estimated that the rate of production of 3-methoxy-4-hydroxyphenethyleneglycol by the awake human brain is approximately 597 nanograms per minute or 35.8 micrograms per hour. Urine specimens were also collected from six of these subjects during a period of 1 to 3.5 hours, which bracketed the time the blood samples were obtained. For these six subjects the output of 3-methyoxy-4-hydroxyphenethyleneglycol by whole brain was estimated to be 40.9 micrograms per hour, whereas the rate of its excretion into urine was 64.5 micrograms per hour.

Adult↗
PubMed1979

Anesthesia and the development of surgery (1846-1896).

The hypothesis that the introduction of anesthesia in 1846 accelerated the development of surgery was tested by compiling statistics on the types of operations performed in this country and abroad in the absence of anesthesia (prior to 1846) and over the 50-year period after 1846. Prior to 1846, surgery involved the extremities and superficial parts of the body almost exclusively. The same was generally true for 50 years following 1846. The introduction of anesthesia was necessary before surgery could advance, but control of infection, establishment of the sciences of pathology and physiology, and development of professionalism in clinical medicine and surgery based on research and teaching were also required. Almost a half-century lapsed after the introduction of anesthesia before surgery advanced significantly beyond the stage it was at prior to the introduction of anesthesia in 1846.

Anesthesiology↗