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Biomedical subjects

A Synnott

Publications and source records attributed to A Synnott.

8 recordsLinked to original sources
PubMed1992

Tomb, temple, machine and self: the social construction of the body.

The body is socially constructed; and in this paper we explore the various and ever-changing constructions of the body, and thus of the embodied self, from the Greeks to the present. The one word, body, may therefore signify very different realities and perceptions of reality; and we consider briefly how and why these meanings changed. Plato believed the body was a 'tomb', Paul said it was the 'temple' of the Holy Spirit, the Stoic philosopher Epictetus taught that it was a 'corpse'. Christians believed, and believe, that the body is not only physical, but also spiritual and mystical, and many believed it was an allegory of church, state and family. Some said it was cosmic: one with the planets and the constellations. Descartes wrote that the body is a 'machine', and this definition has underpinned biomedicine to this day; but Sartre said that the body is the self. In sum, the body has no intrinsic meaning. Populations create their own meanings, and thus their own bodies; but how they create, and then change them, and why, reflects the social body.

Ego↗
PubMed1987

Effects of halothane, isoflurane and enflurane on ventilation in children.

The ventilatory effects of halothane in eight children were compared with those of isoflurane in eight children and enflurane in six children. All studies were completed before surgery commenced, and the children received no preoperative medication. The depression of ventilation produced by the three agents increased in a dose-related fashion as the alveolar concentrations were increased, and the depression of ventilation that they produced in oxygen was greater than that produced by equipotent concentrations in nitrous oxide. While the increase in ventilatory frequency and the decrease in TE associated with increasing concentrations of halothane were statistically significant (P less than 0.05), the increase in frequency associated with isoflurane was not, although it was sufficient to maintain the end-tidal and arterialized venous PCO2 in the isoflurane group at a value which did not differ significantly from that in the halothane group. Profound depression of ventilation was produced in the children by enflurane, clearly because no increase in ventilatory frequency was associated with its use. It was evident that the ventilatory effects of the three volatile agents in unstimulated children are very similar to those described elsewhere in the adult. There was no difference of any clinical significance between the degree of depression of ventilation produced by halothane and isoflurane in children.

Anesthesia, Inhalation↗
PubMed1987

Peak intratracheal pressure during controlled ventilation in infants and children. A computer study of the Servo 900C ventilator.

The mathematical relationship between peak ventilator breathing system pressure displayed on the digital meter of the Siemens SV900C ventilator, and peak intratracheal pressure measured at the distal end of the tracheal tube, was defined and incorporated into a computer program. The mean difference between peak airway pressure calculated by the computer and directly measured peak intratracheal pressure was 0.02 kPa (SD 0.10) in 18 infants and children. The mean difference between ventilator breathing system pressure and intratracheal pressure in the same group was 0.82 kPa (SD 0.91). Bench tests established that the decrease in peak pressure displayed by the ventilator (from 1.36 to 0.38 kPa) while inspiratory time was increased from 20 to 80% of the respiratory period, concealed an increase (from 0.2 to 0.38 kPa) in intratracheal pressure which occurs during this process; and that the large increase in pressure displayed by the ventilator (from 0.3 to 6 kPa) while respiratory frequency was increased from 20 to 120 breaths/minute, concealed a small increase in peak intratracheal pressure (0.2-0.3 kPa) which occurs during this process. These changes were accurately predicted by the computer program. The increase in intratracheal pressure associated with prolonged inspiratory times explains the high incidence of barotrauma which has recently been associated with this procedure in infants.

Child↗
PubMed1986

Effects of nitrous oxide on the respiratory pattern of spontaneously breathing children. A re-appraisal.

An increase in ventilation in spontaneously breathing children, when nitrous oxide was withdrawn from the nitrous oxide-halothane inspired mixture, was previously suggested to be a direct effect of decreased alveolar nitrous oxide concentration. To test whether a "gas effect" of oxygen inflow had caused a false increase in tidal volume signal, in the present study nitrous oxide was withdrawn in two stages, with equilibrium at each stage; there was a 7% increase in VT, to 3.88 ml kg-1. During that nitrous oxide withdrawal, despite a constant vaporizer setting for halothane, the alveolar concentration of halothane decreased (from 1.06% to 0.9%). When the alveolar halothane concentration was subsequently deliberately decreased from 1.06% to 0.9% with nitrous oxide maintained constant at 65%, there was a 14% increase in VT, again to 3.88 ml kg-1. It is concluded that nitrous oxide did not produce significant depression of ventilation in children, and that the observed increases in tidal volume were the result of decreases in end-tidal halothane concentration, produced by a decrease in its inspired concentration.

Anesthesia, General↗
PubMed1986

Effect of nitrous oxide on the output of three halothane vaporizers.

The effect of changing the composition of the carrier gas from 66% nitrous oxide in oxygen to 100% oxygen was examined in three halothane vaporizers (Fluotec Mk 3, Drager Vapor 19 and Abingdon halothane vaporizer). All showed a transient increase in output following the discontinuation of the nitrous oxide. The effect was minor (2-8% of indicated output) and short-lived (1-4 min) at the fresh gas flows used. The steady-state output of the vaporizers, once the transient response was over, was found to be lower with 100% oxygen as carrier gas than it had been with 66% nitrous oxide in oxygen. The difference was minor in the case of the Drager Vapor 19 (1% of indicated output) and Fluotec Mk 3 (5% of indicated output), but greater in the case of the Abingdon (15% of indicated output).

Anesthesia, Inhalation↗