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Biomedical subjects

P G Duncan

Publications and source records attributed to P G Duncan.

11 recordsLinked to original sources
PubMed1992

The Canadian four-centre study of anaesthetic outcomes: I. Description of methods and populations.

The objectives of this study were first to develop and institute a methodology for the study of anaesthetic outcome for parallel use in four teaching hospitals in Canada and second, to compare rates of morbidity and mortality associated with anaesthesia between the four centres. The basic design of the study was occurrence screening with anaesthetists entering data on patient demographics, anaesthetic and surgical factors. Research nurses reviewed anaesthetic records and hospital charts and interviewed patients postoperatively. Data on 37,665 anaesthetics were collected during 1988-89 in the four teaching centres. There were major differences found across the hospitals, particularly with regard to volume, patient case-mix, anaesthetic drugs and monitoring used. The use of parallel training, repeated consultations and use of rounds and inservices contributed to the reliability and validity of the data collection. We conclude that outcome surveillance can be instituted in different hospital Departments of Anaesthesia with sufficient confidence to form the basis of comparison of anaesthetic outcome.

Anesthesia↗
PubMed1979

Preservation of auditory-evoked brainstem responses in anaesthetized children.

In a series of six anaesthetized children we have been unable to demonstrate any effect of anaesthetic concentrations of halothane or thiopentone on the brainstem auditory-evoked response. The results imply preservation of brain stem function during anaesthesia with these drugs and suggest future application of anaesthesia to the testing of hearing disabilities in children, as well as application of evoked response audiometry to neurological critical care.

Anesthesia, General↗
PubMed1979

Efficacy of helium--oxygen mixtures in the management of severe viral and post-intubation croup.

An appreciable number of children with viral or post-intubation croup progress to respiratory failure necessitating an artificial airway. We report seven such patients with critical airway narrowing in whom we reduced the work of breathing by developing helium rather than air as a carrier gas for oxygen. Assessment of patients by a croup-scoring system and blood gas analysis suggests helium-oxygen mixtures to be a useful alternative to intervention with tracheostomy or tracheal intubation. The rationale and limitations of this treatment are discussed.

Airway Obstruction↗
PubMed1979

Clinical experience with brain stem audiometry performed under general anesthesia.

Hearing tests were given to 22 difficult-to-test children using brain stem audiometry performed under general anesthesia. The effect of halothane and sodium thiopental on the brain stem response was assessed as well as the feasibility of using this technique with a difficult-to-test population. No effect on brain stem responses was observed to various levels of anesthesia. Successful hearing tests were carried out on all the children and results were helpful in their management. Brain stem audiometry perfromed under general anesthesia appears to be an effective and helpful technique for testing challenging diagnostic cases.

Adolescent↗
PubMed1978

Conservation of illusion-distorted identity tasks.

Four conservation of illusion-distorted identity tasks were presented to 10 boys ranging in chronological age (CA) from 5-5 to 12, and in mental age (MA) from 3-5 to 10-2, to document individual differences among children with delayed development in acquisition of conservation skills.

Child↗
PubMed1977

Neutrophil chemotaxis and anaesthesia.

Using a modified Boyden technique, the ability of normal human neutrophils to migrate in response to chemotactic stimulation was evaluated during exposure in vitro to halothane and thiopentone. No abnormality in neutrophil chemotaxis could be demonstrated with either agent at concentrations used clinically. The anaesthetics also did not effect serum complement, which was used as the chemotactic stimulant. It is concluded that halothane and thiopentone have little direct effect on the chemotactic activity of human neutrophils.

Chemotaxis, Leukocyte↗
PubMed1977

Thiopental inhibition of tumor immunity.

The ability of leukocytes to kill tumor cells appears central to the defense against neoplastic growth. The authors determined the effect of thiopental on this phenomenon in vitro by incubating 51Cr-labelled YAAC-1 tumor cells obtained from the peritoneal cavities of syngeneic A/JAX white mice with immune leukocytes from the peritoneal cavities of allogeneic C57/black mice. Tumor-cell death was quantitated by the amount of 51Cr released into the medium following tumor-cell lysis. Thiopental, in concentrations used during routine anesthesia, inhibited tumor-cell killing in a dose-related manner. Inhibition of cytotoxicity ranged from 8.6 per cent at 2.8 x 10(-5) M thiopental to 38.1 per cent at 8.5 x 10(-5) M thiopental. Moreover, this inhibitory effect was additive to that previously demonstrated with halothane, and was related to the duration of exposure to the anesthetic. It is postulated that thiopental and other anesthetics contribute to the inhibition of leukocyte responsiveness observed in patients with malignancies who have undergone surgical procedures.

Animals↗
PubMed1976

Inhibition of cell-mediated cytotoxicity by halothane and nitrous oxide.

Killing of tumor cells by lymphoid cells is important in cell-mediated immunity and defense against cancer. The authors determined that halothane, in vitro, inhibits the killing of YAAC-1 ascites tumor cells from A/jax mice by sensitized peritoneal exudate cells from C57/Black/6 mice. Lysis of tumor cells was quantitated by release of 51Cr into the culture medium. Inhibition of cell-mediated cytotoxicity ranged from 5 per cent in 0.5 per cent halothane to 44.7 per cent in 2.5 per cent halothane exposure. A 12 per cent inhibition of cytotoxicity by 80 per cent nitrous oxide was not statistically significant, but was of a magnitude near that of an equipotent concentration of halothane. The inhibition of cytotoxicity by halothane and nitrous oxide observed in vitro may partially account for the inhibition of cytotoxicity observed when patients undergo surgical operation.

Anesthesia, Inhalation↗
PubMed1976

Failure of enflurane and halothane anesthesia to inhibit lymphocyte transformation in volunteers.

Changes in the peripheral blood leukocyte count and in the ability of lymphocytes to transform in response to phytohemagglutinin were studied in healthy volunteers undergoing prolonged enflurane or halothane anesthesia without coincident surgical operation. Anesthesia was associated with a modest leukocytosis that persisted into the first post-anesthesic day, primarily due to an influx of neutrophils into the circulation. There was no significant alteration, either during or following anesthesia, in the ability of the volunteers' lymphocytes to transform in response to phytohemagglutinin when compared with either preanesthetic values or unanesthetized controls. Depression of lymphocyte transformation does not appear to follow prolonged enflurane or halothane anesthesia in the absence of a surgical procedure.

Anesthesia, Inhalation↗
PubMedDate not supplied

Anesthesia and the modification of response to infection in mice.

Anesthetic-induced immunosuppression, if clinically significant, could modify the natural course of infectious disease in vivo. To test this bypothesis, the localized response to IM Candida albicans and the mortality following fecal peritonitis were examined in anesthetized mice. Using these 2 models, halothane anesthesia was found not to modify the natural history of local sepsis but to significantly accentuate the mortality associated with the more severe infection. Possible explanations for these results include significant inhibition of reticuloendothelial function or plasma opsonization with relatively minor derangements of peripheral leukocyte capability.

Anesthesia, Inhalation↗