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Biomedical subjects

M South

Publications and source records attributed to M South.

At least 55 records · Page 3Linked to original sources

Measurement of respiratory rate and timing using a nasal thermocouple.

OBJECTIVE: The aims of this study were to assess aspects of the response of a small thermocouple to temperature change, and to evaluate whether such a thermocouple could be used intermittently to measure respiratory rate and timing by detecting the changes in nasal temperature occurring with breathing. METHODS: The study had three parts. First, three similar, fast-responding thermocouples were immersed repeatedly in warm water. Second, the influence of atmospheric temperature on the signal of a thermocouple placed at different sites within the nasal orifice was studied. The signals produced were continuously displayed and analyzed using a laptop computer to allow evaluation of the thermocouples' response characteristics. Third, simultaneous respiratory recordings were acquired using a nasal thermocouple and a nasal pneumotachograph in 12 teenaged subjects. The respiratory rate and the periods of time taken for inspiration (Ti) and expiration (Te) were calculated and compared. RESULTS: The thermocouples' responses to the temperature changes associated with breathing and immersion into water were rapid and consistent. The rate of the signals' decay, following the peak signal marking expiration, was influenced by the atmospheric temperature. The time constants of the thermocouples were similar (mean time constant = 0.41 sec, standard deviation (SD) = 0.07). Optimal respiratory recordings were obtained, with least discomfort, when the thermocouple was positioned at 0 to 4 mm within the nasal orifice. In comparing the respiratory recordings acquired simultaneously with a thermocouple and pneumotachograph, the respiratory rates were identical, and the Ti and Te values were similar (mean difference 0.04 sec (95% CI: -0.11 to 0.21 sec) and -0.04 sec (95% CI: -0.20 to 0.12 sec), respectively). CONCLUSIONS: Intermittent measurements of respiratory rate and timing using a nasal thermocouple accurately reflected measurements obtained from nasal airflow using a pneumotachograph.

Adolescent↗

Mood swings in patients with panic disorder.

Depression is frequently found in patients with panic disorder. It is known that patients suffering from panic disorder and depression have more severe symptoms of anxiety and avoidance and respond less well to treatment with antidepressants. The General Behaviour Inventory, an instrument that identifies subjects with subsyndromal and syndromal recurrent mood disorders was completed by 108 patients in a panic disorder program. Thirty-four percent (n = 37) were classified as suffering from a mood disorder. Of the mood disordered patients, 25 of 37 (68%) (23% of the total) were classified as suffering from bipolar or cyclothymic mood disorder.

Adult↗

Depression, mastery and number of group sessions attended predict outcome of patients with panic and agoraphobia in a behavioural/medication program.

From a list of 214 patients suffering from panic and agoraphobia and who had been treated with cognitive behaviour therapy, 30 patients who had very good outcomes and 32 who had poor outcomes were selected. The groups were selected by the nurse therapist and psychiatrist on the basis of personal knowledge of the patients. The distinction into good and poor outcome groups was confirmed by the results of a follow-up questionnaire completed by the patient. Of several clinical and demographic variables which had been hypothesized to be predictors of outcome, only depression, as measured by the Beck Depression Inventory, mastery, as measured by the Pearlin Mastery Scale and the number of group therapy sessions attended predicted outcome. Levels of depression and mastery might be clinically modifiable variables which affect the outcome of treatment for patients with panic and agoraphobia.

Adult↗

Computer-assisted instruction in Australian medical schools.

OBJECTIVE: To survey the use of computer-assisted instruction (CAI) in undergraduate medical student education in Australia. SETTING AND DESIGN: A postal questionnaire survey of medical school deans, and department heads, in all Australian medical schools. RESULTS: 90% of deans, and 88% of department heads responded to the questionnaires. There were considerable variations between departments and faculties in the use of CAI. Overall, 36% of departments were using CAI and 65% of those not currently using it were either developing CAI or would like to introduce it into their teaching programs. Some medical faculties had well-developed policies for CAI, and provided considerable resources, while others did not. Some departments had large numbers of student work stations (up to 64), and multiple teaching packages (up to 200). CAI packages were generally thought to be popular with students, and to have improved the standard of learning. CONCLUSION: This form of teaching is currently undergoing rapid expansion, but in an uncoordinated manner that is likely to lead to greatly increased overall development costs.

Australia↗

Reference ranges for respiratory rate measured by thermistry (12-84 months).

Previous studies of respiratory rate in children have had a number of methodological problems. The aim of this study was to construct age specific reference ranges for respiratory rate. Respiratory rate in children attending childcare centres, kindergartens, and schools was measured using a nasal thermocouple to obtain respiratory waveforms. Reference ranges were constructed using data from 293 awake children between 12 and 84 months, and from 123 sleeping children between 12 and 60 months. The mean respiratory rate declined with increasing age and was significantly lower, with lower variability, during sleep than wakefulness. Neither the awake nor sleeping reference ranges were significantly affected by sex, nor by the presence of past respiratory nor current respiratory symptoms.

Age Factors↗

Treatment of neonatal hyperbilirubinaemia by plasmapheresis.

A term baby developed severe hyperbilirubinaemia in association with group-B streptococcal sepsis. Haemodynamic instability deterred us from performing exchange transfusion, and so plasmapheresis was used to lower the bilirubin level. The procedure was very effective and well tolerated.

Bacteremia↗

Microscopic observations on tracheal aspirates from ventilated neonates. II. The onset of bronchopulmonary dysplasia and other changes.

A total of 450 undiluted and unprocessed tracheal aspirates from 120 intubated infants were examined microscopically for evidence of bronchopulmonary dysplasia and other changes. In 19 infants desquamated sheets of dysplastic epithelium in the fresh aspirate provided an early indication of developing bronchopulmonary dysplasia. Examination of unstained tracheal aspirates can provide, within minutes, information not only about the onset and development of bronchopulmonary dysplasia, but also provide evidence for milk or formula aspiration and for gastro-oesophageal reflux.

Bile Pigments↗

Respiratory timing in intubated neonates with respiratory distress syndrome.

Respiratory timing was studied in 100 babies ventilated for respiratory distress syndrome (RDS) during a brief period of continuous positive airway pressure. For the 76 spontaneously breathing babies the mean (SD) inspiratory and expiratory times were 0.31 (0.06) and 0.41 (0.12) seconds. Respiratory rate was predominantly modulated by expiratory time. The severity of RDS was the main influence on expiratory time.

Female↗

Predictions of the AIDS epidemic in the U.K.: the use of the back projection method.

Back projection methods are used to predict the yearly number of new AIDS diagnoses and the number of new HIV infections, to the end of 1992. The AIDS, but not the HIV, predictions are insensitive to the choice of incubation period distribution. A wide range of predictions is consistent with the AIDS diagnoses in years up to 1987, but limited ancillary information on the relative rates of new HIV infection in 1984 to 1987 can be used to narrow this range. The range of prediction based on AIDS reports to the end of 1988 is lower and narrower than the range based on reports to the end of 1987. The number of new AIDS cases in 1992 appears likely to fall in the range 1000-3000.

Acquired Immunodeficiency Syndrome↗

Tracheal aspirates from neonates during endotracheal intubation: detection of surfactant by polarized light microscopy.

A technique for detecting the presence of pulmonary surfactant in the tracheal aspirates obtained from preterm babies is described. The specimens were examined by means of polarized light microscopy. Surfactant could be simply and rapidly identified by its appearance as birefringent particles in volumes of aspirate as little as 1 microliter. Tracheal aspirate specimens from 108 babies, obtained on the first day of life, were examined without knowledge of the patient's clinical details. When the samples from each baby were subdivided into three groups on the basis of the amount of surfactant particles seen, this subgrouping corresponded well with the babies' ventilatory requirements at the time of sample collection. This method of detecting surfactant material may prove valuable in determining the degree of surfactant deficiency in individual preterm babies with respiratory illness.

Humans↗

Randomized trial of artificial surfactant (ALEC) given at birth to babies from 23 to 34 weeks gestation.

Artificial surfactant (ALEC) composed of dipalmitoylphosphatidylcholine and unsaturated phosphatidylglycerol in a ratio of 7:3 (w/w) and a dose of 50-100 mg was suspended in 1 ml of cold saline and used at birth as a prophylaxis against the respiratory distress syndrome and its complications in a two centre randomized prospective trial involving 341 babies from 23 to 34 weeks gestation regardless of their antenatal problems. The surfactant had little effect in babies above 29 weeks gestation and was most beneficial in babies under 30 weeks gestation (67 controls and 69 surfactant treated babies). In this subgroup the artificial surfactant significantly reduced the inspired oxygen and peak ventilator pressure requirements during the first 96 h, the incidence of intraventricular haemorrhages from 40% to 19% (P less than 0.01), the overall mortality from 36% to 17% (P less than 0.02), the mortality due to RDS from 31% to 9% (P less than 0.01), the need for more than 28 days oxygen from 37% to 21% (P = 0.05) and the use of pancuronium in ventilated babies from 52% to 27% (P less than 0.01). There were no apparent side effects. This protein free, artificial surfactant should be a useful addition to the therapy of babies under 30 weeks gestation to reduce the severity of their RDS and the incidence of serious complications.

1,2-Dipalmitoylphosphatidylcholine↗

Simple method for securing umbilical catheters.

A method for securing umbilical catheters is described. It has been used successfully in over 350 babies. It is a simple and rapid method that allows for easy repositioning and, unlike some established techniques, has no potential for damage to the preterm baby's skin.

Catheterization, Peripheral↗

Cerebral blood flow velocity variability in infants receiving assisted ventilation.

Cerebral blood flow velocity was measured using Doppler ultrasonography in 20 babies who weighed less than 2500 g at birth and who were receiving assisted ventilation; their patterns of spontaneous respiration were recorded simultaneously. The babies were induced to breathe synchronously or asynchronously with the ventilator by manipulating the inspiratory and expiratory time settings. The variability of cerebral blood flow velocity (coefficient of variation) was calculated from the area of the maximum Doppler frequency shift envelope for 10 cardiac cycles from 211 recordings made on 42 occasions, and was greatest within 12 hours of birth after which it fell progressively over the next 48 hours. Variability of cerebral blood flow velocity was significantly greater when the infants were breathing out of synchrony with the ventilator (median 11%, interquartile range 8-14%) than when they were either apnoeic (median 5%, 3-7%), or breathing synchronously with the ventilator (median 5%, 3-6%).

Age Factors↗

Expiratory muscle activity in preterm babies.

The activity of the right external abdominal oblique muscle, in relation to respiration, in newborn babies from 25 to 34 weeks' gestation was studied, using surface electrodes. Babies without respiratory difficulties showed no activity associated with respiration in these muscles. Grunting babies with respiratory disease showed pronounced activity during expiration. This activity continued when the babies were endotracheally intubated; if the babies were ventilated it sometimes disturbed the tidal ventilation delivered by the machines. When the baby expired during a ventilator inflation, so that gas came up the endotracheal tube against the inflating pressure, the abdominal oblique muscles contracted in 98% of the breaths.

Electromyography↗

Synchronous mechanical ventilation of the neonate.

We describe a simple technique of neonatal ventilation that induces the neonate to breathe in synchrony with the ventilator. This preserves the beneficial effects of spontaneous respiration (unlike therapeutic paralysis) and reduces potentially harmful interactions between baby and ventilator. The technique uses measurements of the neonate's own respiratory timing.

Humans↗