Biomedical subjects
Publications and source records attributed to M South.
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.
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.
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.
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.
A technique for recording activity in the external abdominal oblique muscles of the human newborn is described. It uses simple, self-adhesive, surface electrodes arranged to reduce electrocardiographic interference. This method is applicable to studies of the respiratory patterns of very pre-term babies undergoing intensive medical care.
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.
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.
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.
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%).
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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.
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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.
A technique for monitoring the ventilated neonate's own respiratory efforts using a pneumatic capsule apnoea alarm is described.
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A case is presented of a very preterm neonate who developed severe cholestatic jaundice in association with prolonged parenteral nutrition. The effects of a therapeutic trial of phenobarbitone on bilirubin and liver enzymes are shown. This case suggests that phenobarbitone may have a role to play in the treatment of this condition, which is contrary to indications in a few other case reports in the literature.
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