Biomedical subjects
S L Tonkin
Publications and source records attributed to S L Tonkin.
A hypothesis about cot death.
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Scabies and pediculosis in Tokelau Island children in New Zealand.
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Upper airway measurements during inspiration and expiration in infants.
Accurate measurements of the upper airway of the infant are important but are difficult to obtain reliably because of the normal variation that occurs during respiration. X-ray films of the lateral upper airway were obtained during inspiration and expiration in healthy infants, by using as a timing device a respiration monitor which was wired to the x-ray machine and was attached to the abdominal wall of the infant. Cephalometric measurements were made of 44 "normal" full-term neonates and 29 infants at 6 weeks of age. Despite significant differences in head circumference between the sexes, only the nasion to sella length was significantly longer in the boys (P less than .01). The lateral upper airway measurements were independent of weight, head circumference, and sex in the neonates and infants at 6 weeks of age but were significantly smaller during inspiration than expiration (P less than .01). The measurements progressively increased from the middle to the posterior airway space at both ages. The middle airway space behind the caudal end of the hard palate was smaller during inspiration at 6 weeks of age compared to the neonate (P less than .01). During expiration, the posterior airway space was larger at 6 weeks compared to the neonate (P less than .01). The method described in this report enables reliable roentgenographic measurements to be made of the upper airway of the infant; normal values for the changes during inspiration and expiration are provided. This may assist in the evaluation of infants with suspected upper airway obstruction.
Infant apnoea: a home monitoring programme.
A home monitoring programme for infants, thought to be at high risk of cot death, has been conducted in Auckland for the past five years. It has included infants who have experienced an apnoea thought to have been a life-threatening event, infants of very low birth weight, and siblings of infants who died of cot death. The supervision of the 84 infants referred to the programme in 1985 are discussed. The 77 referrals for presumed apnoea resembled the population of cot deaths in Auckland, being predominantly Maori--of low birth weight--between one and four months of age and being identified in the winter months. The mean age of occurrence of the last apnoea was 4 months. There were no deaths, but in 60% of the infants further apnoea was considered to occur and half of these infants required stimulation to recommence breathing. In 11 infants an underlying pathology was later identified as the cause of the initial apnoeic events. Hospital facilities for the investigation and supervision of these infants are inadequate in Auckland at present. The establishment of a fully integrated service for the care of infants at high risk of dying from a cot death is an urgent priority.
Methods of infant care which may reduce the chance of a cot death.
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Epidemiology of cot deaths in Auckland.
The cot deaths occurring in Auckland New Zealand have been identified by one pathologist since 1970. The results have been analysed for age, season of occurrence, and race. Auckland cot deaths show a peak at two to three months of age and cluster in the winter months. Maoris have a higher rate than Europeans and Pacific Islanders a lower rate than Europeans. Cot deaths occur to babies of lower than average birth weight, and to babies sleeping prone more often than to babies sleeping in the lateral position. These latter results are not statistically significant but should be examined further.
Tokelau Islands Children's Study: scabies infestation in children.
Tokelau children have been examined for scabies infestation in three groups--those living in their home atolls--those living in New Zealand in 1972-73, and those living in New Zealand in 1975. There was less infestation in Tokelau than in New Zealand. In 1975 the rate of infestation in New Zealand had increased since 1972. The manifestation of the mite in children in New Zealand varied from the classical descriptions, in that the mite itself, and its burrows, were seldom found, and the skin lesions were more often seen on the body than on the wrists and hands. A treatment regime which was found satisfactory is described. It was found essential to treat the entire family at the same time.
The pharyngeal effect of partial nasal obstruction.
The case histroy and cinematoradiographic findings of a baby with partial nasal obstruction are presented. This infant's restriction to air entry at the nose led to severe airway obstruction during inspiration by a forward movement of the posterior pharyngeal wall and backward movement of the tongue and lower jaw. At the height of inspiration, there was total airway occlusion in the pharynx. These events can be explained by the pressure drop that takes place behind a restriction if air is sucked through it forcibly from an area of atmospheric pressure. Studies of postpalatal pressures in adults and infants demonstrate such a drop in pressure during nasal breathing if the nose is partly obstructed. If the adult or infant is able to respond to the diminished nasal airway by mouth breathing, there is no postpalatal pressure drop. It is suggested that partial nasal obstruction in a sleeping obligatory nasal-breathing infant could result in a sucking back of the tongue over the larynx in this "cafe coronary" type of situation. This could be the mechanism of the obstructive type of apnea recorded by Steinschneider, and of the asphyxial type of death that is suggested by autopsies on some "cot death" victims. This hypothesis is consistent with the frequency of infection of rhinitis and pharyngitis in victims of sudden infant death syndrome and with the seasonal incidence. Prevention of this obstructive type of apnea would depend on the recognition of infants showing inspiratory and expiratory changes in pharyngeal airway size as can be seen externally by the movements in the carotid triangle of the neck and confirmed by roentgenography or cinematoradiography.
Serum levels of immunoglobulins A, G and M in New Zealand and Tokelauan children.
Serum levels of immunoglobulins A, G and M are described in a group of New Zealand (NZ) children of European descent. These findings are used as reference standards for three groups of Tokelauan children, atoll residents, migrants in NZ, and NZ-born Tokelauan children. All three Tokelauan groups had high levels of IgA, IgG, and IgM. Breast feeding was diminished and morbidity was higher in the NZ-born group. The IgG level was negatively correlated with duration of breast feeding in this group. In the atoll group IgG was related to present illness but no other consistent relationships were found between present illness status and the immunoglobulin levels. It remains unclear whether the high Tokelauan immunoglobulin levels are genetically or environmentally determined.