Overnight central and peripheral temperature changes in normal infants.

AIM: To explore the relationship between central and peripheral temperature in normal infants after being put down to sleep. METHODS: Overnight shin and rectal temperatures of 21 normal infants were continuously recorded at home for three nights at 2 wk, 6 wk, 3 mo and 5 mo of age. Parents documented the start and end of feed/nappy changes during the night. RESULTS: An initial fall in rectal temperature was recorded on 149 out of 161 nights. This was linearly correlated with a rise in shin temperature for 106/149 (71%) nights (median R2 = 0.95, lower quartile 0.92, upper quartile 0.97). It was not possible to rule out a change in thermal insulation over the shins as a confounding variable in this strong association. However, a similar inverse relationship was seen between shin and rectal temperature during 111 of 121 (92%) feed/nappy changes. CONCLUSION: The fall in rectal temperature after being put down to sleep may be due to redistribution of heat rather than decreased production or heat loss. If causal, the development in early infancy of an inverse relationship between shin and rectal temperature may be important for cardiovascular homeostasis. Further sleep laboratory work is required to distinguish peripheral temperature changes on falling asleep from those associated with changes in thermal insulation.

Failure of simulation training to change residents' management of oesophageal intubation.

BACKGROUND: There are few scientific reports documenting the effects of simulation training on learning. Issues of scientific validity challenge investigators who measure such outcomes. We perceived a failure of residents to change their technical management of oesophageal intubation after simulation training and sought clarification of this observation. METHODS: Twenty-one residents were randomly exposed to two deliberate oesophageal intubation scenarios, first as a junior assistant (JS group) or as a senior managing resident (SS group), and secondly as a senior managing resident. After the first episode, residents were given an explanation and demonstration of the suggested technical management strategy, including: (i) confirmation of oesophageal intubation with a second direct laryngoscopy; and (ii) concurrent insertion of a second tube into the trachea. After the second episode, we retrospectively sought to confirm improvement in technical management within the SS group by measuring videotaped performances. Questionnaires were sent to the residents before and after reporting their performance results. RESULTS: There were 14 SS and seven JS subjects. Within SS, there was no improvement in "confirmation of oesophageal intubation with direct laryngoscopy" (8/14 vs 9/14) or any improvement in "concurrent insertion of a second ETT (tracheal) tube" (1/14 vs 2/14). Questionnaire responses offered considerable insight into these negative results. CONCLUSIONS: This failure to change may have been secondary to a lack of criterion validity, lack of repetition or a long duration between episodes. The expectations for management were not regarded as being advantageous in simulation, but they were successfully adopted in actual clinical emergencies.

A biochemical prevalence study of smoking in pregnancy for a cross-section of women in Christchurch, New Zealand.

OBJECTIVE: To biochemically measure and compare the prevalence of maternal smoking by trimester in a cross-section of pregnant women residing in Christchurch, New Zealand, during 1997. METHODS: Residual sera from routinely collected blood samples drawn in early and late pregnancy over a 12-month period, 1 January 1997 to 31 December 1997, was accumulated and anonymously assayed. Cotinine levels were measured by an ELISA test with a result greater than 14 ng/mL indicative of active smoking. RESULTS: Analysis was conducted upon 4,178 samples collected from 3,082 women. Adjusted cotinine validated smoking rates in the first, second and third trimesters were 26.8% (95% CI 24.5-29.2%), 25.0% (95% CI 22.3-27.8%) and 23.0% (95% CI 20.8-25.2%), respectively. This represents an absolute reduction in smoking rates of 4.7% (p = 0.02), 6.6% (p = 0.04) and 3.8% (p = 0.04) for the first, second and third trimesters, respectively, among pregnant women in Christchurch since 1994. CONCLUSION: Smoke reduction and cessation programs implemented locally and nationally have been effective in significantly reducing the biochemically measured prevalence of maternal smoking in pregnancy within a three-year period. IMPLICATIONS: Cigarette smoking during pregnancy is an important yet preventable factor affecting rates of prenatal, perinatal and paediatric morbidity and mortality. Reliable and repeated surveys of pregnant women are necessary to accurately measure changes in the maternal smoking prevalence and determine the efficacy of smoke reduction and cessation programs.

Hair-element analysis--still on the fringe.

Increasing biological interest in minerals has led to the search for reliable methods to quantify body levels of trace elements and toxic metals. Hair has been a prime candidate because of its ease of collection and the possibility that this body tissue might accurately reflect body loads of these substances. A vast amount of research effort has been expended to explore the value of hair-element analysis. Unfortunately, there are so many confounding factors that influence these measurements that isolated individual results cannot be relied upon. Their current value is in epidemiological studies.

Central and peripheral temperature change in normal infants.

The purpose was to explore the relationship between the fall in rectal temperature seen in normal infants after being put down to sleep and the concomitant rise in peripheral shin temperature. In this observational study 21 normal infants had continuous overnight peripheral shin and central rectal temperature recorded, for three nights at 2 weeks, 6 weeks, 3 months and 5 months of age. Parents documented the start and end of feed/nappy changing episodes during the night. All recordings were made in the infants' own home. A strong inverse linear correlation (median r2 = 0.95, lower quartile 0.92, upper quartile 0.97) was seen between rectal temperature and shin temperature on falling to sleep when put down on 106 (65%) of 161 nights. On many other nights a significant nonlinear association was present. It was not possible to exclude the process of being put down to sleep as a confounding variable in this strong association. However, a similar inverse relationship between shin and rectal temperature was seen overnight during 111 of 121 (92%) feed/nappy changing episodes. If causal, the development in early infancy of an inverse relationship between shin and rectal temperature may be important for cardiovascular homeostasis. Further sleep laboratory work including video recording is required to separate the peripheral and central temperature changes that take place on falling to sleep from those associated with removal of clothing during a nappy change.

SmokeChange for changing smoking in pregnancy.

AIM: To measure the extent to which SmokeChange, a personalised intervene, enabled pregnant women to rede their exposure to tobacco smoke. METHODS: A cross-section of general medical practices was randomly selected. General Practitioners (GPs) were to register all pregnant women with the SmokeChange programme. Smoking women were contacted by a SmokeChange Educator, who visited them at home. The Educator worked with women and their families for up to twelve months in order to support cognitive, environmental and behavioural changes to smoking. RESULTS: GPs registered 1,390 pregnant women. Current smoking, was reported by 437 (31.4%) and 209 (47.8% of smokers) chose to enrol with the SmokeChange intervention programme. of these, 149 women (34.1% of smokers) continued with the programme for at least four visits. From this 'long' participation group, 28 (18.8%) had stopped smoking entirely by their last visit in pregnancy. Another 26 (17.4%) reported at least one cessation attempt, together with a reduction of smoking consumption by 63% at the end of pregnancy. The 95 (63.8%) continued smokers had reduced their smoking consumption by 40%. Substantial smokefree environment (homes and cars) changes were also made. CONCLUSIONS: The SmokeChange approach of personalised intervention, matched to individual readiness for change, was both acceptable to pregnant women and enabled participants to substantially reduce tobacco toxin exposure to themselves and their developing infants.

The burden of symptoms of asthma, allergic rhinoconjunctivitis and atopic eczema in children and adolescents in six New Zealand centres: ISAAC Phase One.

AIM: To describe the burden of symptoms of asthma, allergic rhinoconjunctivitis and atopic eczema in children in six New Zealand centres. METHODS: The International Study of Asthma and Allergies in Childhood (ISAAC) Phase One was undertaken in Auckland, Bay of Plenty, Hawke's Bay, Wellington, Nelson and Christchurch during 1992-1993. In each centre, approximately 3,000 six to seven year old children and 3,000 thirteen to fourteen year old adolescents were studied, a total of 37,592 participants. Both age groups answered written questionnaires and the adolescents a video questionnaire about asthma symptoms. RESULTS: The prevalences of symptoms were high, for asthma 25% and 30%, allergic rhinoconjunctivitis 10% and 19%, and atopic eczema 15% and 13% in each age group respectively. More than 40% of participants had symptoms in the last year of at least one condition, most commonly asthma. There were no significant differences among regions, except for six to seven year olds in Nelson who had significantly lower prevalences of some symptoms of asthma and allergic rhinoconjunctivitis. CONCLUSIONS: Asthma and allergies are common in New Zealand, with resultant morbidity and cost. However, there is little regional variation with the exception of lower rates in Nelson children. Explanations for these findings will be the subject of further studies.

Maternal cannabis use in the sudden death syndrome.

The smoking of cannabis and tobacco is common in many countries. In contrast to tobacco, which is an established risk factor for the sudden infant death syndrome (SIDS), nothing is known about cannabis and its effects on SIDS risk. We analysed data collected in a nation-wide case control study in New Zealand (393 cases, 1592 controls) to determine if there is any association between maternal cannabis use and SIDS risk. Adjusting for ethnicity and maternal tobacco use, the SIDS odds ratio for >weekly maternal cannabis use since the infant's birth was 2.23 (95% CI = 1.39, 3.57) compared to non-users; and the multivariate odds ratio was 1.55 (95% CI = 0.87, 2.75). We conclude that frequent maternal cannabis use may be a weak risk factor for SIDS, but this finding requires further research.

The relationship between inside and outside ambient temperatures in Christchurch, New Zealand.

The objective of this study was to examine and identify relationships between hourly recorded meteorological temperature and ambient temperature, measured from within the home-sleeping environment of young infants' homes in Christchurch, New Zealand. From 1991 to 1994, home polysomnography recordings were conducted for up to 6 weeks on 32 infants aged between 2 and 24 weeks. One of the recorded signals was ambient room temperature. In total, 15735 hourly recordings of this temperature were available for analysis. The New Zealand Meteorological Service supplied hourly recordings of climatic temperature, collected over this time, from an exposed site that was considered to be representative of weather conditions for Christchurch. Temperature seasonality, hourly climatic temperature recordings and the interaction of these variables were found to be significantly related to the indoor ambient temperature recordings (all had P < 0.001). Fluctuations in hourly recorded indoor temperature appeared to lag outdoor temperature fluctuations by approximately 2 h; hence, a strong autocorrelation was identified in the regression residuals. The most parsimonious autoregression model accounted for 97% of the variability in the hourly indoor temperature measurements (r2 = 0.97). In Christchurch houses, which typically have poor thermal insulation properties, yet have no central heating capabilities, a very strong association between indoor and outdoor temperatures was clearly demonstrated.

Audiological screening of neonatal intensive care unit graduates at high risk of sensorineural hearing loss.

AIM: To audit the identification and screening of graduates from a neonatal intensive care unit with risk factors for sensorineural hearing loss. METHODS: Hospital medical records of newborn infants discharged from the neonatal intensive care unit, Christchurch Womens Hospital, between 1 July 1994 and 30 June 1995 (n=564), were examined to identify those at risk for sensorineural hearing loss according to the American Speech-Language Hearing Association risk criteria 1991. Auditory brainstem response test results were obtained from the Christchurch Hospital Audiology Department. Outcome measures were: presence of hearing loss risk factors, numbers tested with auditory brainstem response, age at test and presence and degree of hearing impairment. RESULTS: Of 5,215 live births in Christchurch, 564 infants were discharged through the neonatal intensive care unit. Of these, 86 had risk factors for sensorineural hearing loss. There were 72 (84%) infants tested at audiology, with fifteen (17%) having abnormal test results. There were fourteen with risk factors who did not get audiology screening. CONCLUSION: A high proportion (84%) of high risk newborn infants had auditory brainstem response testing. Further improvement would require strict implementation of standard procedures. Auditory brainstem response screening is part of a wider population surveillance approach to identify hearing loss as early as possible.

Weather and the risk of sudden infant death syndrome: the effect of wind.

STUDY OBJECTIVE: To examine and identify relations between sudden infant death syndrome (SIDS) and wind, particularly the föhn wind, in Christchurch, New Zealand. DESIGN: A retrospective epidemiological study combining details of regional hourly meteorological variables and reported SIDS cases. SETTING: Christchurch, New Zealand, between 1968 and 1997 inclusively. PARTICIPANTS: All 646 infants reported as dying from SIDS within the greater Christchurch region. MAIN RESULTS: Analysis of 1968-1989 data revealed nine wind variables significantly related to SIDS. When compared with corresponding variables calculated over the 1990-1997 period, only the northerly wind on the day of death and the southerly wind three days before a SIDS death had estimated associations with similar effect size and sign. However, both these variables had confidence intervals that included unity. CONCLUSIONS: No evidence was found to suspect that föhn winds influenced SIDS occurrence. The relations identified between SIDS incidence and wind, after controlling for the effects of temperature and trend, were tenuous and relatively small. More data are necessary to substantiate whether northerly winds on the day of death or southerly winds occurring three days before a death are truly associated with SIDS. It seems that wind has little, if any effect on SIDS incidence in Christchurch.

Changes to infant sleep practices in Canterbury.

AIM: "Reducing the risk" is a public health primary initiative to minimise the incidence of Sudden Infant Death Syndrome (SIDS) in New Zealand. A number of SIDS risks relate to infant sleep practices. We describe current prevalences of these practices. METHODS: A cohort of Canterbury mothers delivering live infants during May 1997 (n = 411) were mailed a questionnaire in July surveying their infant's sleep practices. Survey results were compared to results derived from the Canterbury control infant component of the 1987-90 New Zealand Cot Death Study (NZCDS) (n = 174). Those mothers using either plastic or rubber mattress covers (n = 63) were issued a subsequent questionnaire pertaining to this mattress-wrapping practice. RESULTS: Completed questionnaires were returned by 274 (66.7%) mothers. Room sharing with mother was usual for 133 (48.5%) infants, no different from the 94 (54.0%) recorded in the NZCDS (chi 2 = 5.6, df = 2, p = 0.06). However, of those infants sharing a room with their mother, 101 (75.9%) slept in their own bed compared to 46 (48.9%) in the NZCDS (chi 2 = 57.0, df = 2, p < 0.01). Only 8 (2.9%) infants were regularly placed prone to sleep, considerably fewer than the 69 (39.7%) reported in the NZCDS (chi 2 = 100.1, df = 1, p < 0.01). Mattress-wrapping with plastic (14.6% vs. 4.0%; chi 2 = 12.8, df = 1, p < 0.01) and rubber (8.4% vs. 3.4%; chi 2 = 4.4, df = 1, p = 0.04) has significantly increased since the NZCDS. Results from the subsequent questionnaire, completed by 42 (66.7%) respondents, indicated that most, 25 (59.5%), wrapped their infant's mattress to stop soiling. Less than half, 18 (42.9%), wrapped the mattress for the "safety of their baby". CONCLUSION: The "non-prone sleeping" campaign has been successful in Canterbury. Most infants are now routinely placed non-prone for sleep. Of those infants sharing a room with their mothers, an increased proportion is sleeping in separate beds. The use of "drycot" under-blankets and sheepskins has diminished. While impermeable mattress-wrapping usage has significantly increased, over three-quarters of Canterbury mothers did not use plastic or rubber mattress-covers on their infant's beds.

Deterministic properties of apnoeas in an abdominal breathing signal.

The paper describes a general set of properties that represent most apnoeas as found in an abdominal breathing signal. An apnoea is a pause in breathing during sleep, and only central apnoeas in infants are considered. Human experts are consulted to determine what properties of the signal they use to recognise apnoeas. A set of deterministic, or shape, properties is developed to represent expert opinion. An apnoea is modelled as a flat region with four properties: flatness, duration, thinness and smoothness. Mathematical descriptions of each property are formulated that discriminate between apnoea and non-apnoea events, and each description is tested for discrimination and independence. The average power of discrimination is 24% +/- 16% and the average correlation coefficient is 0.28 +/- 0.16. Applications include scoring apnoeas for sleep studies and developing standard definitions of apnoeas.

Water fluoridation and the sudden infant death syndrome.

AIMS: To determine whether exposure to fluoridated water supplies prenatally or postnatally at the time of death increases the risk of sudden infant death syndrome (SIDS). METHODS: A nationwide, case-control study, with infant's water fluoridation status determined from census area unit information for mother's usual address at the time of the infant's birth, infant's usual address at the time of death / nominated sleep and address where infant died / was at nominated sleep. SIDS risk associated with fluoride exposure postnatally was assessed according to method of infant feeding (breast or reconstituted formula), for the two days prior to infant's death / nominated sleep. RESULTS: Infants exposed to fluoridated water supplies during pregnancy were not at increased risk for SIDS, adjusted odds ratio (OR) 1.19 (95% confidence interval (CI) 0.82, 1.74). For breast-fed infants at the time of death / nominated sleep, fluoridated water exposure was not associated with an increased risk for SIDS, adjusted OR 1.09 (95% CI 0.66, 1.79). Similarly, 'fluoridated' formula feeding, when compared with 'unfluoridated' formula feeding, showed no increased risk of SIDS, adjusted OR 1.25 (95% CI 0.73, 2.13). There was no evidence of an interaction between fluoridation and infant feeding for the last two days (chi2 = 0.171, df = 1, p = 0.68). CONCLUSION: Exposure to a fluoridated water supply prenatally or postnatally at the time of death did not affect the relative risk for SIDS.

Seasonal differences in risk factors for sudden infant death syndrome. The New Zealand Cot Death Study Group.

The aim of this study was to explore whether the risk of sudden infant death syndrome (SIDS) associated with prone sleeping position and other risk factors varies with season. The study was a large nation-wide case-control study, which compared 485 cases with 1800 controls. Parents of 393 (81.0%) cases and 1591 (88.4%) controls were interviewed. Obstetric records were also examined. Infants dying in winter were older and had lower birthweights than those dying in summer. The increased risk of SIDS associated with prone sleeping position was greater in winter than in summer. In contrast, the increased risk of SIDS associated with excess thermal insulation and bed sharing was less in winter than in summer. Prone sleeping position accounts for about half of the difference between the mortality rate in summer and that in winter. This suggests that some factor related to season modifies the effect of prone sleeping position.

Factor VIII, von Willebrand factor and the risk of major ischaemic heart disease in the Caerphilly Heart Study.

The relationships of three measurements of the factor VIII/von Willebrand factor (VWF) complex (factor VIII activity, FVIIIc (one-stage assay); VWF antigen, VWF Ag (ELISA); and VWF activity, VWF act, measured by a recently-developed ELISA) to major ischaemic heart disease (IHD) events were studied in 1997 men aged 49-65 years, in the second phase of the Caerphilly Heart Study. These variables were related using logistic regression analysis to myocardial infarction or IHD death, which occurred in 129 men during an average follow-up period of 61 months. All three measurements were highly correlated (r = 0.63-0.77), and each was significantly associated with incident major IHD on univariate analyses (relative odds in highest fifth compared to lowest fifth, 1.68-1.90; P = 0.028-0.006) and on multivariate analyses adjusting for major IHD risk factors and for baseline IHD. Neither FVIIIc nor VWF act was significantly related to incident IHD following adjustment for VWF Ag. We therefore suggest that the associations between these three measurements of the factor VIII/VWF complex and incident IHD might have at least three explanations: VWF Ag is a marker of arterial endothelial disturbance; VWF act promotes platelet adhesion/aggregation and hence the platelet component of arterial thrombosis; and FVIIIc promotes fibrin formation and hence the fibrin component of arterial thrombosis.

Sheepskin bedding and the sudden infant death syndrome. New Zealand Cot Death Study Group.

We carried out a nationwide case-control study, comparing 393 case patients with sudden infant death syndrome (SIDS) with 1592 control subjects, in order to examine sheepskin bedding as a risk factor. Sheepskin use was similar for case patients and control subjects (both, 42%; adjusted odds ratio [OR] = 1.28; 95% CI = 0.92, 1.79). Sheepskin use among the control subjects was associated with socioeconomic advantage. The relative risk for SIDS with sheepskin use was significantly increased in the infants placed prone to sleep (adjusted OR = 1.70; 95% CI = 1.08, 2.67), but not for infants placed in the supine or lateral position (adjusted OR = 0.82; 95% CI = 0.45, 1.48). An interaction between sheepskin use and bed sharing was also found. Sheepskin use was associated with a decreased risk of SIDS among infants sharing beds (adjusted OR = 0.61; 95% CI = 0.38, 0.99), but an increased risk among infants not bed sharing (adjusted OR = 2.25; 95% CI = 1.32, 3.86). We conclude that if an infant needs to be placed prone to sleep for medical reasons, a sheepskin should not be used as underbedding. However, for infants placed supine to sleep, sheepskins are not associated with an increased risk of SIDS.

Immunisation timeliness for a birth cohort in Christchurch. Christchurch Immunisation Coordination Study Group.

AIMS: To determine whether New Zealand's goals for immunisation coverage are being met in Christchurch and to assess whether scheduled vaccinations are being delivered in a timely fashion. METHODS: A cohort of all infants born in Christchurch during June, July and August 1995 were matched with immunisation benefit claim information for the 6-week, 3-month, 5-month and 15-month immunisation events. Those with incomplete reports were traced for amendment or verification of their immunisation status. RESULTS: The cohort contained 1002 infants. The full complement of scheduled immunisations was delivered to an estimated 95.8% (95% CI: 94.5, 97.2) of infants within the cohort by two years of age. Infants who presented late for their 6-week immunisation visits were significantly more likely to be late for their next visits (chi 2 log rank = 8.2, df = 1, p < 0.01), as were those late for their 3-month visits (chi 2 = 20.9, df = 1, p < 0.01), and their 5-month visits (chi 2 = 52.5, df = 1, p < 0.01). Infants were significantly less likely to receive their full complement of immunisations by two years of age if they presented late for their 6-week (Fisher's exact test, p = 0.01), 3-month (p < 0.01) or 5-month (p = 0.01) immunisation visits. CONCLUSIONS: The Immunisation 2000 target of 95% full immunisation coverage by two years of age was met by this cohort. However, infants who were late for any immunisation visits were more likely to be late for subsequent visits and incompletely vaccinated by two years of age, compared to those infants who presented on time.

Residential mobility and sudden infant death syndrome.

OBJECTIVE: To examine whether permanent domicile change of the mother, thence the infant, or temporary relocation of the infant away from his or her usual place of residence affects the risk of sudden infant death syndrome (SIDS). DESIGN: A case-control nation-wide epidemiological study. SETTING: New Zealand between the years 1987-90. PARTICIPANTS: From the 485 SIDS diagnoses over this time, parents of 393 (81%) SIDS infants consented to participate and these comprise the cases. Controls were selected by randomly sampling 1800 infants from all babies born over 78% of the country. Parents of 1592 (88%) control infants participated. RESULTS: Infants away from their usual address were 1.70 (95% CI: 1.09, 2.66) times more likely to die from SIDS than infants sleeping at home, after controlling for likely confounding factors. A partial explanation for this finding was that SIDS infants were less likely to have been mainly breast fed in the last two days and were less likely to have shared a room with at least one adult at the nominated sleep/death. Infants of mothers who shifted house after their birth, infants having mothers who shifted house within a year prior to the study interview date, and infants who slept at numerous different houses were associated with an increased relative risk for SIDS at the univariate level, but not after adjustment. CONCLUSIONS: Infants are less likely to die in their accustomed residential environment. This finding needs confirmation by other studies.

MMR immunisation coverage in Christchurch. Christchurch Immunisation Coordination Committee.

AIM: To measure measles-mumps-rubella (MMR) immunisation status of a birth cohort at 18 months of age. METHOD: All children born in Christchurch in June, July and August 1995 who were alive at 18 months of age (n = 999), were matched with MMR immunisation benefit claims. Those not listed were traced. RESULT: The final immunisation coverage rate was estimated at 85%. CONCLUSION: An 85% coverage rate at 18 months fell well short of the Immunisation 2000 target of 95% coverage by two years of age.