The aims of this review are (a) to critically examine the epidemiologic evidence for a possible association between smoking and the sudden infant death syndrome (SIDS), (b) to review the pathology and postulated physiological mechanism(s) by which smoking might be causally related to SIDS, and (c) to provide recommendations for SIDS prevention in relation to tobacco smoking. Over 60 studies have examined the relation between maternal smoking during pregnancy and risk of SIDS. With regard to prone-sleep-position intervention programs, the pooled relative risk associated with maternal smoking was RR = 2.86 (95% CI = 2.77, 2.95) before and RR = 3.93 (95% CI = 3.78, 4.08) after. Epidemiologically, to distinguish the effect of active maternal smoking during pregnancy from involuntary tobacco smoking by the infants of smoking mothers is difficult. Clear evidence for environmental tobacco smoke exposure can be obtained by examining the risk of SIDS from paternal smoking when the mother is a non-smoker. Seven such studies have been carried out. The pooled unadjusted RR was 1.49 (95% CI = 1.25, 1.77). Consideration of the pathological and physiological effects of tobacco suggests that the predominant effect from maternal smoking comes from the in utero exposure of the fetus to tobacco smoke. Assuming a causal association between smoking and SIDS, about one-third of SIDS deaths might have been prevented if all fetuses had not been exposed to maternal smoking in utero.

Aims: To determine whether combined pre- and postnatal nicotine exposure compared with prenatal exposure alone results in more compromised postnatal hypoxia defense mechanisms and further alteration of the postnatal breathing pattern (reduced tidal volume and increased respiratory rate). Methods: Seven lambs exposed to nicotine prenatally (pN) (approximate maternal dose: 0.5 mg/kg/d) and seven lambs exposed to nicotine pre- and postnatally (ppN) (postnatal dose: 1.6-2 mg/kg/d) were studied without sedation at an average age of 5 d and 21 d during resting (room air) conditions, during exposure to 10% O-2 and during a brief exposure to 100% O-2. Results: Resting minute ventilation, occlusion pressure, effective impedance, heart rate and mean arterial blood pressure were similar in the two groups during wakefulness and quiet sleep. Resting tidal volume was significantly higher in ppN than in pN lambs during wakefulness (9.4 +/- 0.7 vs 7.7 +/- 1.4 ml/kg, p < 0.05) and quiet sleep (9.8 +/- 0.6 vs 7.6 +/- 1.5 ml/kg, p < 0.01) at 5 d and also at 21 d during wakefulness (7.7 +/- 1.0 vs 6.2 +/- 1.1 ml/kg, p < 0.05). The ventilatory, heart rate and blood pressure responses to hypoxia were comparable in the two groups during both activity states. Time to arousal from quiet sleep in response to hypoxia was equivalent in the two groups. The ventilatory response to hyperoxia was not significantly different in the two groups during either activity state.Conclusion: Continued postnatal nicotine exposure after prenatal exposure did not further compromise hypoxia defense mechanisms after birth.

Obstructive sleep apnoea (OSAS) in infants is a risk factor for sudden infant death (SIDS). Snoring in a young child should raise suspicion of OSAS, and according to recent AAP guidelines, evaluation and polysomnographic studies are recommended in selected cases as the diagnostic test of choice. However, infants under 1 y of age are excluded from the guidelines, and interventions to prevent SIDS based on respiratory monitoring remains a matter of controversy. As often happens, the evidence we need most is usually scarce.

Because smoking during pregnancy is a major risk factor for late fetal death and the sudden infant death syndrome, we investigated cardiorespiratory defense mechanisms to hypoxia in 7 prenatally nicotine-exposed (N) lambs (approximate maternal dose: 0.5 mg/kg/day) and 11 control (C) lambs all at an average age of 5 days. The ventilatory response to 10% oxygen (hyperpnea) was significantly attenuated during quiet sleep in N lambs compared with C lambs and in N lambs aroused from sleep later compared with C lambs (161 +/- 90 versus 75 +/- 66 seconds, p < 0.05). The ventilatory response to hypoxia was similar in the two groups during wakefulness (W), whereas the heart rate response (tachycardia) was significantly lower in N lambs compared with C lambs during both activity states. The ventilatory response to hyperoxia was significantly lower in N lambs compared with C lambs during both activity states. Transition from W to quiet sleep was associated with a significant decrease in ventilation in C lambs but not in N lambs. In conclusion, prenatal nicotine exposure, at a dose comparable with moderate smoking, blunts major elements of the cardiorespiratory defense to hypoxia, i.e., the heart rate and ventilatory and arousal responses, and abolishes the normal decrease in ventilation during sleep compared with W.

Aim: To determine instantaneous cardiac variability responses to increased carbon dioxide (CO2) during quiet sleep in infants who may be at risk for the Sudden Infant Death syndrome (SIDS). Methods: The cardiac rate variability before, during and after a CO2 challenge was examined in 41 infants who had experienced an apparent life-threatening event (ALTE) and 41 gender- and age-matched control infants. Results: The ALTE infants responded to CO2 breathing with a significant increase in R-R intervals, i.e. decreases in heart rate, compared to the controls (45.1% increase in R-R intervals vs. 41.4%; p=0.005). The differences between ALTE infants and controls depended primarily on the boys' responses.Conclusion: ALTE infants, particularly ALTE boys, have an autonomic dysfunction-lower sympathetic stimulation and/or inhibited vagal withdrawal when stressed with CO2. The outcome might provide clues to the mechanisms underlying the cardiovascular processes contributing to the terminal event in SIDS.

Maternal smoking during pregnancy is a risk factor for sudden fetal and infant death as well as obstructive airway disease in childhood. Fetal nicotine exposure affects organ development. The aim of the present study was to investigate effects of fetal nicotine exposure on lung function in young lambs. Nine unanesthetized, awake, prenatally nicotine-exposed lambs (N) (approximate maternal dose: 0.5 mg/kg) and 12 nonexposed control lambs (C) were studied repeatedly for 5 weeks after birth using a pneumotachograph and a computerized method for breath-by-breath determinations. N and C lambs had similar minute ventilation but a markedly different breathing pattern. At both 5 and 21 days, average age, N lambs had significantly lower tidal volumes and higher respiratory rates than C lambs. Inspiratory drive (P0.1) and effective impedance were significantly higher in N lambs compared with C lambs only at 5 days. Prenatal nicotine exposure appears to have long-term effects on the postnatal breathing pattern, suggesting altered lung function, e.g., increased airway resistance, decreased lung compliance, or both. The increased inspiratory drive is most likely secondary to increased impedance of the respiratory system. These changes are most marked close to birth but persist during the initial postnatal period.

The objective of this study was to compare the results of polysomnography between infants with a history of apparent life-threatening event (ALTE) and controls. In this case-control study, 40 full-term ALTE infants, aged 2–36 wk at the time of the event, were compared with 40 age- and sex-matched randomly selected controls. SaO2, tcpO2, tcpCO2, heart rate (HR), vector of rib cage and abdominal respiratory movements (phase angle, as an index of inspiratory effort) were recorded during natural nocturnal active and quiet sleep (AS, QS). SaO2, tcpO2, tcpCO2 were similar in ALTE and controls in both sleep states. Phase angle was increased in ALTE infants in both AS (59 ± 46 vs 26 ± 17°) and QS (53 ± 46 vs 18 ± 14, p < 0.001). Eleven ALTE infants (27.5%) experienced SaO2 < 90%, with a mean decrease in SaO2 to 86 ± 1.6% (mean ± SD), compared with 10% for controls (p= 0.003). In eight ALTE infants, SaO2 values < 90% were linked to thoracoabdominal asynchrony. SaO2 < 90% in conjunction with HR < 100 bpm were detected in three ALTE infants and one control. Periodic breathing was observed in 45% of ALTE infants and 40% of controls. Conclusion: The mean values of oxygen saturation, tcpO2 and carbon dioxide levels in ALTE infants are comparable with those of healthy controls but the ALTE infants exhibit more hypoxaemic episodes and increased inspiratory effort during sleep.

AIM:To investigate whether professional training and/or clinical experience affect the ability of caregiver to assess clinical signs of pre-emptive morphine analgesia. METHODS:In the Neurological Outcomes & Pre-emptive Analgesia In Neonates trial preterm infants undergoing mechanical ventilation were randomized to receive continuous infusion, either of morphine or placebo blinded. Staff from centres in Sweden (Stockholm and Orebro) completed an assessment form. RESULTS:A total of 360 assessment forms were collected from 52 neonates. In 59% of the cases, caregivers correctly identified patients group. Comparable proportion of answers were correct between physicians, nurses and assistant nurses (63, 60 and 54%, respectively, p = 0.60). Staff with Neonatal intensive care unit experience <1 year identified 63%, as compared to 65% for working 1-5 year, and 55% that has been working >5 years (p = 0.28). Staff's ability to correctly identify group assignment was reduced by amount of additional morphine (p < 0.01) and severity of illness (p = 0.01). CONCLUSIONS:Clinical medical staffs, including neonatologists, have great difficulties in assessing the presence and severity of pain. Further studies should focus on the methods for assessment of prolonged pain in preterm neonates, define the effects of adequate analgesia, and investigate the clinical factors that may alter neonatal responses to acute and prolonged pain.

BACKGROUND The trends in medical publishing are towards electronic versions and the use of the English language. The objective of this study was to compare general practitioners' ability to retain information when reading on paper versus on screen, and in their mother tongue versus in the English. MATERIAL AND METHODS Randomized controlled trial of 114 Scandinavian general practitioners. They read a review article for 10 minutes either on paper/in English, on screen/in English, on paper/in their mother tongue, or on screen/in their mother tongue. Afterwards they completed a questionnaire with six open questions from the article. The main outcome measure was sum score on a scale from 0 (no correct answers) to 13 (all questions answered correctly). RESULTS We found no difference between readers of paper and screen versions (median (interquartile range) 4 (2-6) vs. 4 (2-5), p = 0.97). Those who read their mother tongue scored significantly higher than those who read English (4 (3-6) vs. 3 (2-4), p = 0.01). INTERPRETATION The medium (paper vs. screen) does not influence the ability of general practitioners to retain medical information. Doctors best retain medical information when reading it in their mother tongue.

CONTEXTTo compare family physicians' ability to retain information when reading a review article on paper vs on screen, and in their mother tongue vs in English.METHODSRandomized trial of 114 Scandinavian family physicians who read a review article in October or November 2000 from the Journal of Trauma for 10 minutes either on paper and in English, on screen and in English, on paper in their mother tongue, or on screen in their mother tongue. To assess comprehension, they immediately completed a questionnaire with 6 open questions about 13 key facts from the review article. Sum score was on a scale from 0 (no correct answers) to 13 points (all questions answered correctly).RESULTSThere was no significant difference between readers of paper vs screen versions, with a median (interquartile range [IQR]) of 4 (2-6) vs 4 (2-5), respectively (P =.97). Physicians who read in their mother tongue scored significantly higher than those who read in English, with a median (IQR) of 4 (3-6) vs 3 (2-4) (P =.01).CONCLUSIONThe medium (paper vs screen) did not influence the ability of family physicians to retain medical information. They best retained medical information when reading in their mother tongue.

BACKGROUND From the early 1970s to the early 1990s, there was a significant rise in the incidence of sudden infant death syndrome (SIDS) in Scandinavia. Following the risk reducing campaign, the incidence has fallen to about the same level as in 1973. AIMS To identify the changes that have occurred in the epidemiology of SIDS. METHODS We compared the Swedish part of the Nordic Epidemiological SIDS Study (NESS), covering the years 1992–1995, with two earlier, descriptive studies during this period. To assess the changing effects of risk factors, we analysed data from the Medical Birth Registry of Sweden, covering the years 1973–1996. RESULTS There was a predominance of deaths during weekends in the 1970s and 1990s. The seasonal variation was most notable in the 1980s. The proportion of young mothers decreased from 14% to 5%. Cohabitation (living with the biological father) was as frequent in the 1990s as in the 1970s. The prevalence of high parity, admissions to neonatal wards, low birth weight, prematurity, and multiple pregnancies were all increased in the 1990s compared to the 1970s. No significant change in the prevalence of previous apparent life threatening events was found. Deaths occurring in cars diminished from 10% to below 2%. In the data from the Medical Birth Registry of Sweden, there were significantly increased odds ratios after the risk reducing campaign of the risk factors smoking during early pregnancy and preterm birth. We could find no increased effects of maternal age, parity, or being small for gestational age over time. The rate of deaths at weekends remained increased; the median age at death fell from 90 to 60 days. Seasonal variation was less notable in the periods of low incidence. Key messages SIDS incidence in Sweden declined from 1.1 per 1000 live births in 1991 to 0.3 in 1999 The predominance of deaths at weekends remained Deaths in cars declined Age at death decreased from 90 to 60 days Seasonality was less notable in periods of low incidence Odds ratios increased for smoking and prematurity

BACKGROUND:The national medical journals in Denmark, Norway, and Sweden publish selected papers from the other journals in their original languages. We wanted to know how well Scandinavian general practitioners understand their neighbour languages and English, today the "lingua franca" in medical publishing.MATERIAL AND METHODS:111 doctors (36 Norwegians, 32 Danes, 43 Swedes) completed a questionnaire in which they rated their own subjective understanding of Danish, Norwegian, Swedish, and English on a five point Likert scale.RESULTS:The Norwegian doctors rated their understanding of Danish significantly higher than Swedish (p < 0.01) and English (p < 0.01). The Swedish doctors rated English significantly higher than Danish (p < 0.01) and Norwegian (p = 0.01) and Norwegian significantly higher than Danish (p = 0.02). The Danish doctors did not rate the foreign languages differently.INTERPRETATION:Particularly because of the Swedish doctors' incomplete understanding of Danish and to some extent Norwegian, there is a risk that future communication between doctors in these countries will be conducted in the English language.

Guidelines for the clinical investigation of young children with stridor and sleep apnea are presented. Clinical examination and flexible videolaryngoscopy performed in local anaesthesia are the most important diagnostic tools for this group of children. If the impairment is severe or an objective evaluation is needed the child should also undergo nocturnal polygraphic recording and lung function tests. Out of 43 children examined with flexible videolaryngoscopy 21 had positive findings, laryngomalacia being the most common diagnosis. Flexible videolaryngoscopy is a good complement to laryngoscopy under general anaesthesia. It can be performed as early as in the neonatal period.

Data on arterial oxygen saturation (SaO2), transcutaneous pO2, pCO2 (tcpO2, tcpCO2) and breathing patterns in sleeping healthy term infants were obtained during the first 9 mo after birth. Forty‐four healthy infants, mean GA at birth 40 ± 1.0 wk, mean BW 3520 ± 562 g were examined between 2 wk and 9 mo postnatally in a cross‐sectional study. SaO2, tcpO2, tcpCO2, heart rate (HR), rib cage and abdominal respiratory movements were recorded during natural nocturnal sleep, stratified for sleep states (active sleep (AS), indeterminate sleep (IS), quiet sleep (QS)). The data on AS and IS were pooled as in previous studies. The variables were analysed with respect to age. SaO2 in AS + IS and QS was 96.1 ± 1.3%, 96.6 ± 1.4%, respectively. TcpO2 in AS + IS was 10.6 ± 1.1 kPa and 10.7 ± 1.3 kPa in QS, while tcpCO2 in AS + IS was 5.4±0.3kPa and 5.4 ± 0.4kPa in QS. Neither SaO2 nor tcpO2 was influenced by age. TcpCO2 decreased significantly postnatally. Five infants (11.3%) experienced episodes of hypoxaemia with a mean decrease in SaO2 to 86 ± 1.5%. In four infants these hypoxaemic episodes were linked to upper airway obstructions. Episodes of SaO2 < 90% in conjunction with a decrease in HR to <100bpm were detected in one infant only. Periodic breathing (PB) was observed in 38.6% of infants. Conclusion: Oxygenation and carbon dioxide levels in sleeping healthy term infants were comparable to those reported in older children. Hypoxaemic episodes, if present, are associated with upper airway obstruction. PB, often assumed to be a pathological feature, is a normal breathing pattern in this age group.