Identification of infants destined to die unexpectedly during infancy: evaluation of predictive importance of prolonged apnoea and disorders of cardiac rhythm or conduction.

Twenty four hour tape recordings of electrocardiogram and breathing movement were made prospectively in 6914 full term and 2337 preterm infants or infants of low birth weight during their first six weeks of life. These recordings included 40 obtained in 29 infants who subsequently suffered the sudden infant death syndrome and 13 obtained in 10 other infants who died suddenly and unexpectedly. None of the recordings obtained in the infants who suffered the sudden infant death syndrome showed prolonged apnoea (cessation of breathing movement for 20 seconds or more) or pre-excitation. One infant had multiple ventricular premature beats (38/hour). Compared with recordings obtained in 211 control infants who did not die none of the recordings obtained in the infants who suffered the syndrome showed abnormal prolongation of the QT interval.     

Interaction between bedding and sleeping position in the sudden infant death syndrome: a population based case-control study.

OBJECTIVE--To determine the relation between sleeping position and quantity of bedding and the risk of sudden unexpected infant death. DESIGN--A study of all infants dying suddenly and unexpectedly and of two controls matched for age and date with each index case. The parents of control infants were interviewed within 72 hours of the index infant''s death. Information was collected on bedding, sleeping position, heating, and recent signs of illness for index and control infants. SETTING--A defined geographical area comprising most of the county of Avon and part of Somerset. SUBJECTS--72 Infants who had died suddenly and unexpectedly (of whom 67 had died from the sudden infant death syndrome) and 144 control infants. RESULTS--Compared with the control infants the infants who had died from the sudden infant death syndrome were more likely to have been sleeping prone (relative risk 8.8; 95% confidence interval 7.0 to 11.0; p less than 0.001), to have been more heavily wrapped (relative risk 1.14 per tog above 8 tog; 1.03 to 1.28; p less than 0.05), and to have had the heating on all night (relative risk 2.7; 1.4 to 5.2; p less than 0.01). These differences were less pronounced in the younger infants (less than 70 days) than the older ones. The risk of sudden unexpected death among infants older than 70 days, nursed prone, and with clothing and bedding of total thermal resistance greater than 10 tog was increased by factors of 15.1 (2.6 to 89.6) and 25.2 (3.7 to 169.0) respectively compared with the risk in infants of the same age nursed supine or on their side and under less than 6 tog of bedding. CONCLUSIONS--Overheating and the prone position are independently associated with an increased risk of sudden unexpected infant death, particularly in infants aged more than 70 days. Educating parents about appropriate thermal care and sleeping position of infants may help to reduce the incidence of the sudden infant death syndrome.     

Sleep related O2 desaturation in COPD patients with normoxaemia and mild hypoxyaemia

It is unknown whether daytime features predict oxygenation during sleep in COPD patients with normoxaemia or mild hypoxaemia. In this study our purpose was to evaluate by a pulse oxymeter, nocturnal desaturation in 33 COPD with PaO2 > 60 mmHg and to examine some daytime parameters as possible predictors of nocturnal hypoxaemia. A significant nocturnal desaturation has been defined by spending > or = 30% of total sleep-time with a TSTSaO2 < 90% > 30. According to this criterion we classified our patients in Desaturators (D) and Non Desaturators (ND). Our results showed that 39% of our patients were D and 61% ND. Among anthropometric and respiratory functional data we found that daytime SaO2B (r = 0.74 p < 0.001) daytime PaO2 (r = 0.47 p < 0.01) and daytime PaCO2 (r = 0.45 p < 0.05) were significantly correlated with the nocturnal oxygen desaturation and can predict the presence of sleep related hypoxaemia. In conclusion, our study confirms that a relatively high percentage of COPD patients with normoxaemia or borderline hypoxaemia exhibits significant nocturnal hypoxaemia. Further studies will suggest whether sleep related hypoxaemia deserves nocturnal oxygen therapy.     

Is there a link between cot death and child abuse?

Forty five babies delivered in Oxford obstetric units who subsequently died unexpectedly in infancy were compared with 134 controls matched for maternal age, social class, parity, and year of birth to see whether five factors identified in an earlier study as predictive of subsequent child abuse would also predict the sudden infant death syndrome. Epidemiological findings had suggested certain similarities between the two events. In contrast with babies who were abused, four of the five factors did not distinguish between babies who died suddenly and unexpectedly and their controls, but there was a slight increase in the proportion of mothers of babies who died suddenly and unexpectedly for whom nursing staff thought that support and advice on feeding the baby were needed. Factors predictive of child abuse did not predict sudden infant death in this study.     

Terminal symptoms in children dying suddenly and unexpectedly at home. Preliminary report of the DHSS multicentre study of postneonatal mortality.

Terminal symptoms in 145 children who died suddenly and unexpectedly at home were investigated and compared with symptoms in 154 control children. Eighty-five (59%) of the children who died had had terminal symptoms, which in 69 cases (48%) appeared to have been major. Non-specific symptoms were especially common among the children who died. Symptoms were often present for several days before death. Only 12 of the 69 children who died with major symptoms had been seen by a doctor within 24 hours before death. We conclude that many deaths in young children might be prevented if doctors and parents were more aware of the importance of non-specific symptoms as markers of life-threatening illness.     

Apparent life-threatening prolonged infant apnea in Saskatchewan.

Life-threatening events such as prolonged apnea and severe bradycardia are uncommon in infants. When such events occur in a family, however, the results may be disastrous. Over a period of 3 years ending June 1986, we have looked after 111 such infants aged 4 weeks to 40 weeks with a mean age of 14 weeks (male-female ratio 1.26:1). Of these infants, 33 had an identifiable cause and were treated according to the diagnoses. A structural approach to this problem yielded good results. Only 10 infants were treated with a home monitor (4 prescribed by physician and 6 by parental request). Sleep and pneumogram (polysomnogram) studies showed fewer apneic episodes with advancing age (P less than .01). Giving theophylline seemed to abolish pneumogram abnormalities. No infants died.     

Effect of exposure to 15% oxygen on breathing patterns and oxygen saturation in infants: interventional study

Objective: To assess the response of healthy infants to airway hypoxia (15% oxygen in nitrogen). Design: Interventional study. Settings: Infants’ homes and paediatric ward. Subjects: 34 healthy infants (20 boys) born at term; mean age at study 3.1 months. 13 of the infants had siblings whose deaths had been ascribed to the sudden infant death syndrome. Intervention: Respiratory variables were measured in room air (pre-challenge), while infants were exposed to 15% oxygen (challenge), and after infants were returned to room air (post-challenge). Main outcome measures: Baseline oxygen saturation as measured by pulse oximetry, frequency of isolated and periodic apnoea, and frequency of desaturation (oxygen saturation ⩽80% for ⩾4 s). Exposure to 15% oxygen was terminated if oxygen saturation fell to ⩽80% for ⩾1 min. Results: Mean duration of exposure to 15% oxygen was 6.3 (SD 2.9) hours. Baseline oxygen saturation fell from a median of 97.6% (range 94.0% to 100%) in room air to 92.8% (84.7% to 100%) in 15% oxygen. There was no correlation between baseline oxygen saturation in room air and the extent of the fall in baseline oxygen saturation on exposure to 15% oxygen. During exposure to 15% oxygen there was a reduction in the proportion of time spent in regular breathing pattern and a 3.5-fold increase in the proportion of time spent in periodic apnoea (P<0.001). There was an increase in the frequency of desaturation from 0 episodes per hour (range 0 to 0.2) to 0.4 episodes per hour (0 to 35) (P<0.001). In 4 infants exposure to hypoxic conditions was ended early because of prolonged and severe falls in oxygen saturation. Conclusions: A proportion of infants had episodes of prolonged (⩽80% for ⩾1 min) or recurrent shorter (⩽80% for ⩾4 s) desaturation, or both, when exposed to airway hypoxia. The quality and quantity of this response was unpredictable. These findings may explain why some infants with airway hypoxia caused by respiratory infection develop more severe hypoxaemia than others. Exposure to airway hypoxia similar to that experienced during air travel or on holiday at high altitude may be harmful to some infants.

Key messages

• A reduction in inspired oxygen concentration to 15% can induce severe prolonged hypoxaemia in a small proportion of infants
• Prediction of which infants will become hypoxaemic does not appear possible from analysing oxygenation or the respiratory pattern of infants breathing room air at sea level
• The way in which an infant responds to airway hypoxia may contribute to understanding the relation between respiratory infections, hypoxaemic episodes, and the sudden infant death syndrome
• Airline travel and holidays at high altitude may result in hypoxaemia in a small proportion of infants

     

Can the fall in Avon's sudden infant death rate be explained by changes in sleeping position?

OBJECTIVE--To examine the impact of changing practice with regard to infant sleeping position on mortality from the sudden infant death syndrome. DESIGN--A population based study of all infants dying suddenly and unexpectedly during February 1990 to July 1991, and two groups of controls; one comprising every 125th baby born to Avon residents and the other comprising pairs of infants matched to each index case for age, neighbourhood, and date of study. Information about sleeping position was collected at home visits soon after the index baby''s death or, for the population based controls, on several occasions in the first six months of life. The design was comparable to that of an earlier study of the same population. SETTING--County of Avon. SUBJECTS--35 infants who died suddenly and unexpectedly (32 of the sudden infant death syndrome), 70 matched controls, and 152 population based controls. RESULTS--The prevalence of prone sleeping in the matched controls was much lower than that found in an earlier study in Avon (28% (18/64) 1990-1 v 58% (76/131) 1987-9; p less than 0.001) and was comparable with the prevalence in population based controls (29%). This would be expected to lead to a reduction in the incidence of the sudden infant death syndrome to 2.0/1000 live births (95% confidence interval 1.8/1000 to 2.5/1000). The actual mortality fell from 3.5/1000 in 1987-9 to 1.7/1000. CONCLUSION--The fall in mortality can be almost entirely accounted for by the reduction in prone sleeping, suggesting a causal relation exists between them. Side and supine positions confer protection but the side position is unstable and the infant may roll prone. We therefore recommend supine as the safest sleeping position for babies.     

Arterial oxygen saturation and breathing movements during the first year of life.

Sixteen healthy term infants underwent 12 hour tape recordings of arterial oxygen saturation (SaO2)(Nellcor N100 in beat to beat mode) and breathing movements at around 6 weeks, 3 and 6 months of age. Six of these infants had an additional recording at around their first birthday. Recordings were analysed throughout for pauses in breathing movements of greater than or equal to 4 s (apnoeic pauses), episodes in which SaO2 fell to 80% (desaturations), and (only during regular breathing) baseline SaO2. In the 16 infants studied at 6 weeks, 3 and 6 months, the median frequency of both apnoeic pauses (5.6, 5.7, and 6.1/h, respectively) and desaturations (0.7, 0.4 and 0.5/h, respectively) showed little change. The majority of desaturations followed an apnoeic pause (median 73.2, 86.2 and 93.8% of desaturations). The median proportion of apnoeic pauses followed by a desaturation did not change significantly (9.0, 7.5 and 9.1%), despite an increase in the proportion of apnoeic pauses of greater than or equal to 8 s in duration from 2.0% at 6 weeks to 5.3% at 3 months (P less than 0.01). Baseline SaO2 was 97.3% or higher in all recordings. Median baseline SaO2 increased from 99.6 to 99.9% between 6 weeks and 3 months (P less than 0.02) and remained unchanged thereafter. In the subgroup of infants studied also at one year of age, again no significant differences were found with increasing age in the frequency of either apnoeic pauses or desaturations. The data show that in healthy subjects no major changes occur between 6 weeks and 1 year of life in apnoeic pause frequency or arterial oxygenation.(ABSTRACT TRUNCATED AT 250 WORDS)     

Circadian variation of the frequency of sudden infant death syndrome and of sudden death from life-threatening conditions in infants

136 infants died of sudden infant death syndrome (SIDS) and 140 infants died suddenly and unexpectedly from life-threatening conditions (LTC) from 1983 to 1989 in Leningrad entered the study. 24-hour distribution of death cases was evaluated in both studied groups. The increased incidence of SIDS was revealed from 04(00) to 06(00). There was not significant difference between circadian variation of SIDS and that of death from LTC. The early morning seems to be the time when the risk factors that lead to sudden death are likely to be prominent.     

Atrial Septal Defect in Infancy

The case histories of seven infants with atrial septal defect are presented to draw attention to certain features and possible dangers of this defect in infancy. Four infants were asymptomatic but one failed to thrive and two died suddenly. Five had ejection murmurs and two, with pulmonary hypertension, had loud pan-systolic murmurs with a thrill. In two infants murmurs were noted at birth, but in five they were first heard between the ages of 1 and 6 months. The second pulmonary sound was initially narrowly split in all, but became widely split between the ages of 12 and 20 months. Electrocardiograms and chest roentgenograms were of little help at the outset but later showed findings characteristic of the defect after one year. All infants were catheterized; a left-to-right atrial shunt was detected in each instance. Pulmonary hypertension was present in two infants, one of whom died.     

Central blood oxygen saturation vs crying in preterm newborns

Infant cry characteristics reflect the development and possibly the integrity of the central nervous system. This study evaluates the distress occurring during cry in preterm newborn infants, as related to decrease of central blood oxygenation. A recording system was developed, that allows synchronised, non-invasive monitoring of blood oxygenation and audio recordings of newborn infant's cry. Cry episodes were identified by an automatic system allowing further analysis of the changes induced by the cry episodes on the oxygen saturation level in the central nervous system. Specifically, decrease in the oxygenation level appears during a cry episode, followed by recovery of the oxygenation after the cry episode is over. In the present work we compare a group of preterm infants with a control group of full term newborns in order to detect possible differences between the two sets of patients.Results indicate that a similar decrease in oxygenation level occurs in both groups of patients, but the recovery time after the crying episode is more stable and rapid in full term newborns than in preterm ones. This could prove useful for clinicians and nurses in the prevention of developmental diseases for this class of patients.     

Negative extrathoracic pressure in treatment of respiratory failure in infants and young children.

OBJECTIVE--To assess the efficacy of a newly developed system for applying continuous or intermittent negative (subatmospheric) extrathoracic pressure in respiratory failure. DESIGN--Uncontrolled clinical trials in infants deteriorating or failing to improve despite standard medical treatment. SETTING--Paediatric and neonatal intensive care units and paediatric wards. PATIENTS--88 Infants and young children aged 1 day to 2 years with respiratory failure due to bronchopulmonary dysplasia, the neonatal respiratory distress syndrome, bronchiolitis, myopathy, the congenital hypoventilation syndrome, pneumonitis, and postoperative phrenic nerve palsy. At the start of treatment 59 were receiving greater than or equal to 50% inspired oxygen and 40 positive airway pressure ventilation. INTERVENTION--Treatment was provided within purpose built Perspex chambers of appropriate size. The chamber incorporated safe and effective latex neck seals; facilities for access, monitoring, and observation; and a heater to control the ambient air temperature. MAIN OUTCOME MEASURES--Inspired oxygen concentration and carbon dioxide pressure before application of negative extrathoracic pressure and two and 48 hours afterwards; duration of treatment; and final outcome (discharge home or death). RESULTS--While arterial oxygen saturation was maintained at constant values 75 infants showed reductions in inspired oxygen concentrations (range 4-50%, median 15%) two hours after starting treatment and 74 showed reductions at 48 hours (2-79%, median 20%). Of 59 infants who had carbon dioxide pressure measured before and after starting negative extrathoracic pressure, 21 showed a reduction (range 0.6-8.9 kPa, median 2.0), 30 no change (+/- 0.5 kPa), and eight a rise (range 0.6-5.1 kPa, median 2.1). In 28 patients extubation was facilitated, 54 patients were discharged home, where six continued treatment, and 34 died. Treatments lasted for between two and 236 days (median 13 days). CONCLUSION--Negative pressure respiratory support is a non-invasive yet effective treatment for respiratory failure. It may avoid the need for intubation, reduce the pathophysiological consequences of positive airway pressure ventilation, and aid extubation.     

Congenital heart defects as a cause of still birth and infant mortality

Among 4,686 still-births and children died from 0 to 1 a in the German Democratic Republic in 1979 there were 307 (6.6%) isolated congenital heart diseases. We only analyzed 294 died infants. The first 5 diagnoses were: Hypoplastic left heart (all infants died within the first 28 d) 9.9%, Ventricular septal defect 9.9%, Transposition of great vessels 8.8%, Coarctation aorta 7.1%, Common truncus arteriosus 5.8%. The most important results are an interesting frequency with advancing years of mothers (3.4% in 10,000 mothers of live-births aged 16 a and less to 20.6% at the age of 40 a and over (see Fig. 1), 13% premature children (under 37 weeks of gestation), 23% children under 2,500 g birth weight, 55% boys and 45% girls. 80% of the above 294 infants died within the first 3 months.     

Acute mitral valve obstruction during infective endocarditis.

Five patients were found during surgery or at necropsy to have the mitral valve orifice obstructed by vegetations. They had had unexplained severe and recurrent episodes of acute febrile pulmonary oedema, and four had few cardiac ausculatory findings. Three patients died suddenly and unexpectedly; the other two were operated on and survived. In view of its ominous prognosis, acute mitral valve obstruction should be considered in patients whose pulmonary symptoms are compatible with endocarditis and are not adequately explained by the findings on examination of the heart. The condition, which should be confirmed by echocardiography, requires emergency surgery.     

First report of Oxyspirura sp. from a captive fulvous owl (Strix fulvescens) in Mexico

Nematodes similar to Oxyspirura sp. were recovered from the cornea and nictitating membrane of a fulvous owl (Strix fulvescens). The bird had been captive for several months, but died suddenly. It had no clinical history of prior diseases, including ocular lesions.     

The aetiology of hypoxaemia in chickens selected for rapid growth

In comparison to other classes of chickens, broilers selected for rapid growth tend to be hypoxaemic, and many develop congestive heart failure (CHF). In order to explain the physiological mechanisms associated with hypoxaemia in fast-growing broiler chickens (Gallus gallus), this study examined several basic physiological parameters including the blood gas profile in arterial [left atrial (LA)] and mixed venous [right atrial (RA)] blood, systemic oxygen extraction ratio, and intrapulmonary shunt fraction. These parameters were further studied in the context of blood flow in the pulmonary circulation, structural characteristics of the lungs, and cardiac function [measured as cardiac index (CI)]. Overall, broilers had lower arterial and mixed venous blood pO(2) levels and higher pCO(2) levels compared to leghorns. The cardiac index was lower in fast-growing and CHF broilers compared to leghorn chickens or feed-restricted broilers. Systemic oxygen extraction ratio (ER) and intrapulmonary shunt fraction were significantly higher in fast-growing broilers and birds with CHF (all P<0.01). Lungs of all broilers, but not leghorns, contained ectopic, irregular nodular formations located within air spaces. Broilers with clinical signs of hypoxaemia revealed the highest number of these formations in their lung. Taken together, the present findings indicate that key factors associated with the development of hypoxaemia in fast-growing broilers include: (1) high demand for oxygen as evidenced by high oxygen ER; (2) inadequate cardiac output (CO) to fulfill the higher oxygen demands, leading to severe depletion of O(2) in mixed venous blood; and (3) elevated intrapulmonary shunt fraction and possibly dead space associated with specific pathological and anatomical characteristics within the lung.     

Sudden unexpected death in children with congenital heart disease.

Of 18,000 children with organic heart disease evaluated at The Hospital for Sick Children, Toronto between 1940 and 1971, 33 died suddenly and unexpectedly between 1 and 21 years of age. Nine had discrete obstruction of the left ventricular outflow tract and five had muscular narrowing of the left ventricular outflow tract and five had muscular narrowing of the left ventricular outflow tract. Pulmonary vascular disease caused seven sudden deaths, and arrhythmias (usually due to atrioventricular block) caused seven more. Of the five other children who died suddenly three had transposition of the great arteries, one had a complex cyanotic heart defect and one had an anomalous course of the left coronary artery, which originated from the right sinus of Valsalva. With earlier investigation of aortic stenosis, earlier closure of ventricular septal defect to avoid pulmonary vascular disease, better design of artificial pacemakers and better investigation of patients with angina, many of these deaths will be avoided in the future.     

Predicting death from initial disease severity in very low birthweight infants: a method for comparing the performance of neonatal units.

OBJECTIVES--To investigate (a) which clinical variables and physiological measures of disease severity best predict death in very low birthweight infants and (b) their use in comparing mortality between two neonatal units. DESIGN--Retrospective study of two cohorts of very low birthweight infants from overlapping time periods who received mechanical ventilation. SETTING--Two neonatal intensive care units (hospitals A and B). SUBJECTS--262 Very low birthweight infants, 130 in hospital A, 132 in hospital B. MAIN OUTCOME MEASURE--Death in hospital. RESULTS--In hospital A the mean level of oxygenation in the first 12 hours of life, whether measured as inspired oxygen requirement (FIO2), arterial/alveolar oxygen (a/AO2) ratio, or alveolar-arterial oxygen difference (A-aDO2), was more closely associated with death than any of four "traditional" risk factors: low birth weight, short gestation, the diagnosis of respiratory distress syndrome, and male sex. Mean pH in the first 12 hours was as strongly associated with death as birth weight. Multiple logistic regression models were derived in infants from hospital A using the four traditional risk factors with measures of oxygenation and pH. The validity of each model was then tested in infants from hospital B. The model based on the four traditional risk factors alone predicted death in hospital B with only 31% sensitivity. Adding mean a/AO2 ratio and mean pH increased its sensitivity to 75%, and when mean a/AO2 ratio was replaced by mean FIO2 its sensitivity increased further to 81%. Based on crude mortality rates alone, the odds of death in hospital A versus hospital B were 0.67 (95% confidence interval 0.37 to 1.23). After correcting for traditional risk factors and mean FIO2 and mean pH, however, the odds of death in hospital A increased to 3.27 (1.35 to 7.92; p less than 0.01). This increased risk persisted after adjusting for the time difference between each cohort. CONCLUSIONS--Crude comparisons of hospital mortality can be highly misleading. Reliable assessment of neonatal outcome is impossible without correcting for major risk factors, particularly initial disease severity. International agreement on a minimum core dataset of clinical and physiological information could improve neonatal audit and help to identify effective treatments and policies.     

Hypoxaemia in young Kenyan children with acute lower respiratory infection.

OBJECTIVES--To determine the prevalence, clinical correlates, and outcome of hypoxaemia in acutely ill children with respiratory symptoms. DESIGN--Prospective observational study. SETTING--Paediatric casualty ward of a referral hospital at 1670 m altitude in Nairobi, Kenya. SUBJECTS--256 Infants and children under 3 years of age with symptoms of respiratory infection. MAIN OUTCOME MEASURES--Prevalence of hypoxaemia, defined as arterial oxygen saturation < 90% determined by pulse oximetry, and condition of patient on the fifth day after admission. RESULTS--Over half (151) of the children were hypoxaemic, and short term mortality was 4.3 times greater in these children. In contrast, the relative risk of a fatal outcome in children with radiographic pneumonia was only 1.03 times that of children without radiographic pneumonia. A logistic regression model showed that in 3-11 month old infants a respiratory rate > or = 70/min, grunting, and retractions were the best independent clinical signs for the prediction of hypoxaemia. In the older children a respiratory rate of > or = 60/min was the single best clinical predictor of hypoxaemia. The presence of hypoxaemia predicted radiographic pneumonia with a sensitivity of 71% and specificity of 55%. CONCLUSIONS--Over half the children presenting to this referral hospital with respiratory symptoms were hypoxaemic. A group of specific clinical signs seem useful in predicting hypoxaemia. The clear association of hypoxaemia with mortality suggests that the detection and effective treatment of hypoxaemia are important aspects of the clinical management of acute infections of the lower respiratory tract in children in hospital in developing regions.