Epidemiology of apparent life threatening events

Aims: To investigate the epidemiology and risk factors of apparent life threatening events (ALTE). Methods: A prospective study enrolled all live-born infants in the Tyrol (1993–2001). Information on pregnancy, sociodemographic characteristics, child care practices, and infant''s behaviour in the first four to six weeks of life was collected with a standardised questionnaire, and was available for 44 184 infants. ALTE was identified from hospital admission records. Results: During the study period 164 ALTE cases were identified, corresponding to an incidence of 2.46/1000 live births. In 73 of these infants no cause for the event and no comorbidity could be found (idiopathic ALTE). On average ALTE manifested ten weeks earlier than SIDS. Of various SIDS risk factors in the survey area, the prone sleeping position, smoking during pregnancy, low gestational age, profuse night sweating, and family history of infant death showed a moderate relation to the risk of overall ALTE, but only smoking maintained significance in the multivariate risk model. None of these variables was associated with idiopathic ALTE. In contrast to SIDS the frequency of ALTE did not change during the study period. None of the ALTE infants experienced SIDS later in life. Behavioural abnormalities such as feeding difficulties, episodes of pallor, cyanotic episodes, and repeated apnoea episodes were strongly associated with an increased risk of overall and idiopathic ALTE. Conclusions: Although there are some similarities in the clinical presentation and epidemiology of SIDS and ALTE, differences clearly predominate. Accordingly, ALTE and SIDS should not be considered different manifestations of the same disease process.     

Epidemiology of apparent life threatening events.

AIMS: To investigate the epidemiology and risk factors of apparent life threatening events (ALTE). METHODS: A prospective study enrolled all live-born infants in the Tyrol (1993-2001). Information on pregnancy, sociodemographic characteristics, child care practices, and infant's behaviour in the first four to six weeks of life was collected with a standardised questionnaire, and was available for 44,184 infants. ALTE was identified from hospital admission records. RESULTS: During the study period 164 ALTE cases were identified, corresponding to an incidence of 2.46/1000 live births. In 73 of these infants no cause for the event and no comorbidity could be found (idiopathic ALTE). On average ALTE manifested ten weeks earlier than SIDS. Of various SIDS risk factors in the survey area, the prone sleeping position, smoking during pregnancy, low gestational age, profuse night sweating, and family history of infant death showed a moderate relation to the risk of overall ALTE, but only smoking maintained significance in the multivariate risk model. None of these variables was associated with idiopathic ALTE. In contrast to SIDS the frequency of ALTE did not change during the study period. None of the ALTE infants experienced SIDS later in life. Behavioural abnormalities such as feeding difficulties, episodes of pallor, cyanotic episodes, and repeated apnoea episodes were strongly associated with an increased risk of overall and idiopathic ALTE. CONCLUSIONS: Although there are some similarities in the clinical presentation and epidemiology of SIDS and ALTE, differences clearly predominate. Accordingly, ALTE and SIDS should not be considered different manifestations of the same disease process.     

Why do ALTE infants not die in SIDS?

Aim: To compare known risk factors for sudden infant death syndrome (SIDS) amongst infants with apparent life threatening events (ALTE) with their matched controls, and ALTE infants who subsequently died of SIDS with infants surviving an ALTE.
Methods: Questionnaires with replies were obtained from 58 ALTE infants and 56 sex and age matched ALTE control infants. 244 SIDS cases and 868 SIDS controls were used as comparison.
Results: The incidence of ALTE was found to be 1.9% among SIDS controls, but 7.4% among infants who later on died of SIDS. The parents sought medical advice in 0.9% vs 3.7%. ALTE infants did not differ from their matched controls. In the ALTE group 13.3% of the survivors had the combination of prone sleeping and maternal smoking compared with 33.3% of those who became SIDS victims.
Conclusions: Our results show some major differences between the ALTE infants and SIDS victims not supporting that these conditions belong to the same entity. However, we cannot exclude the possibility that there is a subpopulation of ALTE infants who did not die in SIDS due to that they were sleeping on the back and not exposed to nicotine.     

Discharge diagnoses in infants with apparent life-threatening event

BACKGROUND: There are various identifiable diseases or conditions that can be associated with an apparent life-threatening event (ALTE) in infancy. The present study was carried out to investigate the etiology of ALTE based on the discharge diagnoses. METHODS: A protocol for the complete work-up used to examine the cause of ALTE was designed, and was carried out for 69 infants with ALTE. RESULTS: Gastroesophageal reflux disease (GERD) was demonstrated in 38 cases, and chronic gastric volvulus (CGV) was diagnosed in 21 (associated with GERD in 13 infants). Four cases of pertussis and two cases each of sepsis, laryngomalacia, respiratory immaturity, and premature ventricular contractions were found. Others cases presented with pneumonia, meningitis, intussuception, food allergy, epilepsy, and adenoid vegetations. In 12 of the 69 infants with ALTE, no abnormalities were found in any of the studies performed, including two patients with breath-holding spells. In 17 cases, two or more possibly contributing findings were diagnosed. CONCLUSION: It is important to recognize that gastroesophageal impairments such as GERD or CGV could be responsible for many incidences of ALTE in infancy. The authors recommend a trial be established to investigate the causes of ALTE, including gastroesophageal evaluations in all infants with ALTE.     

Increased inspiratory effort in infants with a history of apparent life-threatening event

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 degrees) 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.     

Apparent Life-Threatening Events in the Young Infant and Neonate

An infant presenting to the ED with an ALTE remains a difficult clinical challenge. The history and physical examination are key to directing the diagnostic workup. There is no standard evaluation for an infant with an ALTE. Currently, in-hospital observation and monitoring remain an accepted treatment for young infants and especially for those with repeated ALTEs. In young infants, prematurity plays a significant role in the diagnostic possibilities that include GI, neurologic, and infectious disorders. The goal is to identify a treatable cause that will serve to define the expected natural history. Evidence is lacking regarding the true risk of subsequent events and death vs the perceived risk of death. Diagnosis and treatment are complicated by the heterogeneity of the group of infants with ALTE. Collaborative multicenter studies are needed to develop and refine best practice guidelines, to improve coding and diagnostic criteria for infants with ALTE, and to identify the true risk of adverse outcomes.     

Cardiac tamponade presenting as an apparent life-threatening event

The initial emergency department (ED) evaluation of infants with an apparent life-threatening event (ALTE) often fails to identify a definitive cause for the event. Many children that present with an ALTE appear normal by the time they arrive to the ED. These factors can desensitize clinicians into prematurely discounting serious underlying causes of the ALTE or being less prompt in their evaluation of these patients. We present the case of a young infant who presented to an ED with an ALTE resulting from cardiac tamponade. Cardiac tamponade has not been reported as an underlying cause of infants presenting to the ED with an ALTE. Previously reported cases of cardiac tamponade in children have occurred as a complication of malignancies, cardiac surgery, trauma, infections, central venous catheter placement, rheumatologic, and autoimmune diseases. This case should serve as a reminder to clinicians to maintain a broad differential diagnosis and promptly evaluate all infants presenting with an ALTE.     

Smaller mandibular size in infants with a history of an apparent life-threatening event

OBJECTIVES: To examine small mandibular size and preference for a hand-to-chin posture as salient characteristics in infants with a history of an apparent life-threatening event (ALTE). STUDY DESIGN: This was a prospective case-control study of term infants, from birth to 6 months of age, admitted post-ALTE and matched 1:2 with healthy control infants (age within 2 weeks and weight within 0.5 kg). Infants with confirmed gastroesophageal reflux and congenital anomalies, including severe micrognathia, were excluded. RESULTS: Infants with a history of an ALTE (n = 25) were matched to 47 healthy controls. Infants with a history of an ALTE had mandibular indices (larger index indicates a smaller mandible) that were 3.8 mm greater on the left side (95% CI: 2.0-5.6, P < .001) and 4.2 mm greater on the right side (95% CI: 2.7-5.6, P < .001) adjusting for length and non-white race. Controlling for matching and length, a 1-mm increase in the average mandibular index increased the odds of an ALTE by 62% (OR = 1.62, 95% CI: 1.22-2.44, P < .001). CONCLUSIONS: Smaller mandibular size was associated with ALTE, suggesting airway obstruction as a potential cause of ALTE. The association of this characteristic with ALTE also offers the potential for prospective quantification of ALTE risk.     

Heart rate variability in infants with apparent life-threatening events

Heart rate variability (HRV) is often used as an index of sympatho-vagal balance. A decreased HRV has been observed in patients with central hypoventilation and in infants who have later succumbed to sudden infant death syndrome (SIDS). The aim of the present study was to investigate whether HRV is altered in infants with apparent life-threatening events (ALTE), a group with an increased risk of SIDS. Fifty infants with ALTE were compared with 50 age- and sex-matched controls. ECG was recorded overnight in all infants. Two sequences of RR intervals free of artefacts were selected from each sleep state and spectral analysis of RR variability was performed. The mean and SD of RR and the low (LFPow) and high (HFPow) frequency power were analysed. In active sleep (AS) the LF/HF ratio was lower in ALTE infants, but no differences were seen in either the LFPow or the HFPow. In quiet sleep (QS), however, ALTE infants had higher SD-RR (p = 0.006), greater HFPow (p = 0.02) and VLFPow (very low frequency power, p = 0.02) than the control infants. The same results were seen when the two sleep states were combined for analysis, ALTE infants had higher SD-RR (p = 0.004), HFPow (p = 0.006) and VLFPow (p = 0.04). Conclusion: The different HRV pattern in ALTE infants compared to healthy controls suggests an altered autonomic control.     

Brief Resolved Unexplained Events: Analysis of an Apparent Life Threatening Event Database

ObjectiveTo identify the proportion of patients previously diagnosed with apparent life-threatening events (ALTE) who would meet criteria for brief resolved unexplained events (BRUE) and to identify rates of adverse outcomes in subgroups: ALTE not meeting criteria for BRUE, lower-risk BRUE, and higher-risk ALTE.MethodsWe performed a secondary analysis of a single-center prospective registry of patients diagnosed with ALTE in a tertiary care emergency department from March 1, 1997 to October 31, 2007. We identified the proportion of patients meeting criteria for BRUE, and the proportion of patients with BRUE meeting lower-risk criteria. We assessed outcomes of patients in subgroups.ResultsSeven hundred and sixty-two patients were included. Adverse outcomes included recurrent ALTE (n = 49), aspiration (n = 9), trauma (n = 8), and death (n = 4). Three hundred and twenty-six of 762 (42.8%) met criteria for BRUE. Seventy of 326 (21.5%) met criteria for lower-risk BRUE. Adverse outcomes occurred in 40 of 436 (9.2%) with ALTE not meeting criteria for BRUE, 2 of 70 (2.9%) with lower-risk BRUE, and 23 of 256 (9.0%) with higher-risk BRUE. Of 4 patients who died, 1 had an ALTE not meeting criteria for BRUE and 3 had non–lower-risk BRUE. The BRUE risk criteria identified all BRUE patients that died or had substantial morbidity as higher-risk.ConclusionsLess than half of patients with ALTE meet criteria for BRUE. Of those who do, one-fifth is lower-risk. In this series, the risk-stratification in the BRUE criteria identified those patients at highest risk of adverse outcomes. Further research is required to risk-stratify patients with BRUE.     

Surveillance study of apparent life-threatening events (ALTE) in the Netherlands

SIDS and ALTE are different entities that somehow show some similarities. Both constitute heterogeneous conditions. The Netherlands is a low-incidence country for SIDS. To study whether the same would hold for ALTE, we studied the incidence, etiology, and current treatment of ALTE in The Netherlands. Using the Dutch Pediatric Surveillance Unit, pediatricians working in second- and third-level hospitals in the Netherlands were asked to report any case of ALTE presented in their hospital from January 2002 to January 2003. A questionnaire was subsequently sent to collect personal data, data on pregnancy and birth, condition preceding the incident, the incident itself, condition after the incident, investigations performed, monitoring or treatment initiated during admission, any diagnosis made at discharge, and treatment or parental support offered after discharge. A total of 115 cases of ALTE were reported, of which 110 questionnaires were filled in and returned (response rate 97%). Based on the national birth rate of 200,000, the incidence of ALTE amounted 0.58/1,000 live born infants. No deaths occurred. Clinical diagnoses could be assessed in 58.2%. Most frequent diagnoses were (percentages of the total of 110 cases) gastro-esophageal reflux and respiratory tract infection (37.3% and 8.2%, respectively); main symptoms were change of color and muscle tone, choking, and gagging. The differences in diagnoses are heterogeneous. In 34%, parents shook their infants, which is alarmingly high. Pre- and postmature infants were overrepresented in this survey (29.5% and 8.2%, respectively). Ten percent had recurrent ALTE. In total, 15.5% of the infants were discharged with a home monitor. In conclusion, ALTE has a low incidence in second- and third-level hospitals in the Netherlands. Parents should be systematically informed about the possible devastating effects of shaking an infant. Careful history taking and targeted additional investigations are of utmost importance.     

Abnormal heart rate response to hypercapnia in boys with an apparent life-threatening event

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.     

Patterns of gastroesophageal reflux (GER) in patients with apparent life-threatening events

The incidence and temporal patterns of gastroesophageal reflux (GER) in infants presenting with an apparent life-threatening event (ALTE) was compared with GER characteristics of infants evaluated for persistent emesis, utilizing continuous 24 h intraesophageal pH monitoring. These data indicate that the incidence of significant GER was similar in both groups, despite the absence of a clinical vomiting history in 46% of ALTE patients. Furthermore, infants with ALTE demonstrate a significantly higher incidence of sleep reflux when compared with control infants presenting with vomiting alone (27 vs. 0%, p less than 0.001). Awake GER beyond the first two postprandial hours was not observed in either study group. Monitoring results, therefore, indicate that significant GER is common in infants with ALTE; and these infants manifest an apparently unique pattern of GER distinct from that observed in age-matched controls with GER alone. Possible relationships between GER in ALTE patients and the development/onset of apneic episodes are discussed.     

Relationship of sweat electrolytes to apparent life-threatening events (ALTE): a case control study

Twenty infants aged 25 days to 6 months who were consecutively investigated for apparent life-threatening events (ALTE) with negative results and 20 matched normal controls underwent an iontophoresis sweat test. A statistically significant elevated sweat potassium level (22.1 × 8.9 versus 12.4 × 6.5mol/l) was noted in the ALTE patients compared with the control group ( p < 0.001). No difference was found, however, between sweat sodium and chloride levels in the two groups. Na/K ratio in sweat was significantly different between the groups ( p < 0.001). A between-groups discriminant analysis, using Na/K ratio as a discriminant variable, resulted in 80% accuracy in group assignment. A significant increase in sweat potassium concentration at night compared with day time was evident in ALTE patients. Elevated sweat potassium levels specifically characterized infants who experienced ALTE and may possibly indicate an underlying mechanism involving enhanced sympathetic activity.     

Apparent Life-Threatening Events in Neonatal Period: Clinical Manifestations and Diagnostic Challenges in a Pediatric Referral Center

Objective

Apparent Life-Threatening Events (ALTEs) is an episode that is frightening to the observer and is characterized by some combination of apnea, color change, altered muscle tone, choking, and gagging. This study was designed to evaluate and follow up neonates who presented with clinical manifestation of an ALTE in a year.

Methods

In this prospective observational study, all of the neonates with episode of ALTE who were admitted to the Children''s Medical Center (CMC) in Tehran, from June 15^th 2010 to May 14^th 2011 were enrolled in the study. Data from patients consisting of history, physical examinations, and paraclinical findings were recorded in a checklist and all followed up 3 to 6 months after discharge.

Findings

During the study period 18 neonates were admitted due to ALTE episode(s) with mean age of 15±13 days. Nine (50%) neonates had previous attacks of ALTE. The most frequent complaint was cyanosis in 12 (67%) and apnea in 8 (44%) patients. In 10 (56%) the event lasted less than one minute, 13 (72%) were awake, 17 (95%) in supine position and 13 (72%) on their parent''s lap. Primary antagonistic impression on admission was sepsis in 11 (61%) and concomitant seizure in 5 (28%). The most common final diagnosis according to repeated physical examinations, result of paraclinical investigations and follow up was sepsis 4 (22%) and aspiration 9 (50%). ALTE recurred in none of the neonates during follow up.

Conclusion

The rate of ALTE seems to be higher than in this study owing to high incidence of recurrent ALTE. Although most of these attacks regress spontaneously, more attention should be paid for the underlying diseases.     

Associated and prognosis in apparent life threatening events (ALTE)

OBJECTIVE: To verify the etiology and prognosis of ALTE in infancy and its possible relationship to Sudden Infant Death Syndrome (SIDS). METHODS: We studied a group of infants that presented ALTE episodes and were evaluated in our hospital. First we reviewed their clinical history and polysomnographies, then we sent a letter to the families with questions regarding the outcome. RESULTS: 56 patients were included. 92% had ALTE during their first 6 months and 83% in the first trimester. Symptomatic ALTE predominated (71%). The disease most frequently associated was gastroesophageal reflux, followed by neurological diseases. The follow up showed 51.5% of normal outcome, 4 children repeated ALTE, no cases of SIDS were registered. CONCLUSIONS: Our results showed that multifactorial etiologies can be associated to ALTE, and the outcome is generally related to the associated disease. We did not observe any relationship between ALTE and SIDS considering a predominantly symptomatic ALTE population.     

Transepidermal water loss during sleep in infants at risk for sudden death

To search for excessive sweating during sleep in infants considered at risk for sudden infant death syndrome (SIDS), we studied 258 infants during one night. There were 134 normal infants (controls), 85 siblings of SIDS victims (siblings), and 39 infants who survived an apparent life-threatening event (ALTE) with no cause found for the incident. Mean postnatal ages were between 10 and 16 weeks. Transepidermal water evaporation rate was measured from the forehead using an evaporimeter during one night's polygraphic sleep recording. Measurements were made before feedings, during the first part of the night, and evaporation rate values were expressed as grams per square meter of body surface area per hour. In the three groups of patients evaporation rates were significantly lower during rapid eye movement (REM) sleep, compared with values measured during quiet wakefulness or nonrapid eye movement (NREM) sleep. Infants with an ALTE had significantly higher evaporation rate values during NREM sleep than the two other groups (20.1 +/- 1.93, 11.3 +/- 0.68, and 11.5 +/- 0.98 for the ALTE, control, and sibling infants, respectively). The differences were not related to age, sex, weight, or rectal temperature. During NREM sleep, evaporation rate values greater than 25 mg/m2/h were seen in 10/190 (5.3%) of the asymptomatic infants and in 11/36 (30.6%) of the infants with an ALTE. The results are in agreement with reports in the literature of repeated night sweating in infants who eventually died of SIDS. Although we are unable to conclude why evaporation rate values are higher in the ALTE group than in the two other groups, we cannot exclude that it reflects differences in autonomous system activity.(ABSTRACT TRUNCATED AT 250 WORDS)     

Apparent life-threatening event: a review

An "apparent life-threatening event" (ALTE) refers to an episode that is of concern to the caregiver and is associated with a combination of apnea, color change, change in tone, choking, or gagging. Although the natural history of ALTE is most often benign, there is a risk for subsequent morbidity and mortality. The provider must stabilize the infant as needed, obtain key history, identify and address any underlying causes, educate the caregivers, and provide a safe disposition. This article summarizes the body of literature concerning ALTE, with specific attention to the diagnosis and management of these cases.     

Management of an infant with an apparent life-threatening event

Our clinical experience agrees with most of the recent literature that infants with an apparent life-threatening event (ALTE) form a heterogeneous entity. A specific medical or surgical cause for the event could be found in 61% of the cases. Only 14% of the infants with an apparently severe event entered a home monitoring program. The other infants were treated whenever appropriate. All infants survived the first year of life. Home monitoring was shown to require continuous assistance to the parents. The follow-up of the infants up to 10 years after the ALTE reveals no neurodevelopmental abnormality in most of the infants. A systematic exclusional study of the infants with an ALTE, together with appropriate treatment programs, could thus provide the possibility of a good survival for most infants.     

Metabolic disease in 10 patients with sudden unexpected death in infancy or acute life‐threatening events

In order to determine the associations between sudden unexpected death in infancy (SUDI) or acute life‐threatening events (ALTE) and inborn errors of metabolism, particularly organic acidemia and fatty acid oxidation disorders, we evaluated clinical features in patients with SUDI or ALTE. The subjects were infants between the ages of 7 days and 3 years who developed SUDI or ALTE between January 2004 and December 2013. They were then diagnosed as having inborn errors of metabolism on gas chromatography–mass spectrometry (GC/MS) and/or tandem mass spectrometry (MS/MS). The age distribution, onset forms, and clinical findings were evaluated during the acute phase. Inborn errors of metabolism were detected in three of 196 patients with SUDI, and in seven of 167 patients with ALTE. Of these 10 patients, nine had a history of poor feeding and somnolence during the neonatal period, and symptoms of infection such as cough, fever or vomiting during infancy. Routine laboratory tests during an acute phase indicated hyperammonemia, liver dysfunction, increased blood creatine kinase, acidosis, positive ketone bodies in urine or blood, or hypoglycemia. When SUDI or ALTE are encountered in the emergency unit, it is essential that a detailed medical history is taken, particularly with regard to the neonatal period, and that specific abnormalities are investigated on routine laboratory tests. Moreover, samples such as urine, serum, and filter paper blood specimens should be collected for GC/MS and/or MS/MS of organic acids and acylcarnitines, to identify inborn metabolic disorders.