Apparent life-threatening event (ALTE) is a term used to describe an acute, unexpected episode that consists of a change in an infant’s breathing, appearance, or behavior. It is a clinical description, rather than a specific diagnosis, and represents a wide variety of presentations with diverse underlying pathology.
(See Nelson Textbook of Pediatrics , p. 2004.)
Definition
The current definition of ALTE was established at the 1986 National Institutes of Health Consensus Development Conference on Infantile Apnea and Home Monitoring ( Table 5.1 ). ALTE was defined as “an episode that is frightening to the observer, that is characterized by some combination of apnea (central or occasionally obstructive), color change (usually cyanotic or pallid, but occasionally erythematous or plethoric), marked change in muscle tone (usually marked limpness), choking, or gagging.”
| Apparent life-threatening event (ALTE) | An episode that is frightening to the observer and that is characterized by some combination of apnea (central or occasionally obstructive), color change (usually cyanotic or pallid but occasionally erythematous or plethoric), marked change in muscle tone (usually marked limpness), choking, or gagging |
| Apnea | Cessation of respiratory airflow which can be central (i.e., no respiratory effort), obstructive (usually due to upper airway obstruction), or mixed |
| Pathologic apnea | Apnea that is prolonged (20 sec) or associated with cyanosis; abrupt, marked pallor or hypotonia; or bradycardia |
| Periodic breathing | A breathing pattern in which there are three or more respiratory pauses of >3 sec in duration with <20 sec of respiration between pauses |
| Apnea of prematurity (AOP) | Periodic breathing with pathologic apnea in a premature infant that usually ceases by 37 wk of gestation but occasionally persists to several weeks past term |
| Apnea of infancy (AOI) | An unexplained episode of cessation of breathing for 20 sec or longer, or a shorter respiratory pause associated with bradycardia, cyanosis, pallor, and/or marked hypotonia in infants who are >37 wk of gestational age at onset of pathologic apnea |
| Sudden infant death syndrome (SIDS) | The sudden death of any infant or young child, which is unexplained by history and in which a thorough postmortem examination fails to demonstrate an adequate explanation of cause of death |
The term ALTE was in part established to replace previously used labels, including “near-miss SIDS” or “aborted crib death,” which inappropriately suggested a clear association between ALTEs and sudden infant death syndrome (SIDS). SIDS is defined as the sudden death of any infant or young child, which is unexplained by history and in which a thorough postmortem examination fails to demonstrate an adequate explanation of cause of death. Studies have failed to establish a clear association between ALTEs and SIDS. Although there are some overlapping risk factors between SIDS and ALTEs, they are separate entities. The vast majority of SIDS victims do not have a preceding ALTE. The American Academy of Pediatrics Task Force on SIDS is clear in its stance that there is no evidence that an ALTE is a precursor to SIDS.
The subjectivity and vagueness of the current definition has made it difficult to standardize the care of these patients. In 2016 the American Academy of Pediatrics (AAP) released a clinical practice guideline related to the care of these patients. This guideline includes a change in terminology to BRUE (brief resolved unexplained event), which is defined as an event lasting <1 min in an infant under one year of age that is associated with at least one of the following: cyanosis or pallor; absent, decreased, or irregular breathing; marked change in muscle tone (hypertonia or hypotonia); altered level of responsiveness in a patient who at the time of examination is otherwise well-appearing and back to baseline, and, on evaluation, has no condition that could explain the event. The guideline recommends limited interventions for patients designated as being at low risk for recurrence. Low-risk patients include those having their first event who are >60 days old, ≥32 weeks’ gestational age, ≥45 weeks postconceptional age, had an event lasting <1 minute and did not require cardiopulmonary resuscitation, and who have no concerning historical or physical exam findings.
Epidemiology
The exact incidence of ALTEs is unknown because the definition of an ALTE is subjective, and not all children with ALTEs present for evaluation. Reported figures may underestimate the true incidence of patients presenting with ALTEs since studies may not include those cases where the underlying cause is ultimately identified. The incidence is estimated to be between 0.46 and 2.46 per 1000 live births, accounting for 0.6-1% of all emergency department visits by patients younger than 1 year and 2% of pediatric hospitalizations. Most occur in infants less than 1 year of age, with a peak incidence between 1 week and 3 months. Occurrence is equal between males and females. The mortality rates reported to be associated with ALTEs vary widely depending on the definition used and the population studied. Due to the diversity of the potential underlying etiology of an ALTE, clinicians should be cautious in the application of these rates to the ALTE population as a whole ( Table 5.2 ).
| Central Nervous System |
| Arteriovenous malformation |
| Subdural hematoma |
| Seizures |
| Congenital central hypoventilation * |
| Neuromuscular disorders (Spinomuscular atrophy) |
| Chiari crisis |
| Leigh syndrome * |
| Cardiac |
| Subendocardial fibroelastosis * |
| Aortic stenosis |
| Anomalous coronary artery |
| Myocarditis |
| Cardiomyopathy * |
| Arrhythmias (prolonged Q-T syndrome, Wolff-Parkinson-White syndrome, and congenital heart block) * |
| Pulmonary |
| Nasal obstruction |
| Pulmonary hypertension |
| Vocal cord paralysis |
| Aspiration |
| Laryngotracheal obstructive diseases |
| Gastrointestinal |
| Diarrhea and/or dehydration |
| Gastroesophageal reflux |
| Volvulus |
| Endocrine–Metabolic |
| Congenital adrenal hyperplasia * |
| Malignant hyperpyrexia * |
| Long- or medium-chain acyl coenzyme A deficiency * |
| Hyperammonemias (urea cycle enzyme deficiencies) * |
| Glutaric aciduria * |
| Carnitine deficiency (systemic or secondary) * |
| Glycogen storage disease type I * |
| Maple syrup urine disease * |
| Congenital lactic acidosis * |
| Biotinidase deficiency * |
| Infection |
| Sepsis |
| Meningitis |
| Encephalitis |
| Brain abscess |
| Pyelonephritis |
| Bronchiolitis (respiratory syncytial virus) |
| Infant botulism |
| Pertussis |
| Trauma |
| Child abuse * |
| Accidental or intentional suffocation |
| Physical trauma |
| Factitious syndrome (formerly Munchausen syndrome) by proxy * |
| Poisoning (Intentional or Unintentional) |
| Boric acid |
| Carbon monoxide |
| Salicylates |
| Barbiturates |
| Ipecac |
| Cocaine |
| Insulin |
| Others |
Etiology
Because ALTE is a descriptive category based on broad symptomatology, the differential diagnosis is large. Comorbid conditions are frequently identified, but it can be challenging to identify true causation. Thus caution must be used in implicating a specific diagnosis as the true cause of an ALTE. A suspected diagnosis is found in approximately 50% of ALTEs. These diagnoses encompass a wide range of etiologies and systems.
The most commonly cited diagnoses include gastroesophageal reflux (GER), seizures, and lower respiratory tract infections. However, numerous less common but potentially dangerous and/or treatable conditions can also present as an ALTE (see Table 5.2 ). These need to be carefully considered in order to provide prompt life saving or outcome-altering treatment. A thorough and thoughtful history and physical examination is extremely important in the evaluation of a patient with an ALTE, as it provides essential clues to help narrow the differential. It is often helpful to consider the differential diagnosis by a systems-based approach, considering both common and rare but concerning diagnoses in each category. Key systems-based historical and physical examination findings may help discriminate among possible etiologies ( Table 5.3 ).
| Diagnostic Categories | Common and/or Concerning Causes to Consider | Suggestive Historical Findings | Suggestive Physical Examination Findings | Testing to Consider |
|---|---|---|---|---|
| Gastrointestinal | GER Intussusception Volvulus Swallowing abnormalities | Coughing, vomiting, choking, gasping Feeding difficulties Recent preceding feed Irritability following feeds Milk in mouth/nose Bilious emesis Pulling legs to chest Bloody/mucousy stool Lethargy following event | Gastric contents in the nose and mouth Abdominal distention Abdominal tenderness | Upper GI to assess for anatomic anomalies Swallow evaluation Abdominal ultrasound pH probe |
| Infectious | Upper and lower respiratory tract infection (RSV, pertussis, pneumonia) Bacteremia Meningitis Urinary tract infection | Preceding URI symptoms Multiple events on the day of presentation Sick exposures Foul-smelling urine | Fever/hypothermia Lethargy Ill appearance Coryza Cough Wheeze Tachypnea | NP swab for RSV, pertussis Chest radiograph CBC and Blood culture Cerebrospinal fluid analysis and culture Urinalysis and culture |
| Neurologic | Seizures Breath holding spells Congenital central hypoventilation syndrome Neuromuscular disorders Congenital malformations of the brain and brainstem Malignancy Intracranial hemorrhage | Multiple events Loss of consciousness Change in tone Abnormal muscular movements Eye deviation Preceding triggers | Papilledema Abnormal muscular movements Hypertonicity or flaccidity Abnormal reflexes Micro- or macrocephaly Dysmorphic features | EEG Neuroimaging |
| Respiratory/ ENT | Apnea of prematurity Apnea of infancy Periodic breathing Airway anomaly Aspiration Foreign body Obstructive sleep apnea | Prematurity Foreign body Aspiration Noisy breathing | Wheezing Stridor Crackles Rhonchi Tachypnea | Chest radiograph Neck radiograph Laryngoscopy Bronchoscopy Esophagoscopy Polysomnography |
| Child maltreatment | Non-accidental head trauma Smothering Poisoning Factitious syndrome (formerly Munchausen syndrome) by proxy | Multiple events Unexplained vomiting or irritability Recurrent ALTEs Historical discrepancies Family history of unexplained death, SIDS, or ALTEs Single witness of event Delay in seeking care | Bruising (especially in a non-mobile child) Ear trauma, hemotympanum Acute abdomen Painful extremities Oral bleeding/trauma Frenulum tears Unexplained irritability Retinal hemorrhages Depressed mental status | Skeletal survey Computed tomography of the head Dilated funduscopic examination Toxicology screen |
| Cardiac | Dysrhythmia (prolonged QT syndrome, Wolff-Parkinson-White syndrome) Cardiomyopathy Congenital heart disease Myocarditis | Abrupt onset Feeding difficulties Failure to thrive Diaphoresis Prematurity | Abnormal heart rate/rhythm Murmur Decreased femoral pulses | 4 extremity blood pressure Pre- and post-ductal oxygen saturation measurements ECG Echocardiogram Serum electrolytes, calcium, magnesium |
| Metabolic/genetic | Inborn errors of metabolism Electrolyte abnormalities Genetic syndromes including those with craniofacial malformations | Severe initial event Multiple events Event associated with period of stress or fasting Developmental delay Associated anomalies Failure to thrive Severe/frequent illnesses Family history of ALTE, consanguinity, seizure disorder, or SIDS | Dysmorphic features Microcephaly Hepatomegaly | Serum electrolytes; glucose, calcium, and magnesium levels Lactate Ammonia Pyruvate Urine organic and serum amino acids Newborn screen |
Stay updated, free articles. Join our Telegram channel
Full access? Get Clinical Tree
