Pediatrics
Apparent life-threatening events in infants: High risk in the out-of-hospital environment

https://doi.org/10.1016/j.annemergmed.2003.10.038Get rights and content

Abstract

Study objective

The purpose of this study is to define the prevalence and significance of apparent life-threatening events among infants in the out-of-hospital setting.

Methods

This was a retrospective, cohort, outcome study of infants for whom a caregiver activated the emergency medical services (EMS) system. For purposes of the study, an apparent life-threatening event was defined as an episode of apnea, skin color change, or change in muscle tone. Study data characteristics included initial physical appearance, work of breathing, circulation skin signs, pulse rate, respiratory rate, and overall concern for the chief complaint as interpreted by EMS personnel.

Results

Sixty (7.5%) of 804 infants encountered by EMS during the study period met our criteria for apparent life-threatening event. Mean age was 3.1±3.3 months, and 55% were boys. Of the infants with apparent life-threatening event, 50 (83.3%) infants appeared to be in no distress, 8 (13.3%) infants were in mild distress, and 2 (3.3%) infants were in moderate distress. General physical appearance, work of breathing, circulatory signs, respiratory rate, and pulse rate were not clinically abnormal in the study group as a whole. Critical conditions associated with apparent life-threatening event included pneumonia or bronchiolitis (12%), seizure (8%), sepsis (7%), intracranial hemorrhage (3%), bacterial meningitis (2%), dehydration (2%), and severe anemia (2%). Limitations of the study included retrospective design and inability to follow up study patients beyond hospital discharge.

Conclusion

An apparent life-threatening event in an infant can present without signs of acute illness and is commonly encountered in the EMS setting. It is often associated with significant medical conditions, and EMS personnel should be aware of the clinical importance of an apparent life-threatening event. Infants meeting criteria for an apparent life-threatening event should receive a timely and thorough medical evaluation.

Introduction

An apparent life-threatening event is defined as an episode that is frightening to the observer and is characterized by some combination of apnea (central or obstructive), skin color change (cyanosis, pallor, erythema, or plethora), marked change in muscle tone, or unexplained choking or gagging.1 In some cases, the observer fears that the child has died.1 Apparent life-threatening events occur in younger children and should not be confused with choking or gagging episodes that commonly occur during feeding or with rhinorrhea.

Editor's Capsule Summary

What is already known on this topic

Apparent life-threatening events are a combination of symptoms (often transient) affecting infants that may include apnea, skin color change, changes in muscle tone, or unexplained choking or gagging. Frightened caregivers may believe the child is dying, but symptoms are commonly decreased or absent by the time paramedics or emergency department (ED) personnel evaluate the infant.

What question this study addressed

This study evaluated the incidence of apparent life-threatening events encountered by emergency medical services (EMS) providers over a 2-month period and tabulated the EMS providers' assessments of the patients and the disorders diagnosed after full ED evaluation.

What this study adds to our knowledge

Eighty-three percent of these patients appeared to be in no distress when evaluated by EMS providers. Forty-eight percent of patients whose assessments by EMS providers revealed no abnormalities were found to have significant, and occasionally life-threatening, illnesses during ED evaluation.

How this might change clinical practice

Apparent life-threatening events should be considered symptoms of significant illness, even in the presence of normal assessments by EMS providers; all should receive ED evaluation. Education and monitoring should be directed to this potentially deceptive presentation.

“Apparent life-threatening event” is a term that describes a symptom set and not a specific disease. Previous investigators have found a wide variety of illnesses and etiologies associated with apparent life-threatening events, including gastroesophageal reflux, pertussis, respiratory syncytial virus infection, urinary tract infection, metabolic disorders, cerebral lesions, cardiac dysrhythmia, anemia, primary prolonged apnea and obstructive sleep apnea, drug effects from administered drugs or medications, sepsis, dehydration, small airway patency abnormalities, tracheal and pharyngeal abnormalities, facial dysmorphia, child abuse, and factitious complaints by caregivers.2, 3, 4, 5, 6, 7, 8, 9, 10, 11 Before 1986, terminology such as “aborted crib death” and “near miss sudden infant death syndrome (SIDS)” was used to describe syndromes similar to apparent life-threatening events, but this terminology was abandoned because it was used inconsistently and was misleading in implying that there was a close association with SIDS and the symptom set now known as apparent life-threatening events.

A recent British publication reported an incidence rate of apparent life-threatening events of 0.6% per year in an infant population treated in or referred to a pediatric tertiary care center.2 The incidence rate of apparent life-threatening events for the general infant population is estimated to be between 0.5% and 6%.2, 4, 12 Because the term “apparent life-threatening event” denotes a symptom complex and is infrequently or inconsistently reported as a final diagnosis in medical records or diagnosis-related databases, the actual incidence of the condition in a general infant population is unknown.

In studies reporting outcome or final diagnosis, the etiologies of many cases of apparent life-threatening events remain unknown, whereas for other cases, the etiologies range in seriousness from grave to minor.2, 4, 13 As a further consideration, McGuire and Pointer14 reported 2 patients with apparent life-threatening events who were not transported by paramedics after evaluation in the field, suggesting that out-of-hospital personnel may discount caregiver information suggestive of an apparent life-threatening event.

The purposes of this study were to describe the demographic characteristics, clinical characteristics, and outcomes for a population of infants with apparent life-threatening events and for whom an ambulance in an urban emergency medical services (EMS) system was summoned.

Section snippets

Methods

This study was a retrospective, outcomes-focused, cohort analysis of infants with apparent life-threatening events for whom EMS was activated. Although retrospective, the study period occurred after paramedic personnel were prospectively trained in the recognition of apparent life-threatening events and in the standardized assessment of infant physical distress and used a consistent method to prospectively record their level of concern for each patient.

The study population consisted of all

Results

During the study, the EMS system responded to 804 calls about infants, of whom 60 (7.5%) met study criteria for apparent life-threatening events. For infants with an apparent life-threatening event, the mean age was 3.1±3.3 months, and 55% (33/60) of the infants were boys. The racial and ethnic distribution in the group with apparent life-threatening events was 4% Asian, 14% black, 52% Hispanic, 18% white, and 16% other or unknown. The racial and ethnic distribution of the infants with apparent

Limitations

This study was limited by its retrospective design. Furthermore, we were not able to follow up children who had nonspecific diagnoses beyond hospital discharge to determine whether they were neurologically intact or whether an undiagnosed medical condition was later discovered. This lack of posthospital discharge follow-up could have resulted in an underestimation of serious medical conditions associated with apparent life-threatening events. During the study, pulse oximetry was not fully used

Discussion

Our observations are consistent with previous reports that infants with an apparent life-threatening event can present to health care personnel without clinical signs or symptoms of significant illness.2, 4, 12 We found no clinically reliable abnormality in the appearance, work of breathing, circulation signs, pulse rate, or respiratory rate in our study group. This observation, combined with the substantial rate of illness requiring emergency evaluation in the infants with apparent

In retrospect

Given the opportunity to repeat this study, we would have preferred to use a prospective cohort study design. By using defined criteria and informed consent to enter cases into a study, with data collected by using a standardized data form, a prospective study is feasible. Considering the retrospective design we used, this study would have been much stronger with a longer study period and more cases for study, as well as posthospital discharge follow-up for 12 months.

We conclude that apparent

Acknowledgements

We acknowledge the Los Angeles area hospital pediatric liaison nurses for their support of the project and invaluable help in obtaining data, Erin Dorsey, RN, for grant management and coordination of data collection, and Gloria Artidiello for clerical help and typing of manuscript drafts.

References (19)

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Author contributions: SJS and MM conceived and designed the study. SJS obtained the funding and institutional review board approval. SJS, AT, and HC conducted data retrieval and collection. RJL provided statistical advice. SJS, DH, and RJL prepared the manuscript, and all authors contributed substantially to its revision. SJS takes responsibility for the paper as a whole.

Presented in part at California EMS Authority 4th annual Emergency Medical Services for Children Conference, San Diego, CA, November 2001.

Supported in part by the State of California Emergency Medical Services Authority grant EMS-9049 (Emergency Medical Services for Children).

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