Evaluation of Apparent Life-Threatening Events

Abstract & Commentary

Source: Davies F, Gupta R. Apparent life threatening events in infants presenting to an emergency department. Emerg Med J 2002;19:11-16.

Apparent life-threatening events (ALTE) frighten us all. These episodes are defined as alarming events involving apnea, color change, alteration in muscle tone, choking, or gagging. Infants frequently are seen in the emergency department (ED) after "spells" of turning blue, breath-holding, or going limp. Parents understandably are concerned, especially after publicity about sudden infant death syndrome (SIDS). Since most infants are completely normal by the time of arrival in the ED, what must the attending physician ascertain in evaluating the episode? What tests are appropriate? What are the chances of recurrence or worsening? How can the parents be comforted?

To better understand the optimal evaluation and long- term outcomes of ALTEs, Davies and Gupta studied 65 infants younger than 1 year of age seen over a 12-month period in 1997. All were admitted after evaluation of ALTEs in a London ED that sees 67,000 children annually. Cases of febrile convulsions were excluded. Each infant underwent detailed evaluation by parental questionnaire, physical examination, and extensive in-hospital testing: complete blood count (CBC); chemistry panel; urinalysis with culture; urine drug screen; levels of lactate, ammonia, amino acids, and reducing substances; nasal swab for pertussis and respiratory syncytial virus (RSV); chest film; electrocardiogram (ECG); and radioisotope milk scan for gastroesophageal reflux disease (GERD). All infants were followed after hospital discharge for six months to three years. Median age was 7 weeks; 67% were younger than 10 weeks of age. Cases were distributed evenly throughout the study year.

The most frequent symptoms by questionnaire and clinical evaluation were cyanosis (71%), apnea (70%), breathing difficulty (62%), pallor (51%), stiffness (46%), floppiness (43%), choking (35%), red face (29%), limb jerking (22%), and vomiting (18%). Duration greater than 60 seconds occurred in 43%. Minor stimulation was successful in 60% and vigorous stimulation in 11%. Two infants were treated with mouth-to-mouth resuscitation, two required bag-mask ventilation, and one was intubated. None had cardiac compressions. Fifty-four percent had normal clinical evaluation in the ED. White blood cell count was greater than 12,000 in 33%; elevated lactate (> 3 mmol/L) was found in 15%. Only three had oxygen saturation less than 95%—one case each of bronchiolitis, pertussis, and bronchitis with patent ductus arteriosus (PDA). After exhaustive evaluation in the hospital, final diagnoses included GERD (25%); unknown (23%); lower respiratory tract infection (LRTI) (9%); seizure (9%); pertussis (9%); urinary tract infection (8%); factitious/Munchausen’s-by-proxy (3%); and one case each of RSV, hypocalcemia, brain tumor, opiate intoxication from cough syrup, laryngomalacia, paroxysmal atrial tachycardia (heart rate 240 beats/min), PDA, and gastroenteritis.

Of all cases, 88% experienced only one ALTE, while eight (12%) had recurrent episodes. Infants older than 2 months of age were more likely to suffer recurrence (risk ratio [RR] = 2.87; p = 0.009) than were infants with abnormal findings on initial clinical examination (RR = 3.8). Of infants younger than 2 months of age, normal clinical evaluation in the ED, and lactate level less than 2 mmol/L, none had recurrent ALTE or a definitive diagnosis. No infants died during the three-year follow-up period.

Commentary by Michael Felz, MD

The authors conclude that ALTEs in infants are usually single episodes and unassociated with serious underlying disorders. They recommend mandatory inpatient observation, to allow expanded evaluation for definitive etiologies and for parental reassurance. They cite nine earlier studies, one of which is their own, to compare the range of ALTE diagnoses from the worldwide literature involving 4966 infants from 1982 to present. These studies reveal frequencies of GERD (18-62%), unknown (15-51%), LRTI (4-7%), and seizure (2.5-9%) remarkably similar to those observed in the current study, and confirm the rarity of other disorders (e.g., airway, arrhythmia, congenital heart disease, drug effect, central nervous system mass, and electrolyte disorder) and death (0-2%).

I find these data most helpful. ALTEs provoke anxiety in families of victims, prehospital personnel, and in ED personnel. Yet the triad of age younger than 2 months, normal initial clinical assessment in the ED, and low lactate level proved most reassuring. It was noteworthy that GERD accounts for more than 25% of cases in most studies, outranking infectious etiologies and seizures. The rarity of death, including SIDS, is further emphasized.

The authors provide an evidence-based algorithm for evaluation of the first ALTE in infants. I would suggest that ED physicians, as well as nonspecialists caring for infants, be reminded that most ALTEs are innocent, solitary episodes due to unknown causes or treatable conditions such as GERD and LRTI. Seizures, sepsis, RSV, and pertussis are rare, but must not be forgotten. Periodic breathing, with 12-15 seconds of apnea, is normal in healthy infants up to three months of age and is not to be confused with an ALTE. Finally, some parents would benefit from cardiopulmonary resuscitation (CPR) training for personal reassurance and for the possibility of recurrent ALTEs.

Dr. Felz, Associate Professor, Department of Family Medicine, Medical College of Georgia, Augusta, GA, is on the Editorial Board of Emergency Medicine Alert.