Apparent Life-threatening Event Infants Research Articles

Outcomes for the apparent life‐threatening event infant

To examine the outcome for apparent life-threatening event infants and the determining factors for that outcome. A retrospective review of 903 infants (0-12 months of age) presenting to the pediatric wards at Christchurch Hospital between 1985 and 1996 with events characterized by some combination of apnoea, change in color, and muscle tone. Events, resulting in 1088 admissions, were classified from medical record review according to the severity and underlying conditions, with risk factors and long-term outcomes examined. The severity of events was reduced with implementing sudden infant death syndrome recommendations regarding the risk of prone sleeping. There were no sudden infant death syndrome deaths on home apnoea monitoring. Five apparent life-threatening event infants, not referred for home apnoea monitoring, subsequently died of sudden infant death syndrome. Two infants died and one suffered significant hypoxic insult when apnoea monitoring was interrupted under the age of 4 months. Asthma and neurodevelopmental conditions appeared to be over-represented subsequently in the apparent life-threatening event group. Identifying apparent life-threatening event infants at risk of sudden infant death syndrome lacked specificity. The use of apnoea home monitoring appeared protective in this cohort, but safe sleeping practices remained central for reducing sudden infant death syndrome risk.

Fewer Spontaneous Arousals in Infants with Apparent Life-Threatening Event

A deficit in arousal process has been implicated as a mechanism of sudden infant death syndrome (SIDS). Compared with control infants, SIDS victims showed significantly more subcortical activations and fewer cortical arousals than matched control infants. Apparent life-threatening event (ALTE) is often considered as an aborted SIDS event. The aim of this study was to study the arousal characteristics of ALTE infants during the first months of life. 35 ALTE infants were studied with nighttime polysomnography at 2-3, 5-6, and 8-9 months of age. Eighteen of the infants had mothers who smoked. The infants were born full term and were usually supine sleepers. Sleep state and cardiorespiratory parameters were scored according to recommended criteria. Arousals were differentiated into subcortical activations or cortical arousals, according to the presence of autonomic and/or electroencephalographic changes. The results were compared with those of 19 healthy infants with nonsmoking mothers. During NREM sleep, the ALTE infants had fewer total arousals, cortical arousals, and subcortical activations at 2-3 and 5-6 months (P < 0.001) than control infants. ALTE infants with smoking mothers had more obstructive apnea (P = 0.009) and more subcortical activations during REM sleep at 2-3 months of age (P < 0.001) than ALTE infants with nonsmoking mothers. Spontaneous arousals were differently altered in ALTE infants than in SIDS infants, suggesting an entity different from SIDS. ALTE infants with smoking mothers had arousal and respiratory characteristics that were similar to future SIDS victims, suggesting some common abnormalities in brainstem dysfunction.

Nonlinear analysis of heart rate variability in infants with apparent life-threatening events.

Some studies have shown that neonates having experienced an Apparent Life-Threatening Event (ALTE) have an increased risk of dying of the Sudden Infant Death Syndrome (SIDS). In this study the heart rate variability in neonates has been analyzed through a study of the long range correlations and scale invariance (self-similarity) in their cardiac rhythm. The goal is to see whether it is possible to distinguish normal infants from infants with ALTEs using the previously mentioned nonlinear measures of the heart rate variability. Twelve ALTE infants are included in this study. To determine the degree to which these neonates suffer from ALTEs two examinations are performed: a polysomnography and home monitoring. Using the nonlinear measures obtained from the nonlinear analysis of the heart rate variability, the group suffering most from ALTEs can clearly be separated from the other neonates.

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.

Altered autonomic function and reduced arousability in apparent life-threatening event infants with obstructive sleep apnea.

The aim of this study was to examine cardiorespiratory control in infants presenting with an apparent life-threatening event (ALTE). We performed six to eight 45 degrees head-up tilts in 10 ALTE infants (age, 14 +/- 3 weeks) and 12 age-matched control subjects during slow wave sleep and rapid eye movement sleep (REM). All infants underwent full overnight polygraphic sleep recordings with noninvasive measurement of beat-to-beat blood pressure. All control infants had normal sleep breathing. In contrast, 5 of the 10 ALTE infants had more than two obstructive apneas per hour of sleep, with short hypoxic episodes (obstructive sleep apnea [OSA]). In slow wave sleep, in response to the tilt, the ALTE infants with OSA showed a reduced heart rate response, and three of the five showed a marked postural hypotension. The ALTE infants with OSA also had altered heart rate and blood pressure variability and an increased arousal threshold in REM (p = 0.0002). By contrast, those ALTE infants with normal sleep breathing had cardiovascular and arousal responses similar to those of the control infants. We conclude that a number of ALTE infants with OSA have abnormal cardiovascular autonomic control that, combined with their decreased arousability in REM, may provide an explanation for the ALTE episodes.

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°) and QS (53 ± 46 vs 18 ± 14, p &lt; 0.001). Eleven ALTE infants (27.5%) experienced SaO2 &lt; 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 &lt; 90% were linked to thoracoabdominal asynchrony. SaO2 &lt; 90% in conjunction with HR &lt; 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.

Observation of movements during sleep in ALTE (apparent life threatening event) and apnoeic infants — a pilot study

Fourteen infants of 2 months or 6 months of age were video-recorded during polysomnography. Four were normal infants, five had a history of ALTE (apparent life threatening event) and five had repeated and prolonged apnoea during sleep. Two ALTE infants have been recorded at 2 months as well as at 6 months of age. Movements during sleep could be classified into general movements, isolated movements of the upper extremity, startles, head rotations, and trunk rotations. In the ALTE cases at 2 months of age, the motility was quantitatively not different from the control infants but was markedly reduced at 6 months of age. (All cases had their event before 8 weeks of age.) In contrast to these findings, infants with repeated apnoea did not show a clear change in the quantity of their movements. With the exception of one ALTE case at 2 months, all observed cases of ALTE and apnoeic infants showed an abnormal quality of their spontaneous movements during sleep. As reported in a previous study [3], all these cases had also been found moving abnormally during wakefulness. It is suggested that the abnormal motility is a sequelae of the event (ALTE or repeated apnoeas) with as a consequence, an impairment of neural functions.