The diagnosis of sleep apnea--possibility for the prevention of SID?

Groups of children with a statistically enhanced risk for SIDS: siblings of SIDS-victims and other full-term and preterm infants with anamnestic signs for an enhanced risk of SIDS and a control group of healthy infants without anamnestic signs of risk were polysomnographically investigated in the first year of life. The mean apnoea duration (MA-value estimated by frequency and length of apnoeas greater than or equal to 3s) in the sleep states active and quiet sleep was calculated. During active sleep there is a significant inverse correlation between MA and postnatal age in the full-term and preterm SIDS-risk infants but not in the controls and siblings of SIDS-victims. In all age groups there are some children in the full-term and preterm infants with extremely enhanced MA-values. For 6 age groups of the first year of life the 90% percentile of the MA-value was calculated separately in the sleep states active and quiet sleep to select infants with an abnormal breathing pattern. This limit could be a help for the decision on therapy.     

Sleep apnoea in acute bronchiolitis.

Three- to 4-hour polygraphic sleep studies were carried out in 16 infants aged between 1 and 6 months during and after recovery from acute bronchiolitis. During bronchiolitis 35% of total sleep time was active sleep compared with 31% after recovery. Respiration rate was increased during bronchiolitis and was higher in active sleep and quiet sleep irrespective of the stage of the illness. Apnoeic pauses were invariably shorter than 15 seconds, the mean duration for active sleep and quiet sleep being similar during infection and after recovery. Apnoeic episodes were central in type and generally initiated by a sign or body movements. Preapnoea heart rate was significantly higher than during or after apnoea. Apnoea index (the percentage of time the baby spends apnoeic), apnoea attack rate (the number of episodes of apnoea per unit time), and apnoea percentage (the distribution of episodes of apnoea while in a given sleep state) were increased significantly in quiet sleep during the index illness. Transcutaneous oxygen tension was significantly reduced during the course of infection, but comparable values were obtained in active sleep and quiet sleep during initial and recovery periods. These results show that the main changes in respiration pattern during the course of acute bronchiolitis occur in quiet sleep.     

The maturation of respiratory patterns in normal full term infants during the first six postnatal months. I: Sleep states and respiratory variability.

ABSTRACT. Four term healthy infants had their respiratory pattern monitored during a 2-hour afternoon nap recording period at monthly intervals up to six months of age. The time spent asleep significantly decreased with a marked reduction in active sleep (66% to 10%) while maintaining one long epoch of quiet sleep (mean 31 mins). Mean breathing rate at one week was higher in active sleep than quiet sleep (47 vs 41 breaths/min.) and decreased by 6 months in both sleep states (31 breaths/min. in both). Variability of breathing rate at 1 week was significantly increased in active sleep compared to quiet sleep and both decreased by 6 months. These findings confirm a significant maturational change in the respiratory pattern and variability of normal infants in the afternoon nap from 1 to 6 months.     

Infant behaviour in response to a change in body position from side to prone during sleep

Abstract The consequences of provoking a change in the sleeping position from side to prone during quiet (non-REM) and active (REM) sleep in young infants were studied in terms of ability to turn the face away from the mattress within 3 min, and in terms of ventilatory and heart rate responses in those who remained face down. Twenty-six infants were exposed to repeated tilts from the side to prone at 2.5 months, and 20 at 5 months of age. Eighteen infants were tested on both occasions. A computer-aided multichannel system was used for polysomnographic recordings. Approximately 66% of the infants did not rotate the face away from the mattress on at least one occasion. There were no significant differences in the rate of face down outcome between sleep states or ages, and no consistent pattern of final face position following repeated tilts. The face to side position was commonly accomplished after considerable difficulties involving vigorous body movements, particularly if the arm became positioned between the body and the mattress or alongside the trunk after the tilt. Apnoeas of 3–14 s in immediate response to the tilt were observed in 75% of the infants monitored electronically. In 13% of the infants, all in a face down position, the test was terminated because of increases in heart and respiratory rates, drop in oxygen saturation, or marked pallor. Conclusions The observed difficulties of obtaining a face to side position when suddenly exposed to the prone position during sleep, may render some young infants at risk of sudden infant death (SID).     

Sleep apnoea in infants

Infancy is characterized by an instability of the control of breathing. Apnoeas of short duration are common, mostly central and more frequent during rapid eye movement sleep. Obstructive apnoeas are rare in healthy infants. Triggering factors, such as respiratory syncytial virus infection, can increase the frequency and duration of apnoeas. Upper airway problems are responsible for obstructive apnoeas as well as for episodes of partial airway obstruction or upper airway resistance syndrome. In some infants, apparent life-threatening events have been related to upper airway anomalies. Congenital central hypoventilation syndrome, a rare respiratory control disorder, may present with apnoeas. Polysomnography is the gold standard for diagnosing sleep-disordered breathing in infants. Nasal continuous positive airway pressure is feasible in infants, and the early diagnosis of abnormal breathing during sleep is of critical importance for neurocognitive development in infants.     

Responses to partial nasal obstruction in sleeping infants

Partial nasal obstruction was performed during a morning of quiet sleep (QS: non-REM) and active sleep (AS: REM) at ages 1 week, 2 weeks, 1, 2, 3, 4 and 6 months on 12 normal infants, 15 subsequent siblings of victims of the Sudden Infant Death Syndrome (SIDS) and 12 infants admitted for investigation of infant apnoea ('near-miss' SIDS). In all three groups the numbers failing to arouse after 240 s (FTA-240) in QS were significantly greater than those in AS. After 2 months of age all groups showed a decrease in the number FTA-240 in AS, whereas in QS the number did not change significantly. Subsequent siblings of SIDS had a significantly higher number FTA-240 in QS than controls. There was no significant difference in FTA-240 in QS between controls and infant apnoeas, although there was a trend for this to be higher in subsequent siblings of SIDS than infant apnoeas.
It was concluded that arousal from AS is more marked than from QS, that after 2 months of age the ability to arouse from AS increases, and that in relation to SIDS, QS is the sleep state in which the infant is less able to arouse. Furthermore, subsequent siblings of SIDS differ from normal infants in their ability to arouse from QS.     

Behaviour and physiological responses during prone and supine sleep in early infancy

AIMS: To study the effect of prone and supine sleep on infant behaviour, peripheral skin temperature, and cardiorespiratory parameters to aid understanding of why prone sleeping is associated with an increased risk of sudden infant death syndrome. METHODS: Of 33 enrolled infants, 32 were studied at 2.5 and 28 at 5 months of age. A computer aided multichannel system was used for polysomnographic recordings. Behaviour was charted separately. RESULTS: Prone REM (active) sleep was associated with lower frequencies of short arousals, body movements and sighs, and a shorter duration of apnoeas than supine REM sleep at both ages. At 2.5 months there were less frequent episodes of periodic breathing during prone sleep in non-REM (quiet) and REM sleep. Heart rate and peripheral skin temperature were higher in the prone position during both sleep states at both ages. CONCLUSIONS: The observation of decreased variation in behaviour and respiratory pattern, increased heart rate, and increased peripheral skin temperature during prone compared with supine sleep may indicate that young infants are less able to maintain adequate respiratory and metabolic homoeostasis during prone sleep.     

Responses to partial nasal obstruction in sleeping infants

Partial nasal obstruction was performed during a morning of quiet sleep (QS: non-REM) and active sleep (AS: REM) at ages 1 week, 2 weeks, 1, 2, 3, 4 and 6 months on 12 normal infants, 15 subsequent siblings of victims of the Sudden Infant Death Syndrome (SIDS) and 12 infants admitted for investigation of infant apnoea ('near-miss' SIDS). In all three groups the numbers failing to arouse after 240 s (FTA-240) in QS were significantly greater than those in AS. After 2 months of age all groups showed a decrease in the number FTA-240 in AS, whereas in QS the number did not change significantly. Subsequent siblings of SIDS had a significantly higher number FTA-240 in QS than controls. There was no significant difference in FTA-240 in QS between controls and infant apnoeas, although there was a trend for this to be higher in subsequent siblings of SIDS than infant apnoeas. It was concluded that arousal from AS is more marked than from QS, that after 2 months of age the ability to arouse from AS increases, and that in relation to SIDS, QS is the sleep state in which the infant is less able to arouse. Furthermore, subsequent siblings of SIDS differ from normal infants in their ability to arouse from QS.     

Effects of naloxone on apnoea duration during sleep in infants at risk for SIDS

The effects of intravenous injections of the opiate antagonist naloxone (0.005–0.4 mg/kg body weight) on respiratory pattern, apnoea duration and frequency were investigated in six infants with severe sleep apnoea syndrome. Since several authors found elevated plasma- and CSF-levels of endogenous opioids (endorphines) in infants with sleep apnoea syndrome, we wanted to determine whether the impairment of the control mechanisms of respiration during sleep is due to an effect of endogenous opioids.Independent of the dose, naloxone did not exert any effect on respiratory pattern and occurrence of periodic apnoea. We were unable to prove that endorphines play a major role in pathogenesis of sleep apnoea syndrome in infancy and possibly in sudden infant death syndrome (SIDS).We speculate that elevated levels of endorphines reported by some investigators rather seem to be a consequence of hypoxic stress than a cause for sleep apnoeas.Abbreviations SIDS sudden infant death syndrome - CSF cerebral spinal fluid Supported by the Austrian Research Fund     

Apnoea of prematurity and arousal from sleep

The incidence of sudden infant death syndrome (SIDS) has been found to be consistently higher in preterm and low birth weight infants than in infants born at term and this increase is inversely related to gestational age. The incidence and severity of apnoea of prematurity, are also inversely related to gestational age. The aim of this study was to investigate whether a neonatal history of apnoea/bradycardia affected the maturation of arousal responses. Twenty-five premature infants were studied. A perinatal risk score was determined for each infant and infants were divided into those with a neonatal history of apnoea/bradycardia (n=16) and those without (n=9). All infants were studied using daytime polysomnography on three occasions: (a) a preterm study around 36 weeks gestation, (b) within 3 weeks of term, and (c) 2-3 months post-term. Multiple measurements of arousal threshold (cm H2O) in response to air-jet stimulation applied alternately to the nares were made in both active sleep (AS) and quiet sleep (QS). Arousal thresholds were elevated in apnoeic infants compared to control infants in both AS (P<0.05) and QS (P<0.001) at the term study and in QS at 2-3 months post-term (P<0.01). In addition, arousal thresholds were positively correlated with perinatal risk score in both sleep states, in all studies, with the exception of AS at 2-3 months when all infants were readily arouseable. We conclude that a history of prematurity with neonatal apnoea has a persisting effect on decreasing arousabilty from sleep and these infants may be at increased risk for SIDS.     

Model of normal prepubertal growth

Overheating may cause terminal apnoea and cot death. Rectal temperature and breathing patterns were examined in normal infants at home during the first 6 months of life. Twenty one infants had continuous overnight rectal temperature and breathing recordings for 429 nights (mean 20.4 nights, range 7-30) spaced over the first six months of life. Periods when breathing was 'regular' were directly marked on single night records. Sleep state was determined from respiratory variables. 'Regular' breathing was a reliable marker of 'quiet' sleep (specificity 93%). The duration of 'quiet' sleep increased from 6 to 22 minutes from two weeks to three months of age and then remained static, as did the proportion of sleep spent in the quiet phase (9% to 34%). Rectal temperature fell during 66% of quiet sleep and usually rose during rapid eye movement (REM) sleep. The drop in rectal temperature was maximal at the start of quiet sleep, whereas the maximum rise during REM sleep was reached after 10 to 15 minutes. Oscillations in rectal temperature are associated with changes in sleep and breathing state. The maturation of rectal temperature patterns during the first six months of life are closely related to a maturation of sleep state and breathing patterns.     

Effects of nasal continuous positive airway pressure on apnoea index and sleep in infants

Objectives: We examined the effectiveness of nasal continuous positive airway pressure (CPAP) for treatment of sleep apnoea in infants.
Methodology: We studied five infants who all had significant central and mixed apnoea and severe sleep fragmentation. Polysomnographic recordings were performed on 2 consecutive nights in these infants. One night was used as a control study and during the second night nasal CPAP was applied throughout the night
Results: Nasal CPAP significantly reduced apnoea in each infant, with the apnoea index (apnoeas/h) decreasing from 65.6± 14.6 during the control study to 10.5± 14.6 during CPAP in non-rapid eye movement (non-REM) sleep, and from 106± 13.9 during the control study to 26.6± 13.9 during CPAP in REM sleep. Nasal CPAP also improved the sleep fragmentation markedly; REM sleep increased from 14.2± 1.2% of sleep during the control study to 27.1 ± 1.2% of sleep during CPAP.
Conclusions: We conclude that nasal CPAP is an effective treatment for infantile apnoea. Sleep apnoea in these infants is associated with profound sleep fragmentation, which is reversed by nasal CPAP.     

A screening program for detecting children with an increased SIDS risk (sudden and unexpected infant death)

The prospective study presented conducted to prevent SIDS (sudden infant death syndrome). One of the proposed hypotheses on SIDS postulates a brainstem abnormality in the neuroregulation of cardiorespiratory processes. Therefore we characterized cardiorespiratory control mechanisms by examining the neurotransmitter substance P in plasma and polysomnographic investigations. With respect to the probable multifactorial origin of SIDS we selected children firstly anamnestically by means of an epidemiologically evaluated pre-, peri- and postnatal risk score. We reported the results of 208 polysomnographically and biochemically examined children anamnestically selected from a group of 2500 neonates. Examinations were performed on infants aged 2-4 weeks up to 1 year. To characterize respiratory control, length and frequency of apnoeas were separately estimated by means of polysomnography in the sleep states active and quiet sleep. If there were polygraphic risk factors representing a disturbance of respiratory control, the children were prophylactically treated with aminophylline 3 x 3 mg/kg b.w. for 4 weeks. We found a significant age dependence both of the mean apnoea duration in active sleep and the substance P level in plasma in the SIDS-risk group but not in the controls. High mean apnoea duration was correlated with low substance P level in the first months of age in SIDS risk infants selected anamnestically. This may reflect a delayed maturation of respiratory control mechanisms. In this way the polysomnography and the investigation of the neuropeptide substance P may be useful for a screening method indicating wether the respiratory control mechanisms are mature or not.     

Breathing,sleep state,and rectal temperature oscillations.

Overheating may cause terminal apnoea and cot death. Rectal temperature and breathing patterns were examined in normal infants at home during the first 6 months of life. Twenty one infants had continuous overnight rectal temperature and breathing recordings for 429 nights (mean 20.4 nights, range 7-30) spaced over the first six months of life. Periods when breathing was ''regular'' were directly marked on single night records. Sleep state was determined from respiratory variables. ''Regular'' breathing was a reliable marker of ''quiet'' sleep (specificity 93%). The duration of ''quiet'' sleep increased from 6 to 22 minutes from two weeks to three months of age and then remained static, as did the proportion of sleep spent in the quiet phase (9% to 34%). Rectal temperature fell during 66% of quiet sleep and usually rose during rapid eye movement (REM) sleep. The drop in rectal temperature was maximal at the start of quiet sleep, whereas the maximum rise during REM sleep was reached after 10 to 15 minutes. Oscillations in rectal temperature are associated with changes in sleep and breathing state. The maturation of rectal temperature patterns during the first six months of life are closely related to a maturation of sleep state and breathing patterns.     

Vasoconstriction following spontaneous sighs and head-up tilts in infants sleeping prone and supine

The cutaneous vasoconstrictor responses following a 60 degrees head-up tilt and a spontaneous sigh were measured in 36 infants at 1 and 3 months age to investigate the effects of age, sleep state and sleep position on these responses. The vasoconstrictor response was determined by a measure of cutaneous blood flow using a laser Doppler flowmeter. The mean reduction in blood flow (vasoconstriction) was 52% following the tilt, and 33% following the sigh. Prone positioning 1-month-old infants as compared to supine, reduced the degree of vasoconstriction following the tilt (P=0.027) and sigh (P=0.026). The supine to prone reduction was: tilt, -11% in quiet sleep (QS) (from 55.1 to 49.1% vasoconstriction) and -18% in active sleep (AS) (from 52.0 to 42.9%) and; sigh, -26% in QS (35-26%), and -15% in AS (31-26%). The degree of vasoconstriction following the sigh was significantly greater in 3- compared to 1-month-old infants (+26%, P=0.040). The mean response to the tilt in the older age group was 12% greater but this did not reach significance (P=0.069). Sleep state did not affect the degree of vasoconstriction but influenced transmission of the response so that latency to minimal vasoconstriction was 1 s shorter in AS than QS. This study provides data on two simple measures of sympathetic activity during sleep that have not previously been described in any detail in infant studies, and add more evidence that autonomic activity is reduced in the prone position compared to supine during sleep.     

Body movements during sleep in healthy and neurologically damaged infants

The body movements of sixteen healthy and twenty-one neurologically damaged infants were recorded during sleep on the static charge sensitive bed (SCSB). The SCSB method allows long-term monitoring of body movements, respiration and ballistocardiogram. Different body movement variables were estimated at the ages of 1 week, 1 month and 3 months. The results showed a constant duration and number of body movements during active and quiet sleep at each studied age both in healthy and neurologically damaged infants. A decreasing tendency in the number of body movements could only be seen if no differentiation between sleep states was made. No statistically significant differences were found between healthy and neurologically damaged infants in any of the variables. The results suggest that quantitative changes--the duration and number--in motor patterns during sleep are inadequate criteria for differentiation between healthy and neurologically damaged infants.     

Relation of sleep state to hypoxemic episodes in ventilated extremely-low-birth-weight infants

OBJECTIVE: To determine whether hypoxemic episodes in ventilated extremely-low-birth-weight infants correlate with specific behavioral states.Study design: Three-hour video-electroencephalography-polysomnography was performed on 13 ventilated extremely-low-birth-weight infants with mean postconceptional age of 28.3 weeks. The electroencephalogram was scored for discontinuity. Rapid eye movements, body, head, and limb movements were scored from synchronized video. Sleep states were defined from electroencephalography, rapid eye movements, and movement criteria. Nonparametric statistics were used to test for differences in the proportion of time hypoxemic (oxygen saturation 相似文献   

Apnoea detection: human performance and reliability of a computer algorithm

We examined the consistency of apnoea recognition between three human experts. The hypothesis was that computer detection of apnoea could emulate human expert apnoea recognition. The aim was to detect apnoeas with the highest possible accuracy from a single breathing signal, by both human experts and computer. Three human experts independently examined recordings of breathing waveform from overnight sleep studies from 10 infants aged 3-17 weeks. All apnoeas of 5 s or more were identified and reviewed. However, there still remained 10% disagreement. A computer apnoea detector was implemented. An algorithm analysed statistical properties of the signal to find breathing pauses. Optimal performance was 1 % missed apnoeas (compared with the agreed apnoeas identified by the three experts) and 29% false detections. This computer algorithm reliably identified most apnoeas but did not replace the human expert. Algorithm, apnoea, breathing, detection, expert     

Behaviour and physiological responses during prone and supine sleep in early infancy

Accepted 23 December 1996
AIMS—To study the effect of prone and supine sleep on infant behaviour, peripheral skin temperature, and cardiorespiratory parameters to aid understanding of why prone sleeping is associated with an increased risk of sudden infant death syndrome.
METHODS—Of 33 enrolled infants, 32 were studied at 2.5 and 28 at 5 months of age. A computer aided multichannel system was used for polysomnographic recordings. Behaviour was charted separately.
RESULTS—Prone REM (active) sleep was associated with lower frequencies of short arousals, body movements and sighs, and a shorter duration of apnoeas than supine REM sleep at both ages. At 2.5months there were less frequent episodes of periodic breathing during prone sleep in non-REM (quiet) and REM sleep. Heart rate and peripheral skin temperature were higher in the prone position during both sleep states at both ages.
CONCLUSIONS—The observation of decreased variation in behaviour and respiratory pattern, increased heart rate, and increased peripheral skin temperature during prone compared with supine sleep may indicate that young infants are less able to maintain adequate respiratory and metabolic homoeostasis during prone sleep.

     

Sleep phase and gastro-oesophageal reflux in infants at possible risk of SIDS.

The association between gastro-oesophageal reflux and sleep state in 24 infants with confirmed or suspected gastro-oesophageal reflux was studied by monitoring both the pH in the lower oesophagus and polygraphic tracings made during sleep at night. Gastro-oesophageal reflux during the night was confirmed in 20 infants. Three hundred and sixteen precipitous drops of more than one unit of pH were recorded during the studies, 186 during periods of wakefulness. Of 130 drops in pH during sleep, 62 (48%) began during active sleep and 62 during indeterminate sleep. Of the latter, 56 (90%) were associated with brief gross body movements. Only five of the drops in pH (4%) began during quiet sleep. Gastro-oesophageal reflux stopped during active sleep on 56 occasions (43%), in indeterminate sleep in 62 (47%), and in quiet sleep in 12 (9%). Episodes of gastro-oesophageal reflux starting or ending in quiet sleep were uncommon. The occurrence of gastro-oesophageal reflux during active sleep may partly explain why reflux during sleep is a risk factor for pulmonary disease.