Evidence Based Medicine on SuddenInfant Death Syndrome
Soha Mohamed MoslehEltokhey;
Abstract
McNamara et al. (2002) tested the arousal response of 10 healthy infants to tactile stimuli. Arousal could be abolished by repeated exposure (habituation). While brainstem and spinalmediated responses were more resistant to habituation than cortically mediated responses, even they were eventually inhibited.
As mentioned, repeated exposure to hypoxia blunted hypoxic arousal responses. Thus, habituation of the infant arousal response to repeated stimuli, especially hypoxia, hypercapnia, or airway occlusion, may be relevant to SIDS.
Prenatal and postnatal exposure to cigarette smoking are now recognized as significant risk factors for SIDS. Infants born to cigarette smoking mothers have higher arousal thresholds to auditory stimuli than infants not so exposed. Thus, decreased arousal is associated with an important risk factor for SIDS.
Poet and associates analyzed recordings from nine infants on home apnea-bradycardia monitors, who died suddenly. The monitor alarm which triggered the recording and audible alarm was low heartrate, not apnea. However, these infants also showed a breathing pattern most consistent with gasping, which only occurs in the presence of profound hypoxia (Pao2 <15-20 torr). This indicates that at least for these infants, they were profoundly hypoxia just prior to death, consistent with this theory(Thomas et al.,2002).
Preliminary evidence suggested that infants at high risk for SIDS had abnormal arousal responses to hypoxia. These same infants also had alterations in circulating catecholamine levels.
However, normal control infants also often fail to arouse in response to hypoxia. Normal infants arouse frequently under 9-weeks of age, but not between 9-weeks and 6-months of age.
This corresponds to the peak age distribution for SIDS. It is possible that infants are born with a protective brainstem-mediated hypoxic arousal response, which is inhibited by increasing cortical development after 2-months of age.
However, this is quite preliminary, and not proven. Other factors also affect arousal. For example, repetitive hypoxic events depress the arousal response to hypoxia. Thus, infants with frequent hypoxic events may d
As mentioned, repeated exposure to hypoxia blunted hypoxic arousal responses. Thus, habituation of the infant arousal response to repeated stimuli, especially hypoxia, hypercapnia, or airway occlusion, may be relevant to SIDS.
Prenatal and postnatal exposure to cigarette smoking are now recognized as significant risk factors for SIDS. Infants born to cigarette smoking mothers have higher arousal thresholds to auditory stimuli than infants not so exposed. Thus, decreased arousal is associated with an important risk factor for SIDS.
Poet and associates analyzed recordings from nine infants on home apnea-bradycardia monitors, who died suddenly. The monitor alarm which triggered the recording and audible alarm was low heartrate, not apnea. However, these infants also showed a breathing pattern most consistent with gasping, which only occurs in the presence of profound hypoxia (Pao2 <15-20 torr). This indicates that at least for these infants, they were profoundly hypoxia just prior to death, consistent with this theory(Thomas et al.,2002).
Preliminary evidence suggested that infants at high risk for SIDS had abnormal arousal responses to hypoxia. These same infants also had alterations in circulating catecholamine levels.
However, normal control infants also often fail to arouse in response to hypoxia. Normal infants arouse frequently under 9-weeks of age, but not between 9-weeks and 6-months of age.
This corresponds to the peak age distribution for SIDS. It is possible that infants are born with a protective brainstem-mediated hypoxic arousal response, which is inhibited by increasing cortical development after 2-months of age.
However, this is quite preliminary, and not proven. Other factors also affect arousal. For example, repetitive hypoxic events depress the arousal response to hypoxia. Thus, infants with frequent hypoxic events may d
Other data
| Title | Evidence Based Medicine on SuddenInfant Death Syndrome | Other Titles | متلازمــة المــوت الفجائـى للأطفــال من خلال الطب القائم علي الأدلة | Authors | Soha Mohamed MoslehEltokhey | Issue Date | 2014 |
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