Pathophysiology

Over 70 different theories for SIDS has been proposed, including suffocation from sleeping with a parent, milk allergy, and thymic enlargement (status thymicolymphaticus). The main disturbance in some victims appears to be with the infant's ventilatory response, and SIDS and infantile apnea appear related, although the exact nature of this relation is uncertain.3 Death is due to respiratory rather than cardiac arrest, and some potential SIDS victims may be successfully resuscitated with ventilation alone. Dysrhythmias probably occur only as a terminal event, and syndromes such as prolonged QT interval or Wolff-Parkinson-White syndrome are rare associations.4 Prospective studies monitoring normal infants showed no antecedent dysrhythmias in infants who eventually succumbed to SIDS. Conversely, approximately 2 percent of premature and low-birth-weight infants experienced bradycardia (fewer than 50 bpm) without apnea 1 week after discharge. 5

Information implicating ventilation disturbances and hypoxemia has been obtained from two sources: autopsies of infants who succumbed to SIDS, and studies of those who experienced an ALTE but survived. This later group represents infants who were found limp, cyanotic, pale, and lifeless, without any respiratory effort, but who were successfully resuscitated.

Autopsies of some SIDS victims reveal pathologic changes initially felt to be indicative of long-standing hypoxemia. These changes include smooth muscle thickening in small pulmonary arteries, right ventricular hypertrophy, hematopoiesis in the liver, increase in periadrenal brown fat, adrenal medullary hyperplasia, and abnormalities of the carotid body. The only marker now reported with regularity is brainstem gliosis. 6

Recently, much attention has been given to SIDS and sleeping in the prone position. 7,,8,9 and!9 Epidemiologic studies indicate that the incidence of SIDS is lower in countries where infants sleep supine or in the side-down position, and that a reduction in the incidence of SIDS follows a reduction in prone sleeping. Concern about aspiration in infants sleeping in the supine position are unfounded. Two mechanisms linking SIDS to prone sleeping are noted. With prone sleeping, infants will assume a face-down position, particularly in response to a cold stimulus on the face. This may result in upper airway obstruction. However, upper airway obstruction has not been observed in clinical trials; rather, it has been noted that infants rebreathe expired air and experience hypercarbia. 11 Because of these observations related to the prone position, the American Academy of Pediatrics now recommends a supine or side sleeping position for normal infants.

The link between child abuse, SIDS, and ALTE has also received renewed interest.113!415 andl6 Familial cases of SIDS raise the possibility of abuse. Some investigators report that 10 percent of SIDS cases are due to abuse. Some children with ALTE have been purposefully asphyxiated, and in some cases the complaints have simply been fabricated. These problems are referred to as Munchausen syndrome by proxy. Child abuse is the diagnosed cause of death in 2000 cases a year. The presence of bruises, long-bone fractures, rib fractures, internal hemorrhages, evidence of physical neglect, or trauma around the nares suggests abuse. Rib fractures in infants are not induced by cardiopulmonary resuscitation. A history inconsistent with the usual events surrounding a SIDS death may also raise the suspicion of abuse. An interesting report on death-scene investigations revealed that in 23 of 26 infants studied, circumstantial evidence of accidental death was present.17 It is beyond the scope of emergency physicians to conduct such investigations. However, more and more communities are convening Child Death Review Boards to assure the full evaluation of sudden and unexpected death among children. It is important, however, to be aware of the possible role of accidental or intentional trauma in some SIDS victims.

Blood Pressure Health

Blood Pressure Health

Your heart pumps blood throughout your body using a network of tubing called arteries and capillaries which return the blood back to your heart via your veins. Blood pressure is the force of the blood pushing against the walls of your arteries as your heart beats.Learn more...

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