Apparent hypoxic changes in pulmonary arterioles and small arteries in infancy.

Abstract

Some signs indicating a terminal hypoxic episode have been found in cases of the sudden infant death syndrome (SIDS). These include intrathoracic petechial haemorrhages in the lungs, heart, and thymus. Nevertheless the actual cause of such a hypoxic episode is still speculative. One of the current theories concerning the aetiology of the SIDS is that of Steinschneider (1974). He has suggested that in many cases of sudden infant death there are episodes of prolonged sleep apnoea and while such episodes may be a normal physiological phenomenon, gradually becoming less frequent and completely disappearing within the first year of life, it is possible that such an episode of apnoea may become so prolonged as to cause the death of the child by hypoxia.Naeye, in 1973, looked for evidence of chronic hypoxia in the lungs of cases of SIDS and in control infants. He reported a pulmonary arteriole abnormality commonly associated with chronic alveolar hypoxia. This took the form of hypertrophy and hyperplasia of the smooth muscle fibres in the small pulmonary vessels. He During the past three years in Newcastle upon Tyne we have attempted to measure the size of the small pulmonary vessels in a series of infants, including a group of SIDS cases, and to quantify and compare the degree of hypertrophy or hyperplasia which may or may not be present. Material and methodsLung sections were taken from 90 infants and young children. These included 30 cases of the SIDS. The criteria for diagnosis of SIDS were the sudden death of an infant which is unexpected by history, that is, the infant was in apparently good health or gave a history of minor illness immediately before death, and in whom there is no clear and acceptable cause of death at the time of necropsy.The remaining 60 cases were divided into four groups. Group 1 comprised 15 infants who died as a result of acute respiratory illness of less than one week's duration and were presumably subjected to acute hypoxia during their terminal illness. Within this group were cases of acute bronchiolitis and acute lobular pneumonia. Group 2 comprised 15 481 on 11 May 2018 by guest. Protected by copyright.

Sudden Infant Death Syndrome (SIDS): An Integration of Ontogenetic Pathologic, Physiologic and Epidemiologic Factors1

“…The evidenee that chronic mild hypoxia preceded death of SIDS is based on detailed studies of tissues obtained at autopsy. Naeye (1973) reported that approximately 60 percent of the SIDS infants exhibited medial museie hypertrophy of the pulmonary arterioles, a finding eonfinned by Wi/liams et al (1979), but not found by Kendeel and Ferris (1977). A similar pereentage had an increase in the weight of the right ventriele, persistent extra medullary hematopoesis in the liver and retention of brown fat (Naeye 1980 Fetal and neonatal heart rates in subsequent siblings and controls.…”

Pulmonary arterial medial smooth muscle thickness in sudden infant death syndrome: an analysis of subsets of 73 cases

“…In our study, the relative medial thickness of the alveolar wall arteries did not significantly differ between SIDS cases and age-matched controls, confirming our previous finding [ 15 ]. The conflicting results of other studies [ 8 , 9 , 12 , 14 ] are likely a result of differing analytical methods and the lack of standardized SIDS definitions, case investigations, and autopsies. Given hypoxia-induced smooth muscle proliferation in pulmonary arteries requires several days, the duration and/or severity of hypoxic exposure relative to the time of death must also be considered.…”

Sudden Infant Death Syndrome

“…These changes suggested the presence of chronic hypoxemia in infants with SIDS and refuted the concept that death was a result of a single asphyxiating episode. Naeye's results were challenged by Kendeel and Ferris, 9 who failed to find similarities between infants with SIDS and infants who lived at high altitudes. Naeye's results were expanded and supported by Williams and associates, 10 who found extension of muscle in the pulmonary arterioles toward the periphery of the bronchioles in victims of SIDS.…”