Placental transfusion insult in the predisposition for SIDS: a mathematical study

Association between auditory system pathology and sudden infant death syndrome (SIDS): a systematic review

OBJECTIVE

A theory has emerged, suggesting that abnormalities in the auditory system may be associated with sudden infant death syndrome (SIDS). However, current clinical evidence has never been systematically reviewed.

DESIGN

A systematic review was conducted according to the guideline of Preferred Reporting Items for Systematic Reviews and Meta-Analyses.

DATA SOURCES

PubMed, Embase and Web of Science were systematically searched through 7 September 2020.

ELIGIBILITY CRITERIA FOR SELECTING STUDIES

Only human studies with a reference group were included. Studies were eligible for inclusion if they examined infants exposed to otoacoustic emissions (OAEs), auditory brainstem response (ABR) or had autopsies with brainstem histology of the auditory system. SIDS was the primary outcome, while the secondary outcome was near-miss sudden infant death syndrome episodes.

DATA EXTRACTION AND SYNTHESIS

Two independent reviewers extracted data and assessed risk of bias, and the quality of evidence. Due to high heterogeneity, a narrative synthesis was conducted. Risk of bias and quality of evidence was assessed using the Newcastle-Ottawa Scale and Grading of Recommendations Assessment, Development and Evaluation.

RESULTS

Twelve case-control studies were included. Seven studies on OAEs or ABR had a high degree of inconsistency. Contrarily, four out of five studies reporting on brainstem histology found that auditory brainstem abnormalities were more prevalent in SIDS cases than in controls. However, the quality of evidence across all studies was very low.

CONCLUSION

This systematic review found no clear association between auditory system pathology and SIDS. The higher prevalence of histological abnormalities in the auditory system of SIDS may indicate an association. However, further studies of higher quality and larger study populations are needed to determine whether these findings are valid.

PROSPERO REGISTRATION NUMBER

CRD42020208045.

The role of morphology in mathematical models of placental gas exchange

The performance of the placenta as a gas exchanger has a direct impact on the future health of the newborn. To provide accurate estimates of respiratory gas exchange rates, placenta models need to account for both the physiology of exchange and the organ morphology. While the former has been extensively studied, accounting for the latter is still a challenge. The geometrical complexity of placental structure requires use of carefully crafted approximations. We present here the state of the art of respiratory gas exchange placenta modeling and demonstrate the influence of the morphology description on model predictions. Advantages and shortcomings of various classes of models are discussed, and experimental techniques that may be used for model validation are summarized. Several directions for future development are suggested.

Sudden infant death syndrome: an update and new perspectives of etiology

Sudden infant death syndrome (SIDS) is a condition in which an infant, usually in the early postnatal period and nearly always before 6 months of age, dies during sleep for unexplained reasons and the standard autopsy fails to disclose an etiology. Various physiological explanations of risk factors include the prone sleeping position, overheating by excessive bundling, viral upper respiratory tract infections, parental smoking at home, and birthing injury resulting in an insult to the inner ear and central chemoreceptor zone, an immaturity that involves CO2 chemoreceptors that regulate respiratory control. Neuropathological studies and theories implicate: (1) hypoplasia or defective transmitter function in the medullary arcuate nucleus, a derivative of the rhombencephalic lip of His; (2) synaptic or receptor immaturity of the nucleus of the fasciculus solitarius, the "pneumotaxic center"; and (3) functional impairment of the serotonergic raphé nuclei of the pontine and medullary ventral median septum and other serotonergic neurons of the brainstem. Additional neurological risk factors for SIDS include perinatal neuromuscular diseases, infantile epilepsies or status epilepticus, and genetic metabolic encephalopathies.

Theoretical models for coronary vascular biomechanics: progress & challenges

A key aim of the cardiac Physiome Project is to develop theoretical models to simulate the functional behaviour of the heart under physiological and pathophysiological conditions. Heart function is critically dependent on the delivery of an adequate blood supply to the myocardium via the coronary vasculature. Key to this critical function of the coronary vasculature is system dynamics that emerge via the interactions of the numerous constituent components at a range of spatial and temporal scales. Here, we focus on several components for which theoretical approaches can be applied, including vascular structure and mechanics, blood flow and mass transport, flow regulation, angiogenesis and vascular remodelling, and vascular cellular mechanics. For each component, we summarise the current state of the art in model development, and discuss areas requiring further research. We highlight the major challenges associated with integrating the component models to develop a computational tool that can ultimately be used to simulate the responses of the coronary vascular system to changing demands and to diseases and therapies.