Aspiration of gastric contents in sudden infant death syndrome without cardiopulmonary resuscitation

Gastric aspiration in sudden unexpected infant death of Prader-Willi syndrome: immunohistochemical detection of feeding components

Prader–Willi syndrome (PWS) in infants is characterized by hypotonia and poor sucking with feeding difficulties. Two autopsy cases of sudden unexpected death during sleep after tube feeding are described herein. For one, gastric aspiration caused by the possible milk regurgitation was suspected. Immunohistochemical examination of lung sections was performed using three antibodies to human α-lactalbumin, human gross cystic disease fluid protein 15, and cow whey β-lactoglobulin. Five cases of sudden unexpected infant death occurring earlier than at 6 months old were selected as controls. Marked immune-staining for infant formula in one PWS subject was evident within terminal bronchioles and alveoli with granular and amorphous features. However, no positive staining was apparent in the other subject, who exhibited contrasting features in milk distribution. Among control cases, one showed mild staining in the bronchiole, but the others did not. The antibody to β-lactoglobulin reacted specifically with formula, with no nonspecific background. Gastric contents in the airway can be a difficult issue because of the consequent terminal gasping. However, because of an episode of antemortem symptoms of potential regurgitation, and from findings at autopsy such as petechiae, we inferred that fatal regurgitation occurred in this PWS infant after tube feeding. Several clinical reports have described milk aspiration, but this pathological report is the first related to aspiration in PWS during tube feeding.

Multidisciplinary approach to suspected sudden unexpected infant death caused by milk-aspiration: A case report

BACKGROUND

The term sudden unexpected infant death (SUID) is not always properly invoked. It refers to a broad range of conditions that sometimes defy classification. There is not only a strong emotional impact on the family, but such cases are also quite complex. Underlying causes may be multiple, not always readily apparent, and have potential repercussions, especially in terms of forensics.

CASE SUMMARY

A 5-month-old male baby was pronounced dead following acute lung failure and cardiopulmonary arrest. The parents had immediately rushed their child to the hospital, stating the baby was found prone and not breathing. Total-body postmortem computed tomography (PMCT) was performed, revealing a hypodense material of indeterminate nature within the main airways and areas of ground-glass parenchymal change. At autopsy, the respiratory tract mucosa appeared edematous and was coated with a whitish stringy material. There was widespread airspace reduction due to parenchymal collapse. Alveolar sacs and bronchial openings contained abundant amorphous material admixed with white blood cells. Immunohistochemical studies were performed, targeting CD15, CD68, and alpha-lactalbumin. Ultimately, the focus was on alpha-lactalbumin (milk protein), which showed marked immunopositivity within alveolar spaces. Cytoplasmic staining of macrophages was also particularly prominent.

CONCLUSION

Postmortem investigations are thus essential to identify causes of death and surrounding circumstances. PMCT is a useful tool in this setting, given the frequent dearth of autopsy findings and ambiguity as to cause of death in SUID cases. These findings, later confirmed by immunohistochemical investigations, were indicative of active pneumonia due to aspirated milk. The present account illustrates the importance a broad diagnostic approach to SUID in cases of forensic concern. PMCT is a very valuable aid in cases of forensic interest, as it can provide useful information in all those situations in which the cause of death is uncertain or there are no suggestive dynamics or lesions.

Infants dying suddenly and unexpectedly share demographic features with infants who die with retinal and dural bleeding: a review of neural mechanisms

The cause of death in infants who die suddenly and unexpectedly (sudden unexpected death in infancy [SUDI]) remains a diagnostic challenge. Some infants have identified diseases (explained SUDI); those without explanation are called sudden infant death syndrome (SIDS). Demographic data indicate subgroups among SUDI and SIDS cases, such as unsafe sleeping and apparent life-threatening events. Infants dying suddenly with retinal and dural bleeding are often classified as abused, but in many there is no evidence of trauma. Demographic features suggest that they may represent a further subgroup of SUDI. This review examines the neuropathological hypotheses to explain SIDS and highlights the interaction of infant oxygen-conserving reflexes with the brainstem networks considered responsible for SIDS. We consider sex- and age-specific vulnerabilities related to dural bleeding and how sensitization of the dural innervation by bleeding may influence these reflexes, potentially leading to collapse or even death after otherwise trivial insults.

Potential Central Nervous System Involvement in Sudden Unexpected Infant Deaths and the Sudden Infant Death Syndrome

Sudden unexpected infant death (SUID) in infancy which includes Sudden Infant Death Syndrome (SIDS) is the commonest diagnosed cause of death in the United States for infants 1 month to 1 year of age. Central nervous system mechanisms likely contribute to many of these deaths. We discuss some of these including seizure disorders, prolonged breath holding, arousal from sleep and its habituation, laryngeal reflex apnea potentiated by upper airway infection, and failure of brainstem-mediated autoresuscitation. In the conclusions section, we speculate how lives saved through back sleeping might result in later developmental problems in certain infants who otherwise might have died while sleeping prone.

Severe intestinal ischemia can trigger cardiovascular collapse and sudden death via a parasympathetic mechanism

Hemorrhagic shock and splanchnic arterial occlusion (SAO) followed by reperfusion are associated with high mortality. However, rapid cardiovascular failure and death may also occur before reperfusion in hemorrhagic shock and SAO. We show in a rat SAO model that, upon gut ischemia, mean arterial blood pressure transiently elevates and then drops fatally in one of two time courses: (i) gradually over ∼1 to 3 h or (ii) rapidly (often by >80 mmHg) over a period of 1 to 6 min. We hypothesize that fast fatal pressure drops (FFPDs) are due to failure of autonomic nervous system control. To test this, we treated rats with Glucose (10%) in the small intestinal lumen and intramuscularly administered xylazine to activate the parasympathetic nervous system or with a muscarinic anticholinergic (glycopyrrolate) or by total subdiaphragmatic vagotomy to attenuate parasympathetic nervous system activity. We also tested nafamostat mesilate (ANGD [6-amidino-2-naphthyl p-guanidinobenzoate dimethanesulfonate]), a protease inhibitor efficacious in preventing blood pressure loss in SAO with reperfusion, in the intestinal lumen. Fifty percent of animals receiving xylazine and Glucose died by FFPD (vs. 33% with neither, not statistically significant). Total subdiaphragmatic vagotomy or glycopyrrolate treatment significantly reduced the incidence to 0% (P < 0.008), although slow fatal pressure drops still occurred. ANGD did not prevent FFPDs, but delayed onset of slow fatal pressure drops (P < 0.013). These results suggest that gut ischemia can cause sudden death via an autonomic nervous system mechanism and that SAO with Glucose and xylazine may serve as a useful model for the study of neurogenic shock or autonomic dysregulation associated with sudden death.

Relationship between sleep and acid gastro-oesophageal reflux in neonates

The aim of the present study was to investigate the impact of gastro-oesophageal acid reflux on sleep in neonates and, reciprocally, the influence of wakefulness (W) and sleep stages on the characteristics of the reflux (including the retrograde bolus migration of oesophageal acid contents). The pH and multichannel intraluminal impedance were measured during nocturnal polysomnography in 25 infants hospitalised for suspicion of gastro-oesophageal reflux. Two groups were constituted according to whether or not the infants displayed gastro-oesophageal reflux (i.e. a reflux group and a control group). There were no differences between the reflux and control groups in terms of sleep duration, sleep structure and sleep state change frequency. Vigilance states significantly influenced the gastro-oesophageal reflux pattern: the occurrence of gastro-oesophageal reflux episodes was greater during W (59 ± 32%) and active sleep (AS; 35 ± 30%) than during quiet sleep (QS; 6 ± 11%), whereas the mean duration of gastro-oesophageal reflux episodes was higher in QS than in W and AS. The percentage of retrograde bolus migrations of distal oesophageal acid content was significantly higher in AS (62 ± 26%) than in W (42 ± 26%) and QS (4.5 ± 9%). In neonates, gastro-oesophageal reflux occurred more frequently during W, whereas the physiological changes associated with sleep state increase the physiopathological impact of the gastro-oesophageal reflux. The duration of oesophagus-acid contact was greater during sleep; AS facilitated the retrograde migration of oesophageal acid content, and QS was characterised by the risk of prolonged acid mucosal contact.

Gastroesophageal reflux disease and sudden infant death: mechanisms behind an under-recognized association

We present 4 cases of sudden infant death in which we believe that gastroesophageal reflux (GOR) was a contributory, if not a causative, factor. Two of our patients had documented GOR reflux disease during life, and all 4 cases showed histologic evidence of GOR. No other cause of death was identified in any of the patients. Gastroesophageal reflux can cause sudden death in a vulnerable infant during a critical period of development through failure of "autoresuscitation" mechanisms.

Exploration of the relationships among medical health history variables and aspiration

OBJECTIVES

(1) Determine the relationships among a family's specific answers to health history questions and their child's risk for aspiration as determined by a swallow study. (2) Identify key factors which may predict a child's risk for aspiration.

METHODS

Answers to questions and results of Functional Endoscopic Evaluation of Swallow (FEES) and/or Video Swallow Study (VSS) for a sample of 198 children were collected. Subjects were categorized into groups: "aspiration", "penetration" or "no aspiration or penetration". Logistic regression modeling was used to determine the contribution of certain characteristics to the odds of aspiration. A model for predicting aspiration or penetration based on those characteristics was assessed. The sensitivity and specificity of the model in predicting aspiration and penetration was determined.

RESULTS

One hundred ninety eight subjects had a FEES or VSS. Of these, 18% (n=36) aspirated and 21% (n=42) were found to have penetration. Many of the factors identified in the health history were found to be significantly associated with aspiration or penetration. The variables "demonstrated aspiration" (this included parent or caregiver seeing food in the tracheotomy tube or aspiration noted on a previous FEES or VSS) (p=0.02), "hypotonia" (p=0.02) and "tracheotomy" (p=0.001) were most predictive of aspiration. History of tracheotomy was found to have an inverse relationship with aspiration. "gastroesophageal reflux" (GER) (p=0.0007) was most significantly associated with penetration, followed by "prematurity" (p=0.03) and "developmental delays" (p=0.04). Based on the prediction model, the probabilities for a child with a history of combinations of the above variables to have aspiration or penetration were calculated.

CONCLUSIONS

Significant relationships exist between aspiration or penetration and the family's answers about their child's medical history. Practitioners should consider a swallow assessment whenever a child has a history which includes variables with a strong association with aspiration or penetration.

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

Previous studies addressing pulmonary artery morphology have compared cases of sudden infant death syndrome (SIDS) to controls but none have compared demographic profiles, exposure to potentially hypoxic risk factors and other pathologic variables in SIDS cases grouped according to pulmonary artery medial smooth muscle thickness. Aims: To compare the relative medial thickness (RMT) in alveolar wall arteries (AW) in SIDS cases with that in age-matched controls and 2. Compare demographic, clinical, and pathologic characteristics among three subsets of SIDS cases based upon alveolar wall (AW) RMT. Retrospective morphometric planimetry of all muscularized arteries in standardized right apical lung sections in 73 SIDS cases divided into three groups based on increasing AW RMT as well as 19 controls age-matched to 19 of the SIDS cases. SIDS and age-matched control cases did not differ with respect to AW RMT or other demographic variables. The SIDS group with the thickest AW RMT had significantly more males and premature birth than the other groups, but the groups did not differ for known clinical risk factors that would potentially expose them to hypoxia. Pathologic variables, including pulmonary inflammation, gastric aspiration, intra-alveolar siderophages, cardiac valve circumferences, and heart and liver weights, were not different between groups. Age was not significantly correlated with RMT of alveolar wall and pre-acinar arteries but was significant at p = .018 for small intra-acinar arteries. The groups were different for RMT of small pre-acinar and intra-acinar arteries, which increased with increasing AW RMT. Statistical differences should not necessarily be equated with clinical importance, however future research incorporating more quantified historical data is recommended.

Infant sleep position: a randomized clinical trial of an educational intervention in the maternity ward in Porto Alegre, Brazil

BACKGROUND

Few studies in Brazil have been published about sudden infant death syndrome (SIDS), and none has addressed the mother's orientation about placing the infant to sleep in the supine position. The aim of this study was to evaluate the effect on mothers of an individual educational intervention in the maternity ward about infant sleep position.

METHODS

A randomized clinical trial was conducted with a study sample of 228 mother-infant pairs assigned to an intervention or a control group. The intervention consisted of an individual orientation session at the maternity ward, at which folders and an oral explanation were given to mothers at discharge about the importance of the supine position as a preventive measure for SIDS. The outcome was the sleeping position at 3 months of age assessed during a home visit. The variables with p< 0.2 at a bivariate analysis were included in a logistic regression model.

RESULTS

Among mothers in the intervention group, 42.9 percent put their infants to sleep in a supine position at the 3-month visit, compared with 24 percent of mothers in the control group (p = 0.009). In a multivariate analysis, the intervention at the hospital was the only variable that influenced maternal practices with respect to infant sleep positioning (OR 2.22; 95% CI 1.17-4.19).

CONCLUSIONS

An individual educational session in the maternity ward about infant sleep position significantly increased the prevalence of supine position for sleeping in the infant's third month. Nevertheless, the intervention was not sufficient to guarantee that most mothers would put their infants to sleep in the recommended position.

Some aspects of clinical relevance in the maturation of respiratory control in infants

Two reflex mechanisms important for survival are discussed. Brain stem and cardiovascular mechanisms that are responsible for recovery from severe hypoxia (autoresuscitation) are important for survival in acutely hypoxic infants and adults. Failure of this mechanism may be important in sudden infant death syndrome (SIDS), because brain stem-mediated hypoxic gasping is essential for successful autoresuscitation and because SIDS infants appear to attempt to autoresuscitate just before death. A major function of another mechanism is to protect the airway from fluid aspiration. The various components of the laryngeal chemoreflex (LCR) change during maturation. The LCR is an important cause of prolonged apneic spells in infants. Consequently, it also may have a role in causing SIDS. Maturational changes and/or inadequacy of this reflex may be responsible for pulmonary aspiration and infectious pneumonia in both children and adults.

Sudden infant death while awake

Epidemiologic data suggest that SIDS is related to the sleep state, but exiguous literature has addressed infants who had been awake at the time of sudden catastrophic deterioration and subsequent death. The aims of this study are to: (1) Report five infants who were awake at the onset of the lethal event, and (2) Discuss potential lethal pathophysiological events that may lead to these circumstances. The demographic and pathologic profiles of these cases are similar to SIDS. Altered responses to severe hypotension, bradycardia, and apnea, perhaps elicited by aspiration and mediated by cerebellar and vestibular structures, might be involved in the pathogenesis of these deaths. Comprehensive medical history review, investigation of the circumstances of death, thorough postmortem examination with ancillary studies, and preservation of tissues for gene testing, are crucial to explaining these deaths. Careful attention should be given to the awake or sleep state immediately prior to the sudden clinical collapse, and death of infants; those who were awake should be reported to enhance understanding of this phenomenon.