Are bedding and rebreathing suffocation a cause of SIDS?

Abstract

Suffocation by bedclothes became a popular diagnosis in the 1940s but gradually became replaced with the diagnostic label of Sudden Infant Death Syndrome (SIDS). In 1991 a paper purported that, instead of SIDS, pillows filled with polystyrene beads had caused death by rebreathing suffocation; this conclusion was reached on the basis of experiments with anesthetized rabbits breathing through a doll's head that was placed face down on the pillow. Because of the anesthesia, rabbits could not change their face down position. The doll's nares could not collapse, which would have resulted in rapid death due to conventional suffocation. The rabbits required up to 3 hours or more to die of hypercarbia and hypoxia. Studies in normal infants revealed that they turned from the face‐down position after only 2 minutes. (The only infant who retained CO2 soon died of a fatal neurologic disorder, with central hypoventilation). Using the rabbit/doll's head and mechanical models, a wide range of bedding was indicted, including cushions, sheepskins, pillows, comforters, foam mattresses, and even simple blankets and sheets as potentially causing fatal rebreathing. Except for the use of pillows in general, as well as mattresses filled with kapok and bark, there has been no epidemiologic support for these indictments. Although normal infants are unlikely to succumb to rebreathing suffocation, infants with blunted ventilatory responsiveness and delayed arousal duo to prior hypoxia were hypothesized to be at increased risk. Support for this concept was found in the pathology of the brain stem in victims of SIDS that was attributed to prior hypoxic injury. In infants who survived prolonged apnea, less than 20% have demonstrated a diminished ventilatory responsiveness to hypercarbia, but, more significantly, none had an absent response. Arousal to hypercarbia, an abnormality which is crucial to the hypothesis of rebreathing suffocation, is regularly present in normal subjects, but the threshold is higher in near‐SIDS infants; however, no instances of failure to arouse have been reported in near‐SIDS. If the infant is placed on his or her back or side, the issue of bedding could become moot; unfortunately, a sizable percentage of infants are still being placed prone for sleep. Instead of confusing parents with an ever‐expanding list of “dangerous bedding,” the message “Back to Sleep” should be emphasized. Pediatr Pulmonol, 1996; 22:335–341. © 1996 Wiley‐Liss, Inc.

Sudden infant death triggered by dive reflex

“…We found, in both stillborns and infants, a wide variety of structural defects of the arcuate nucleus, ranging from neuronal immaturity in a well shaped structure to total agenesis. 13 In our study, the histological examination of serially sectioned coronary and cardiac conduction arteries revealed the presence of atherosclerotic lesions (figs [3][4][5]. In recent studies we have reported that early atherosclerotic or preatherosclerotic lesions are already detectable in infancy, 11 and even during fetal life, 17 and are significantly related to parental cigarette smoking 11 and formula feeding.…”

“…1 The most important pathogenic hypotheses of SIDS are: a respiratory (apnoea), a cardiac (arrhythmogenic), or a visceral dyskinetic (glottal spasm and/or oesophagogastric reflux) cause. [2][3][4] It has been stressed that the autonomic nervous system (respiratory, cardiovascular, and upper digestive) must interact in all such aetiopathogenic hypotheses. [5][6][7] The dive reflex is the reflex mechanism most frequently considered in the aetiopathogenesis of SIDS.…”

The German case–control scene investigation study on SIDS: epidemiological approach and main results

“…In that study, however, data were collected by parental report rather than by objective measurements. Experimental evidence suggests that soft bedding may result in rebreathing and CO 2 retention in infants sleeping prone [27,[35][36][37] and this has been hypothesised as a potential death mechanism in SIDS [38].…”

Head covering - a major modifiable risk factor for sudden infant death syndrome: a systematic review

“…An in depth review is given by Guntheroth and Spiers58 who conclude that current evidence does not make for a credible case. SIDS is associated with soft bedding, but the soft surfaces implicated by Kemp and Thach that may facilitate an accumulation of CO 2 , such as polystyrene-filled cushions,59 sheepskins60 and ti-tree bark61 mattresses, are not commonly used and any association needs to be demonstrated with controlled observations.…”