• Gas mask (320); modified gas mask and anesthetic gas (321); anesthetic face mask and anesthetic gas (see Subheading 2.7.1. and ref. 291); air-filter mask and helium (322).
• Motorcycle helmet (visor taped, bath towel encircled neck) combined with asphyxiant (269).
• Duct tape (case report description: tape started on the left side of the mouth, covered the eyes, nose, and mouth, and ended on the lower right cheek ).
• Pillow (case report description: 32-yr-old male chronic schizophrenic ).
• Children younger than 1 yr of age have been found dead facedown on soft surfaces (e.g., pillow, bean bag, waterbed, sheepskin rug, polystyrene-filled cushions, suspended rocking cradle [32,35,113,117,302,323-325]). The child is unable to extricate itself (113,324). The nose and mouth are obstructed, worsened by mucus and regurgitated milk (Fig. 52; refs. 113 and 323). Rebreathing of carbon dioxide has been demonstrated experimentally (323,326,327). Smothering by this means is uncommon in adults (Fig. 53).
Sleeping in the prone position is a risk factor for death from SIDS (38). An abnormal response to increased inspired carbon dioxide concentration has been proposed (327). In a small percentage of infants, nasal obstruction during sleep and a delayed or absent mouth breathing response were considered factors leading to apnea (328). Normally, when a child is aroused under these conditions, it should move away from the potentially lethal environment (327). In the presence of soft bedding, movement of the head from side to side could worsen the situation by creating a deeper pocket, which traps expired air (327). Controlled lifting of the head, while in the prone position, is not
attained until 3 mo of age. The ability of infants to turn from lying facedown to the supine position is reached by 6 mo (327). These actions are hindered if the child is tightly covered by bedding (327).
Anatomic characteristics of the infant pharynx and upper respiratory tract have been postulated as factors in airway obstruction (32). When prone, the softer nasal cartilage of infants is compressed. Certain infants could have increased tongue bulk and relatively small jaws, which decrease airflow. During sleep, there may be close approximation of the base of the tongue, soft palate, epiglottis, and pharynx owing to relaxation.
The baby's head is a major temperature-regulating site. If covered, this could predispose to hyperthermia and hypoventilation (32,35,329,330).
Underlying pulmonary infection may increase the risk of dying, perhaps by contributing to laryngospasm or bronchospasm (34,329,330).
220.127.116.11. External Examination
• Gas mask deaths—conjunctival petechiae and facial congestion (mechanical pressure of mask on the face); indentations on facial skin (320).
• Anesthetic face mask—marks around mouth and nose (291).
• Compression of face in soft material—pallor around pressure points (tip of nose, perioral area, midpart of forehead, cheeks, chin) surrounded by lividity ("circumoral pallor"); tip of nose can be deviated (Fig. 53; refs. 22 and 325). If dentition is present, then abrasions on the lips and buccal mucosa from biting may be seen (Fig. 54).
Other trauma (e.g., blunt force, penetrating trauma) suggests a struggle and possible homicide (22,296). Binding of other body sites can be seen (e.g., ankles ).
Intrathoracic petechiae are absent or seen in variable numbers in children (113). No petechial hemorrhages have been described in suicidal smotherings using duct tape or a pillow (22,296). Nonspecific pulmonary congestion is observed (22). Larger lung intraparenchymal hemorrhages may be resuscitative in origin (113).
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