—Victim advocate: Someone who provides immediate crisis intervention, confidential emotional support, and information and advocacy to victims and their loved ones. The advocate is part of a coordinated response team and facilitates medical and legal services while providing trauma-informed, victim-centered care.
METHODS OF STRANGULATION
—Complete hanging: Suspension from a ligature around the neck holding the full body weight.
—Incomplete hanging: Suspension from a ligature around the neck holding partial body weight (ie, the feet, legs, pelvis, or torso is in contact with the ground).
—Ligature strangulation: Strangulation without suspension using some form of flexible linear object (eg, cord-like item).
—Manual strangulation: Strangulation using the hands, fingers, arms, or legs.
MECHANISMS OF STRANGULATION
—Compression of the laryngopharynx, larynx, or trachea: Inhibits inhalation and exhalation causing hypoxia and eventually anoxia.
—Compression over the carotid artery ganglion: May stimulate the carotid sinus reflex; produces bradycardia and hypotension; however, it does not cause cardiac arrest.21,22
—Sustained compression of the carotid arteries: Prevents 80% to 85% of oxygenated blood flow to the brain, which leads to cerebral anoxia and unconsciousness within 10 seconds.
—Sustained compression of the carotid and vertebral arteries: Prevents 100% of oxygenated blood flow to the brain. Without any arterial inflow to the head, no petechial hemorrhages develop, leading to “pale strangulation” or “pale hanging.”
—Sustained compression of the jugular veins: Prevents outflow of venous blood from the brain. Leads to a gradual backup of venous blood into the face and brain causing “venous congestion” and eventually petechial hemorrhages. However, the jugular vein and the carotid artery are anatomically side-by-side, and the difference between the collapse of the jugular vein and the carotid artery is only 7 pounds of pressure.
ANATOMY OF THE NECK
To best understand the clinical features associated with strangulation, one must understand the basic anatomy and functions of the neck (Figure 1). The neck is comprised of subcutaneous fat, muscle, cartilage, bone, vessels, nerves, lymph nodes, and salivary glands. The underlying neck structures that are especially vulnerable to the intentional external pressure from strangulation are located in the anterior and anterolateral neck. These structures include the hyoid bone, larynx, trachea, jugular veins, and carotid arteries. The vertebral arteries are located on the side of the neck (Figure 2-a and b). To grasp the importance of these structures, it is important to understand the role of the individual structure in the cardiovascular and respiratory system.
Life-sustaining oxygenation depends on the combination of air and blood flow. Respiration starts with the free movement of oxygenated air through the upper air passages (ie, the nose and mouth). Then, the air must flow freely through the larynx, to the trachea, and finally, to the lungs. Oxygenation occurs when the lungs shift oxygen from inhaled air into the blood. Then, the cardiovascular system pumps oxygenated blood through the heart and up into the carotid and vertebral arteries of the neck for oxygenation of the brain. At the brain’s cellular level, blood exchanges oxygen for CO2 gas, which is then transported down the neck’s jugular veins to the lungs for exhalation. Other liquid and solid waste products travel through the circulatory system and are excreted by the kidneys and gastrointestinal track.
Figure 1. Vital neck structures. (Illustration courtesy Yesenia Aceves and the Training Institute on Strangulation Prevention.)
Figure 2-a and b. Carotid and vertebral arteries.
Cessation of oxygenated blood flow to the brain cells leads to anoxia. Hypoxia (eg, decreased oxygen levels) results from strangulation when pressure to the neck compromises air flow. Anoxia and hypoxia from compressive force on the arteries and air passages of the neck is the most common cause of death in strangulation. Based on videotapes of hanging death, the last breath occurs between 62 and 157 seconds.6,23 Injuries to neck structures may also lead to compromised air and blood flow. Pressure to the neck can result in hyoid bone or laryngeal fractures, carotid or vertebral artery dissections, intrinsic neck muscle bleeding, cervical spine ligament tears, nerve injury, and cervical spine fractures. Injury-associated bleeding, swelling, and/or functional disability in maintaining a patent airway interferes with oxygenation leading to hypoxia. The following is a more detailed explanation of underlying neck structures, including their location, function, and susceptibility to compressive forces of strangulation.
CAROTID ARTERIES
The carotid arteries originate from the aortic arch at the top of the heart and are located on the left and right side of the neck. Protected by neck muscles, the carotid arteries lie slightly deeper and medial to the jugular veins. The carotid arteries carry approximately 80% of the oxygenated, nutrient-rich blood from the heart to the head and brain. Pressure inside the carotid arteries exerts the force required not only to deliver oxygenated blood but to diffuse oxygen throughout the brain tissues.
It takes approximately 11 pounds of pressure to occlude the carotid arteries and compromise oxygenated blood flow to the brain. Sustained pressure causes unconsciousness within 10 seconds as a result of immediate cessation of oxygenated blood flow. Immediate relief of pressure allows consciousness to return in approximately 10 seconds. Death occurs within 1 to 2.5 minutes of constant pressure on the arteries.23 A tear, called a dissection, can occur to the internal lining of the carotid arteries. The body’s response to a dissection is to form a blood clot around the tear and begin the hemostasis phase of healing. Blood clots can completely occlude the artery or can break off, travel to the brain, and compromise blood flow and oxygenation, resulting in neurologic compromise and stroke. The clot may not break off until days, weeks, or months after injury, and the strangulation victim remains asymptomatic until the moment of the stroke.24 A screening CTA is required to rule out the presence of a carotid artery dissection (Appendix 7).
VERTEBRAL ARTERIES
The vertebral arteries originate from the subclavian arteries and are the primary blood supply to the upper spinal cord, brainstem, cerebellum, and the posterior circulation of the brain. They carry 15% to 20% of the brain’s blood supply. When the carotid arteries are occluded but the vertebral arteries remain patent, the vertebral arterial blood flow is primarily responsible for the development of petechial hemorrhages on the integument skin and mucous membrane surfaces of the face and the oto-oral-pharyngeal areas. There are 2 mechanisms for occluded vertebral arteries. First, if pressure is applied just above the collarbone to occlude the subclavian arteries4,25 or second, if lateral neck pressure is applied from a thin ligature or with hands in a choke hold, 100% of arterial blood flow to the brain can be blocked.26 Compression of both the carotid and vertebral arteries will result in a “pale strangulation” or a “pale hanging” because petechiae will not develop. A screening CTA is required to rule out the presence of a vertebral artery dissection (Appendix 7).
CAROTID