Traumatic and positional asphyxia

What it is

Asphyxia from chest compression prevents breathing movements. In traumatic asphyxia a heavy weight crushes the chest or abdomen: a vehicle, a collapse or a crowd crush. It causes intense congestion of the face, neck and upper chest, with petechiae and conjunctival haemorrhages, sometimes with a sharp boundary. In positional asphyxia the body's posture (head down, neck sharply flexed, body trapped) prevents breathing and the person cannot get out of it, often because of intoxication. Face-down restraint with weight on the back, in custody or during physical restraint, is a setting that demands an independent investigation.

How to tell it apart

• Versus strangulation: the congestion also covers the upper chest and there are no neck marks.
• Versus livor in a head-down body: livor appears after death and follows gravity.
• Versus sudden natural death: look for the natural cause; if present, judge whether the posture contributed.
• Criteria for positional asphyxia: a posture that prevents breathing, inability to change it and exclusion of other causes.

How to recognise it

• Intense congestion and cyanosis of the head, neck and upper chest, with a sharp boundary.
• Facial petechiae and subconjunctival haemorrhages.
• Pale areas where clothing or an object pressed on the skin.
• Chest and abdominal injuries depending on the force: rib fractures, contusions.
• In positional asphyxia: an abnormal posture documented at the scene and few or no specific internal findings.

How it forms

• Chest compression prevents lung expansion; venous pressure rises and blood backs up into the head and neck.
• In positional asphyxia, neck flexion or a head-down position obstructs the airway or tires the breathing muscles.
• In face-down restraint, weight on the back and prior agitation worsen ventilation.

Next step: what to do and document

• Document and photograph the body's position, the objects trapping it and the spread of congestion before moving it.
• Request toxicology with a chain of custody: intoxication is common in positional asphyxia.
• In a crush survivor, describe petechiae, conjunctival haemorrhages and chest injuries, and refer for trauma assessment.
• In every death during restraint or in custody: notify the Fiscalía at once and secure a full medico-legal autopsy.
• State in the report which circumstances are on record and which are missing; do not conclude without the scene.

Common mistakes

• Attributing a death to posture without ruling out intoxication and natural disease.
• Moving the body without documenting its exact position at the scene.
• Confusing livor in a head-down body with vital congestion.
• Not requesting the records of the restraint or custody (videos, times, who intervened).

Test yourself

Think of the answer, then tap the question to see it.

Add to my cards (4)

Connections

← All of forensic medicine

Educational content on forensic and legal medicine; not legal advice and no substitute for the technical guides of Colombia's National Institute of Legal Medicine and Forensic Sciences. Laws change: each page links the official text and says when it was last checked. For a real case, follow the guide in force and ask the competent authority.

Sources: Sudden deaths from positional asphyxia: a case report (Medicine (Baltimore), PubMed Central, 2018); The Minnesota Protocol on the Investigation of Potentially Unlawful Death (2016) (Office of the United Nations High Commissioner for Human Rights, 2017).

Spotted a mistake?We are always improving for the community. Tell us what is wrong and our team will review it.Report a mistake

Send

Representative model, for educational purposes only.