Asphyxia is generally accompanied by ‘dyspnoea’ i.e. the sensation of laboured breathing described by patients as ‘air hunger’.
Prolonged suffocation leads to hypoxemia and hypoxia, i.e. a lack of oxygen in the blood and tissues, which mainly affects the tissues and organs most sensitive to oxygen deficiency, such as the brain (cerebral hypoxia).
If the hypoxia is prolonged, the tissues stop functioning and a series of sequential events quickly occur: loss of consciousness, irreversible brain damage, coma and death of the patient; even if death does not occur, the severe cerebral hypoxia could still lead to necrosis (death) of the nerve tissue, with possible severe and irreversible motor and/or sensory damage.
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Symptoms of suffocation
The main symptom of choking is an urge to breathe induced by increasing levels of carbon dioxide in the blood, i.e. dyspnoea.
Other signs and symptoms vary depending on the underlying cause of choking and may include:
- cyanosis (bluish skin and conjunctivae);
- violent or weak cough (if the subject cannot fill the lungs with air);
- the subject brings their hands to their throat;
- breathing may make noises;
- miosis (pupil constriction);
- bleeding from nasal mucosa and ear canal;
- arterial hypertension;
- altered respiratory rate;
- motor and/or sensory deficits;
- loss of consciousness;
- coma and death (in cases where breathing is not restored within a time frame usually ranging from 3 to 6 minutes).
Death by suffocation: signs, symptoms and timing
If suffocation, and therefore hypoxia, is prolonged over time, the tissues stop functioning one after the other, starting with the brain (whose tissue is particularly oxygen-hungry), and a series of events, symptoms and signs occur rapidly in sequence
- loss of consciousness
- irreversible brain damage;
- death of the patient.
Death from suffocation is preceded by four stages:
1) Irritative or ‘respiratory dyspnoea’ stage: lasts from 30 to 60 seconds and is characterised by:
- tachypnoea (increased respiratory rate);
- arterial hypotension (‘low blood pressure’);
- cyanosis (bluish skin);
- miosis (narrowing of the pupil diameter of the eye).
2) Convulsive or ‘expiratory dyspnoea’ stage: lasts about 1 minute and is characterised by:
- severe dyspnoea (marked expiratory difficulty);
- arterial hypertension;
- high release of adrenaline into the circulation;
- obnubilation of consciousness;
- cerebral hypoxia;
- reduced motor reflexes;
- sensory alteration;
- sphincter release (faeces and/or urine may be involuntarily released).
3) Apnoic or ‘apparent death’ stage: lasts about 1 minute and is characterised by:
- progressive bradypnoea (progressive reduction in the frequency of respiratory acts);
- total loss of consciousness;
- muscle relaxation;
- severe bradycardia (slow and weak heartbeat);
- deep coma.
4) Terminal or ‘gasping’ stage: lasts approximately 1 to 3 minutes and is characterised by:
- continued loss of consciousness;
- slow and irregular respiratory movements;
- severe cardiac arrhythmia;
- cardiac arrest;
- cessation of breathing;
How quickly does one die?
The time in which death occurs is extremely variable depending on various factors such as age, state of health, state of fitness and mode of asphyxia.
An elderly person, suffering from diabetes, hypertension and pulmonary emphysema, if subjected to a compressive force (e.g. strangulation) resulting in mechanical asphyxia, can lose consciousness and die in less than a minute, as can a child suffering from bronchial asthma.
An adult, fit individual, accustomed to prolonged exertion (think of a professional athlete or scuba diver), subjected to chemical asphyxia, such as that from carbon monoxide inhalation, may, on the other hand, take several minutes to lose consciousness and die, but in the majority of cases death occurs in a variable time of between approximately 3 and 6 minutes, in which the four phases described in the previous paragraph alternate.