Poisoning by carbon monoxide (CO)


I- Overview :

  • frequent seasonal poisoning in Algeria.
  • Often accidental and collective.
  • Immediate or insidious gravity :
  • Hundred deaths a year (November to February)
  • 300 at 400 annual deaths in France,
  • 1000 at 2000 death in the United States (Consultation of thousands in the ER / Intox CO)
  • Risk of neuropsychiatric sequelae, long-term, further evaluation difficult.


  • CO is the main product of any incomplete combustion of carbonaceous substances :

C + O2 → CO2
C + ½O2 → CO

  • The amount produced depends on the efficiency of combustion and the availability of oxygen during combustion.
  • odorless, colorless, tasteless, nonirritating density = 0,976 hence its widely
  • A great affinity with HB (240 time)
  • Once the bond is formed, unable to fix it and carry F02.
  • Decrease of F02 in the blood => tissue anoxia.
  • CO binds to hemoglobin and cytochromes.
  • Eliminated pulmonary.
  • 4-5 H outdoors.
  • oxygen isobaric : 1H Vi.
  • 20 My one Hyperbaric.

II- CO domestic sources :

  • Le Brasero ou Kanoun.
  • The water heater improperly installed natural gas: defective unit; Installation unsuited
  • The insufficient draft in chimneys.
  • The auto ignition engines.
  • Inhalation of fire smoke, tobacco, narghile or hookah, etc…

III- The forms forensic :

A- The accidental form :

C & rsquo; is the most common form, they are poisoning that nocturnal and collective character, it mainly occurs with domestic heating.

B- The professional form :

She sees herself in workers, mining smelter, and gas plants, or in metallurgical plants.

C- The suicidal form :

also common and difficult to achieve, it is the prerogative of women and young people nervous, often an association to another is toxic to search.

D- The criminal form :

Exceptional and difficult to achieve.

IV- pathophysiology :

CO is essentially on breathing.

A- Action on hemoglobin :

HbO2 + CO + O2 ↔ HbCO

  • As previously described the COHb (carboxyhémoglobine) formed is unable to bring t 02 which has the result acute anoxia.
  • And 2/3 hemoglobin is blocked in the form of COHb death is certain.
  • However this reaction is reversible and the hemoglobin released is not altered and immediately resumes its role in breathing

B- Action on cellular oxidations :

  • CO blocks the cellular oxidations acting directly on the cytochrome oxidase resulting in cell anoxia.

V- The clinic :

A- acute intoxication :

1- The toxic impregnation step :

It is accompanied by neurosensory manifestations type : cephalalgia, fear of heights, nausea, buzzing ear, disorders of hearing and visual, a drunk.

2- The phase of coma :

  • This is a deep coma and quiet
  • Pupils are miosis
  • Tendon reflexes abolished
  • The bilateral Babinski's.
  • This phase is accompanied by events :

– cutaneous : coloration and lots phlyctène (exceptional).
– Respiratory : bronchial congestion.
– Cardiovascular : collapsed.

3- complications :

  • They are many, some appear early and aggravate coma, while others are later and are rather part of the legacy.

a- early :

  • PAO and cardiovascular collapse without parallel, or with, disorders of consciousness.
  • Rhythm disorders, Death.
  • Crises convulsives.

b- late :

  • S. Extrapyramidaux : Parkinson.
  • S. Complex basal ganglia.
  • Mental disorders.
  • Sensory disorders : Blindness, deafness, peripheral neuritis.

B- chronic intoxication :

  • It is seen especially in industry and in heavy smokers, characterized by the triad of DUVOIR-GAULTIER :

– headaches : fronto-temporal, often times permanent pulsatile.
– Asthenia : early onset and progressive installation.
– Dizziness : can go to syncope.

  • This triad can be associated with digestive disorders, heart, neurological or sensory.

WE- Forensic Diagnosis :

A- In the living :

It is based primarily on :

  • The history.
  • The importance of clinical signs.
  • The toxicology assay. (+++)
  • Venous blood sampling and measurement of the percentage of COHb from the CO- oximeter :
  • and HbCO > 66% some death.
  • If COHb around 50% unfortunate prognosis.

Exp :

  • A rate of COHb < 0,8 ml / 100 ml of blood is considered a normal rate.
  • A rate of COHb < 5 at lOml / lOOml blood is an important rate (some impregnation).
  • A rate of COHb > lOml / lOOml blood is a very serious rate.

B- Among the dead body :

1- external examination :

  • Cyanosis of the face and nails.
  • Cadaveric lividity have a bright pink or carmine color pink.
  • Blood suffusions (bruise subconjunctival, hyperhémie) under the conjunctiva, under the scalp, and in the oral mucosa.
  • des phlyctènes (+/-) and pressure sores may appear to support points.

2- at autopsy :

  • The brain and meninges are congestive.
  • Presence airy spume (mousse d&rsquo;OAP). The lungs are congested and colorful pink carmine.
  • Under the pleura appear Ecchymotic spots. Task TARDIEU
  • Muscles have a bright red color.
  • Blood is fluid and currant pink color.

3- supplementary examinations :

  • The pathological examination : Micro cell foci of necrosis in organs.
  • The toxicological examination : (the definitive diagnosis) +++

– the dosage of CO and T COHb
+ Blood heart on tight syringe.
+ Muscle (10 to 15gr) if putrefaction.
– The coefficient of BALTHAZARD = COHb / total Hb If it is equal to 2/3 (66%) => certain death by CO.

Courses of Dr. Ghennam – Faculty of Constantine