Management of Severe Cases in the ED

Severe cases of CO poisoning should be managed as follows in the ED:

• Maintain clear airway and ensure adequate ventilation
• Administer 100% oxygen as soon as possible
• Measure COHb – venous or arterial
• In the symptomatic patient – check FBC, U&E, CK, Trop and ABG
• 12 lead ECG and measure QRS duration and QT interval. There are specific treatments for QRS prolongation (such as sodium bicarbonate) and QT prolongation (such as magnesium sulphate)
• Hypotension – correct by raising the foot of the bed and by adequate fluid resuscitation with crystalloid
• Metabolic acidosis – if severe metabolic acidosis persists despite correction of hypoxia and adequate fluid resuscitation, consider correction with intravenous sodium bicarbonate

Indications for hyperbaric oxygen therapy (HBOT)

There is debate about the added value provided by hyperbaric oxygen [4,5]. The National Poisons Information Service does not currently recommend hyperbaric oxygen therapy. Contact your local NPIS advice line if you are considering it. A COHb concentration of >25% should be an indication to consider hyperbaric oxygen [9] although the decision should be taken with other indicators listed below:

• Loss of consciousness at any stage
• Neurological signs other than headache
• Myocardial ischaemia/arrhythmia diagnosed by ECG
• The patient is pregnant

HBOT is also thought to be of use for chronic exposure to CO and neurological damage is suspected. Its use should be on a case-by-case basis.

Other indications (other than diving emergencies) for HBOT include:

• Air or gas embolism
• Clostridial myositis and myonecrosis (gas gangrene)
• Crush injury, compartment syndrome and other acute traumatic ischemias
• Arterial insufficiencies:
  • Central retinal artery occlusion
  • Enhancement of healing in selected problem wounds
• Severe anaemia
• Intracranial abscess
• Necrotizing soft tissue infections
• Osteomyelitis (refractory)
• Delayed radiation injury (soft tissue and bony necrosis)
• Compromised grafts and flaps
• Acute thermal burn injury
• Idiopathic sudden sensorineural hearing loss