% of COHb than can cause death -

% of CoHb Clinical features 0 - 10 No symptoms 10 - 20 Tightness across forehead Slight headache Dilatation of cutaneous blood vessels 20 - 30 Headache Throbbing in temples 30 - 40 Severe headache Weakness Dizziness Dimness of vision Nausea and vomiting Collapse 40 - 50 Same as above plus greater possibility of collapse or syncope Increased respiration and pulse 50 - 60 Syncope Coma with intermittent convulsions Cheyne-strokes respiration 60 - 70 increasing coma 70 - 80 deep coma,absnet reflexes above 80% causes death from respiratory arrest REF;THE SYNOPSIS OF FORENSIC MEDICINE:KS NARAYANA REDDY;28th EDITION;PAGE NO 359