They appear to involve Displacement of oxygen from hemoglobin (because CO has greater affinity for hemoglobin than does oxygen) Shifting of the oxygen-hemoglobin dissociation curve to the left (decreasing release of oxygen from hemoglobin to tissues—see figure Oxyhemoglobin dissociation curve) Inhibition of mitochondrial respiration Possibly direct toxic effects on brain tissue Symptoms and Signs of CO Poisoning Carbon monoxide (CO) poisoning symptoms tend to correlate well with the patient's peak blood carboxyhemoglobin levels.