Regarding carbon monoxide toxicity true are all, except -a) Cytochrome toxicity is lethalb) Treated by 5% CO2c) PO2 is decreasedd) Shift HbO2 dissociation curve to lefte) Gaseous vasodilator

CO to be lethal to cytochrome, the dose needs to be 100 times than that of the lethal dose.   Since Hb has more affinity to CO than oxygen, it results in anemic hypoxia. PO2 remain normal as it is the dissolved form. Hb-O2 dissociation curve shifts to left. Treatment for CO poisoning is by hyperbaric oxygen. But 95% O2 + 5% CO2 can also be used. CO is a gaseous vasodilator.