All are false about N20 except?
Ans. is 'a' i.e., Least potent Nitrous oxide N2Q It is colourless, odourless, heavier than air, nonirritating and noninflammable gas. o It is also called laughing gas. MAC is 105% (least potent) - even pure N20 at 1 atmospheric pressure can not produce adequate anaesthesia. o It has good analgesic but poor muscle relaxant activity. It is supplied under pressure in blue coloured steel cyclinders. It has very low blood solubility --> induction is quick and smooth with rapid recovery. Second gas effect and diffusion hypoxia occur with N20 only. N20 is generally used as a carrier and adjuvant to other anaesthetics --> A mixture of 70% N20 + 25 - 30% 02+ 0.2 - 2% another potent anaesthetic is employed for most of the surgical procedures. Entonox is a mixture of 50% N20 and 50% 02. It has little effect on respiration, hea and BP. It can cause bone marrow depression and vit B12 deficiency. N20 is the only anaesthetic repoed to produce hematologic toxicity and neurotoxicity with long term administration. Both toxicities are the result of the interaction of N20 with vit B12. Complete bone marrow failure can be expected after several days of continuous exposure. Bone marrow changes are preventable by pretreating patients with large doses of folinic acid. Other manifestations of vit B 12 deficiency eg. megaloblastic anemia, subacute combined degeneration of cord may also occur. Methemoglobinemia and laryngospasm may occur. It is contraindicated in patients with air cavities like pneumothorax, pneumoperitoneum and volvulus --> expansion and increase in pressure occur.
Least potent
Good muscle relaxant
Lighter than air
No diffusion hypoxia