<s>[INST] context: Tube/cuff/drapes Oxidant O2/N2O Volatile agents - Desflurane, sevoflurane, halothane, isoflurane - non combustible- Laser surgery - we use laser tube * Covered by a metallic & nonmetallic reflecting layer which is wrapped around the tube* Laser reflecting material is used to cover the tube * So that the tube doesn't catch fire* Usually high volume, low pressure cuff is used, but for laser Sx Low volume, high pressure cuff is used (because we don't want any gas to pass through this cuff from lower airway to upper airway (tight seal) * We don't inflate the tube with air, inflate with H2O+dye added to it (if cuff breaks dye spread in entire area, come to know cuff has damaged, immediately we change the tube)* H2O act as extinguisher Surgical drapes - Are arranged in proper order so that gases doesn't accumulate inside the surgical drape- Wet gauges are used to prevent fire Management of airway fire- Stoppage of O2 +N2O (disconnect the circuit)- Try to extinguish the fire with normal saline or distilled water- Remove the ET tube - Reintubate with fresh ET tube- IV steroid + IV antibiotic- Steroids given to prevent airway edema- Antibiotic to prevent infection- Minimum O2, maximum air There are three elements essential to the creation of an airway fire: heat or an ignition source (laser or electrosurgical unit), fuel (paper drapes, ETT, or gauze swabs),and an oxidizer (O2, air, or N2O). The danger of an airway fire is not limited to general anesthesia. It can also occur during facial procedures under monitored anesthesia care electrocautery used in close proximity to delivered supplemental oxygen. [/INST] question: To prevent combustion during anesthesia what combination is used? | options: A: O2 25% & N2O 75% B: O2 50% & N2O 50% C: O2 25% & He 75% D: O2 75% & N2O 25% | answer: C </s>