Anaesthetic gases are replaced by air or oxygen. Muscle relaxants, and sometimes the powerful pain killers, may need special drugs to reverse their effects. Once you are sufficiently awake, any tube in your mouth can be removed. You will stay in the Recovery Room for an hour or two until you are completely awake. You should remember not to operate machinery or drive a car for 24 hours after your anaesthetic.
Modern anaesthetics are extremely safe.
Thanks to the excellent modern monitors, better drugs, and the training of modern anaesthetists, anaesthesia is getting safer all the time. For healthy patients, anaesthesia is so safe that it is difficult to measure the degree of risk any more. People with serious heart, lung or other disease, obviously, have an increased risk. Accidents can still happen, but modern monitors usually ensure that any problems are picked up at an early stage. Older and sicker patients now undergo surgery, but with care, and perhaps with a few days in an Intensive Care Unit, most of them can be got through even major surgery.