Unlike the anaesthetists of yesteryears, who utilized a single agent like ether or chloroform alone for anaesthesia, the present day anaesthetists use different drugs for specific effects. This helps them avoid using large doses- (causing dangerous side effects at times) of a single drug that was often required to produce sleep, lack of pain sensation & muscle relaxation simultaneously.
The later part of the 19th century also saw the development of anaesthetics that could be administered through the veins as an injection and machines that would continuously monitor the patients' vital parameters. The anaesthetist could therefore, now, pick up changes in the patients heart, pulse etc and quickly take remedial steps if required.
Advances in technology helped develop machines that could monitor not just the level of oxygen or carbon dioxide in the patient's blood but even the anaesthetic gases used, so that the anaesthetist can fine tune the amount of anaesthetic needed. Almost every organ in the body can be monitored during the course of an operation involving that particular organ. If aviation scientists send people soaring to the skies, safely, on supersonic jets, so do anaesthetists plunge the patients into a painless sleep, safely, during surgery.
Thus, today, one could have anaesthesia for the most complicated surgeries that could stretch for hours or you could have an anaesthetic in the morning for a short surgery and walk home by evening to have dinner in the comfort of your home. From fragile premature babies to the frail elderly individual, anaesthesia can be administered to almost everyone. Anaesthesia today is safe, versatile and indispensable to the patient.
The foundation of modern anesthesia and surgery was laid by brave doctors who experimented with the various agents on themselves rather then on their patients. Modern anesthesia owes a lot to doctors like Horace Wells and August Bier who had the conviction about their discovery and dedication to the profession and wanted to make their patients experience surgery without pain.