On December 10, 1844, dentist H. Wells attended a traveling stage performance in Hartford, USA, where volunteers could inhale nitrous oxide (laughing gas) as a special attraction. During the performance, Wells observed that one of the subjects sustained a gaping lower leg wound without showing any pain reaction. The next morning, Wells, who had intuitively recognized the tremendous significance of this procedure, had a wisdom tooth extracted under nitrous oxide; he felt no pain.
Evolution of anesthesia
Five weeks later, he went public with his discovery after seeing for himself the effectiveness of the gas in numerous patients: At Boston General Hospital, he wanted to perform a painless tooth extraction. The attempt failed, and Wells was booed. In 1848 he committed suicide – a broken man. But there was no stopping the development of anesthesia.
At the same point where Wells had failed, as early as October 1846, W. Morton, a former collaborator of Wells, achieved the first clinical anesthesia with ether. In 1847, J. Simpson in Edinburgh introduced chloroform as an anesthetic. A few years after that, all operating rooms in the world performed surgery only under anesthesia.
General anesthesia
The term “anesthesia” is derived from the Greek word “narce” (“rigidity”). During anesthesia, paralysis of parts of the central nervous system causes
- The sensation of pain
- The consciousness
- The defensive reflexes
- The muscle tension
reversible, that is, temporarily switched off. General anesthesia (“general anesthesia”) therefore requires a combination of different drugs: sleeping pills, painkillers, muscle relaxants (agents to make the muscles slack) and reflex depressants. The state thus achieved is characterized by deep sleep as well as insensitivity to pain. In contrast to general anesthesia, consciousness is preserved during partial anesthesia. In this form of anesthesia, only part of the body becomes numb and thus insensitive to pain.
Vital signs
For a long time, 4 stages of anesthesia (Guedel) were the basis of anesthesia management. However, they have since become less important. In modern combination anesthesia, the anesthesiologist is guided by other clinical signs, which include blood pressure and pulse patterns, skin condition (sweating, blood flow), muscle tone, and eye signs (eg, lacrimation).
So during general anesthesia, anesthesiologists must constantly check the patient’s “vital signs.” So they always know if the heart is working properly (ECG is permanently running, blood pressure and pulse are permanently measured), if there is enough oxygen in the blood (is permanently measured), if the lungs are working well (ventilation pressure is permanently measured).
Older and younger brain regions
Above all, breathing and heartbeat – our vital functions still work quite well even under anesthesia. In contrast, consciousness is completely shut down. How is that possible? The fact that anesthesia is feasible at all is based on the fact that our brain has developed in a different way. In order to survive, a central nervous system had to develop first.
Only at a much later point in time did consciousness and intellect develop in our brain. Now, during anesthesia, the younger regions of our brain are the first to be turned off, but older brain regions with the appropriate functions are still largely active.
