Anesthesia is unique in that it is not a direct means of treatment; rather, it allows the clinician to do things that may treat, diagnose, or cure an ailment which would otherwise be painful or complicated.

[3] The same minimum standards for patient safety apply regardless of the provider, including continuous clinical and biometric monitoring of tissue oxygenation, perfusion and blood pressure; confirmation of correct placement of airway management devices by auscultation and carbon dioxide detection; use of the WHO Surgical Safety Checklist; and safe onward transfer of the patient's care following the procedure.

Anesthesia is a combination of the endpoints (discussed above) that are reached by drugs acting on different but overlapping sites in the central nervous system.

In the early days of anesthesia, anesthetics could reliably achieve the first two, allowing surgeons to perform necessary procedures, but many patients died because the extremes of blood pressure and pulse caused by the surgical insult were ultimately harmful.

Eventually, the need for blunting of the surgical stress response was identified by Harvey Cushing, who injected local anesthetic prior to hernia repairs.

This relationship exists because the drugs bind directly to cavities in proteins of the central nervous system, although several theories of general anesthetic action have been described.

The ideal anesthetic drug would provide hypnosis, amnesia, analgesia, and muscle relaxation without undesirable changes in blood pressure, pulse or breathing.

Since inhalational anesthetics are flammable, various checklists have been developed to confirm that the machine is ready for use, that the safety features are active and the electrical hazards are removed.

From the perspective of the person giving the sedation, the patient appears sleepy, relaxed and forgetful, allowing unpleasant procedures to be more easily completed.

[9] From the perspective of the subject receiving a sedative, the effect is a feeling of general relaxation, amnesia (loss of memory) and time passing quickly.

Evidence supports the use of ultrasound guidance alone, or in combination with peripheral nerve stimulation, as superior for improved sensory and motor block, a reduction in the need for supplementation and fewer complications.

[2]: 1639–41 Central neuraxial anesthesia is the injection of local anesthetic around the spinal cord to provide analgesia in the abdomen, pelvis or lower extremities.

On-demand pain medications typically include either opioid or non-steroidal anti-inflammatory drugs but can also make use of novel approaches such as inhaled nitrous oxide[14] or ketamine.

Prior to the introduction of anesthesia in the early 19th century, the physiologic stress from surgery caused significant complications and many deaths from shock.

"[23] Patient advocates noted that a randomized clinical trial would be unethical, that the mechanism of injury is well-established in animals, and that studies had shown exposure to multiple uses of anesthetic significantly increased the risk of developing learning disabilities in young children, with a hazard ratio of 2.12 (95% confidence interval, 1.26–3.54).

[27] According to a recent study conducted at the David Geffen School of Medicine at UCLA, the brain navigates its way through a series of activity clusters, or "hubs" on its way back to consciousness.

[31][32] The ancient Egyptians had some surgical instruments,[33][34] as well as crude analgesics and sedatives, including possibly an extract prepared from the mandrake fruit.

[36] Despite this, it was the Chinese physician Hua Tuo whom historians considered the first verifiable historical figure to develop a type of mixture of anesthesia, though his recipe has yet to be fully discovered.

In 13th-century Italy, Theodoric Borgognoni used similar mixtures along with opiates to induce unconsciousness, and treatment with the combined alkaloids proved a mainstay of anesthesia until the 19th century.

[46] In 1800 Davy wrote about the potential anesthetic properties of nitrous oxide in relieving pain during surgery, but nobody at that time pursued the matter any further.

After years of research and experimentation, he finally developed a formula which he named tsūsensan (also known as mafutsu-san), which combined Korean morning glory and other herbs.

Hanaoka went on to perform many operations using tsūsensan, including resection of malignant tumors, extraction of bladder stones, and extremity amputations.

[50] Nearly forty years would pass before Crawford Long, who is titled as the inventor of modern anesthetics in the West, used general anesthesia in Jefferson, Georgia.

[53] On 16 October 1846, Boston dentist William Thomas Green Morton gave a successful demonstration using diethyl ether to medical students at the same venue.

After Morton had induced anesthesia, surgeon John Collins Warren removed a tumor from the neck of Edward Gilbert Abbott.

In a letter to Morton shortly thereafter, physician and writer Oliver Wendell Holmes Sr. proposed naming the state produced "anesthesia", and the procedure an "anesthetic".

Respected surgeons in Europe including Liston, Dieffenbach, Pirogov, and Syme quickly undertook numerous operations with ether.

[citation needed] Discovered in 1831 by an American physician Samuel Guthrie (1782–1848), and independently a few months later by Frenchman Eugène Soubeiran (1797–1859) and Justus von Liebig (1803–1873) in Germany, chloroform was named and chemically characterized in 1834 by Jean-Baptiste Dumas (1800–1884).

[56] In 1847, Scottish obstetrician James Young Simpson was the first to demonstrate the anesthetic properties of chloroform on humans and helped to popularize the drug for use in medicine.

Magaw's records and outcomes created a legacy defining that the delivery of anesthesia by nurses would serve the surgical community without increasing the risks to patients.