Editing Anesthesia (section)

== Risks and complications ==
{{See also|Patient safety}}
Risks and complications as they relate to anesthesia are classified as either [[Disease|morbidity]] (a disease or disorder that results from anesthesia) or [[Perioperative mortality|mortality]] (death that results from anesthesia).  Quantifying how anesthesia contributes to morbidity and mortality can be difficult because the patient's health prior to surgery and the complexity of the surgical procedure can also contribute to the risks.
[[File:Mortality rates by ASA status from Anesthesiology, V 97, No 6, Dec 2002 p1615.png|thumb|Anesthesia-related deaths by [[ASA physical status classification system|ASA status]]<ref name="Lagasse" />]]
Prior to the introduction of anesthesia in the early 19th century, the [[Stress (physiology)|physiologic stress]] from surgery caused significant complications and many deaths from [[Shock (circulatory)|shock]].  The faster the surgery was, the lower the rate of complications (leading to reports of very quick amputations).  The advent of anesthesia allowed more complicated and life-saving surgery to be completed, decreased the physiologic stress of the surgery, but added an element of risk.  It was two years after the introduction of ether anesthetics that the first death directly related to the use of anesthesia was reported.<ref name="Chaloner">{{cite journal | vauthors = Chaloner EJ, Flora HS, Ham RJ | title = Amputations at the London Hospital 1852–1857 | journal = Journal of the Royal Society of Medicine | volume = 94 | issue = 8 | pages = 409–12 | date = August 2001 | pmid = 11461989 | pmc = 1281639 | doi = 10.1177/014107680109400812 }}</ref>

Morbidity can be major ([[myocardial infarction]], [[pneumonia]], [[pulmonary embolism]], [[kidney failure]]/[[chronic kidney disease]], postoperative [[cognitive dysfunction]] and [[Allergic reactions to anaesthesia|allergy]]) or minor (minor [[nausea]], vomiting, readmission).  There is usually overlap in the contributing factors that lead to morbidity and mortality between the health of the patients, the type of surgery being performed and the anesthetic.  To understand the [[relative risk]] of each contributing factor, consider that the rate of deaths totally attributed to the patient's health is 1:870.  Compare that to the rate of deaths totally attributed to surgical factors (1:2860) or anesthesia alone (1:185,056) illustrating that the single greatest factor in anesthetic mortality is the health of the patient.  These statistics can also be compared to the first such study on mortality in anesthesia from 1954, which reported a rate of death from all causes at 1:75 and a rate attributed to anesthesia alone at 1:2680.<ref name="Miller 2010" />{{rp|993}}  Direct comparisons between mortality statistics cannot reliably be made over time and across countries because of differences in the stratification of risk factors, however, there is evidence that anesthetics have made a significant improvement in safety<ref name="Braz">{{cite journal | vauthors = Braz LG, Braz DG, Cruz DS, Fernandes LA, Módolo NS, Braz JR | title = Mortality in anesthesia: a systematic review | journal = Clinics | volume = 64 | issue = 10 | pages = 999–1006 | date = Oct 2009 | pmid = 19841708 | pmc = 2763076 | doi = 10.1590/S1807-59322009001000011 }}</ref> but to what degree is uncertain.<ref name="Lagasse">{{cite journal | vauthors = Lagasse RS | title = Anesthesia safety: model or myth? A review of the published literature and analysis of current original data | journal = Anesthesiology | volume = 97 | issue = 6 | pages = 1609–17 | date = December 2002 | pmid = 12459692 | doi = 10.1097/00000542-200212000-00038 | s2cid = 32903609 | doi-access = free }}</ref>

Rather than stating a flat rate of morbidity or mortality, many factors are reported as contributing to the relative risk of the procedure and anesthetic combined.  For instance, an operation on a person who is between the ages of 60–79 years old places the patient at 2.3 times greater risk than someone less than 60 years old.  Having an ASA score of 3, 4 or 5 places the person at 10.7 times greater risk than someone with an ASA score of 1 or 2.  Other variables include age greater than 80 (3.3 times risk compared to those under 60), gender (females have a lower risk of 0.8), urgency of the procedure (emergencies have a 4.4 times greater risk), experience of the person completing the procedure (less than 8 years experience and/or less than 600 cases have a 1.1 times greater risk) and the type of anesthetic (regional anesthetics are lower risk than general anesthetics).<ref name="Miller 2010" />{{rp|984}} [[Obstetrical]], the very young and the very old are all at greater risk of complication so extra precautions may need to be taken.<ref name="Miller 2010" />{{rp|969–86}}

On 14 December 2016, the Food and Drug Administration issued a Public Safety Communication warning that "repeated or lengthy use of general anesthetic and sedation drugs during surgeries or procedures in children younger than 3 years or in pregnant women during their third trimester may affect the development of children's brains."<ref>Food and Drug Administration [https://www.fda.gov/Drugs/DrugSafety/ucm532356.htm "FDA Drug Safety Communication: FDA review results in new warnings about using general anesthetics and sedation drugs in young children and pregnant women"], FDA Website, 14 December 2016. Retrieved on 3 January 2017.</ref> The warning was criticized by the American College of Obstetricians and Gynecologists, which pointed out the absence of direct evidence regarding use in pregnant women and the possibility that "this warning could inappropriately dissuade providers from providing medically indicated care during pregnancy."<ref>American College of Obstetricians and Gynecologists [http://www.acog.org/About-ACOG/News-Room/Practice-Advisories/FDA-Warnings-Regarding-Use-of-General-Anesthetics-and-Sedation-Drugs "Practice Advisory: FDA Warnings Regarding Use of General Anesthetics and Sedation Drugs in Young Children and Pregnant Women"], ACOG Website, 21 December 2016. Retrieved on 3 January 2017.</ref> 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).<ref>Kennerly Loutey [https://www.kennerlyloutey.com/anesthesia-pregnant-women-young-children/ "Anesthesia in Pregnant Women And Young Children: The FDA Versus ACOG"] {{Webarchive|url=https://web.archive.org/web/20180714153354/https://www.kennerlyloutey.com/anesthesia-pregnant-women-young-children/ |date=14 July 2018 }}, Website, Retrieved on 3 January 2017.</ref>