Anesthesia associated mortality 1 in 200,000 to 400,000 anesthesia procedures.

About 21 million patients given anesthesia annually in the U.S.

Requires a comprehensive preoperative evaluation with a complete history with medication use and prior anesthetic exposure.

There are two major classes of anesthesia available: general and neuroaxial anesthesia.
General anesthesia comprises Hipnosis, analgesia, and muscle relaxation.
During the induction phase of general anesthesia, ian intravenous combination of a sedative-hypnotic, in advance, and a neuromuscular blocking agents are used.
An inhalation agent may be added once initial loss of consciousness is achieved.
Maintenance of anesthesia is achieved by using an inhalation agent, intravenous anesthesia, or most commonly combination of both.
General anesthesia leads to multi system physiologic changes particularly during induction and emergence.
The most important effects of generalized seizure are hypotension due to vasodilatation, decreased heart rate, decrease stroke volume, and respiratory impairment due to loss of respiratory muscle tone, reduce lung volume, and airway closure.

Evaluation preoperatively includes exaination of the airway and ability to maintain vascular access.

A complete CBC is the only preoperative testing needed in patients without preexisting disease and under the age of 40 years.

Pre-anesthesia chest x-ray and electrocardiogram should be obtained on individuals 50 years or older or if history or physical examination suggests their indication in younger patients.

Pre-anesthesia pregnancy test should be done on women of childbearing age.

Pre-anesthesia serum electrolytes should be evaluated in patients with diabetes, renal insufficiency and in those who are taking drugs that can alter electrolytes or renal function.

Patients on anticoagulants or with a history of personal bleeding or family history of a bleeding disorder should have a pre-anesthesia PT and PTT.

Exposure of elderly to anesthesia and surgery can transiently affect postoperative cognition, referred to as postoperative cognitive dysfunction.

The population a 65 years and older now accounts for a disproportionate number of surgical procedures requiring anesthesia.

Aging results in alterations in the brain that may contribute to decreased cognitive reserve, susceptibility to surgical stress and anesthesia, and increased risk of neurologic injury such as postoperative neurocognitive disorders.

Intake of clear fluids up until 2 hours before surgery does not increase gastric content, reduce gastric fluid pH, or increase complication rates.

There is no significant association between cumulative exposure to surgical anesthesia after 40 years of age and mild cognitive impairment.

Obesity is associated with increased risk of atelectasis and impaired respiratory function during general anesthesia.

Pre-anesthesia evaluation must be expanded for individuals with cardiac pulmonary or renal insufficiency.

Customary to abstain from oral intake except for medications with sips of water for 8 hours before elective surgery.

For adults not at risk for aspiration solid foods may be permitted up to 6 hours before surgery, and clear liquids may be taken until 2 hours before surgery.

Clear fluids should be allowed up to 2 hours before induction of anesthesia and solids up to 6 hours prior.

Approximately one third of patients given general anesthesia experience postoperative nausea and vomiting, which can last for several days.

In high-risk patients postoperative nausea and vomiting following general anesthesia can approach 80%.

Nerve block analgesia has a lower effect on the occurrence of post-operative nausea or vomiting compared with epidural anesthesia.

For patients with slow or incomplete gastric emptying may require longer periods of fasting prior to anesthesia and the use of pretreatment metoclopramide or histamine H2-receptor antagonists.

Three major anti-emetic drug classes are used in the perioperative period and they include: dopamine-2 receptor antagonists, serotonin-3 receptor antagonist (5HT3R) and corticosteroids, each which reduce the relative risk of nausea by approximately 25%.

Cardiovascular or other required medications may be given with sips of water on the morning of surgery.

Insulin dependent diabetics should be switched to sliding scale insulin of the day of surgery.

American Society of Anesthesiologists (ASA) Criteria

ASA Grade I-no organic, physiologic biochemical, or psychiatric disturbance: the pathologic prcess for which the operation is to be performed is localized and is not a systemic distrubance.

ASA Grade II-mild to moderate systemic distubance caused either by the condition to be treated or by other pathophysiologic processes.

ASA Grade III-severe systemic disturbance of disease for whatever cause, even though it may not be possible to define the degree of disability.

ASA Grade IV-indicative of the patient with severe systemic disorder that is already life threatening and not always correctable by the operative procedure.

ASA Grade V-the moribund patient who has little chance of survival but is submitted to operation in desperation.

Patients with class 1 stage have a 0.1% risk of cardiac complications and mortality, whereas patients with severe systemic disease that is a constant threat to life which is a ASA class IV has an 80% risk.

Both surgery and anesthesia suppress cell-mediated immunity and increase angiogenesis and can promote metastases of cancer cells during the perioperative period.

Anesthesia can affect immune function by decreased levels of circulating antiinflammatory cytokines and change in the functioning of natural killer cells.

Cancer care provided by anesthesiologists who perform six or more complex gastrointestinal (GI) procedures a year was independently associated with a lower risk of adverse postoperative outcomes compared to anesthesiologists with low procedural volume, a population-based cohort study found.

In a study cohort of 8,096 patients who had undergone esophagectomy, pancreatectomy, or hepatectomy for GI cancer, the primary outcome of 90-day major morbidity and hospital readmission occurred in 36.3% of patients treated by high-volume (six procedures a year or more) anesthesiologists compared with 45.7% of patients treated with their low-volume counterparts, (Julie Hallet).

There is increasing evidence that surgery with general anesthesia is not implicated in persistent neurocognitive disorders at a population level and patients can be reassured the general anesthesia sedation for hip fracture repair and possibly other invasive procedures without an increase risk of early postoperative delirium.

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