Anesthesia is the use of medicine to prevent the feeling of pain or another sensation during surgery or other procedures that might be painful. Given as an injection or through inhaled gases or vapors, different types of anesthesia affect the nervous system in various ways by blocking nerve impulses and, therefore, pain.

In today's hospitals and surgery centers, highly trained professionals use a wide variety of safe, modern medications and extremely capable monitoring technology. An anesthesiologist is a doctor who specializes in giving and managing anesthetics — the medications that numb an area of the body or help you fall and stay asleep.

In addition to administering anesthesia medications before the surgery, the anesthesiologist will:

• monitor your major bodily functions (such as breathing, heart rate and rhythm, body temperature, blood pressure, and blood oxygen levels) during surgery
• address any problems that might arise during surgery • manage any pain you may have after surgery
• keep you as comfortable as possible before, during, and after surgery

A specially trained nurse anesthetist, who works with the anesthesiologist and surgeon, may assist in giving you anesthesia (although the anesthesiologist will be the one to manage the anesthesia and make all major anesthesia-related decisions during the operation).

Prior to surgery, the anesthetist interviews the patient to determine the best combination and drugs and dosages and the degree of how much monitoring is required to ensure a safe and effective procedure.

Pertinent information is the patient's age, weight, medical history, current medications, previous anesthetics, and fasting time. Usually, the patients are required to fill out this information on a separate form during the pre-operative evaluation. Depending on the existing medical conditions reported, the anesthetist will review this information with the patient either during his pre-operative evaluation or on the day of his or her surgery.

Truthful and accurate answering of the questions is important so the anesthetist can select the proper anesthetics. For instance, a heavy drinker or drug user who does not disclose their chemical uses could be under medicated, which could then lead to anesthesia awareness or dangerously high blood pressure. Commonly used medications such as Viagra can interact with anesthesia drugs; failure to disclose such usage can endanger the patient.

An important aspect of this assessment is that of the patient's airway, involving inspection of the mouth opening and visualization of the soft tissues of the pharynx. The condition of teeth and location of dental crowns and caps are checked, neck flexibility and head extension observed. If an endotracheal tube is indicated and airway management is deemed difficult, then alternative placement methods such as fiber optic intubation may be used.

Stage 1

Stage 1 anesthesia, also known as the "induction," is the period between the initial administration of the induction medications and loss of consciousness. During this stage the patient progresses from analgesia without amnesia to analgesia with amnesia. Patients can carry on a conversation at the time.

Stage 2

Stage 2 anesthesia, also known as the "excitement stage," is the period following loss of consciousness and marked by excited and delirious activity. During this stage, respirations and heart rate may become irregular. In addition, there may be uncontrolled movements, vomiting, breath holding, and pupillary dilation. Since the combination of spastic movements, vomiting, and irregular respirations may lead to airway compromise, rapidly acting drugs are used to minimize time in this stage and reach stage 3 as fast as possible.

Stage 3

Stage 3 is Surgical Anesthesia. During this stage, the skeletal muscles relax, and the patient's breathing becomes regular. Eye movements slow, then stop, and surgery can begin.

Stage 4

Stage 4 anesthesia, also known as "overdose," is the stage where too much medication has been given and the patient has severe brain stem or medullary depression. This results in a cessation of respiration and potential cardiovascular collapse. This stage is lethal without cardiovascular and respiratory support.

The anesthesia concludes with a management plan for postoperative pain relief. This may be in the form of regional analgesia, oral, transdermal or parenteral medication. Minor surgical procedures are amenable to oral pain relief medications such as paracetamol and NSAIDS such as ibuprofen. Moderate levels of pain require the addition of mild opiates such as codeine.

Major surgical procedures may require a combination of modalities to confer adequate pain relief. Parenteral methods include Patient Controlled Analgesia System (PCAS) involving morphine, a strong opiate. Here, the patient presses a button to activate a pump containing morphine. This administers a preset dose of the drug. As the pump is programmed not to exceed a safe amount of the drug, the patient cannot self administer a toxic dose.

Overall, the mortality rate for general anesthesia is about five deaths per million anesthetic administrations.[1] Death during anesthesia is most commonly related to surgical factors or pre-existing medical conditions. These include major hemorrhage, sepsis, and organ failure (eg. heart, lungs, kidneys, liver). Common causes of death directly related to anesthesia include:

• aspiration of stomach contents
• suffocation (due to inadequate airway management)
• allergic reactions to anesthesia (specifically and not limited to anti-nausea agents) and other deadly genetic predispositions
• human error
• equipment failure

 

In the US, up until about 1980 anesthesia was a significant risk, with at least one death per 10,000 times administered. After becoming something of a public scandal, a careful effort was made to understand the causes and improve the results. It is generally believed that anesthesia is now at least ten times safer than it was then. However, there is some controversy about this. In the US, the data is not made public (in fact, the data is not even collected), so the truth is uncertain. The rate for dental anesthesia is reported to be one out of 350,000.