Anesthesia Demystified

So you are going to have an operation and are wondering what happens when the anesthesiologist puts you to sleep. For a lot of patients, the big worry is not waking up. Some fear that they will not be able to cope up with the pain of surgery. Others just fear the unknown.

Studies have shown that the more information patients have about what is going to happen to them, the less their levels of anxiety and the less their requirements for pain medication after the procedure.

So without much ado, I shall endeavor to delve deep into the mysteries of anesthetics so that you, my dear reader, can feel more at ease or can satisfy your curiosity.

A long long time ago, in a galaxy far far away (with apologies to George Lucas), all surgery was done with the patient awake. Patients would sometime be stunned with a blow on the head which involved a leather helmet and a wooden hammer, or rendered stuporous with lots of alcohol or weird concoctions of henbane. A branch of a tree between the teeth to bite on was an effective tool to keep them from screaming. The surgeons, who were mostly barbers by profession, were of necessity forced to be quick and none of the meticulous work done today was possible.

And then came Joseph Priestly who isolated Nitrous oxide in the later half of the seventeenth century. While initially used mainly for entertainment at laughing parties by the aristocracy, its use as an anesthetic agent was first demonstrated by an American dentist named Wells who performed a painless tooth extraction using nitrous oxide. Di- ethyl ether came into its own as an anesthetic agent around the same time. It was introduced as an anesthetic by another dentist named William Clarke. Both nitrous oxide and ether were short lived and chloroform replaced them as it was safer to use.

Over the years, anesthesia evolved from trial and error methods used in those days to the art and science it has evolved into today.

Depending on what type of surgery you are having done, you can be offered two kinds of anesthetics.

General Anesthesia

A general anesthetic as opposed to a regional anesthetic implies that the patient is completely under anesthesia or asleep. All general anesthetics have three stages- Induction, Maintenance and Recovery. In a way, it is quite similar to an airplane taking off, cruising and landing. In fact, anesthetic training has borrowed a lot from pilot training programs using simulators that use software to mimic patient’s responses to various mishaps that can happen during surgery.

In the vast majority of cases, a general anesthetic is induced or started using a drug injected into a vein (intravenous anesthetic agent). It is then maintained by using an inhaled gas or vapor as the anesthetic agent. Most of these gases have a chemical structure similar to ether and have been derived from this grand daddy of all anesthetic agents.

A tube is inserted through the patient’s mouth into the patient’s windpipe after he she has been paralyzed by another drug that owes its origin to a poison used by pygmies to tip their arrows when hunting animals. This tube is connected to an anesthetic machine which acts as a source of anesthetic gas and oxygen breathed by the patient.

Once the surgery is finished, the patient is then woken up or “recovered” by the anesthetist and the recovery nursing staff. During this phase, the anesthetist makes sure that the patient is pain free and is not suffering from any other adverse reactions like nausea or vomiting.

Regional Anesthesia

Regional anesthesia implies that it is only a part of the body that is anesthetized, with the patient either awake or asleep under light sedation(very different from a general anesthetic).

The drugs used to provide regional anesthesia are derived primarily from cocaine, itself derived from coca leaves that were found by the Spanish when they first went to South America. There is a large variety of drugs available (lignocaine, chirocaine, bupivicaine etc) that are used by anesthetists to perform nerve blocks. The drug is injected in close proximity to a major nerve supplying a body part and goes on to block the nerve. This results in a total loss of sensation in that nerve enabling the surgery to proceed with the patient awake.

Two specialized forms of regional anesthesia worth a mention here are spinals and epidurals. These form a subset of regional techniques referred to as “central neuraxial blocks” which is a fancy way of implying that they block all the nerves as they emerge from the spinal cord. Local anesthetics are injected in close proximity to the spinal cord using special needles and techniques.

This results in a loss of sensation from the lower half of the body (approximately below the level at which the injection is given). These techniques are very helpful in providing anesthesia or analgesia for lower limb surgery. They also hold a special place in obstetric anesthesia. The epidural is one of the most popular methods of analgesia for women in labor.

As with all things in medicine, anesthesia comes with its own side effects. The anesthetic gases are a recognized cause of nausea and vomiting in the post operative period. Prolonged ventilation can lead to chest infections, which can sometimes be made worse by stomach contents soiling the lungs which can turn out to be quite serious. Regional anesthesia, which involves injecting drugs in close vicinity of nerves with needles, can obviously cause nerve damage. Spinals and epidurals can cause bad headaches at times. If the local anesthetic drugs are injected into a blood vessel, serious complications can occur. However, these side effects are quite rare and any anesthesiologist worth his salt will try his best to prevent them from happening.

So if indeed you are going to have surgery done, rest assured that you are in safe hands. Having an anesthetic is probably safer than driving a car especially if you have a competent person at the controls.