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Is Anesthesia Safe?

Is Anesthesia Safe?

| On 06, Mar 2013


an-es-the-sia [an-uh s-thee-zhuh] ]


1. Medicinal/ Medical, general or local insensibility, as to pain and other sensation, induced by certain interventions or drugs to permit the performance of surgery or other painful procedures.


We’ve all been to the doctor. Whether it was for a check up or major surgery, if someone has to go under the knife, most people would opt for an operation under anesthesia. Someone could be the toughest OG from the Bronx and yet even he could get ‘soft’ and refuse being conscious while getting his wisdom teeth pulled.  Here are some types of anesthesia:


Local Anesthesia

This is when an anesthetic agent is applied to temporarily numb a particular area of the body. This is usually a small area. The drug is generally injected into the skin. The patient is conscious during application. I’ve had plenty of these at the dentist.


Regional Anesthesia

Regional anesthesia is used to numb up an area of the body, usually the part going under operation. The anesthetic is applied to the nerves that detect sensation in a particular area of the body. It can also be applied to the bloodstream.  Targeting a major nerve can numb up an entire body part as well.


General Anesthesia

This is for the hardcore stuff. General anesthesia means your generally unconscious during the duration of the operation. The cocktail can be administered via an intravenous line (thin plastic tube attached into the vein) or be inhaled through a breathing mask/tube. A tube can also be inserted into the windpipe to maintain proper oxygen levels.


Now these doctors — anesthesiologists, have a tremendous responsibility to properly administer the correct mixture of cocktails according to the patients age, weight, underlying health conditions and many other factors. My advice is, if your going to go under general anesthesia, make sure you approve of the doctor applying it.

One out of every 1000 patients recall moments of awareness while under general anesthesia. The patient’s eyes may be closed but they fully recall the pain and immobility of the procedure.

Now remember, surgeons can only monitor vital signs such as heart rate and blood pressure. They cannot monitor when a patient is conscious.  But a recently new study claims that the brain may produce early warning signals when nearing consciousness. These warning signals were detected by an electroencephalograph (EEG), by recording neural activity through implants of electrodes on the skull.

We’ve known since the 1930s that brain activity changes dramatically with increasing doses of anesthetic, but monitoring a patient’s brain with EEG has never become routine practice.”

Dr. Patrick Purdon of Massachusetts

In the early 1990’s,  an experimental procedure known as the bispectral (BIS) index  was used to monitor brain activity – particularly consciousness. A number (1-100) is calculated from readings of a single electrode. 100 means fully conscious and zero means flatline. Anything between 40-60 is considered the target area of consciousness. Unfortunately this procedure often produced inaccurate measures and inconsistencies. It was in 2011 when Dr. Avidian of the Washington University School of Medicine in St. Louis found that the BIS Index was less successful at preventing awareness during general anesthesia than measuring exhaled anesthesia in the patient’s breath.

One doctor believed he could find the “unconsciousness signature” in the brain. Dr. Purdon of Massachusetts and his team worked with three epileptic patients who received electrode implants in their brain. They were then given an injection of anesthetic propofol and had readings taken from single neurons in the cortex — the area where awareness is thought to reside.  The volunteers were then instructed to press a button whenever they heard a tone recording the activity of their neurons. It took only 40 seconds for the patients to lose consciousness — defined by when the patient failed to press the button. Right before this event, a group of neurons started emitting slow oscillations. The readings didn’t show that the neurons were entirely active however they did show inconsistent brain activity at specific points in the oscillation.

The next procedure was to try to detect the same signature wave externally with an electroencephalograph (EEG). 10 healthy volunteers agreed to go under general anesthesia however the process was slower due to the drug being administered gradually. The process this time took an hour. Every 4 seconds, the volunteers were instructed to press a button in response to words and sounds until they fell unconscious.

The researchers reported yesterday to the Proceedings of the National Academy of Sciences, that EEG readings showed activity analogous to readings from epileptic patients.

“Alpha waves, associated with relaxation and drowsiness, increased with loss of consciousness, as did the even slower, “low-frequency waves.” Both patterns of activity began to decrease with returning consciousness .”

Next time ask for an EEG before you go under.