Balanced Anesthesia Achieved by Combining Anesthesia Agents

About the Author

TahoeDoc is a board-certified, physician anesthesiologist with more than a dozen years experience in the field. Although the author is a physician, this article is not dispensing medical advice; it is for informational purposes only.
TahoeDoc is a board-certified, physician anesthesiologist with more than a dozen years experience in the field. Although the author is a physician, this article is not dispensing medical advice; it is for informational purposes only. | Source

What is Balanced Anesthesia?

General anesthesia renders you unconscious and unable to feel or respond to the operation. In fact, that is the definition of general anesthesia. There are several major goals of general anesthesia. It goes without saying that the anesthesiologists' job is to provide these (or as many as possible) while keeping the patient alive and safe. During general anesthesia, several goals are accomplished by the induction of unconsciousness. Among the goals of an anesthetic are:

  • Anesthesia- Inability to feel pain
  • Amnesia- lack of memory of the events
  • Immobility- no voluntary or involuntary movement (important for surgical precision)

Obviously, strong medications must be used to induce such a dramatic change in the human body. All medications have side effects, which are usually worse with increasing amounts of the drug.

In order to achieve all of the above goals of anesthesia AND minimize the side effects of using large doses of a medication, "balanced anesthesia" is given. This refers to the practice of using smaller doses of many different kinds of medication rather than higher doses of fewer medicines.

Balanced Anesthesia Medications

Each general anesthetic involves the use of many different medications. This allows all of the goals of anesthesia to be met, while minimizing the side effects of each medicine. This is the approach of 'balanced anesthesia'.
Each general anesthetic involves the use of many different medications. This allows all of the goals of anesthesia to be met, while minimizing the side effects of each medicine. This is the approach of 'balanced anesthesia'. | Source
Providing anesthesia while keeping the patient safe is the job of the anesthesiologist.
Providing anesthesia while keeping the patient safe is the job of the anesthesiologist. | Source

Anesthesia Induction - Example

Anesthesia Agents Used in Balanced Anesthesia

General anesthesia can be divided into 3 main phases, the induction, the maintenance and the emergence phase. Different medications may be used in these phases to achieve the desired goals, although there may be significant overlap.

The "going to sleep" phase is called induction. Medications that induce amnesia include midazolam (often given as a premedication), before even going to the operating room.

Induction:

During induction, the goal is to achieve a state of unconsciousness, maintain hemodynamic (heart, blood pressure, etc) stability and allow the placement of a breathing tube (ETT) or other breathing device. This last task requires a state of 'sleep' deep enough (really, unconsciousness) that normal reflexes like cough and gag are suppressed. It takes very strong drugs to achieve this. A combination of a narcotic pain medicine, a hypnotic/sedative and muscle relaxants (paralytics) are used so that this can be done while maintaining adequate vital signs without the patient reacting (by reflex) to this procedure. Oxygen is a component of every phase of anesthesia.

There is significant variability in the induction sequence for general anesthesia. Which drugs are actually used changes from case to case and is determined by the procedure, the type of airway device used (endotracheal tube vs. laryngeal mask airway-LMA), the medical condition of the patient and the anesthesiologist's preference. If the goals of anesthesia are achieved, there is no right or wrong way to induce the anesthesia.

In the O.R., a common sequence of medicine given into the intravenous line (IV) might include any combination of the following (or others):

Induction Agent
Action
Anesthesia Goal
fentanyl
narcotic pain medication
analgesia/anesthesia
lidocaine
adjunctive agent to prevent burning from propofol, but has some sedative and airway-calming action
hypnosis
propofol
hypnotic agent
unconsciousness
succinylcholine
fast-acting muscle relaxant to facilitate endotracheal tube placement
immobility
 
 
 
These are examples of medications that can be used during the induction of anesthesia. Some anesthesiologists may use only a hypnotic agent, then add other medicines as needed based on the individual. There are many combinations that are equally acce

Maintenance:

The goal of the maintenance phase is to keep the patient unconscious, pain-free, with good muscle relaxation (paralysis) while also ensuring that he or she is safe and stable.

The anesthesia gases provide unconsciousness and have pain-fighting properties. By themselves, however, they have the capacity to slow the heart rate and lower the blood-pressure too much. So, the concentration of the gas can be decreased and narcotic pain medications can be used during this phase to block pain receptors. If the narcotics were used alone, they are good pain blockers, but don't have reliable ability to ensure amnesia or unconsciousness. Neither of those classes of drugs can give enough muscle relaxation to provide good conditions for the surgeon to operate in some cases. A muscle relaxant only paralyzes the muscles and does not induce unconsciousness or provide pain relief.

So, a narcotic pain medicine, an anesthesia gas and muscle relaxant may be combined. In this way, the goals are met by balancing the best qualities of each medicine while minimizing the side effects of each. This is just one simplified example of how the anesthesia drugs may be combined to provide balanced anesthesia.

Maintenance Agent
Type of Medication
Primary Function
Sevoflurane, Desflurane, Isoflurane
Anesthesia gas
Unconsciousness
Fentanyl, Morphine, Diluadid, Demerol
Narcotic Pain Medication
Pain Prevention
Rocuronium, Vecuronium, Mivacurium
Muscle Relaxant/Paralytic
Immobility, Relaxation of muscles for better surgical conditions
Nitrous oxide
Anesthesia gas
Added to other gases to decrease amount of them used
Propofol
Hypnotic
Unconsciousness
This table is by no means a comprehensive list of all the medications that could or should be used during a balanced anesthetic. This is an example of medications available for combination.

Emergence:

During emergence, the anesthesia gas or other hypnotic agent is stopped so the patient can awaken. Some anesthesia agents have reversal agents that may or may not need to be used. Most just wear off with time, though. More pain medicine or anti-nausea medicine may be given at this time. Oxygen is supplied during the awakening phase, as well.

Source

Final Thoughts

Each stage of anesthesia has specific goals. Balanced anesthesia can be used from the induction, through the maintenance and during emergence to make the anesthetic as safe and effective as possible.

Your anesthesia provider will be monitoring your vital signs continuously during your general anesthetic. Heart rate, heart rhythm, blood pressure, oxygen level, breathing and other indicators are used to decide what medications should be throughout your operation. The selection of medications during each phase is influenced by your particular needs and reactions to the medicines and even the surgical procedure. It is the years of training that an anesthesiologist goes through that gives him or her the experience to make these decisions.

Were you aware that so many medications could be combined for general anesthesia

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Comments 3 comments

AliciaC profile image

AliciaC 4 years ago from British Columbia, Canada

Thank you for an interesting and very informative hub. I appreciate the details about some of the different medications used in anesthesia.


Dolphan5 profile image

Dolphan5 4 years ago from Warwick R.I

Way to go Doc! Had some idea,but didn't know the details. Thanks again for the enlightenment.

I think if I ever need surgery I'm coming to see you!

Thanks again!

Voted thumbs up,useful and interesting!

Ciao!


TahoeDoc profile image

TahoeDoc 4 years ago from Lake Tahoe, California Author

Thanks both of you for checking out this hub and taking the time to comment. :)

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