1.10 General Anesthsia (definition, principles, types and Indications)

1. What is general anesthesia (the 4)?
2. What are its principles (the 4)?
3. What are its types (the 4)?
4. And indications for each of them.

So lets start with the first one.

The 4 requirements of general anesthesia are:

1. Hypnosis or Anesthesia (meaning unconciousness)
2. Amnesia (the person forgets these events)
3. Analgesia (the person shouldn't feel pain)
4. Immobility (the person shouldn't move)

These can be memorized by the hook: As a person is given general anesthesia and you say to them Hi!, they respond by Haai! and they dose off.

Next, are the 4 principles of general anesthesia:

There is a pre-op anesthetic visit where the anesthetic history is taken.

1. The first step is pre-medications in the evening before and in the morning. Nothing per os 6 hours before.
2. The next step is the induction of anesthesia. first step is the iv line, then monitors are also attached, then propofol for induction, then opoids for analgesia, then muscle relaxants and then intubation.
3. Then there is the maintainance phase where generally inhaled anesthetics are used.
4. Lastly, there is the bringing the patient out of anesthesia. Wait for the 3 Rs to restore: Regain conciousness, Regain muscle tone and Regain reflexes.

At the end, there is a one hour monitoring period in the ICU. That's it.

Now, lets talk about the 4 types of general anesthetics

1. Inhaled: Non halogenated include Nitrous Oxide. Halogenated include Sevoflurane, Desflurane etc.
2. TIVA (total intra venous anesthesia): these can include propofol (widely used), Thiopental (Barbiturate), Etiomadate and Ketamine (the patient looks awake but isn't).
3. Balanced: most common. Both the intravenous and inhaled are used.
4. Combined: General Anesthesia + Specific (eg. general anesthesia and epidural for a major abdominal surgery).