Warning - deep stuff - for med students etc.
General Anesthesia & Children
That was a lot of hard stuff, all that chemistry. But what it all boils down to is that solvents or gasses which dissolve in fat or oil - make good anesthetic agents - providing that they don't sludge up the circulation (can't use butter, or Krisco).
OK, given that commonality, what does "going to sleep" by anesthesia look like? How does it behave?
Stage I :There are three stages to anesthesia. The first stage can be called the goofy stage, in that the person isn't actually unconscious. Weak anesthesia agents may hover in this zone near full consciousness and merely tweak at inhibitions. Hence, laughing gas. A person may act silly.
But for sure, kids will grab at the face mask with great precision and effectiveness as stage two is approached. But even for stage I anesthesia, the arms need to be held to prevent grabbing at the mask or from folding and blocking IV flow. When stage I is used for small procedures to assist local anesthetics, drugs which block memory can be given. The youngster will not recall anything even though fully conversant. Another method is described below.
Stage II : This is the one parents freak at. It is called the excitement stage. In the excitement stage consciousness is gone aand the reactions to be described are not remembered. Amnestic drugs are not required. There is no perception and no memory. But there is undirected aggitation or arching struggle. It looks alot like something going wrong.
Anesthesiologists don't want to linger in this troublesome zone. That is why they try to speed through stage II. Getting a poor delivery of gas or med can trap one in stage II.
Stage III : This is what everybody calls "anesthesia". Stage three is the common conception of anesthesia. In stage III, there is no consciousness, but breathing is spontaneous and heart rate pretty much unaltered. Muscles have tone.
However, as the concentration of gasses or intravenous agent increases the control of breathing gets lost and is taken over by the anesthesiologist. This requires a good airway without obstruction.
As breathing uses muscle power, in order to get the kind of "muscle relaxation" that is required by certain types of surgery, the depth of anesthesia must be deep. How deep? Depends.
For certain orthopedic work, the tone of muscles is desired in as near to awake state as possible . But for other work, muscle tension makes the job impossible. Muscle tension is tailored to the job at hand.
Well parents frequently ask that their child only get light anesthesia. That sounds so much safer than deep anesthesia. Ooooo. Deep. It isn't. In fact, hovering in stage II can be down right dangerous.
So we are either mildly sedating and using local anesthetics or we are going to stage III.
Past stage III is the stage we don't speak about. Things stop. Can't go there. The art is a fast trip through stage II into stage III without skidding into stage four.
Because the anesthesiologist is in control going past stage II typically is just a few moments of "it's OK, she'll relax in just a moment".. then nice. But waking up is another issue. As anesthetic agents leave the body, those same stages occur in reverse, but NOT with any special tricks to zoom past stage II. The recovery room is a study of weird acting patients, crying out or flailing excitedly. That's stage II.
The excitement actually wakes the kids up somewhat. When the excitement passes they then (no longer excited) fall back asleep ala stage I with real snoring and curling up sleeping postures of bed time. Restated, they wake up twice. First they wake up in a tizzy. They fall back asleep then wake up calmly and have no recollection of the first wake up.
But there are always tricks. Pain - from the procedure - may stimulate the onset of stage II from stage III and sustain stage II longer. Emergence drugs are often used to get folks over this rough spot. Local anesthetics and narcotics are common methods for avoiding this wild phase.
Caudal anesthetics, by blocking all pain, often allow a morning-like wake up with no struggle at all. Even so, when the caudal is discontinued, pain will be experienced. It just isn't happening during stage II excitement.
Caudal anesthesia makes for great wake up experience but pretty much guarantees that the patient will not be able to urinate spontaneously until it is discontinued. So, Foley catheters go with caudal anesthesia.
Another issue, is that the body adapts to the thing causing pain. This happens in the brain. Delaying the experience of pain may also delay the adaptive process to pain. So, long drip caudal protocols might actually delay the ability to switch to oral or lesser medications which allow going home.
Strange but true stuff :