Now that I'm verified and all.... I can give you a little bit of info without getting a timeout

this is a throwback to multiple posts on page 6.
"Induced comas"
Personally, I hate the term medically induced coma, because it sounds so dire - and you can be kept sedated, intubated and ventilated from something a simple as a dental abscess - because there is the possibility of swelling obstructing the airway.
Any time a person is placed under general anaesthetic they are placed in a medically induced coma. You are intubated, however briefly, and sedated for the duration of the operation.
Its very dramatic wording within the psyche - coma brings images of brain death and loss of all hope.
I recall caring for a patient who had come in for elective day surgery. She had an allergic reaction to the prophylactic antibiotic dose given intraoperatively. Anaphylaxis at home is a serious issue. Anaphylaxis in an operating theatre isn't anywhere near as bad. It's actually the best place to do it. How lucky are you that you first discover a serious allergy in an operating theatre - rather than at home alone when you're sick with a chest infection and you take the first dose of an antibiotic your GP prescribed!!!
You have an anaethesist in the room with you - the well trained gods of advanced life support. They have adrenaline on hand - not because anaphylaxis is common, but because it's also used to treat hypotension due to sedation and/or hypovolemia (blood loss) which are both common in surgery. They have all the drugs. And the reason why anaphylaxis is fatal is because you lose your airway - but guess what ? They had already put one in, right after you drifted off to sleep with a face mask on , counting backwards from 100. The operation will continue. There is no reason why it shouldn't. (Throwing back to an earlier post - this person would have been described as "serious but stable" - the anaphylaxis was a serious and unforeseen occurance, but clinically managed)
Even though the reaction had been handled, we kept her in ICU for the night, and kept the tube in - just in case their was a recurrent reaction.
I have empathy for the fact that this was a scary experience for her - but she really clung to the term "medically induced coma" - and proceeded to text all her family members and friends that statement when we took the tube out less than 24 hours later.
What that meant was that the phone rang off the hook - I'm not kidding - 49 phone calls in three hours. She was the "well-est" patient by a long shot, in all of ICU and HDU - but monopolised resources (ie nursing time) that other patients needed.
An "induced coma" is most often done for what we call "tube tolerance" - it is very difficult for the body to accept volumes, oxygenation, and the rate during mechanical ventilation. There are a variety of different "modes" of ventilation that we tweak based on a patients requirements, in including allowing them to initiate their own breath ( rate ) but providing pressure support or peep to ensure adequate volumes exist in the lungs for gas exchange. The modes are determined by CNS functioning (and this is influenced by level of sedation) as well as respiratory functioning.
Whether through an nasal/endo-tracheal tube (NTT/ETT) or tracheostomy it's unnatural and uncomfortable. Based on the injuries - like rib fractures resulting in a flail segment, chest expansion can be painful for the patient. Someone with multi-organ failure is likely to accumulate fluid in the lungs (APO)- and if they were not intubated, would be breathing rapidly but very shallowly as to not disrupt the fluid bubbling away there - and yet we are forcing expansion - making them cough uncontrollably.
The existence of the tube bypassing the gag reflex is uncomfortable on its own.
We have various levels of sedation, and different sedation drugs available, based on what is wrong with them, and what they need.
The tube has a "cuff" which is inflated to create a seal of the airway, so we can control PEEP and volume. It's a natural reflex to try to pull it out. The trouble is, if the cuff is still up, the pulling out of the tube creates trauma - resulting in bleeding (which enters the lungs) and swelling (which closes off the airway. If a patient manages to pull out their tube - and aggravate their airway, we don't have a lot of recourse available to save them - regardless if how fit and healthy they may be.
Some patients can tolerate a tube while awake. Not many. Mostly those who were expecting it - like a submandibular abscess or epiglottitis. Even then, there is still a risk, that while they are asleep they may try to self extubate - logically they know they shouldn't - but the sleepy brain just wants that thing OUT and doesn't contemplate the consequences.
Typical drugs for sedation used are propofol(the white stuff) either on its own or in a combination of that, fentanyl, midazolam, and precedex (a paralytic). Sometimes we will use ketamine too - because it has a side effect of creating a sort of fugue state - where if traumatic and painful interventions need to take place, the person is not likely to remember it. It's not as common, but very useful for burns patients, who in the early days we scrape down that ravaged flesh on a daily basis to change the dressings and get them on the path towards healing. Burns dressings take hours, and a person on the maximum possible levels of sedation can still wake up during them simply due to the sheer amount of pain we are causing.
We often "wake the patient" by turning off all sedation for as long as it takes to accurately asses neurological functioning. How frequently this is is a risk assessment based on the patient's condition - as the sedation can be aiding in their recovery - it's not all just about the tube! (But the tube always comes first).
There are serious risks caused by prolonged mechanical ventilation - especially VAP (ventilator acquired pneumonia) and so the aim for everyone is to get the tube out as soon as it is possible from a respiratory and central nervous system standpoint.
The drugs we use to sedate people also have an effect on heart rate and blood pressure, which can assist in taking the load off the body - preventing hypertension and tachycardia - which are common during illness and injury so we can protect to a certain extent the heart and kidneys.
Extubation (taking the tube out) can occur only when the person is capable of protecting their own airway. We normally require someone to be able to poke their tongue out and cough on demand (neurological functioning - capacity to obey commands, and ability to protect their own airway) as well as their respiratory capacity to maintain oxygenation.
It's a process that can be fast or slow, that we call wake and wean.
Sedation is gradually decreased, and ventilation parameters scaled down, all the while assessing oxygenation status with arterial blood gasses.
It depends what is wrong with the patient as to how long this takes.
A wake and wean post op - like the lady I mentioned above -is quite simple. She had come in during the afternoon. At midnight, her sedation was turned off. She was groggy but able to obey commands - and tolerated the tube fine The ventilation was switched over so she was basically doing it all herself. A blood gas confirmed it. A laryngoscope showed no residual swelling. Handover on an early shift takes about 15 minutes. I tested her. I got one of our registrars to test her too - he was happy - and viola - she was extubated by 7:35am. And immediately her condition was "good". She went to an ordinary ward not long after.
Some people can take months. Some may never be able to obtain adequate oxygenation on their own (certain traumas like spinal) and will have a ventilator for the rest of their life.
Some people are weaned - are on the mend - and then a sepsis or a VAP makes them deteriorate, and we need to tube them for a second time.
Here is a fast one minute summary of how an emergency intubation goes down. (It's designed as a refresher for rural doctors who know the skill but haven't needed to do it for years.)
[ame="http://www.youtube.com/watch?v=NztDqYlED4M"]JAMIT RSI - YouTube[/ame]
I'll do a little post on trauma and head injuries in general a little later on.
Hope this helps.