OPA/NPA trauma question

[Tigger]

Yes. Talking about this sort of stuff is fascinating. They nearly dragged me from the OR. So many questions.

 

[Carlos Danger]

This is a naive question, but I never entirely understood the role of opioids (fentanyl, dilaudid, etc) in general anesthesia. (I'm in a surgical ICU now and dealing with it daily.) Is the idea that to bring make them totally insensate would require far deeper anesthesia than if you combined sedation with analgesia? In other words, opioids (or epidurals, regional blocks, local, whatever) are sedation-sparing?

Good question, Brandon.

As you know, pain is more than just a feeling of discomfort. It is a complex phenomenon that has many physical and psychological effects. The feeling of pain is just the tip of the iceberg - just a symptom of the underlying processes. Think of pain as a physical stimulus that affects the physiology like any other potent physical stimulus, like an infection or exposure to an environmental extreme. It directly affects all the major hormonal pathways - most notably the sympathetic and the RAAS and the hematologic, and in turn everything that they affect. And as you can imagine, the stimulus of surgery can be really profound, depending on the specific case. The bigger the surgery and the more tissue damage that results, the more nociceptors are activated and the more problems result.

So, any general anesthetic (volatile anesthetic gas, propofol, large doses of a benzo or a barb) will essentially turn off the higher CNS and abolish the awareness of pain, but it won't do much to prevent the other physiologic effects of the painful stimulus, at least not unless you use such high doses that you start to cause other sorts of problems. That's where opioids come in. Opioids block the painful stimulus from being transmitted to the spinal cord where that stimulus would travel to second-order neurons and alert the rest of the body that it needs to react. Fentanyl is like a linebacker that stuffs the running back before he can make a down.

Also, poorly managed acute pain - even pain that the patient isn't aware of because they are asleep - can set a patient up for a tougher post op experience, even precipitating chronic pain in susceptible individuals. A couple small doses of fentanyl given at the right time during the case can avoid several mg's of dilaudid post op and potentially even refills of percocet. This is called sensitization and "wind up" (technically different things, but conceptually very similar), and it has to do with changes in the afferent neurons that are related to the effects of neurotransmitter over-exposure and possibly partly due to tolerance that develops to endogenous opioids. Chronic pain gets really complex.

Opioids are also used for purely practical reasons that have nothing to do with pain per se, like controlling tachycardia and blunting sympathetic discharge in fragile patients and keeping your patient with restless leg syndrome's feet still during a podiatric procedure (happened to me just yesterday), and smoothing out wake ups, especially in young patients and folks who seem psychologically predisposed to waking up disoriented and combative.

Opioids have downsides too, of course, which is why we generally try to limit them and use as little as we can get away with. In many cases regional anesthesia can be used to completely block the pain response while avoiding all the negative effects of opioids. In the SICU, I suspect you'll notice a big difference, for instance, in the early post-op course of a patient who had a big bowel resection or a thoracotomy with an epidural vs. someone who had the same procedure done with a bunch of narcotic.

Esmolol has some really interesting properties related to all this stuff, too. I use it a fair amount in lieu of fentanyl, more and more as I gain experience and confidence in my technique, actually. It does more than just lower the heart rate, it seems to actually block much of the negative effects of a painful stimulus in a manner similar to the opioids. There's a fair amount of research that supports it, though the mechanism is still unclear.

 

[Brandon O]

Brilliant! Fascinating stuff.

 

[jwk]

It can be. Healthy, non obese patients usually do fine as long as they aren't too narcotized. You just have to learn how to time things and how much of each agent to use.

Ah, the ART of anesthesia. Procedures are the easy part.

 

[jwk]

Good question, Brandon.

As you know, pain is more than just a feeling of discomfort. It is a complex phenomenon that has many physical and psychological effects. The feeling of pain is just the tip of the iceberg - just a symptom of the underlying processes. Think of pain as a physical stimulus that affects the physiology like any other potent physical stimulus, like an infection or exposure to an environmental extreme. It directly affects all the major hormonal pathways - most notably the sympathetic and the RAAS and the hematologic, and in turn everything that they affect. And as you can imagine, the stimulus of surgery can be really profound, depending on the specific case. The bigger the surgery and the more tissue damage that results, the more nociceptors are activated and the more problems result.

So, any general anesthetic (volatile anesthetic gas, propofol, large doses of a benzo or a barb) will essentially turn off the higher CNS and abolish the awareness of pain, but it won't do much to prevent the other physiologic effects of the painful stimulus, at least not unless you use such high doses that you start to cause other sorts of problems. That's where opioids come in. Opioids block the painful stimulus from being transmitted to the spinal cord where that stimulus would travel to second-order neurons and alert the rest of the body that it needs to react. Fentanyl is like a linebacker that stuffs the running back before he can make a down.

Also, poorly managed acute pain - even pain that the patient isn't aware of because they are asleep - can set a patient up for a tougher post op experience, even precipitating chronic pain in susceptible individuals. A couple small doses of fentanyl given at the right time during the case can avoid several mg's of dilaudid post op and potentially even refills of percocet. This is called sensitization and "wind up" (technically different things, but conceptually very similar), and it has to do with changes in the afferent neurons that are related to the effects of neurotransmitter over-exposure and possibly partly due to tolerance that develops to endogenous opioids. Chronic pain gets really complex.

Opioids are also used for purely practical reasons that have nothing to do with pain per se, like controlling tachycardia and blunting sympathetic discharge in fragile patients and keeping your patient with restless leg syndrome's feet still during a podiatric procedure (happened to me just yesterday), and smoothing out wake ups, especially in young patients and folks who seem psychologically predisposed to waking up disoriented and combative.

Opioids have downsides too, of course, which is why we generally try to limit them and use as little as we can get away with. In many cases regional anesthesia can be used to completely block the pain response while avoiding all the negative effects of opioids. In the SICU, I suspect you'll notice a big difference, for instance, in the early post-op course of a patient who had a big bowel resection or a thoracotomy with an epidural vs. someone who had the same procedure done with a bunch of narcotic.

Esmolol has some really interesting properties related to all this stuff, too. I use it a fair amount in lieu of fentanyl, more and more as I gain experience and confidence in my technique, actually. It does more than just lower the heart rate, it seems to actually block much of the negative effects of a painful stimulus in a manner similar to the opioids. There's a fair amount of research that supports it, though the mechanism is still unclear.

I'm sure you're doing as much multi-modal stuff as we are. Funny - in the 80's when I started out, we called it "balanced anesthesia". Now it's "multi-modal", just a different word for using a little of this and a little of that and not a lot of anything. We do a lot of fairly big cases with zero narcotics, especially if we're able to do a block or other type of regional anesthetic. We're doing total knees/hips with spinals as outpatient procedures - they go home about 6-8 hours post-op. They get many different drugs along the way - lyrica, celebrex, ketamine, dexamethasone, IV tylenol, and toradol, but hopefully no narcotics. They do surprisingly well.

 

[Carlos Danger]

I'm sure you're doing as much multi-modal stuff as we are. Funny - in the 80's when I started out, we called it "balanced anesthesia". Now it's "multi-modal", just a different word for using a little of this and a little of that and not a lot of anything. We do a lot of fairly big cases with zero narcotics, especially if we're able to do a block or other type of regional anesthetic. We're doing total knees/hips with spinals as outpatient procedures - they go home about 6-8 hours post-op. They get many different drugs along the way - lyrica, celebrex, ketamine, dexamethasone, IV tylenol, and toradol, but hopefully no narcotics. They do surprisingly well.

That's cool. I assume these patients are "awake" for the total joints?

 

[SpecialK]

I don't see a problem using an LMA (or for that matter, an OPA or NPA) in the situation described. Lacerations to the tongue or mouth shouldn't bleed that much but in the circumstance bleeding is significant I'd turn the patient on their side, suction their mouth and use an NPA if they needed an airway adjunct.

Laryngeal masks are cheap, easy to insert, have little risk, allow for "hands-free" ventilation and can be used by all levels of ambulance personnel. I've personally only had good results with them

 

[meatanchor]

Question: It appears that the NPA has become the BLS airway adjunct of choice for military and TCCC programs. Is this because it can be theoretically be tolerated by patients with an intact gag reflex? Also, I notice that most of individual first aid kits I've seen LEOs and military folks carry do not include a lube packet. Are people taught to insert these dry?

 

[Jim37F]

Yeah as far as the military is considered, facial and head trauma is not considered a contraindication for NPA, we were taught to use the patient's saliva to lube it up if you don't have a petroleum jelly pack.

 

[jwk]

That's cool. I assume these patients are "awake" for the total joints?

A little background propofol infusion so they don't hear the drills and saws.

 

[SpecialK]

Many procedures once only performed using traditional general anaesthesia are now done with a combination of any, or all, of regional blockade, local anaesthetic infiltration (lignocaine or similar) and a little bit of sedation (midazolam or similar).

Probably the best example is cesarian section, but I've seen intramedullary nails for fractured femurs, arthroscopies, appendectomies, nerve decompressions, wrist and hand ORIFs and others all done with the patient awake.