Tuesday, February 17, 2009

Comparing two anesthetic techniques: sciatic-femoral nerve block and regional spinal anesthesia

I reviewed an article from a recent issue of the Journal of Clinical Anesthesia. This journal is very interesting to me and includes reviews of different methods, case studies, and other physiological experiments with anesthesia. The purpose of this study was to determine which of the two anesthetic methods worked more efficiently and effectively for outpatient knee arthroscopy. This practice was done as an ambulatory surgical procedure, which means that the patient will go home the same day as the surgery barring any unseen complications. The two methods studied were a peripheral nerve block to the sciatic-femoral nerve and regional spinal anesthesia. Arthroscopic knee surgeries are very common today, and it would be interesting to know if one method worked quicker because then outpatient knee surgery centers could possibly get more surgeries done in one day, thus making more money. On the other side of the coin, patient satisfaction is equally as important. Another question that was asked was whether or not the patient would have the same anesthesia practice conducted again if they were to have surgery again. A randomized survey was conducted to determine if a combined sciatic-femoral nerve block allows the patient to be discharged quicker than a spinal anesthesia technique.

Without having any knowledge about anesthesia besides what I have purely observed, I decided to do research on the two techniques, because detailed information was not included in the article. The combined sciatic-femoral nerve block is exactly what it sounds like. It is a combination of two nerve blocks on each the sciatic and femoral nerves, which will numb the lower extremities of the body. It was noted that few surgeries can be performed with just a sciatic nerve block, but with the combination of the femoral nerve block patients do not endure as much postoperative pain. Also of note that some administrators of the anesthetic have had trouble with this technique, but I do not actually know how difficult this block is to perform. Some of the websites I came across gave pretty in depth instructions on how to perform this procedure. The other technique used was a spinal anesthesia procedure which involves injection of the anesthetic bupivacaine, although others are used as well. This technique allows for surgery to occur with no pain in the area of choice. If the technique is done the right way, some surgeries can be performed with the patient wide awake. It seems to me that this procedure is done for a good amount of surgeries on the lower half of the body as well, just like the sciatic-femoral nerve block. The spinal anesthesia procedure allows for surgeries on the abdomen, hernias, and caesarian sections as well as others. One of the difficulties with this procedure is that it may not be as comfortable, and the right amount of anesthetic has to be used because if too much is used the diaphragm can be affected, seriously complicating breathing.

Fifty patients were studied with twenty five of them receiving the spinal anesthesia regional technique, and twenty four of them receiving the sciatic-femoral anesthesia procedure. One patient was not included in the sciatic-femoral nerve block group because of failure of the regional technique, so he was not included. There was not a statistically significant difference in the total operating room time, duration of surgery, or surgical preparation time between the groups. The combined sciatic-femoral nerve block took on average six minutes longer to perform. The groups did not differ in pain determined by a visual analog scale assessment every fifteen minutes until the patient was discharged from the hospital. The most important aspect is that all patients reported that they would have the same anesthesia procedure performed if needed in a future operation.

I do not think hospitals or ambulatory surgery centers should consider one procedure over another because they think is faster, because this study shows that there really isn’t a huge difference, if any. Patient care, safety and satisfaction are always primary concerns for any surgery. I found it interesting that each of the groups said that they would have the same exact anesthesia technique performed if need be, without knowing if the other procedure would be more comfortable or not. Future studies should include patients that have had both types of procedures performed, to see which one seemed more comforting to them. This study seems like it would not be hard to perform, and could be very informative. I learned a lot from this study, and learned even more in doing my own research on the two techniques. It is very interesting to me how many different types of anesthesia there are, and how they act physiologically on a person’s body before, during, and after surgery.


  1. So is there any advantage at all to the more specific nerve blocker? If the more general / regional anesthesia works just as well and wears off just as quick, then why have a more specific technique at all? This is especially true if both sets of patients are equally satisfied. Maybe you (or the journal) mentioned some specific benefit to the more specific nerve blocker, but it wasn't clear to me.

  2. It somewhat goes back to our "placebo" argument. The journal clearly looked at the situation as if a)which one was quicker and b)what did the patient think. They found they took approximately the same amount of time, and that the patients would have the same type of anesthesia again if the same surgery was needed. The more specific nerve blocker is just for a certain area of surgical area. Some techniques are easier to do as well, as I mentioned in the review. What is not clear to you? I thought I did a relatively good job of reviewing that article...

  3. You would be correct to say that the next step needs to ask people, who have had both anesthetic techniques done, which one they like better. I think the problem would be that if a procedure worked for the patient (which they all say it did) for the first time, then wouldn't they want that procedure the next time (since they know it works well). Also, I don't know much about the procedure, but is it common for people to have more than one of these done? If so, that might be an important factor.

    I guess most of the decision is based on personal preference as well. My grandmother has had double knee replacement surgery and has two different knee caps. This was because two different doctors worked at the same time and each had their own preference.

    Overall I think this is a good review. I don't remember much from the A&P days, but I feel like I had a good understanding as to what you were talking about.

  4. It is quite interesting, like you noted, that all people asked if they would get the same anesthetic technique performed again if need be, said that they would.

    However, I think this is hardly an unexpected result as it is commonly known that people will always fear the unknown. What is known to these people is that they recently had a procedure done and, becuase of whatever anesthetic treament they recieved, felt what they determined to be an acceptable amount of pain. What is not known to them is whether the alternate anesthetic technique would work as well.

    Also, another somewhat related note...
    My mother works as an RN where she helps in different surgeries. I just remember once she brought home a video of someone getting a knee replacement operation. It was really fascinating to watch how the surgeons used saws and hammers in addition to the surgical instruments most people are familiar with from watching various medical shows.

  5. We did a virtual knee replacement surgery in my A&P class in high school! I don't think I could handle the real thing...

  6. It's not clear to me that there is any reason to have a specific nerve blocking technique, unless it is easier to do. If it's easier to do, then that explains it. I just wasn't sure of that based on your write-up.

  7. "The purpose of this study was to determine which of the two anesthetic methods worked more efficiently and effectively for outpatient knee arthroscopy." How is that unclear?

  8. The premise is not unclear. The conclusion is. If both methods are equally efficient and comfortable, then why do the nerve blocker? If the general technique works why should the nerve blocker still be tried? In what cases is it better? Or is it just cheaper / easier?