Block Evaluation 3

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     I have made a number of observations and recognized a number of patterns over the last several years working with nerve block patients. Here’s another I’d like to share. A point that I’ve made a dozen times in lecturing is that as you change or add techniques or processes, do so methodically and ‘get a feel  for it’ before you move on. This is a pattern that I noticed as I changed from doing total knees with a continuous femoral to doing so with the addition of a single injection sciatic nerve block. (The same pattern also  happened when I added a parasacral block to a fascia iliaca or lumbar plexus block for total hips.) [nonmember]…

 

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 It hadn’t been uncommon to hear a total knee patient complain of pain post-operatively and recognize that it was posterior knee pain. Sometimes it was mild, and other times, it was registered as more intense. It was the same thing for hip patients. Anesthetists would ‘know’ to add some opioid to these cases (when they recognized intra-operative patterns) so that those ‘missed parts’ would be covered. (Actually, at first, they had to learn to give less opioid by far than they had been accustomed to giving.)

     Anyway, once I added the sciatic block, they started giving only the fentanyl for induction and even minimizing that dose. Despite ‘railroad track’ vitals, patients were sometimes responding affirmatively to questions of pain or acting very strange for a while in the PACU. We had gotten accustomed to very short (30 minutes or so) PACU times with these patients, but now PACU times lengthened with some patients.

     Here was the pattern. Patients ‘came alive suddenly’ in the PACU. The RN took this, or even their affirmative responses to the question of pain, as indications of significant discomfort. Accordingly, they would give opioids, and patients would fall asleep again -for significant periods of time. When they awoke again, they reported good analgesia or no pain at all. The problem seemed solved, but they were in the PACU for longer despite theoretically better pain coverage.

     I have to admit that I wasn’t fully aware of this pattern or the extended PACU stays at first. I’m always running around, and my perception of the time frames in PACU do not always occur to me. When RN’s told me about it, I figured it was a reaction to the tourniquet pain (Surely it wasn’t a failed block!?!). I saw the unexpected behavior for myself a few times and inquired to a few patients about their perception of ‘all that difficulty’ when they first woke up. They had no recollection of it. None of them remembered. The anesthesia records demonstrated no reaction to surgical stimulation throughout the cases, and they weren’t giving opioids. It appeared that they were leaving the gas on pretty high (relatively, though still much less than a MAC) until the case was completely over.

     So here’s what I came up with on these cases. I believe they were experiencing a ‘complete gas wake up’ instead of a wake up tempered by the typical slow and unconcerned appearance of a patient that received a moderate dose of opioids, an ‘opioid wake up’. They were awakening, still with a reasonable amount of gas on board, into a disorienting experience in a new environment that likely would’ve occurred later on had opioids been on board (and more gas had been breathed off). This confusing experience (though not remembered) along with specific questioning quickly lead to a relatively high dose of opioids, a long nap and a slow wake up later on. Granted, patients emerging from a high opioid or balanced anesthetic sometimes do not remember their ‘first wake-up’, but they are usually not so delirious, confused and animated.

     Once this experience was accounted for, we made some adjustments. First, anesthetists turn the gas down sooner and will sometimes give short-acting opioids if the signs of tourniquet pain begin to show toward the end of the case. They aim to get them awake earlier and assess them in the finals moments of the case. Further, RN’s in the PACU are aware of this phenomenon and do not react so quickly by giving opioids when it occurs. Or if they do, it is with short-acting opioids and smaller doses. Issue addressed. System tweeked. Problem solved.

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