Total Shoulder, Bad Lungs
NOT MY USUAL STRATEGY
I’ve mentioned elsewhere on this site that I have successfully taken care of many patients with this particular scenario, even those who are ‘oxygen-dependent’. The basic dilemma is whether to offer an interscalene block to someone that may have respiratory embarrassment due to spread to the phrenic nerve, knowing that without a nerve block for an extensive case like this, it may make it hard to get them extubated -and keep them extubated anyway (due to the time on the vent, acute pain, large amounts of opioids, blood loss etc). This is more of an issue if the choice is limited to a single injection nerve block since you will have to guess ahead of time the amount and concentration of local anesthetic you will use. If you do give a bit too much, you are in trouble before the case even starts. If you don’t give enough, your relief is not optimized in intensity or in length. If you do not use ultrasound, you are even more handicapped. That is, without visualization of needle/nerve orientation and local anesthetic spread, your recognition of an appropriate dose is further limited.
In this scenario, some choose to do a supraclavicular block or a block between an interscalene and supraclavicular block (a ‘supra-scalene’ approach). This is a reasonable option. It will still get the axillary nerve and, depending on their technique, the suprascapular nerve (SSN) may get covered adequately (see Regional Anesthesia and Pain Medicine article, May-June 2012, vol 37, number 5, pages 325-8 for interesting insight into determining SSN position). Again, we know going into this scenario that we are not trying to completely eliminate 100% of the pain. We are trying to ‘optimize’ the analgesic options that we do have without running into adverse consequences. This strategy does the best at minimizing phrenic nerve effects and gives us a reasonable chance of covering the all-important SSN. It has one weakness in that it significantly diminishes the chances of covering the superficial cervical plexus, and pain due to the incision may be significant. Coverage of this plexus results from the bolus tracking medially and up to the higher nerve roots. The short-term fix to this is just to add a single injection superficial cervical plexus block (It would be helpful, but a continuous/intermittent catheter would be hard to secure in place, and repeated blocks probably becomes impractical.). A traditional supraclavicular or infraclavicular catheter plus SSN catheter may minimize phrenic palsy more, but this would be equivalent in analgesic coverage.
My usual analgesic strategy to all cases ‘in general’ is to use local anesthetic as the primary agent, mitigating the inflammatory reaction with other agents in the background, and making oral opioids (small IV doses for those that are NPO) available for breakthrough that is not amenable to local anesthetic boluses. Depending on the circumstances, various adjuncts are added, but that is another topic of discussion. When there is pain at the surgical site, I usually look to increasing the local anesthetic infusion or bolus as the first intervention. I try to minimize opioid use as much as possible due to their side-effects which are troublesome and hinder recovery. In this particular scenario, I shift my usual plans.
In this scenario, I will [nonmember]…
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do an ultrasound-guided continuous interscalene block with a small amount (about 5mls) of dilute short-acting local anesthetic and incrementally bolus the catheter. I believe the ‘spread factor’ is less with catheter boluses than with an 18 gauge needle. I add a superficial cervical plexus block with a long-acting local anesthetic to this, and I incrementally bolus the catheter over an extended period of time. Ten to fifteen mls should be adequate and is almost always achievable. This gives me a baseline for my infusion (which will be more or less cut in half) and bolus rate. The change comes in that I will determine a ‘ceiling’ dose of local anesthetics, and I elect to lean more on oral doses of opioids.
These will usually be more elderly patients with additional comorbidities which will additionally guide my therapy. I will be following any trends in subjective symptoms of dyspnea (which will likely precede any decreases in O2 saturation), CXR (for hemidiaphragmatic elevation and atelectasis) in addition to oxygen requirements and saturation. I will also significantly emphasize and follow deep breathing and coughing to the patient and staff. With early doses of less potent opioids before pain escalates (for example, PRIOR to PT, even if not presently in pain), total dosage and side-effects of opioids are minimized. After the first 24 hours as I see how they are responding, I will more readily elect to make opioids scheduled instead of PRN. Additionally, a very low infusion rate (or bolus only) of local anesthetic will minimize spread to the phrenic nerve. Generally, the patient will have the shoulder immobilized most of the time and will have only intermittently painful stimuli from PT at known times, so a low infusion with an adequate bolus strategy is reasonable. I am also more apt to diminish the infusion rate during the hospitalization as inflammation subsides to limit local anesthetic spread over time.
This is a delicate balance between analgesia and side-effects from two different analgesic modes. It requires good patient evaluation of pain and other symptoms on the part of the pain service as well as the nurses attending to the patient. As well, it is important that the other services caring for the patient are aware of the expected effects and side-effects of your continuous block, the balance you are trying to strike and that your service must be notified if there are changes in the status of the patient that might otherwise appear unrelated. This level of acute pain service requires an investment in RN education and a collegial relationship with other attending physicians and associated medical services.
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