ASRA Pain Medicine Update

Perioperative regional nerve blockade has become a staple of anesthetic practice, particularly in academic centers and orthopedic surgical centers. Short-term benefits, such as improved pain control and decreased opioid use, are clinically apparent to many anesthesiologists and well-supported by the evidence.^[1] Less obvious are the long-term benefits to the patient, the surgeon, and the health system. The continual quest for improvement using patient-centered outcome measures ought to remain the main driver of current and future practice. However, as we move from a fee-for-service to bundled payment reimbursement model, there will continue to be pressure for anesthesiologists to demonstrate the value provided by regional anesthetic procedures and the resources needed to support them.^[2]

It is our responsibility to continue to advocate for regional anesthesia when it is in the best interest of our patients.

So why is it that the short-term benefits of regional anesthetics do not always translate into demonstrable long-term improvements months later? What long-term outcome measures are important? Studies evaluating outcomes months after surgery largely focus on development of persistent pain and ongoing opioid consumption. Such inquiry is important but can be fraught with confounders and may not fully highlight all the benefits to be realized through use of regional techniques. The full story may be better told by also examining effects on a broader range of outcomes, such as postoperative cognitive function in vulnerable populations, cancer recurrence, cost, OR utilization and patient satisfaction.^[2],[3] Furthermore, a careful reading of the evidence may suggest that a more selective application of continuous peripheral nerve catheters (cPNC) is needed. Strategic development of appropriate clinical pathways for cPNCs may help maximize their benefits and demonstrate the advantages many regionalists observe clinically. 

There Are Hidden Benefits

The first challenge is that regional procedures offer several “hidden” benefits that are inherently difficult to quantify. These pertain to cost savings to the health system and mitigation of patient-specific anesthetic risks. For example, potential avoidance of general anesthesia and airway instrumentation in select patients remains a major advantage. Regional blockade may facilitate reduction of risk and expense associated with special equipment or monitoring necessary for safe administration of general anesthesia in patients with challenging airways or severe systemic disease. Regional blocks also provide a valuable tool for minimizing opioids and possibly even avoiding general anesthesia in populations broadly at risk for cognitive dysfunction, such as the elderly. Lastly, the opioid-sparing effects of regional anesthesia may reduce health system costs by enabling patients with comorbidities, such as obesity or sleep apnea, to be candidates for surgery on an outpatient basis.^[5] These types of cost savings are not generally accounted for by conventional study design and outcome analyses.

Not All Regional Blocks Are Created Equal

In addition to capturing a broader set of outcomes, it is important to recognize that blending of existing data in the literature likely obscures the reality. The ability to distinguish between single-shot peripheral nerve blocks (sPNB) and cPNCs is instructive. For different reasons, both under- and overuse of continuous catheters may falsely impact the perceived benefit they have on long-term outcomes. If too many sPNBs are performed for major surgery then one might not be surprised to see improvement in short-term, but not long-term outcomes. Furthermore, failing to differentiate these techniques could be responsible for under-reporting long-term successes of cPNCs. As has been argued elsewhere, the data may also suggest a real opportunity for current practice improvement.^[4] Based on known mechanisms for development of chronic pain, it may be beneficial to use more cPNCs for major surgery where severe pain is expected to last longer than the analgesic duration of a single injection of local anesthetic. A selective increase in cPNC placement based on appropriate patient and/or surgical factors may increase the number of patients who can transition directly from regional nerve blockade to relatively opioid-sparing analgesic regimens. In better aligning the duration of therapy with anticipated need for pain control, a stronger clinical rationale can be made for expecting a decrease in development of chronic pain. By contrast, placing too many catheters may inflate cost without commensurate clinical benefit and may statistically dilute the real benefit of such intervention in well-selected patients. It is possible for the pendulum to swing too far in either direction, and clear data is needed to guide us.

The Value of an Acute Pain Service Is Not Well-Studied

In many centers, patients who undergo peripheral nerve blockade have the added benefit of being followed each day by the acute pain service. This team assesses pain control, functional status, and potential complications. Common practice is for inpatients to be visited at the bedside and outpatients to be contacted by phone. In our experience, these patients benefit from more robust multimodal pain regimens during hospitalization and at discharge. These interactions provide an opportunity to reinforce patient education regarding shared goals such as fall prevention and early participation in physical therapy. We anticipate long-term follow up would reflect positively on the value provided by this additional care. As a boon to the surgeon, this contact point provides an opportunity to identify and address any pressing patient concerns prior to the first postoperative visit.

Lastly, to our knowledge there are no studies in the anesthesia literature examining the long-term impact of pre-surgical counseling on the role of regional techniques in management of postoperative pain. A comprehensive, multidisciplinary approach to preoperative pain counseling may be a potentially significant modifier of patient expectations and long-term outcomes.

Conclusion

An overall lack of long-term supportive data is likely due to a combination of hidden cost savings, narrow focus on pain scores and opioid use and possibly an underutilization of cPNCs in clinical scenarios where there is high risk of persistent pain development. It is our responsibility to continue to advocate for regional anesthesia when it is in the best interest of our patients. We increase our value as regional anesthesia becomes more accessible. Experts in our subspecialty will tell us to “put local anesthetic somewhere!” as a simple motto that we can all remember. In the research arena, we should tailor our efforts in a way that accurately monitors our progress with meaningful outcomes. The long game is promising, but we must be prepared to jump the hurdles.

References

1. Joshi G, Gandhi K, Shah N, Gadsden J, Corman SL. Peripheral nerve blocks in the management of postoperative pain: challenges and opportunities. J Clin Anesth. 2016;35:524-9. https://doi.org/10.1016/j.jclinane.2016.08.041
2. Atchabahian A, Andreae, M. Long-term functional outcomes after regional anesthesia: a summary of the published evidence and a recent Cochrane review. Refresh Courses Anesthesiol. 2015;43(1):15-26. 
3. Liu Q,  Chelly JE, Williams JP, Gold MS. Impact of peripheral nerve block with low dose local anesthetics on analgesia and functional outcomes following total knee arthroplasty: a retrospective study. Pain Med. 2015;16(5):998-1006. https://doi.org/10.1111/pme.12652
4. Sun EC, Memtsoudis SG, Mariano ER. Regional anesthesia: a silver bullet, red herring or neither? Anesthesiology. 2019;131(6):1205-6. https://doi.org/10.1097/ALN.0000000000002964
5. Hamilton GM, Ramlogan R, Lui A, et al. Peripheral nerve blocks for ambulatory shoulder surgery: a population-based cohort study of outcomes and resource utilization. Anesthesiology. 2019;131(6):1254–63. https://doi.org/10.1097/ALN.0000000000002865