Making sense of block "success" in ambulatory anesthesia practice

A double-blind randomized controlled trial comparing dexamethasone and clonidine as adjuvants to a ropivacaine sciatic popliteal block for foot surgery

Background and aims

A popliteal block is effective in managing postoperative pain for foot surgery, but since the duration of analgesia is limited following a single-shot popliteal fossa block technique, methods to prolong effective postoperative analgesia are mandatory. The aim of this study was to assess the effect of adjuvants to ropivacaine on the duration of sensory and motor block.

Methods

In this double-blind randomized placebo-controlled study, we evaluated the analgesic effect of clonidine or dexamethasone (DXM) when added to ropivacaine for hallux valgus surgery. After obtaining institutional ethics research board approval and written informed consent, a total of 72 patients were randomly allocated. Fifty-seven of these patients were statistically analyzed. All patients received an ultrasound-guided single-shot popliteal fossa block with 30 mL of ropivacaine 0.75%, supplemented with saline, clonidine 100 µg, or DXM 5 mg. The primary end point was time to first pain sensation. Secondary end points were time to complete sensory and motor block regression.

Results

Compared to saline, duration to first pain sensation was prolonged by 9 hours (mean ± standard deviation: 31±9 hours) (42%) in the DXM group (P=0.024) and by 6 hours (28±10 hours) (27%) in the clonidine group (P=0.024). Compared to saline, DXM prolonged both complete sensory and motor blockade by 12 hours (25±7 hours) (46%) and 13 hours (36±6 hours) (55%), respectively, while clonidine prolonged complete sensory and motor blockade by 7 hours (30±7 hours) (27%) and 2 hours (22±5 hours) (10%), respectively. DXM prolonged sensory block regression time by 6 hours (21±7 hours) (41%) and clonidine by 2 hours (17±6 hours) (13%) compared to the control group (P=0.006). Similarly, DXM prolonged motor block regression by 7 hours (25±7 hours) (46%) and clonidine by 4 hours (21±4 hours) (19%) (P<0.0001).

Conclusion

Addition of DXM and clonidine to ropivacaine significantly prolonged the duration of postoperative sensory and motor block.

The evolution and practice of acute pain medicine

BACKGROUND

In recent years, the field of acute pain medicine (APM) has witnessed a surge in its development, and pain has begun to be recognized not merely as a symptom, but as an actual disease process. This development warrants increased education of residents both in the performance of regional anesthesia as well as in the disease course of acute pain and the biopsychosocial mechanisms that define interindividual variability.

REVIEW SUMMARY

We reviewed the organization and function of the modern APM program. Following a discussion of the nomenclature of acute pain-related practices, we discuss the historical evolution and modern role of APM teams, including the use of traditional, as well as complementary and alternative, therapies for treating acute pain. Staffing and equipment requirements are also evaluated, in addition to the training requirements for achieving expertise in APM. Lastly, we briefly explore future considerations related to the essential role and development of APM.

CONCLUSION

The scope and practice of APM must be expanded to include pre-pain/pre-intervention risk stratification and extended through the phase of subacute pain.