Howard Meng

Background: Continuous regional anesthesia (CRA) techniques are used for analgesia in patients with acute rib fractures. However, there is a paucity of evidence supporting the initiation of CRA in patients receiving mechanical ventilation (MV). We therefore performed this retrospective study to assess changes in opioid consumption and the rate of liberation from MV in patients with traumatic rib fractures. Methods: Patients referred to the Acute Pain Service (January 2022–July 2023) who were mechanically ventilated with acute rib fractures were included in this study. Patients received consultation either with or without CRA. Demographic and severity of injury data were collected. Mechanical ventilator requirements, pain scores, sedation use, opioids, adjunct analgesics, neurological status, and sedation status were collected for the 24 h prior to APS consultation/CRA intervention and for 48 h afterward. Results: Forty patients were included in the study, with 18 in the non‐CRA group and 22 in the CRA group. There was a statistically significant decrease in overall opioid consumption (oral morphine equivalents) for the CRA group compared to the non‐CRA group 0–48 h postintervention (0–24 h post‐CRA [median 135 mg { 33.1‐296.6}]) versus non‐CRA 368.3 (121.5–727.9) ( p = 0.018), 24–48 h post‐CRA (31.5 mg [11.5‐131.6] vs. non‐CRA 342.8 [99.3‐645.8]) ( p = 0.001). There was no significant difference in rates of liberation from MV between groups. Conclusions: CRA use was associated with a decrease in opioid consumption 24–48 h after CRA intervention compared to baseline. CRA did not facilitate early liberation from MV. Editorial Comment: This retrospective study provides evidence that CRA may reduce opioid requirements in mechanically ventilated patients with rib fractures. Although CRA did not facilitate earlier liberation from ventilation, the opioid‐sparing effect is clinically relevant in this population. Larger prospective studies are warranted to define optimal timing, patient selection, and integration of CRA into critical care pathways.

Background Distal femur fractures account for approximately 3%–6% of all femoral fractures. Non-operative management may be an attractive option for the elderly with significant perioperative mortality risk. Adequate pain control is a major barrier to non-operative fracture management. Chemical neurolysis has been described for analgesic management of proximal hip fractures, however no description of interventional management of distal femur fracture exists in literature. We describe a case of phenol chemical neurolysis of genicular nerves in addition to injection at the site of fracture to provide effective analgesia for distal femur fracture. Case presentation A patient in their 90s with a witnessed mechanical fall sustained an intra-articular displaced fracture of the distal right femur shaft with extension into the distal femoral condyle. The patient elected to undergo non-surgical management given the high perioperative mortality risk. Acute pain service was involved and multimodal oral analgesics including opioids were insufficient in managing the patient’s pain. The addition of femoral nerve catheter local anesthetic infusion did not sufficiently improve analgesia. Phenol chemical neurolysis of the superolateral, superomedial, inferomedial genicular nerves and of the fracture site was offered and performed. Resting pain decreased from Numerical Rating Scale 5/10 to 0/10 on postprocedure day 1. This was sustained at the 2-month timepoint. Conclusions We report the successful use of phenol neurolysis of genicular nerves and the fracture site in an elderly patient with a conservatively managed distal femur fracture. These interventions resulted in improved analgesia and achieved prolonged duration of effect.

Background: Insulin resistance is strongly associated with the development of type 2 diabetes and cardiovascular disease. However, the underlying mechanisms linking insulin resistance and the development of atherosclerosis have not been fully elucidated. Moreover, the protective effect of antihyperglycemic agent, metformin, is not fully understood. This study investigated the protective effects and underlying mechanisms of metformin in balloon-injury induced stenosis in insulin resistant rats. Methods: After 4 weeks high fructose diet, rats received balloon catheter injury on carotid arteries and were sacrificed at 1 and 4 weeks post injury. Biochemical, histological, and molecular changes were investigated. Results: Plasma levels of glucose, insulin, total cholesterol, triglyceride, free fatty acids, and methylglyoxal were highly increased in fructose-induced insulin resistant rats and treatment with metformin significantly improved this metabolic profile. The neointimal formation of the carotid arteries was enhanced, and treatment with metformin markedly attenuated neointimal hyperplasia. A significant reduction in BrdU-positive cells in the neointima was observed in the metformin-treated group (P < 0.01). Insulin signaling pathways were inhibited in insulin resistant rats while treatment with metformin enhanced the expression of insulin signaling pathways. Increased expression of JNK and NFKB was suppressed following metformin treatment. Vasoreactivity was impaired while treatment with metformin attenuated phenylephrine-induced vasoconstriction and enhanced methacholine-induced vasorelaxation of the balloon injured carotid arteries in insulin resistant rats. Conclusion: The balloon-injury induced neointimal formation of the carotid arteries is enhanced by insulin resistance. Treatment with metformin significantly attenuates neointimal hyperplasia through inhibition of smooth muscle cell proliferation, migration, and inflammation as well as by improvement of the insulin signaling pathway.