Comparison of continuous pericapsular nerve group (PENG) block versus continuous fascia iliaca compartment block on pain management and quadriceps muscle strength after total hip arthroplasty: a prospective, randomized controlled study.

BACKGROUND: This investigation aimed to evaluate the impact of continuous pericapsular nerve group (PENG) block and continuous fascia iliac compartment block (FICB) on postoperative pain following total hip arthroplasty (THA). METHODS: This prospective, randomized, and controlled trial recruited a cohort of fifty-seven patients with unilateral femoral neck fractures from Xi'an Aerospace General Hospital in northwest China between July 2020 and November 2021. These patients were randomly assigned to two groups: the continuous PENG block group (PENG group, n = 29) and the continuous FICB group (FICB group, n = 28). Under ultrasound guidance, PENG block and FICB procedures were performed prior to spinal anesthesia, utilizing 20 ml of 0.25% ropivacaine for PENG block and 30 ml of 0.25% ropivacaine for FICB. Subsequently, a catheter was inserted. All study participants received a standardized postoperative multimodal analgesic regimen, including intravenous administration of 30 mg Ketorolac tromethamine every eight hours and patient-controlled neural analgesia (PCNA) after surgery. Numerical rating scale (NRS) scores at rest and during exercise were recorded at various time points: prior to block (T0), 30 min post-blockade (T1), and 6 h (T2), 12 h (T3), 24 h (T4), and 48 h (T5) postoperatively. Additional data collected encompassed postoperative quadriceps muscle strength, the time of initial ambulation after surgery, the number of effective PCNA activations, rescue analgesia requirements, and occurrences of adverse events (such as nausea and vomiting, hematoma, infection, catheter detachment, or displacement) within 48 h following surgery. RESULTS: In the PENG group, the resting NRS pain scores exhibited lower values at T1, T4, and T5 than those at T0. Furthermore, exercise NRS pain scores at T1-T5 were lower in the PENG group than in the FICB group. Similarly, during the same postoperative period, the PENG group demonstrated enhanced quadriceps strength on the affected side compared to the FICB group. Additionally, the PENG group displayed earlier postoperative ambulation and reduced occurrences of effective PCNA activations and rescue analgesia requirements compared to the FICB group. CONCLUSION: Continuous PENG block exhibited superior analgesic efficacy after THA compared to continuous FICB, promoting recovery of quadriceps strength on the affected side and facilitating early postoperative ambulation. TRIAL REGISTRATION: This clinical trial was registered in the China Clinical Trials Center ( http://www.chictr.org.cn ) on 20/07/2020, with the registration number ChiCTR2000034821.

Thermal Conductivity of Natural Rubber Using Molecular Dynamics Simulation.

Thermal conductivity of natural rubber has been studied by classic molecular dynamics simulations. These simulations are performed on natural rubber models using the adaptive intermolecular reactive empirical bond order (AIREBO) and the Green-Kubo molecular dynamics (MD) simulations. Thermal conductivity results are found to be very sensitive to the time step used in the simulations. For a time step of 0.1 fs, the converged thermal conductivity is 0.35 W/mK. Additionally the anisotropic thermal conductivity of a specially-modeled natural rubber model with straight molecular chains was studied and values of thermal conductivity parallel to the molecular chains was found to be 1.71 W/mK and the anisotropy, 2Kz/(Kx + Ky), was 2.67.