Ultrasound guidance has reduced the amount of local anesthetics to achieve a successful block. Previous studies of the relationship between the volume or concentration of local anesthetics and the effects of the block were based on relatively high doses of local anesthetics. We tested the hypothesis that providing low dose of ropivacaine at three combinations of volumes and concentrations for ultrasound-guided interscalene brachial plexus block would produce different effects in the aspect of onset time, pain control and the incidence of side effects. Ninety-nine patients undergoing elective arthroscopic shoulder surgery were randomized to receive an ultrasound guided combined with nerve stimulator mediated interscalene block with ropivacaine 0.75 % (6.7 ml, Group 0.75), 0.5 % (10 ml, Group 0.5) or 0.25 % (20 ml, Group 0.25). The primary end point was the onset time of the sensory blockade, assessed by using a pinprick in the C5-6 dermatome. The secondary end points included the onset time of the motor blockade, block success rate, postoperative pain rating score, rescue analgesics requirement, sleep quality, strength of the hand on the block side,and the incidence of hemi-diaphragmatic paresis which was evaluated by ultrasonography. There was a statistically significant difference of the sensory block median onset times among Group 0.75 (5 min), Group 0.5 (10 min) and Group 0.25 (20 min). One patient in Group 0.5 and 20 patients in Group 0.25 did not achieve a complete motor block within 30 min, which were also significantly different. No significant difference was observed in postoperative analgesia, decrease of handgrip strength and the incidence of hemi-diaphragmatic paresis among the 3 groups. This study demonstrates that ropivacaine 50 mg as 0.25, 0.5 or 0.75 % solution for interscalene brachial plexus block before arthroscopic shoulder surgery produces comparable blockade with few side effects, while 0.75 % seems to be more preferable as it is associated with faster onset time. ChiCTR-TRC-13004058 . Registered 4 December 2013.

(1) Background: Previous evidence demonstrates that tight glycemic control and good physical function could reduce the risk of delirium. This study aimed to investigate whether the occurrence of postoperative delirium (POD) in older hip fracture surgery patients is associated with preoperative glycemic control factors or pre-injury physical performance. (2) Methods: Three-hundred and nine individuals aged over 65 years and scheduled for hip fracture surgery were included at a single center. Glycemic control factors and pre-injury physical performance were assessed preoperatively. The presence of delirium was assessed using the Confusion Assessment Method on postoperative hospitalization days. Univariate and multivariable logistic regression models and a risk prediction model of POD were established. (3) Results: Among the 309 patients, 52 (16.83%) experienced POD during the hospital stay. The numbers of pre-injury physical performance and type 2 diabetes mellitus (T2DM) patients were significantly different in the POD and non-POD groups. The multivariable model showed that development of delirium was significantly explained by preoperative fasting blood glucose (FBG) (OR 0.804, p = 0.004), stair climbing (OR 0.709, p = 0.003), T2DM (odds ratio (OR) 3.654, p = 0.001), and age-adjusted Charlson comorbidity index (ACCI) (OR 1.270, p = 0.038). The area under the receiver operating characteristic curve (AUROC) of the risk prediction model including those covariates was 0.770. (4) Conclusions: More older T2DM patients develop POD after hip fracture surgery than patients without T2DM. A simple assessment of preoperative FBG and pre-injury stair climbing capacity may identify those at high risk for the development of POD. Higher preoperative FBG and good pre-injury stair climbing capacity are protective factors for POD.