Intraoperative dexmedetomidine sedation reduces the postoperative agitated behavior in elderly patients undergoing orthopedic surgery compared to the propofol sedation.

BACKGROUND: Postoperative agitation or confusion is one of the symptoms of hyperactive delirium in elderly patients. We retrospectively evaluated the incidence of postoperative abnormal psychomotor behavior in elderly surgical patients according to the use of different intraoperative sedative agents: dexmedetomidine vs. propofol. METHODS: The medical records of 855 elderly patients, who underwent orthopedic surgery with regional anesthesia between July 2012 and September 2015, were divided into two groups, the dexmedetomidine group (N.=263) and the propofol group (N.=592), and then evaluated. Agitated behavior was evaluated as the primary outcome, and patient-, surgery-, and anesthesia-related factors, as well as other postoperative complications, were investigated as secondary outcomes. To reduce the risk of confounder effects between the two groups, 263 patients were selected from the propofol group by propensity score matching. RESULTS: In the propensity-score-matched groups, the incidence of agitated behavior was lower in the dexmedetomidine group compared with the propofol group (6 [2.3%] vs. 17 [6.5%], P=0.027). All pre- and postoperative laboratory values were comparable between the two groups, including hemoglobin, hematocrit, platelet count, C-reactive protein, electrolytes, creatinine, glomerular filtration rate, and albumin. Moreover, intraoperative propofol sedation, older age, higher Charlson comorbidity index, and hip surgery were found to be significant factors for the occurrence of agitation. CONCLUSIONS: This study suggests that intraoperative dexmedetomidine sedation, as compared with propofol sedation, may have a greater beneficial effect in reducing agitated behavior in elderly patients undergoing orthopedic surgery with regional anesthesia.

Minimum effective local anesthetic volume for surgical anesthesia by subparaneural, ultrasound-guided popliteal sciatic nerve block: A prospective dose-finding study.

Because of its rapid onset time, recent years have seen an increase in the use of ultrasound (US)-guided popliteal sciatic nerve block (PSNB) via subparaneural injection for induction of surgical anesthesia. Moreover, in below-knee surgery, combined blocks, as opposed to sciatic nerve block alone, have become more common. These combined blocks often require a large volume of local anesthetic (LA), thus increasing the risk of local-anesthetic systemic toxicity (LAST). Thus, to decrease the risk of LAST, it is important to know the minimum effective volume (MEV) required for an adequate block. We, therefore, aimed to determine the MEV of ropivacaine 0.75% for induction of surgical anesthesia by the method of US-guided popliteal sciatic nerve block via subparaneural injection.Thirty patients underwent a US-guided PSNB with ropivacaine 0.75% at a 20-mL starting volume. Using a step-up/step-down method, we determined injection volumes for consecutive patients from the preceding patient's outcome. When an effective block was achieved within 40 minutes after injection, the next patient's volume was decreased by 2 mL. If the block failed, the next patient's volume was increased by 2 mL. The sensory and motor blockade was graded according to a 4-point scale. The block was considered a success if a combination of anesthesia and paresis (a score of 3 for both the sensory and motor nerves) was achieved within 40 minutes. The primary outcome measure was the MEV resulting in a successful subparaneural block of the sciatic nerve in 50% of patients (MEV50). Additionally, the data were processed with a probit regression analysis to determine the volume required to produce a complete sciatic nerve block in 90% of subjects (ED90).The MEV50 of 0.75% ropivacaine is 6.14 mL (95% confidence interval, 4.33-7.94 mL). The ED90 by probit analysis for a subparaneural injection was 8.9 mL (95% CI, 7.09-21.75 mL).The 6.14-mL MEV50 of ropivacaine 0.75% represents a 71% reduction in volume compared with neurostimulation techniques and a 14.7% reduction in volume compared with US-guided PSNB using the alternative perineural injection technique.

Peripheral nerve blocks as the sole anesthetic technique in a patient with severe Duchenne muscular dystrophy.

General anesthesia and central neuraxial blockades in patients with severe Duchenne muscular dystrophy are associated with high risks of complications, including rhabdomyolysis, malignant hyperthermia, hemodynamic instability, and postoperative mechanical ventilation. Here, we describe peripheral nerve blocks as a safe approach to anesthesia in a patient with severe Duchenne muscular dystrophy who was scheduled to undergo surgery. A 22-year-old male patient was scheduled to undergo reduction and internal fixation of a left distal femur fracture. He had been diagnosed with Duchenne muscular dystrophy at 5 years of age, and had no locomotive capability except for that of the finger flexors and toe extensors. He had developed symptoms associated with dyspnea 5 years before and required intermittent ventilation. We blocked the femoral nerve, lateral femoral cutaneous nerve, and parasacral plexus under ultrasound on the left leg. The patient underwent a successful operation using peripheral nerve blocks with no complications. In conclusion general anesthesia and central neuraxial blockades in patients with severe Duchenne muscular dystrophy are unsafe approaches to anesthesia because of hemodynamic instability and respiratory depression. Peripheral nerve blocks are the best way to reduce the risks of critical complications, and are a safe and feasible approach to anesthesia in patients with severe Duchenne muscular dystrophy.