Utilization of the pericapsular nerve group block in preoperative rehabilitation of patients with femoral neck fractures: a case series.

Background: Elderly patients with femoral neck fractures, particularly those with severe comorbidities or living in regions with limited medical resources, may experience delays in surgical treatment. Although the benefits of preoperative rehabilitation (prehabilitation) in hip arthroplasty have been reported, pain management remains a challenge. The pericapsular nerve group (PENG) block, known for its exceptional analgesic effect and motor function preservation, may be a promising intervention during prehabilitation in these patients. Case: We enrolled ten patients with Garden classification 3-4 femoral neck fractures scheduled for hip arthroplasty. After receiving a PENG block with 20 ml of 0.375% ropivacaine, all patients underwent initial prehabilitation sessions comprising 9 mobility levels, ranging from bed-sitting to walking. One patient was excluded due to experiencing high blood pressure during prehabilitation. Six of the nine remaining patients (66.7%) were successfully transferred from bed to wheelchair. Conclusions: The PENG block enhanced prehabilitation for patients with femoral neck fractures undergoing hip arthroplasty.

Pulse-shaped high-energy and high-average-power fiber laser in the nanosecond regime.

A high-energy and high-average-power pulsed fiber laser has been investigated in a master oscillator power amplifier (MOPA) configuration seeding with a diode laser at a programmed pulse duration of ∼250ns. The fiber amplifier successfully demonstrates the pulse with 21.4 mJ at the repetition rate of 50 kHz and a maximum average output power of 1535 W with a slope efficiency of 81.6% at 250 kHz. To overcome fiber nonlinearities such as stimulated Raman scattering (SRS) and self-phase modulation (SPM), extra-large mode area ytterbium (Yb)-doped step-index dual cladding fiber has been utilized as gain fiber in the MOPA laser system. The gain saturation effect in the power amplifier was greatly mitigated by the programmed seed signal. This pulse-shaped MOPA system can provide practical applications in many fields such as laser cleaning, paint stripping, and other applications requiring special pulse shapes.

Transesophageal echocardiography for thoracic spinal cord imaging and confirmation of epidural catheter placement in pediatrics.

INTRODUCTION: Transesophageal echocardiography (TEE) use continues to expand to include extracardiac applications. However, there is limited research investigating the use of TEE as a tool to confirm the position of the epidural catheter. This prospective observational study aimed to evaluate whether TEE could be used to visualize the anatomy of the thoracic spinal canal in pediatrics. A subsequent prospective case series was conducted to evaluate whether TEE could be used to assist in the placement of epidural catheters in pediatric surgical patients. METHODS: Seventy-five patients (50 pediatric and 25 adult subjects) were enrolled. The operators attempted to identify four structures (spinal cord, cerebrospinal fluid, dura mater, epidural space) within the thoracic spinal canal with TEE. After demonstrating the feasibility of this technique for observing the spinal anatomy, 20 pediatric surgical patients were enrolled in a case series. These patients had epidural catheter placement, and the final catheter position was confirmed with TEE. RESULTS: The total number of thoracic spinal segment visualized in pediatric patients was 542 out of 550 (99%) segments, and 191 out of 275 (70%) segments in adult subjects (difference, 29% [95% confidence interval, 23-34]; p < 0.001). Additionally, a case series of 20 pediatric surgical patients demonstrated successful caudal or epidural catheter placement at target spinal level in 17 cases. CONCLUSIONS: This observational study demonstrated the successful visualization of the thoracic spinal cord at virtually every level in pediatric patients. A subsequent case series demonstrated that TEE could be used to successfully confirm the position of the epidural catheter in the targeted thoracic spinal segment for pediatric surgical patients.

Anaesthetic Management of a Patient With Immune-Mediated Necrotizing Muscle Disease With the Use of a Novel Ultrashort-Acting Benzodiazepine, Remimazolam: A Case Report.

We reported the anesthetic management of remimazolam, a novel ultra-short-acting benzodiazepine, for a 21-month-old female with immune-mediated necrotizing myopathy (IMNM). Remimazolam has a similar chemical structure to midazolam but possesses a unique side chain that reduces its propensity to accumulate in the body, thereby minimizing prolonged sedation or respiratory depression. Our experience supports that remimazolam could be a suitable agent for anesthetizing the patient with IMNM.

Zombies, again? The COVID-19 business support programs in Japan.

We design and conduct a firm-level survey on the use of COVID-19-related government programs, in collaboration with Tokyo Shoko Research, LTD (TSR). Combining the survey results with the financial statements of the respondent firms, we investigate the factors behind the allocation of various government programs. We find that firms that had low credit scores in 2019, before the COVID-19 pandemic, were more likely to apply for and receive the subsidies and concessional loans offered by the Japanese government in 2020, controlling for the sales growth after the onset of the pandemic. Firms with low credit scores are not necessarily zombies, which are defined to be the firms that are non-viable but kept alive by assistance from creditors and/or the government. Our result suggests that the government assistance may have subsidized some poorly performing firms that were not yet zombies before the pandemic.

Efficient Nd:YAG crystal laser with rotatory pumping.

The performance of solid-state laser is limited by the thermal effects in the gain medium. In this study, we investigated the implementation of an efficient short-cavity continuous-wave 1064 nm Nd:YAG solid-state laser by using a rotatory pumping scheme to alleviate the thermal accumulation in the gain medium. With this method, the laser power reached 25.7 W with a slope efficiency of 41.5% at a 10.0-mm pump rotation radius and an optimum rotation rate of 2300 rpm. The influence of rotatory pumping radius and rotation rates was analyzed, and the results indicated that the rotatory pumping would be promising technique for the power scaling of solid-state lasers.

Comparison of Time to Intubation of a Double-Lumen Endobronchial Tube Utilizing C-MAC® Versus GlideScope® Versus Macintosh Blade: A Randomized Crossover Manikin Study.

BACKGROUND: Macintosh blade direct laryngoscopy is widely used for endotracheal intubation. It may, however, provide an incomplete view of the glottis in patients with challenging airway anatomy. Consequently, various video laryngoscopes have been developed to enhance the visualization of the glottis and facilitate intubation. Yet, the effectiveness of these video laryngoscopes for intubation using a double-lumen endotracheal tube (DLT), which is longer, larger, and more rigid and has a linear configuration as opposed to the naturally semicircular curvature of a single-lumen endotracheal tube, remains uncertain. We hypothesized that video laryngoscopes would be more efficient for DLT intubation compared to the Macintosh blade in an adult manikin. METHODS: Ninety-four anesthesia providers, comprising 67 residents, 15 fellows, and 12 attendings, attempted to intubate an adult manikin with normal airway anatomy (Laerdal, Wappingers Falls, NY, USA) using a 37 Fr left-sided DLT. Three different intubation devices were used: the C-MAC® video laryngoscope (Karl Storz GmbH & Co. KG, Tuttlingen, Germany), the GlideScope® video laryngoscope (Verathon Inc., Bothell, WA), and the Macintosh blade direct laryngoscope-were used. Each participant intubated a manikin once with each of the three devices. Participants were randomized via a crossover design with the order of devices determined by using a Latin square design. Time to intubation and the number of failed intubations (esophageal intubation) were compared across the three different devices. RESULTS: Mean times to intubation for the C-MAC®, GlideScope®, and Macintosh blades were 18.57 ± 0.77, 36.26 ± 2.69, and 20.76 ± 0.96 seconds, respectively. There was a statistically significant difference (P<0.001) between the GlideScope® and the other two laryngoscopes. The times for C-MAC® and Macintosh blades were not significantly different. There were two instances of first-attempt failed intubation with the Macintosh. CONCLUSION: Both the C-MAC® and the Macintosh blades proved more efficient in terms of time to DLT intubation in the manikin with normal airway anatomy, when compared to the GlideScope®. Considering the occurrence of first-attempt failed intubation, the C-MAC® was the most effective device among the three laryngoscopes for timely successful DLT intubation in the adult manikin. Further studies are needed to confirm these results in human subjects.

Eight weeks of inorganic nitrate/nitrite supplementation improves aerobic exercise capacity and the gas exchange threshold in patients with type 2 diabetes.

Patients with type 2 diabetes mellitus (T2DM) have reduced exercise capacity, indexed by lower maximal oxygen consumption (V̇o2max) and achievement of the gas exchange threshold (GET) at a lower % V̇o2max. The ubiquitous signaling molecule nitric oxide (NO) plays a multifaceted role during exercise and, as patients with T2DM have poor endogenous NO production, we investigated if inorganic nitrate/nitrite supplementation (an exogenous source of NO) improves exercise capacity in patients with T2DM. Thirty-six patients with T2DM (10F, 59 ± 9 yr, 32.0 ± 5.1 kg/m2, HbA1c = 7.4 ± 1.4%) consumed beetroot juice containing either inorganic nitrate/nitrite (4.03 mmol/0.29 mmol) or a placebo (0.8 mmol/0.00 mmol) for 8 wk. A maximal exercise test was completed before and after both interventions. V̇o2max was determined by averaging 15-s data, whereas the GET was identified using the V-slope method and breath-by-breath data. Inorganic nitrate/nitrite increased both absolute (1.96 ± 0.67 to 2.07 ± 0.75 L/min) and relative (20.7 ± 7.0 to 21.9 ± 7.4 mL/kg/min, P < 0.05 for both) V̇o2max, whereas no changes were observed following placebo (1.94 ± 0.40 to 1.90 ± 0.39 L/min, P = 0.33; 20.0 ± 4.2 to 19.7 ± 4.6 mL/kg/min, P = 0.39). Maximal workload was also increased following inorganic nitrate/nitrite supplementation (134 ± 47 to 140 ± 51 W, P < 0.05) but not placebo (138 ± 32 to 138 ± 32 W, P = 0.98). V̇o2 at the GET (1.11 ± 0.27 to 1.27 ± 0.38L/min) and the %V̇o2max in which GET occurred (56 ± 8 to 61 ± 7%, P < 0.05 for both) increased following inorganic nitrate/nitrite supplementation but not placebo (1.10 ± 0.23 to 1.08 ± 0.21 L/min, P = 0.60; 57 ± 9 to 57 ± 8%, P = 0.90) although the workload at GET did not achieve statistical significance (group-by-time P = 0.06). Combined inorganic nitrate/nitrite consumption improves exercise capacity, maximal workload, and promotes a rightward shift in the GET in patients with T2DM. This manuscript reports data from a registered Clinical Trial at ClinicalTrials.gov ID: NCT02804932.NEW & NOTEWORTHY We report that increasing nitric oxide bioavailability via 8 wk of inorganic nitrate/nitrite supplementation improves maximal aerobic exercise capacity in patients with type 2 diabetes mellitus. Similarly, we observed a rightward shift in the gas exchange threshold. Taken together, these data indicate inorganic nitrate/nitrite may serve as a means to improve fitness in patients with type 2 diabetes mellitus.

Effects of Combined Inorganic Nitrate and Nitrite Supplementation on Cardiorespiratory Fitness and Skeletal Muscle Oxidative Capacity in Type 2 Diabetes: A Pilot Randomized Controlled Trial.

Nitric oxide (NO) stimulates mitochondrial biogenesis in skeletal muscle. However, NO metabolism is disrupted in individuals with type 2 diabetes mellitus (T2DM) potentially contributing to their decreased cardiorespiratory fitness (i.e., VO2max) and skeletal muscle oxidative capacity. We used a randomized, double-blind, placebo-controlled, 8-week trial with beetroot juice containing nitrate (NO3−) and nitrite (NO2−) (250 mg and 20 mg/day) to test potential benefits on VO2max and skeletal muscle oxidative capacity in T2DM. T2DM (N = 36, Age = 59 ± 9 years; BMI = 31.9 ± 5.0 kg/m2) and age- and BMI-matched non-diabetic controls (N = 15, Age = 60 ± 9 years; BMI = 29.5 ± 4.6 kg/m2) were studied. Mitochondrial respiratory capacity was assessed in muscle biopsies from a subgroup of T2DM and controls (N = 19 and N = 10, respectively). At baseline, T2DM had higher plasma NO3− (100%; p < 0.001) and lower plasma NO2− levels (−46.8%; p < 0.0001) than controls. VO2max was lower in T2DM (−26.4%; p < 0.001), as was maximal carbohydrate- and fatty acid-supported oxygen consumption in permeabilized muscle fibers (−26.1% and −25.5%, respectively; p < 0.05). NO3−/NO2− supplementation increased VO2max (5.3%; p < 0.01). Further, circulating NO2−, but not NO3−, positively correlated with VO2max after supplementation (R2= 0.40; p < 0.05). Within the NO3−/NO2− group, 42% of subjects presented improvements in both carbohydrate- and fatty acid-supported oxygen consumption in skeletal muscle (vs. 0% in placebo; p < 0.05). VO2max improvements in these individuals tended to be larger than in the rest of the NO3−/NO2− group (1.21 ± 0.51 mL/(kg*min) vs. 0.31 ± 0.10 mL/(kg*min); p = 0.09). NO3−/NO2− supplementation increases VO2max in T2DM individuals and improvements in skeletal muscle oxidative capacity appear to occur in those with more pronounced increases in VO2max.

Anesthetic management of a patient with trisomy 18 undergoing esophageal banding and preceding gastrostomy-A case report.

A patient diagnosed with trisomy 18 is at great risk of perioperative morbidity and mortality, especially with complex congenital cardiac anomalies. Here, we report successful anesthetic management of palliative esophageal-banding and gastrostomy for trachea-esophageal fistula in a patient who had a complex congenital heart disease with trisomy 18.

Bronchogenic cyst with atypical imaging findings and repeated ruptures in a short period of time: A case report.

Bronchogenic cysts are the most common primary cysts of the mediastinum. Although most are asymptomatic, some bronchogenic cysts cause symptoms such as chest pain and dyspnea. Here, we report a case of bronchogenic cyst that ruptured twice in a short period of time in a patient who presented with sudden back pain. The lesion was apparent on computed tomography (CT) as a mass lesion with heterogeneous and high attenuation in the posterior mediastinal region. CT-guided puncture performed for diagnostic purposes revealed the contents as bloody fluid. The patient suffered chest pain approximately 3 months after the first presentation, and re-growth and re-rupture of the mass was suspected. The lesion was surgically resected and pathologically diagnosed as a bronchogenic cyst. Spontaneous rupture is a very rare complication of bronchogenic cyst, usually into the trachea, pleural cavity, or pericardial cavity. However, there are no reports of multiple ruptures. This case highlights the importance of recognizing the atypical imaging findings of bronchogenic cyst and the rare complication of rupture.

Dietary Inorganic Nitrate/Nitrite Supplementation Reduces Central and Peripheral Blood Pressure in Patients With Type 2 Diabetes Mellitus.

BACKGROUND: Patients with type 2 diabetes mellitus (T2DM) have increased cardiovascular risk due to elevated blood pressure (BP). As low levels of nitric oxide (NO) may contribute to increased BP, we determined if increasing NO bioavailability via eight weeks of supplementation with beetroot juice containing inorganic nitrate/nitrite (4.03 mmol nitrate, 0.29 mmol nitrite) improves peripheral and central BP relative to nitrate/nitrite-depleted beetroot juice. METHODS: Peripheral and central BP were assessed at heart-level in supine subjects using a brachial artery catheter and applanation tonometry, respectively. RESULTS: Nitrate/nitrite supplementation reduced peripheral systolic BP (148 ± 16 to 142 ± 18 mm Hg, P < 0.05) but not placebo (150 ± 19 to 149 ± 17 mm Hg, P = 0.93); however, diastolic BP was unaffected (supplement-by-time P = 0.08). Central systolic BP (131 ± 16 to 127 ± 17 mm Hg) and augmented pressure (13.3 ± 6.6 to 11.6 ± 6.9 mm Hg, both P < 0.05) were reduced after nitrate/nitrite, but not placebo (134 ± 17 to 135 ± 16 mm Hg, P = 0.62; 14.1 ± 6.6 to 15.2 ± 7.4 mm Hg, P = 0.20); central diastolic BP was unchanged by the interventions (supplement-by-time P = 0.16). Inorganic nitrate/nitrite also reduced AIx (24.3 ± 9.9% to 21.0 ± 9.6%) whereas no changes were observed following placebo (24.6 ± 9.3% to 25.6 ± 9.9%, P = 0.46). CONCLUSIONS: Inorganic nitrate/nitrite supplementation improves peripheral and central BP as well as AIx in T2DM. CLINICAL TRIALS REGISTRATION: Trial Number NCT02804932.

Invasive Metastatic Well-Differentiated Liposarcoma to the Heart, Found in Intraoperative Transesophageal Echocardiography.

Hematogenous metastasis of liposarcoma to the heart is rare, even though other types of distant metastatic cardiac tumors are relatively more common than primary cardiac tumors. We experienced a case of distant metastasis of liposarcoma to the right interatrial septum, mimicking lipomatous hypertrophy in transesophageal echocardiography (TEE). There were no significant findings in the preoperative transthoracic echocardiography (TTE) or computed tomography (CT). TEE was the only tool to suspect the presence of a cardiac tumor. It also helped evaluate the spread of tumor invasion and make a decision for operation.

Sodium nitrate supplementation improves blood pressure reactivity in patients with peripheral artery disease.

BACKGROUND & AIMS: Peripheral artery disease (PAD) is characterized by elevated blood pressure (BP), low nitric oxide availability (NO), and exaggerated pressor responses to sympatho-excitatory stressors. Inorganic nitrate reduces peripheral BP in healthy and chronically diseased populations. The objective of this study was to investigate the effects of eight-weeks of sodium nitrate (NaNO3) supplementation on indices of BP in PAD patients. METHODS: 21 patients with PAD were recruited to participate in this study, undergoing 8-weeks of NaNO3 (n = 13; 73 ± 9 years) or placebo (n = 8; 69 ± 10 years) supplementation. BP responsiveness to a cold pressor test (CPT) were examined prior to and following the supplementation period. The systolic BP response (change from rest) during the first (26 ± 10 vs. 19 ± 11 mmHg) and second minutes (32 ± 10 vs. 26 ± 12 mmHg) of CPT were reduced following NaNO3 (P < 0.05 for both) but not after placebo (first minute: 22 ± 10 vs. 24 ± 10 mmHg, P = 0.30; second minute 26 ± 10 vs 27 ± 10 mmHg, P = 0.72) supplementation. CONCLUSION: Our data suggest that eight-weeks of NaNO3 supplementation reduces BP responsiveness to sympatho-excitatory stimuli. CLINICAL TRIALS REGISTRATION NUMBER: NCT01983826.

Combined inorganic nitrate/nitrite supplementation blunts α-mediated vasoconstriction during exercise in patients with type 2 diabetes.

AIMS: Patients with type 2 diabetes mellitus (T2DM) have reduced vasodilatory responses during exercise partially attributable to low nitric oxide (NO) levels. Low NO contributes to greater α-adrenergic mediated vasoconstriction in contracting skeletal muscle. We hypothesized boosting NO bioavailability via 8wks of active beetroot juice (BRA, 4.03 mmol nitrate, 0.29 mmol nitrite, n = 19) improves hyperemia, via reduced α-mediated vasoconstriction, during handgrip exercise relative to nitrate/nitrite-depleted beetroot juice (BRP, n = 18) in patients with T2DM. METHODS: Forearm blood flow (FBF) and vascular conductance (FVC) were calculated at rest and during handgrip exercise (20%max, 20contractions·min-1). Phenylephrine (α1-agonist) and dexmedetomidine (α2-agonist) were infused intra-arterially during independent trials to determine the influence of α-mediated vasoconstriction on exercise hyperemia. Vasoconstriction was quantified as the percent-reduction in FVC during α-agonist infusion, relative to pre-infusion, as well as the absolute change in %FVC during exercise relative to the respective rest trial (magnitude of sympatholysis). RESULTS: ΔFBF (156 ± 69 to 175 ± 73 ml min-1) and ΔFVC (130 ± 54 to 156 ± 63 ml min-1·100 mmHg-1, both P < 0.05) during exercise were augmented following BRA, but not BRP (P = 0.96 and 0.51). Phenylephrine-induced vasoconstriction during exercise was blunted following BRA (-17.1 ± 5.9 to -12.6 ± 3.1%, P < 0.01), but not BRP (P = 0.58) supplementation; the magnitude of sympatholysis was unchanged by either (beverage-by-time P = 0.15). BRA supplementation reduced dexmedetomidine-induced vasoconstriction during exercise (-23.3 ± 6.7 to -19.7 ± 5.2%) and improved the corresponding magnitude of sympatholysis (25.3 ± 11.4 to 34.4 ± 15.5%, both P < 0.05). CONCLUSIONS: BRA supplementation improves the hyperemic and vasodilatory responses to exercise in patients with T2DM which appears to be attributable to reduced α-adrenergic mediated vasoconstriction in contracting skeletal muscle.

Glycemic management is inversely related to skeletal muscle microvascular endothelial function in patients with type 2 diabetes.

Microvascular endothelial dysfunction precipitates cardiovascular disease mortality in patients with type 2 diabetes mellitus (T2DM). However, the relationship between glycemic management and microvascular endothelial function of these patients remains ill defined. We investigated the association between skeletal muscle microvascular endothelial function with glycemic management (HbA1c) and responses to an oral glucose challenge (OGTT) in 30 patients with T2DM (59 ± 9 years, 31.2 ± 5.1 kg/m2 , HbA1c = 7.3 ± 1.3%). On study day 1, microvascular endothelial function was quantified as the increase (Δ from rest) in forearm vascular conductance (FVC, ml/min/100 mmHg) during intra-arterial acetylcholine infusion at 4.0 and 8.0 µg/dl forearm volume/min (ACh4 and ACh8, respectively). [Glucose] and [insulin] were measured in a fasted state as well as following a 75 g OGTT on a second day with an additional fasting blood sample collected to measure HbA1c. FVC increased (Δ) 221 ± 118 and 251 ± 144 ml/min/100 mm Hg during ACh4 and ACh8 trials, respectively (p < 0.05 between doses). [Glucose] and [insulin] increased at the 1-h time point, relative to fasting levels, and remained elevated 2 h post-consumption (p < 0.05 for both variables and time points). [Glucose] nor [insulin], fasting or during the OGTT, were associated with ΔFVC during ACh4 or ACh8, respectively (p = 0.11-0.86), although HbA1c was inversely related (r = -0.47 and -0.46, respectively, p < 0.01 for both). Patients whose HbA1c met the ADA's therapeutic target of ≤7.0% had greater ΔFVC to ACh4 (272 ± 147 vs. 182 ± 74 ml/100 mm Hg/min) and ACh8 (324 ± 171 vs. 196 ± 90 ml/100 mm Hg/min, p < 0.05 for both trials) compared to those with >7.0%, respectively. Our data show glycemic management is related to acetylcholine-mediated vasodilation (e.g., microvascular endothelial function) in skeletal muscle of patients with T2DM.

Median effective dose of 0.5% ropivacaine for ultrasound-guided femoral nerve block: dose per unit femoral nerve cross-sectional area / 中华麻醉学杂志

Objective:To determine the median effective dose (ED 50) of 0.5% ropivacaine based on femoral nerve cross-sectional area for ultrasound-guided femoral nerve block. Methods:Patients of both sexes, aged 18-64 yr, of American Society of Anesthesiologists physical status I or Ⅱ, with body mass index of 20-30 kg/m 2, scheduled for elective open reduction and internal fixation for patella fracture or removal of patella fracture by internal fixation, were enrolled in this study.Ultrasonic localization of femoral nerve was performed for measurement of the femoral nerve cross-sectional area, and 0.5% ropivacaine was injected based on the area.ED 50 was determined by Dixon′s up-and-down sequential method.The initial dose was 0.22 ml/mm 2, and the difference between the two successive doses was 0.02 ml/mm 2.The effective block was defined as complete loss of pain sensation in the areas of anterior skin of knee joint, skin on the inner side of the calf and dorsal medial skin of the foot and the degree of motor block was in stages 1-3 assessed using Brunnstrom motor function within 30 min after nerve block.Nerve block was considered ineffective if pain occurred in any nerve distribution area mentioned above.The study was terminated if 7 effective and ineffective alternating waves occurred.ED 50 and 95% confidence interval (CI) were calculated using Probit analysis. Results:Twenty-seven patients were enrolled in the study with the femoral nerve cross-sectional area (75±5) mm 2.ED 50 (95%CI) of 0.5% ropivacaine for ultrasound-guided femoral nerve block was 0.106 (0.069-0.125) ml/mm 2. Conclusion:ED 50 of 0.5% ropivacaine based on femoral nerve cross-sectional area for ultrasound-guided femoral nerve block is 0.106 ml/mm 2.

Median effective dose of 0.5% ropivacaine for ultrasound-guided femoral nerve block when combined with dexmedetomidine: dose based on per unit femoral nerve cross-sectional area / 中华麻醉学杂志

Objective:To determine the median effective dose (ED 50) of 0.5% ropivacaine when combined with dexmedetomidine based on femoral nerve cross-sectional area for ultrasound-guided femoral nerve block. Methods:American Society of Anesthesiologists physical statusⅠor Ⅱ patients of both sexes, aged 18-64 yr, with body mass index of 20-30 kg/m 2, scheduled for elective open reduction and internal fixation for patella fracture or removal of patella fracture by internal fixation, were randomly divided into dexmedetomidine and ropivacaine group (group DR) and ropivacaine group (group R). In group DR, 0.5% ropivacaine and 0.5 μg/kg dexmedetomidine were injected.In group R, 0.5% ropivacaine was injected.Ultrasonic localization of femoral nerve was performed for measurement of the femoral nerve cross-sectional area, and 0.5% ropivacaine was injected based on the area.ED 50 was determined by Dixon′ s up-and-down sequential method.The initial dose was 0.22 ml/mm 2, and the difference between the two successive doses was 0.02 ml/mm 2.The effective block was defined as complete loss of pain sensation in the areas of anterior skin of knee joint, skin on the inner side of the calf and dorsal medial skin of the foot and the degree of motor block was in stages 1-3 assessed using Brunnstrom motor function within 30 min after nerve block.Nerve block was considered ineffective if pain occurred in any nerve distribution area mentioned above.The study was terminated if 7 effective and ineffective alternating waves occurred.ED 50 and 95% confidence interval (CI) were calculated using Probit analysis. Results:In group R, 27 patients were enrolled in the study, and ED 50 (95%CI) of 0.5% ropivacaine for ultrasound-guided femoral nerve block was 0.106 (0.069-0.125) ml/mm 2.In group DR, 23 patients were enrolled in the study, and ED 50 (95% CI) of 0.5% ropivacaine for ultrasound-guided femoral nerve block was 0.038 (0.011-0.059) ml/mm 2.Compared with group R, ED 50 of 0.5% ropivacaine for femoral nerve block was significantly decreased in group R. Conclusion:When combined with dexmedetomidine 0.5 μg/kg, ED 50 of 0.5% ropivacaine based on femoral nerve cross-sectional area for ultrasound-guided femoral nerve block is 0.038 ml/mm 2.

Arterial Stiffness Predicts General Anesthesia-Induced Vasopressor-Resistant Hypotension in Patients Taking Angiotensin-Converting Enzyme Inhibitors.

OBJECTIVES: Patients chronically treated with angiotensin-converting enzyme inhibitors (ACEIs) may develop hypotension after induction of general anesthesia. A fraction of these patients are resistant to therapeutic doses of vasopressors, which poses serious concerns for hemodynamic management. The authors hypothesized that the patients who develop refractory hypotension, compared with those who do not, show lower central arterial stiffness due to the profound effect of ACEIs. DESIGN: Prospective observational study. SETTING: Single tertiary center. INTERVENTIONS: Fifty surgical patients chronically treated with ACEIs were enrolled. Prior to surgery, all the patients had central arterial stiffness assessment measured by carotid-femoral pulse-wave velocity. Patients were categorized into 2 groups according to the systolic blood pressure response during the first 10 minutes after induction of general anesthesia: a vasopressor-resistant hypotension group requiring more than 200 µg phenylephrine, or a control group requiring no more than 200 µg of phenylephrine to maintain systolic blood pressure above 90 mmHg during the study period. MEASUREMENTS AND MAIN RESULTS: Carotid-femoral pulse-wave velocity was significantly lower in the vasopressor-resistant hypotension group compared to the control group (7.6 [7.2-8.3] m/s v 9.9 [8.7-12.0] m/s, p = 0.001 [Hodges-Lehman median difference 2.2, 95% confidence interval = 1.1-4.4]). CONCLUSION: These findings suggested that preoperative measurement of carotid-femoral pulse-wave velocity in patients chronically treated with ACEIs could help identify patients at increased risk of developing hypotension refractory to vasopressors after induction of general anesthesia.