[PECS I block for postoperative analgesia in patients undergoing breast augmentation surgery: a randomized double-blind placebo-controlled study]. / Bloqueio PECS I para analgesia pós­operatória em pacientes submetidos a mamoplastia de aumento: estudo randomizado, duplo­cego, controlado por placebo.

BACKGROUND AND OBJECTIVES: PECS I block was first described for surgery involving the pectoralis muscles. No randomized clinical trial has been conducted on surgeries that directly involve these muscles, such as subpectoral breast augmentation. We hypothesized that PECS I block would decrease pain in the postoperative period in this population. METHODS: This was a randomized, double-blind, placebo-controlled trial in women undergoing subpectoral breast augmentation surgery. PECS I block was performed using 0.4 mL.kg-1 of 0.9% saline on one side and bupivacaine (0.25%) on the other side, each patient being her own control. Numeric Rating Scale (NRS) pain scores (0-10) were measured at rest and during movement. The primary outcome was pain score at rest 30 minutes after arrival in the PACU. To detect a clinically significant difference of 50% in pain reduction, 14 volunteers were enrolled (power of 90% and alpha<0.05). RESULTS: In the PACU, three patients had no difference in pain between sides, five had reduced pain on the placebo side, and six had reduced pain on the bupivacaine side. In the bupivacaine group, pain scores at rest at 5, 30 and 60 minutes and 24 hours were 4.89 (4.23-5.56; mean 95% CI), 3.75 (3.13-4.37), 3.79 (2.93-4.64), and 2.29 (1.56-3.01), respectively, whereas in the placebo group, they were 4.96 (4.32-5.60), 4.00 (3.50-4.49), 3.93 (3.12-4.73), and 2.29 (1.56-3.01), respectively. CONCLUSIONS: PECS I block in patients undergoing breast augmentation surgery does not provide better pain relief than placebo. Therefore, the indications for PECS I block in breast augmentation surgery should be reconsidered.

PECS I block for postoperative analgesia in patients undergoing breast augmentation surgery: a randomized double-blind placebo-controlled study / Bloqueio PECS I para analgesia pós-operatória em pacientes submetidos a mamoplastia de aumento: estudo randomizado, duplo-cego, controlado por placebo

Abstract Background and objectives: PECS I block was first described for surgery involving the pectoralis muscles. No randomized clinical trial has been conducted on surgeries that directly involve these muscles, such as subpectoral breast augmentation. We hypothesized that PECS I block would decrease pain in the postoperative period in this population. Methods: This was a randomized, double-blind, placebo-controlled trial in women undergoing subpectoral breast augmentation surgery. PECS I block was performed using 0.4 mL.kg-1 of 0.9% saline on one side and bupivacaine (0.25%) on the other side, each patient being her own control. Numeric Rating Scale (NRS) pain scores (0 - 10) were measured at rest and during movement. The primary outcome was pain score at rest 30 minutes after arrival in the PACU. To detect a clinically significant difference of 50% in pain reduction, 14 volunteers were enrolled (power of 90% and alpha < 0.05). Results: In the PACU, three patients had no difference in pain between sides, five had reduced pain on the placebo side, and six had reduced pain on the bupivacaine side. In the bupivacaine group, pain scores at rest at 5, 30 and 60 minutes and 24 hours were 4.89 (4.23 - 5.56; mean 95% CI), 3.75 (3.13 - 4.37), 3.79 (2.93 - 4.64), and 2.29 (1.56 - 3.01), respectively, whereas in the placebo group, they were 4.96 (4.32 - 5.60), 4.00 (3.50 - 4.49), 3.93 (3.12 - 4.73), and 2.29 (1.56 - 3.01), respectively. Conclusions: PECS I block in patients undergoing breast augmentation surgery does not provide better pain relief than placebo. Therefore, the indications for PECS I block in breast augmentation surgery should be reconsidered.

Resumo Justificativa e objetivos: O bloqueio PECS I foi descrito pela primeira vez para cirurgia envolvendo os músculos peitorais. Nenhum estudo clínico randomizado foi realizado em procedimentos envolvendo diretamente os músculos peitorais, como a mamoplastia de aumento submuscular. Nossa hipótese foi de que o bloqueio PECS I diminuiria a dor pós-operatória nessa população. Método: Realizamos estudo randomizado, duplo-cego, controlado por placebo em mulheres submetidas à mamoplastia de aumento submuscular. Realizamos o bloqueio PECS I com 0,4 mL.kg-1 de solução salina a 0,9% de um lado e bupivacaína (0,25%) do outro lado, sendo cada paciente seu próprio controle. Os escores da Escala de Avaliação Numérica (EAN) de dor (0 - 10) foram obtidos em repouso e durante movimento. O desfecho primário foi o escore de dor em repouso 30 minutos após a chegada à SRPA. Para detectar uma diferença clinicamente significante de 50% na redução da dor, 14 voluntárias foram incluídas (poder de 90% e alfa < 0,05). Resultados: Na SRPA, três pacientes não apresentaram diferença na dor entre os lados, cinco relataram menos dor no lado do placebo e seis, menos dor no lado da bupivacaína. No grupo bupivacaína, os escores de dor em repouso aos 5, 30 e 60 minutos e 24 horas foram 4,89 (4,23 - 5,56; IC médio 95%), 3,75 (3,13 - 4,37), 3,79 (2,93 - 4,64) e 2,29 (1,56 - 3,01), respectivamente, enquanto no grupo placebo foram 4,96 (4,32 - 5,60), 4,00 (3,50 - 4,49), 3,93 (3,12 - 4,73) e 2,29 (1,56 - 3,01), respectivamente. Conclusões: O bloqueio PECS I em pacientes submetidas a mamoplastia de aumento não oferece melhor alívio da dor do que o placebo. Portanto, as indicações para bloqueio de PECS I na cirurgia de aumento de mama devem ser reconsideradas.

Pectoral nerves I block is associated with a significant motor blockade with no dermatomal sensory changes: a prospective volunteer randomized-controlled double-blind study.

PURPOSE: The pectoral nerves (PECS) I block, first described in 2011 for surgery involving the pectoralis muscle, has principally been used for breast cancer surgery. No formal evaluation of its differential motor- and sensory-blocking abilities has been reported. We hypothesize that the PECS I block will produce a motor block of the pectoralis muscles with diminished upper limb adduction strength as measured with a handheld dynamometer. METHODS: We conducted a PECS I block in a randomized placebo-controlled trial in six healthy subjects who received 0.4 mL·kg-1 of 0.9% saline (placebo) on one side and bupivacaine (0.25% with 1:400 000 epinephrine) on the other. We measured both upper limb adduction strength with a dynamometer and sensory skin levels over the thorax. RESULTS: The mean (standard deviation [SD]) adductor strength evaluated before the block was 119.4 (20.7) Newtons (N). After the PECS I block with bupivacaine, the mean (SD) strength of 54.2 (16.3) N was compared with 116.0 (30.4) N in the placebo group (difference in means 61.8 N; 95% confidence interval [CI], 27.8 to 95.8 N; P = 0.005), showing a 54.6% (95% CI, 43.6 to 65.6%) reduction in adductor strength. There was no difference in dermatomal skin sensory testing between the placebo and bupivacaine sides. CONCLUSIONS: This study shows that a PECS I block produces motor blockade as shown by reduced upper limb adductor strength without any overlying dermatomal sensory loss. TRIAL REGISTRATION: www.clinicaltrials.gov (NCT03040167) 2 February 2017.

Complex Fluids and Hydraulic Fracturing.

Nearly 70 years old, hydraulic fracturing is a core technique for stimulating hydrocarbon production in a majority of oil and gas reservoirs. Complex fluids are implemented in nearly every step of the fracturing process, most significantly to generate and sustain fractures and transport and distribute proppant particles during and following fluid injection. An extremely wide range of complex fluids are used: naturally occurring polysaccharide and synthetic polymer solutions, aqueous physical and chemical gels, organic gels, micellar surfactant solutions, emulsions, and foams. These fluids are loaded over a wide range of concentrations with particles of varying sizes and aspect ratios and are subjected to extreme mechanical and environmental conditions. We describe the settings of hydraulic fracturing (framed by geology), fracturing mechanics and physics, and the critical role that non-Newtonian fluid dynamics and complex fluids play in the hydraulic fracturing process.

Pressure-driven suspension flow near jamming.

We report here magnetic resonance imaging measurements performed on suspensions with a bulk solid volume fraction (ϕ_{0}) up to 0.55 flowing in a pipe. We visualize and quantify spatial distributions of ϕ and velocity across the pipe at different axial positions. For dense suspensions (ϕ_{0}>0.5), we found a different behavior compared to the known cases of lower ϕ_{0}. Our experimental results demonstrate compaction within the jammed region (characterized by a zero macroscopic shear rate) from the jamming limit ϕ_{m}≈0.58 at its outer boundary to the random close packing limit ϕ_{rcp}≈0.64 at the center. Additionally, we show that ϕ and velocity profiles can be fairly well captured by a frictional rheology accounting for both further compaction of jammed regions as well as normal stress differences.

Alteration of Asian lacquer: in-depth insight using a physico-chemical multiscale approach.

Oriental lacquer has been used in Asian countries for thousands of years as a durable and aesthetic coating material for its adhesive, consolidating, protective and decorative properties. Although these objects are made from an unusual material in Occident, Western museum collections host many lacquerwares. Curators, restorers and scientists are daily confronted with questions of their conservation and their alteration. The characterization of their conservation state is usually assessed through visual observations. However deterioration often starts at the microscopic level and cannot be detected by a simple visual inspection. Often, ageing and deterioration of artworks are connected to physical, mechanical and chemical transformations. Thus new insight into alteration of lacquer involves the monitoring of macro-, microscopic and molecular modifications, and this can be assessed from physico-chemical measurements. Non-invasive (microtopography and Scanning Electron Microscopy - SEM) and micro-invasive (infrared micro-spectroscopy using a synchrotron source - SR-µFTIR) investigations were performed to study the degradation processes of lacquers and evaluate their level of alteration. In particular, spectral decomposition and fitting procedure were performed in the 1820-1520 cm(-1) region to follow the shift of the C=O and C=C band positions during lacquer ageing. The present work proves the potential of this physico-chemical approach in conservation studies of lacquers and in the quantification of the state of alteration. It evidences chemical phenomena of alteration such as oxidation and decomposition of a lacquer polymeric network. It also demonstrates for the first time the degradation front of artificially aged lacquer and the chemical imaging of a more than 2000 years old archaeological lacquer by using SR-µFTIR.

Selective ultrasound guided pectoral nerve targeting in breast augmentation: How to spare the brachial plexus cords?

Subpectoral breast augmentation surgery under regional anesthesia requires the selective neural blockade of the medial and lateral pectoral nerves to diminish postoperative pain syndromes. The purpose of this cadaver study is to demonstrate a reliable ultrasound guided approach to selectively target the pectoral nerves and their branches while sparing the brachial plexus cords. After evaluating the position and appearance of the pectoral nerves in 25 cadavers (50 sides), a portable ultrasound machine was used to guide the injection of 10 ml of 0.2% aqueous methylene blue solution in the pectoral region on both sides of three Thiel's embalmed cadavers using a single entry point-triple injection technique. This technique uses a medial to lateral approach with the entry point just medial to the pectoral minor muscle and three subsequent infiltrations: (1) deep lateral part of the pectoralis minor muscle, (2) between the pectoralis minor and major muscles, and (3) between the pectoralis major muscle and its posterior fascia under ultrasound visualization. Dissection demonstrates that the medial and lateral pectoral nerves were well stained while leaving the brachial plexus cords unstained. We show that 10 ml of an injected solution is sufficient to stain all the medial and lateral pectoral nerve branches without a proximal extension to the cords of the brachial plexus.

Evaluation of bacterial contamination and control methods in soluble metalworking fluids.

In the United States, 1.2 million workers are exposed to metalworking fluids. During operations, aerosols are produced and airborne contaminants can be inhaled. Although biocides are used to control the bacterial content of metalworking fluids, they can create health-related problems, and their efficiency remains to be proved. The objectives of this project were (1) to verify whether rigorous cleaning according to a standard protocol could reduce microbial contamination and (2) whether the use of biocides with different spectra could reduce the bacterial population. Four similar machines producing similar components were evaluated; a specific treatment was applied to each machine. The machine used as a control (1) was thoroughly cleaned prior to sampling, (2) did not undergo any major cleaning afterward, and (3) was operated without the use of any biocide. A major cleaning is a protocol described and recommended by the fluid manufacturer and was performed on the three other machines, two of which were subsequently treated with biocides weekly. Fluid samples from the four lathes were collected weekly during a 6-month period, and total bacterial and cultivable Gram-negative bacteria were analyzed for each sample. Major cleaning of the machines (120-4) did not significantly reduce the concentration of bacteria in the cutting fluids when compared with the control machine (120-3), which had not undergone major cleaning. The concentrations of total bacteria were in the 10(6) CFU/mL range for these two lathes; however, a reduction in the total number of fluid changes was observed for this machine. Bacterial flora in the cutting fluids was significantly controlled with the use of biocides. Bacteria concentrations were in the 10(3)-10(5) CFU/mL range for the lathes with the use of biocides. Since thorough cleaning is insufficient and biocides are recognized as being responsible for some worker health problems, other avenues for controlling bacterial flora in cutting fluids should be evaluated to reduce worker exposure to their bacterial contaminants.

The infraclavicular brachial plexus block by the coracoid approach is clinically effective: an observational study of 150 patients.

PURPOSE: To evaluate the sensory distribution, motor block and the clinical efficacy of the infraclavicular block by the coracoid approach. METHODS: In this prospective descriptive study, 150 patients received an infraclavicular block by the coracoid approach performed by a single anesthesiologist. Neurostimulation was used and 40 mL of mepivacaine 1.5% with adrenaline were injected. Block performance time, sensory distribution, motor block and tourniquet tolerance were evaluated. RESULTS: Time to perform the block was 5 +/- 2 min (mean +/- SD). Success rate defined as analgesia in the five nerves distal to the elbow (musculocutaneous, median, ulnar, radial and medial cutaneous nerve of the forearm) was 91% (137 patients). A proximal block of the axillary nerve was present in 98.5% of the patients and of the medial cutaneous nerve of the arm in 60%. An arm tourniquet ( 250 mmHg of pressure ) was applied to 115 of the 137 patients with a successful block and all tolerated the tourniquet for a duration of 37 +/- 21 min ( mean +/- SD). CONCLUSION: Infraclavicular block by the coracoid approach provides an extensive sensory distribution with an excellent tourniquet tolerance. We conclude that this approach provides highly consistent brachial plexus anesthesia for upper extremity surgery.