ABSTRACT
To determine whether end-expiratory lung volume measured with volumetric capnography (EELVCO2) can individualize positive end-expiratory pressure (PEEP) setting during laparoscopic surgery. We studied patients undergoing laparoscopic surgery subjected to Fowler (F-group; n = 20) or Trendelenburg (T-group; n = 20) positions. EELVCO2 was measured at 0° supine (baseline), during capnoperitoneum (CP) at 0° supine, during CP with Fowler (head up + 20°) or Trendelenburg (head down - 30°) positions and after CP back to 0° supine. PEEP was adjusted to preserve baseline EELVCO2 during and after CP. Baseline EELVCO2 was statistically similar to predicted FRC in both groups. At supine and CP, EELVCO2 decreased from baseline values in F-group [median and IQR 2079 (768) to 1545 (725) mL; p = 0.0001] and in T-group [2164 (789) to 1870 (940) mL; p = 0.0001]. Change in body position maintained EELVCO2 unchanged in both groups. PEEP adjustments from 5.6 (1.1) to 10.0 (2.5) cmH2O in the F-group (p = 0.0001) and from 5.6 (0.9) to 10.0 (2.6) cmH2O in T-group (p = 0.0001) were necessary to reach baseline EELVCO2 values. EELVCO2 increased close to baseline with PEEP in the F-group [1984 (600) mL; p = 0.073] and in the T-group [2175 (703) mL; p = 0.167]. After capnoperitoneum and back to 0° supine, PEEP needed to maintain EELVCO2 was similar to baseline PEEP in F-group [5.9 (1.8) cmH2O; p = 0.179] but slightly higher in the T-group [6.5 (2.2) cmH2O; p = 0.006]. Those new PEEP values gave EELVCO2 similar to baseline in the F-group [2039 (980) mL; p = 0.370] and in the T-group [2150 (715) mL; p = 0.881]. Breath-by-breath noninvasive EELVCO2 detected changes in lung volume induced by capnoperitoneum and body position and was useful to individualize the level of PEEP during laparoscopy.Trial registry: Clinicaltrials.gov NCT03693352. Protocol started 1st October 2018.
Subject(s)
Carbon Dioxide , Laparoscopy , Humans , Lung , Lung Volume Measurements , Positive-Pressure Respiration/methods , RespirationABSTRACT
Abstract Objective This study evaluated the fracture resistance of endodontically treated teeth restored with fiber reinforced composite posts, using three resin composite core build-up materials, (Clearfil Photo Core (CPC), MultiCore Flow (MCF), and LuxaCore Z-Dual (LCZ)), and a nanohybrid composite, (Tetric N-Ceram (TNC)). Material and Methods Forty endodontically treated lower first premolars were restored with quartz fiber posts (D.T. Light-Post) cemented with resin cement (Panavia F2.0). Samples were randomly divided into four groups (n=10). Each group was built-up with one of the four core materials following its manufacturers’ instructions. The teeth were embedded in acrylic resin blocks. Nickel-Chromium crowns were fixed on the specimens with resin cement. The fracture resistance was determined using a universal testing machine with a crosshead speed of 1 mm/min at 1350 to the tooth axis until failure occurred. All core materials used in the study were subjected to test for the flexural modulus according to ISO 4049:2009. Results One-way ANOVA and Bonferroni multiple comparisons test indicated that the fracture resistance was higher in the groups with CPC and MCF, which presented no statistically significant difference (p>0.05), but was significantly higher than in those with LCZ and TNC (p<0.05). In terms of the flexural modulus, the ranking from the highest values of the materials was aligned with the same tendency of fracture loads. Conclusion Among the cores used in this study, the composite core with high filler content tended to enhance fracture thresholds of teeth restored with fiber posts more than others.
Subject(s)
Humans , Tooth Fractures , Post and Core Technique , Composite Resins/chemistry , Tooth, Nonvital/therapy , Surface Properties , Viscosity , Materials Testing , Random Allocation , Reproducibility of Results , Analysis of Variance , Statistics, Nonparametric , Pliability , Resin Cements/chemistry , Dental Restoration Failure , Methacrylates/chemistryABSTRACT
ABSTRACT This paper presents the experimental results of a reinforced concrete beams (RC) strengthened with internal steel fibers (SF) and external glass fiber reinforced polymer laminates (GFRP). The research work studied the load carrying capacity, deformation, crack width and ductility of the reinforced concrete beams strengthened with different steel fiber ratios and steel fiber reinforced concrete beams strengthened with three different glass fiber reinforced polymer laminates of two different thickness. The experimental results clearly shows that incorporating steel fibers in to the reinforced concrete beams reduced the crack width and distribute the crack evenly and also increases the bonding between tension face of the beam with glass fiber reinforced polymer laminates. The results also shows that glass fiber reinforced polymer laminates strengthened steel fiber reinforced concrete beams increases the flexural strength and ductility as compared with unstrengthened counterpart. In addition to this experimental work, theoretical calculations were done to find the ultimate load carrying capacity of the beam tested, and also compared with the experimental results.
ABSTRACT
La incorporación de fibras de refuerzo a resinas compuestas se ha convertido en una alternativa de tratamiento protésico altamente conservador. De esta investigación fue evaluar la resistencia flexural (RF) de una resina compuesta indirecta reforzada con tres diferentes marcas comerciales de fibras de vidrio, variando su ubicación y sometidas a envejecido físico ó químico. Se fabricaron 98 especímenes de resina compuesta Gradia (GC-America Inc.) de 22 mm x 2 mm x 3 mm; a 14 muestras no se les colocó fibras (SF), se almacenaron en agua destilada por 60 días, luego se subdividieron en dos grupos de 7 muestras,G1 - SFA y G2 - SFT el cual se sometió a termociclado (3000 ciclos de 5°/55°C en intervalos de 1 min); las otras 84 muestras se reforzaron fibras unidireccionales: 42 muestras para ser almacenadas en agua por 60 días (CFA), divididas en dos sub-grupos de 21, en relación a la ubicación de la fibra en la zona de compresión (CFAC) ó tracción (CFAT); finalmente en tres grupos de 7, dependiendo de la marca; Fibrex-Lab® (Angelus) los grupos G3 - CFACFLab y G6 - CFATFLab, FibreKor® (Jeneric/Penton) los grupos G4 - CFACFKor y G7 - CFATFKor y Vectris® (Ivoclar/Vivadent) los grupos G5 - CFACVectris y G8 - CFATVectris. Las 42 restantes después del almacenamiento en agua se sometieron al termociclado , se dividieron en dos subgrupos de 21, en relación a la ubicación de la fibra en la zona de compresión (CFTC) ó de tracción (CFTT); finalmente se dividió en tres grupos de 7, entonces Fibrex-Lab® conformó los grupos G9 - CFTCFLab y G12 - CFTTFLab, FibreKor® los grupos G10 - CFTCFKor y G13 - CFTTFKor y Vectris® los grupos G11 - CFTCVectris y G14 - CFTTVectris. Las muestras fueron sometidas a la prueba de flexión de tres puntos hasta su fractura, en maquina de pruebas universales (Shimadzu AGS-J) a una velocidad de 1mm/min. Los datos fueron recolectados, tabulados en hoja de cálculo y luego analizados con un estadístico de t de student....
The incorporation of reinforce fibers to composite has turned into an alternative of high conservative prosthetic treatment. The aim of this study was to evaluate the flexure strength (RF) of a indirect reinforce composite using three fiber glass commercial brands, varying the location and submitted to physical o chemical aging. 98 specimen were made of 22 mm x 2 mm x 3 mm Gradia resin compound (GC-America Inc.); 14 samples were not reinforce with fiber glass (SF), They were store in distilled water for 60 days then divided in 2 groups of 7 samples, G1 - SFA and G2 - SFT was thermocycled (3000 cycles of 5 °/55°C in intervals of 1 min); the other 82 samples were reinforce with unidirectional fibers: 42 to be stored in distilled water for 60 days (CFA), divided in 2 subgroups of 21, in relation with the localization of the fiber on the compression zone (CFAC) or traction (CFAT); Finally divided in 3 groups of 7, depending on the brand; Fibrex-Lab® (Angelus) the groups G3 - CFACFLab and G6 - CFATFLab, FibreKor® (Jeneric/Penton) the groups G4 - CFACFKor and G7 - CFATFKor and Vectris® (Ivoclar/Vivadent) the groups G5 - CFACVectris and G8 - CFATVectris. The remaining 42 samples after storage in water were submitted to thermocycling, divided in 2 subgroups of 21, in relation with the localization of the fiber on the compression zone (CFTC) or traction (CFTT); Finally divided in 3 groups of 7 then G9 was conformed Fibrex-Lab® CFTCFLab and G12 - CFTTFLab, FibreKor® the groups G10 - CFTCFKor and G13 - CFTTFKor and Vectris® the groups G11 - CFTCVectris and G14 - CFTTVectris. The samples were submitted to the three points flexion test until fracture, in a universal testing machine (Shimadzu AGS-J) to a speed of 1mm/min. The information was gathered, tabulated in spreadsheet and then analyzed with a statistician t of student to determine differences between the groups without fibers and 3 factors ANOVA on the reinforced groups for the varying location...