ABSTRACT
Objective To assess the gastric contents before cesarean section using antral cross-sectional area (CSA) measured by ultrasonography.Methods One hundred and seventy-seven American Society of Anesthesiologists physical status Ⅰ-Ⅲ patients,aged 20-44 yr,undergoing cesarean section,were enrolled in this study.The antral CSA in the semi-recumbent and right lateral decubitus positions was measured through the ultrasound images of the antrum in the sagittal plane below xiphoid before anesthesia and qualitatively graded.Qualitative grade 0 was considered as the gold standard,and the receiver operating characteristic (ROC) curve of CSA in assessing the preoperative gastric contents was plotted.Results The critical value of ROC curve of CSA in the semi-recumbent position was 6.025 cm2.The critical value of ROC curve of CSA in the right lateral decubitus position was 9.095 cm2.Conclusion CSA ＜ 6.025 cm2 measured by ultrasonography in the semi-recumbent position or CSA＜9.095 cm2 measured by ultrasonography in the right lateral decubitus position can confirm that the gastric emptying state is achieved before cesarean section.
ABSTRACT
Objective To observe the biomechanieal properties of tendons repaired by five suture techniques in different stage of healing process.Methods After establishing the zone Ⅱ FDP transection model in 2nd,3rd,4th too of both feet in female fowls,the ruptured tendons were repaired with Modified Kessler ( M K ),Kessler plus running ( K +R ),double-strand Kessler ( DK ),double loop (DT) and modified double loop (MT) methods,respectively.Passive and active mobilizations were applied on the 3rd day and 21st day postoperatively.Animals were executed postoperatively,on the 14th,21st and 35th days,respectively and both feet were harvested for biomechanical test.Results Anatomical findings included: The breakage incidence of K+R group was smaller than that of MK group.The excellent and good results of K+R and DK groups were higher compared with that of MK group.Biomechanical results showed: The MK group had the poorest biomechanical results in every stage of tendon healing (P＜0.05) except that the results from MK group on the 35th showed no statistical difference compared with that of MT and DT in extreme load;K+R group exbited the greatest extreme load and tensile strength (P＜0.05);Biomechanical test results from all groups showed significant differences on different testing point: 35th day＞21st day＞14th day(P＜0.05 );No significant differences were found in all groups between the immediate postoperative results onlst day and that from 14th day.ConclusionDuring the recovery of tendon,biomechanical properties returned to the immediate postoperative level on the 14th day and increased along with time.K+R group shows the superiority to the other methods in biomechanical properties as well as low breaking incidence ratein every stage of tendon healing.Kessler plus running is an effective method with high strength against breakage and great resistance to adhesion formation.
ABSTRACT
Objective To compare the biomechanical effect of several commonly used internal fixators in treating the femoral neck fractures so as to provide clinical basis for the selection of ideal internal fixation.Methods Twelve artificial PMMA femoral models were selected,and the central neck of the specimens was sawn with an electric saw at Pauwels angle of 70° to form adduction type femoral neck fracture models.After anatomic reduction,the specimens were fixed with dynamic hip screw ( DHS),three hollow screws,proximal femoral nail (PFN) and dynamic sleeve three-wing screw according to the operative approach,respectively.Instron-8874 servo-hydraulic mechanical testing machine was used to fix the specimens which simulated uniped standing.Fifteen key points on proximal femur were selected as test points and were given gradation loading at speed of 10 mm/min with linear load 0-1 200 N.The strain of each point under 1200 N load,head sink displacement under different loads and the strain of eight points on principal pressure side were measured.Results There was a peak at the eight resistance strain gage at 1200 N load and the strain values of the DHS,three hollow screws,PFN and dynamic sleeve three-wing screw were (700 ±35) μεz,(756 ± 14) με,( 1362 ± 136) με and (3024 ± 127) με,with statistical significance (P ＜ 0.01 ).Under the same load,the head sink displacement in the group of dynamic sleeve three-wing screw was greater than that of the hollow screws group and the PFN group ( P ＜0.01 ),but smaller thau that of the DHS group ( P ＜ 0.01 ).The strain values at the eight resistance strain gage in the group of dynamic sleeve three-wing screw was larger than that of the other three groups under the same load (P ＜ 0.01 ),and the strain values increased with the increase of load at the same fixation group.Conclusion Dynamic sleeve three-wing screw has good biomechanical stability for treatment of femoral neck fracture,which can be applied in the clinical practice.