ABSTRACT
Objective: To investigate the impact of stent porosity on hemodynamics in the simulated sigmoid sinus diverticulum. Methods: An idealized hemodynamic model of sigmoid sinus diverticulum (S0 model, no stent) was constructed based on computational fluid dynamics (CFD). The hemodynamic changes in models stented with different porosities of 75%, 50% and 25% (corresponding to S1, S2, S3 model) were observed. Results: The mean flow velocities in sigmoid sinus diverticulum of model S0, S1, S2 and S3 was 12.65, 4.68, 2.20 and 0.41 mm/s, respectively. Compared with model S0, the velocities in model S1, S2 and S3 decreased by 63.00%(7.97/12.65), 82.61%(10.45/12.65) and 96.76%(12.24/12.65), respectively. The area of high pressure and high wall shear stress (WSS) in diverticulum distal wall reduced gradually with the decrease of stent porosity. Meanwhile, the pressure and WSS tended to distribute uniformly in the entire diverticulum. However, the mean pressures for model S0, S1, S2 and S3 in diverticulum (64.04, 63.86, 62.54 and 60.95 Pa, respectively) showed no significant change. Conclusion: Stent with lower porosity can significantly improve blood flow and hemodynamic stress conditions in the simulated sigmoid sinus diverticulum.
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Objective To study CT-guided localization of additional pulmonary nodules with microcoils prior to video-assisted thoracoscopic surgery (VATS) resection in patients with suspected lung cancer.Methods Eleven patients suspected lung cancer underwent preoperative microcoils localization towards additional small pulmonary nodules.The head of microcoil was pinpointed adjacent to the target nodule while its end tail remained above the visceral pleura.VATS were performed within 24 hours, and comprehensive assessments were conducted according to surgical and pathological outcomes of primary and additional lesions, and suitable surgical processes were followed.Results All 11 localizing pulmonary nodules (4-15 mm in diameter) were successfully removed after VATS, 9 microcoils'' end tails of which were placed above visceral pleural surface.There were no serious complications related with localizing procedure.Other 16 lesions including 11 primary ones were resected.The surgical and pathological outcomes for lung lesions were utterly assessed.Conclusion Microcoil preoperative localization provides helpful orientation for complete resection and assessment of multiple pulmonary lesions in patients with suspected lung cancer.
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Objective To investigate effect of dexmedetomidine sedation anesthesia on perioperative hemo-dynamics and heart rate variability in patients with hypertension .Methods 50 cases with selective laparoscopic chol-ecystectomy were randomly divided into Group A ( dexmedetomidine sedation ) and Group B ( saline control ) ,25 cases each group .Low-frequency ( LFnu ) , high-frequency ( HFnu ) , LF/HF, LFnu ( LF/TP ×100%) , HFnu ( HF/TP × 100%)and total-power(TP)were recorded at the time points of baseline (T0),immediately after administration(T1), immediately after anesthesia induction (T2),1 min after anesthesia induction (T3),5 min after anesthesia induction (T4)and 10 min after anesthesia induction (T5).NIBP and HR were recorded at the points of T0 ~T5.Results Compared with T0 or Group A,there was an increase in SBP and HR at T2~T4(P<0.05)in Group B.Heart rate variability changes showed that Lfnu [(66.3 ±7.8),(64.5 ±6.0),(65.3 ±6.5)],LF/HF[(1.9 ±0.7),(1.7 ± 0.5),(1.7 ±0.8)],TP[(2 283 ±472),(2 197 ±310),(2 108 ±256)]decreased significantly at T2-T4(tLFnu=5.16,4.15,4.40,tLF/HF=4.55,4.24,3.49,tTP=3.27,1.71,0.96,P<0.05) in Group A,while there was no significant change in Group A .Conclusion Dexmedetomidine sedation may have less influence on hemodynamics and automomic nerve ,which be an useful analgesic adjuvanct for the patients undergoing selective laparoscopic chole -cystectom.