Delayed gastric emptying following pancreatic resection: Incidence, risk factors, and impact on healthcare utilization

Background: Delayed gastric emptying (DGE) frequently occurs following pancreaticoduodenectomy (PD). This study characterizes incidence and risk factors for DGE and examines its implications on healthcare utilization. Methods: A prospectively-maintained database was reviewed. DGE was classified using International Study Group of Pancreatic Surgery criteria. Patients who developed DGE and those who did not were compared. Results: 276 patients underwent PD (\u3e80% pylorus-preserving, antecolic-reconstruction). DGE developed in 49 patients (17.8%): 5.1% grade B, 3.6% grade C. Demographic, clinical, and operative variables were similar between patients with DGE and those without. DGE patients were more likely to present multiple complications (32.6% versus 4.4%, ≥3 complications, P\u3c0.001), including postoperative pancreatic fistula (POPF) (42.9% versus 18.9%, P=0.001) and intra-abdominal abscess (16.3% versus 4.0%, P=0.012). Patients with DGE had longer hospital stay (median, 12 versus 7 days, P\u3c0.001) and were more likely to require transitional care upon discharge (24.5% versus 6.6%, P\u3c0.001). On multivariate analysis, POPF was the only predictor for DGE (OR 3.29, P=0.021). Conclusions: Although DGE occurred in \u3c20% of patients after PD, it was associated with increased healthcare utilization. Patients with POPF were at risk for DGE. Anticipating DGE can help individualize care and allocate resources to high-risk patients

Seismic Metamaterials: Rayleigh Wave Control in an Elastic Half-Space

Seismic surface waves and Rayleigh waves, in particular, are usually responsible for the failure of structures during an earthquake as they carry the highest energy and have maximum amplitudes. In order to mitigate the hazard associated with earthquakes, seismologists and engineers have been exploring novel ideas that can lead to a paradigm shift. One such idea which has recently been explored is that of seismic metamaterials. The idea of metamaterials, originally conceptualized in electromagnetics for applications on the nanoscale has been extended and applied to seismic waves on the geophysical scale. Metamaterials have been found to interact with waves in an exceptional manner not necessarily seen in nature. In this thesis, two different classes of seismic metamaterials have been comprehensively reviewed. To understand the physics of these metamaterials we perform numerical simulations in both frequency-domain and time-domain. Periodic inclusions arranged in the soil can lead to permitted and prohibited frequency bands for seismic wave propagation. Both 1D and 2D periodic media using concrete as the inclusion material have been studied. The results show that bandgaps can be obtained when the size of the inclusion is comparable to the wavelength. By anchoring the ends of the piles into a stiff layer, complete stop bands for seismic waves can be obtained. Another way to achieve this is by exploiting the localized displacements of resonant mass units to dampen propagating seismic waves. A locally resonant structure has been designed to obtain a very wide bandgap for Rayleigh waves in the low-frequency range. It has been found that the stiffness of the soil plays a vital role in deciding the design and performance of the barrier. An unprecedented way to improve the sensitivity of Terrestrial GW Detectors in the low-frequency regime (< 20 Hz) has been proposed using a metabarrier of locally resonant devices. Another barrier consisting of clamped piles is suggested for a site where the bedrock is at a shallow depth. This can potentially address the problem of seismic gravity gradient noise which currently limits the detector sensitivity in the 9-15 Hz band. The spectral- element method has been used to carry out numerical studies in time-domain for evaluating realistic design of seismic barriers. The metamaterials approach also has a good scope in the shielding of infrastructure such as Nuclear Power Plants which pose a high environmental risk and also for those structures located in regions where uncertainty in the hazard estimation is high. From this study, we conclude that seismic metamaterials indeed offer an appealing alternative to mitigate the destructive surface Rayleigh waves

Treatment of bacteriobilia decreases wound infection rates after pancreaticoduodenectomy

AbstractBackgroundAlthough mortality following pancreaticoduodenectomy is decreasing, postoperative morbidity remains high. It was hypothesized that culture-directed treatment of bacteriobilia would decrease the incidence of infectious complications following pancreaticoduodenectomy.MethodsIn a retrospective study of 197 pancreaticoduodenectomy patients, those in the control group (n = 128, 2005–2009) were given perioperative prophylactic antibiotics, whereas those in the treatment group (n = 69, 2009–2011) were continued on antibiotics until intraoperative bile culture results became available. Patients with bacteriobilia received 10 days of antibiotic treatment, which was otherwise discontinued in patients without bacteriobilia. Various complication rates were compared using Fisher's exact test for categorical variables, Wilcoxon rank sum test for ordinal variables, and a two-sample t-test for continuous variables.ResultsDemographics, comorbidities, baseline clinical characteristics, and intraoperative and postoperative variables were similar between the two groups. There were higher incidences of elevated creatinine (19% versus 4%; P = 0.004) and preoperative hyperglycaemia (18% versus 7%; P = 0.053) in the control group. Fewer patients in the control group underwent preoperative biliary stenting (48% versus 67%; P = 0.017) and intraperitoneal drains were placed at the time of resection more frequently in the control group (85% versus 38%; P < 0.001). Bacteriobilia was found in 59% of patients. Treatment of bacteriobilia was associated with a decrease in the rate of postoperative wound infections (12% in the control group versus 3% in the treatment group; P = 0.036) and overall complication severity score (1 in the control group versus 0 in the treatment group; P = 0.027).ConclusionsProlonged antibiotic therapy for bacteriobilia may decrease postoperative wound infection rates after pancreaticoduodenectomy. A randomized prospective trial is warranted to provide evidence to further support this practice