This computational study was the first to assess blood flow characteristics at the site of infrarenal AAA rupture in realistic aortic geometries. In contradiction to our initial hypothesis, rupture occurred not at sites of high pressure and WSS but rather at regions of predicted flow recirculation, where low WSS and thrombus deposition predominated. These findings raise the possibility that this flow pattern may lead to thrombus deposition, which may elaborate adventitial degeneration and eventual AAA rupture.
Objectives: This study evaluated the safety and hospital impact of transition from a routine to a selective policy of postoperative transfer to the intensive care unit (ICU) for elective open abdominal aortic aneurysm (AAA) repair.Methods: This retrospective study included all open elective AAA repairs from August 8 2010, to December 1, 2014, performed in our center. The study was approved by the Institutional Review Board, and informed consent was waived. Patients were identified through our prospective database, and electronic records were reviewed to extract patient characteristics, operative details, and postoperative complications. Patients operated on before March 13, 2012, were routinely sent to the ICU after operation (group A). Patients treated after this date were sent directly to an intermediate care unit with a ratio of one nurse for three patients (group B), unless otherwise determined preoperatively by the surgeon or after intraoperative complications. We evaluated the safety of our change in practice, looking at complications and mortality rate, length of stay, and transfer from an intermediate care unit to the ICU.Results: The study included 310 patients (266 men, 44 women), with a mean age 70 of years, and a mean AAA diameter 65 mm. Group A and B included 118 and 192 patients, respectively. The postoperative mortality rate was similar in each group (1%). ICU admission in group B was spared in 78% (149 of 192) of patients. Only two patients (1%) from the intermediate care unit were subsequently admitted to the ICU. There was no increase in mortality in group B (0.5%) compared with group A (0.8%) during hospital stay. Hospital lengths of stay were similar between groups group A (8.6 days) and group B (8.0 days; P ¼ NS).Conclusions: Our results confirm the safety of a selective ICU pathway after open elective AAA repair, with most patients sent directly to an intermediate care unit.
Laboratory experiments were conducted to evaluate the potential to utilize ultraviolet (UV) photooxidation as a pre-treatment to render recalcitrant volatile organic compounds into more biodegradable compounds. α-Pinene was selected due to its low water solubility and low biodegradability. α-Pinene-contaminated gaseous streams with inlet loadings between 250 and 2500 g m −3 h −1 were passed through an annular reactor equipped with a UV lamp that emitted light at 254 nm and 185 nm wavelengths. The outlet stream containing UV photooxidation intermediates was then sparged through nanopure water that was then analyzed for its total organic carbon (TOC) content and subjected to batch biodegradability tests. UV photooxidation effectively degraded α-pinene with a maximum removal rate of about 700 g m −3 h −1 . The removal rate followed first order kinetics at low inlet loadings (less than 1200 g m −3 h −1 ) and approached zero order behavior at higher inlet loadings. The principal oxidizing species in the reactor was ozone. Of the total α-pinene removed, measured as TOC, 50% was converted to water-soluble and more biodegradable intermediates. The biodegradability of the resultant intermediates was similar to that of methyl ethyl ketone (MEK), which is 3-30 times more biodegradable than α-pinene. These results show that the use of UV photooxidation is a promising and effective pre-treatment technique for enhancing the biodegradability of hydrophobic and recalcitrant organic compounds such as α-pinene.
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