Streamwise-travelling viscous waves in channel flows

The unsteady viscous flow induced by streamwise-travelling waves of spanwise wall velocity in an incompressible laminar channel flow is investigated. Wall waves belonging to this category have found important practical applications, such as microfluidic flow manipulation via electro-osmosis and surface acoustic forcing and reduction of wall friction in turbulent wall-bounded flows. An analytical solution composed of the classical streamwise Poiseuille flow and a spanwise velocity profile described by the parabolic cylinder function is found. The solution depends on the bulk Reynolds number R, the scaled streamwise wavelength (Formula presented.), and the scaled wave phase speed U. Numerical solutions are discussed for various combinations of these parameters. The flow is studied by the boundary-layer theory, thereby revealing the dominant physical balances and quantifying the thickness of the near-wall spanwise flow. The Wentzel–Kramers–Brillouin–Jeffreys (WKBJ) theory is also employed to obtain an analytical solution, which is valid across the whole channel. For positive wave speeds which are smaller than or equal to the maximum streamwise velocity, a turning-point behaviour emerges through the WKBJ analysis. Between the wall and the turning point, the wall-normal viscous effects are balanced solely by the convection driven by the wall forcing, while between the turning point and the centreline, the Poiseuille convection balances the wall-normal diffusion. At the turning point, the Poiseuille convection and the convection from the wall forcing cancel each other out, which leads to a constant viscous stress and to the break down of the WKBJ solution. This flow regime is analysed through a WKBJ composite expansion and the Langer method. The Langer solution is simpler and more accurate than the WKBJ composite solution, while the latter quantifies the thickness of the turning-point region. We also discuss how these waves can be generated via surface acoustic forcing and electro-osmosis and propose their use as microfluidic flow mixing devices. For the electro-osmosis case, the Helmholtz–Smoluchowski velocity at the edge of the Debye–Hückel layer, which drives the bulk electrically neutral flow, is obtained by matched asymptotic expansion

Complications of mechanical thrombectomy for acute ischemic stroke: Incidence, risk factors, and clinical relevance in the Italian Registry of Endovascular Treatment in acute stroke

BACKGROUND: There are limited data concerning procedure-related complications of endovascular thrombectomy for large vessel occlusion strokes. AIMS: We evaluated the cumulative incidence, the clinical relevance in terms of increased disability and mortality, and risk factors for complications. METHODS: From January 2011 to December 2017, 4799 patients were enrolled by 36 centers in the Italian Registry of Endovascular Stroke Treatment. Data on demographic and procedural characteristics, complications, and clinical outcome at three months were prospectively collected. RESULTS: The complications cumulative incidence was 201 per 1000 patients undergoing endovascular thrombectomy. Ongoing antiplatelet therapy (p < 0.01; OR 1.82, 95% CI: 1.21-2.73) and large vessel occlusion site (carotid-T, p < 0.03; OR 3.05, 95% CI: 1.13-8.19; M2-segment-MCA, p < 0.01; OR 4.54, 95% CI: 1.66-12.44) were associated with a higher risk of subarachnoid hemorrhage/arterial perforation. Thrombectomy alone (p < 0.01; OR 0.50, 95% CI: 0.31-0.83) and younger age (p < 0.04; OR 0.98, 95% CI: 0.97-0.99) revealed a lower risk of developing dissection. M2-segment-MCA occlusion (p < 0.01; OR 0.35, 95% CI: 0.19-0.64) and hypertension (p < 0.04; OR 0.77, 95% CI: 0.6-0.98) were less related to clot embolization. Higher NIHSS at onset (p < 0.01; OR 1.04, 95% CI: 1.02-1.06), longer groin-to-reperfusion time (p < 0.01; OR 1.05, 95% CI: 1.02-1.07), diabetes (p < 0.01; OR 1.67, 95% CI: 1.25-2.23), and LVO site (carotid-T, p < 0.01; OR 1.96, 95% CI: 1.26-3.05; M2-segment-MCA, p < 0.02; OR 1.62, 95% CI: 1.08-2.42) were associated with a higher risk of developing symptomatic intracerebral hemorrhage compared to no/asymptomatic intracerebral hemorrhage. The subgroup of patients treated with thrombectomy alone presented a lower risk of symptomatic intracerebral hemorrhage (p < 0.01; OR 0.70; 95% CI: 0.55-0.90). Subarachnoid hemorrhage/arterial perforation and symptomatic intracerebral hemorrhage after endovascular thrombectomy worsen both functional independence and mortality at three-month follow-up (p < 0.01). Distal embolization is associated with neurological deterioration (p < 0.01), while arterial dissection did not affect clinical outcome at follow-up. CONCLUSIONS: Complications globally considered are not uncommon and may result in poor clinical outcome. Early recognition of risk factors might help to prevent complications and manage them appropriately in order to maximize endovascular thrombectomy benefits

Adherence to antibiotic treatment guidelines and outcomes in the hospitalized elderly with different types of pneumonia

Background: Few studies evaluated the clinical outcomes of Community Acquired Pneumonia (CAP), Hospital-Acquired Pneumonia (HAP) and Health Care-Associated Pneumonia (HCAP) in relation to the adherence of antibiotic treatment to the guidelines of the Infectious Diseases Society of America (IDSA) and the American Thoracic Society (ATS) in hospitalized elderly people (65 years or older). Methods: Data were obtained from REPOSI, a prospective registry held in 87 Italian internal medicine and geriatric wards. Patients with a diagnosis of pneumonia (ICD-9 480-487) or prescribed with an antibiotic for pneumonia as indication were selected. The empirical antibiotic regimen was defined to be adherent to guidelines if concordant with the treatment regimens recommended by IDSA/ATS for CAP, HAP, and HCAP. Outcomes were assessed by logistic regression models. Results: A diagnosis of pneumonia was made in 317 patients. Only 38.8% of them received an empirical antibiotic regimen that was adherent to guidelines. However, no significant association was found between adherence to guidelines and outcomes. Having HAP, older age, and higher CIRS severity index were the main factors associated with in-hospital mortality. Conclusions: The adherence to antibiotic treatment guidelines was poor, particularly for HAP and HCAP, suggesting the need for more adherence to the optimal management of antibiotics in the elderly with pneumonia

Improved results of extracorporeal shock wave lithotripsy with the Dornier MPL 9000 for single gallstones.

Our aim was to compare the results of extracorporeal shock wave lithotripsy with the Dornier MPL 9000 for patients with single radiolucent gallstones less than or equal to 20-mm diameter using higher power (kV) and more shock waves during lithotripsy with our results during the Dornier National Biliary Lithotripsy Study using lower power and fewer shock waves. Nineteen patients were treated at higher power (mean +/- SE, 21.0 +/- 0.4 kV) vs 11 patients at lower power (18.8 +/- 0.5 kV). In the higher power group, the actuarial rate for complete clearance of gallstone fragments was 39 +/- 9%, 63 +/- 9% and 78 +/- 9% after 6 weeks, 3- and 6-months follow-up, respectively, versus only 19 +/- 12% after 6 months in the lower power group. We conclude that the use of higher power and more shock waves during extracorporeal shock wave lithotripsy with the MPL 9000 results in fragment clearance rates over 6 months for patients with single gallstones that are significantly higher than those previously achieved in the Dornier National Biliary Lithotripsy Study

Clinical and Morphologic Predictors of Outcome in a Multicenter Cohort of ITP Patients Treated with Trombopoietin Analogues

Background: The role of bone marrow response in patients with immune thrombocytopenia (ITP) has gained paramount importance since the last 10 years, with the demonstrations that marrow megakaryocytes (MGK) are unable to properly compensate platelets peripheral destruction. TPO receptor agonists (TPOa), namely romiplostim (ROMI) and eltrombopag (EPAG), by stimulating megakaryopoiesis are able to induce a response in 74% to 94% of cases in clinical trials. However, real world use of these drugs has shown frequent changes in individual dose requirement, the possibility of treatment discontinuation, and their effectiveness outside registered indications; moreover, nothing is known about predictors of response. Aim: To evaluate clinical and morphologic predictors of response in a real world cohort of ITP patients treated with TPOa. Methods: ITP patients treated with EPAG and ROMI from September 2009 to May 2018 at seven Italian Centers were evaluated. Clinical and hematologic parameters including treatment response and marrow characteristics were retrospectively collected. Results: Table 1 shows baseline clinical and morphologic characteristics for the 86 cases enrolled, altogether and divided according to the TPOa used: patients were mainly middle-aged females presenting with severe thrombocytopenia; anti-PLT autoantibodies were positive in 32.6% of cases, and 58.1% of cases presented with bleeding, 22% of grade III-IV. All cases had received 1st line treatment with steroids and 43% at list a 2nd line among those listed in Tab1. Pre-TPOa marrow evalutation showed hypocellularity in 30.2% of cases, reticulinic fibrosis in 33.7%, a polyclonal lymphoid infiltrate in 43% (mostly mixed or T-cell), and reduced MGK in 4.7% of patients. Some dysplastic features were present in about 50% of cases, either dysmegakaryopoiesis (46.5%) or dyserythropoiesis (25.6%). Median time from diagnosis to TPOa was 2.4 years (0.1-28.8). Patients were treated for a median of 1.4 years (0.3-10.8), and ORR at 3 months and 9 months were 75.6% (CR 44.2 and PR 31.4%) and 65.1% (CR 36 and PR 29.1%), respectively. Response rates to EPAG and ROMI were comparable. Regarding predictors of response, bone marrow hypocellularity (40 NR vs 21% ORR, p=0.05) and megakaryocytopenia (33 vs 6%, p=0.06) were significantly more frequent among NRs. Other factors associated with poor response were dyserythropoiesis (58 vs 26%, p=0.04) and erythroid hyperplasia (18 vs 8%, p=0.03), and presence of a T cell infiltrate (66 vs 18.9%, p=0.03). Finally, NRs cases showed significantly lower neutrophil counts at baseline (1.9 vs 2.3x103/mmc in ORR, p=0.01), and had been more frequently exposed to cyclosporine or azathioprine (50 vs 18% in ORR, p=0.01). Fifty-five patients are still on treatment, whereas 31 (20 EPAG/11 ROMI) discontinued because of NR or relapse (17), adverse events or intolerance (2); of note, 12 patients with ORR discontinued the drug because of sustained CR, and 7 of them are still in remission. 14/65(21.5%) responding cases (10 EPAG/4 ROMI) lost the response after a median of 6.2 months (1.8-60) and were variably managed (3 splenectomized, 1 switched from ROMI to EPAG, 1 received danazol, 5 were re-treated with EPAG, and the remaining were managed with steroids and supportive treatment). Median RFS was 2.3 years (0.1-10), longer in patients without megakaryocytopenia (9.9+0.5 vs 4.1+0.6, p=0.06), dyserythropoiesis (mean 9.1+0.5 vs 4.9+0.7, p=0.2), and reticular fibrosis (9.6+0.5 vs 5.5+0.6, p=0.08). During EPAG treatment 7 grade adverse events occurred: 2 grade IV (1 stroke with PLT counts of about 30x103/mmc, and 1 NSTEMI 1 month after EPAG discontinuation for sustained CR), 1 grade III pneumonia, and 4 grade I/II transaminase elevation. No events occurred under ROMI. Conclusions: TPOa use in the real world setting confirms their reported efficacy, the option to switch and/or re-treat with either EPAG or ROMI, and the possibility to discontinue the drugs. The presence of hypocellularity and megakaryocytopenia, along with dysplastic features and of a lymphoid T cell infiltrate are associated with a reduced response to TPOa and a shorter RFS. Pre-treatment bone marrow evaluation may give hints to unravel the physiopathologic mechanisms underlying TPOa refractoriness