A Cutting Force and Hole Geometry Study for Precision Deep-Hole Microdrilling of Magnesium

Size effects, high thrust forces, limited heat dissipation, and tool deterioration are just some of the challenges that deep microdrilling poses, underscoring the importance of effective process control to ensure quality. In this paper, an investigation performed on a microdrilling process on pure magnesium using a 0.138 mm diameter microdrill to achieve an aspect ratio equal to 36 is proposed. The effect of the variation of the cutting parameters feed per tooth (Formula presented.) and cutting speed (Formula presented.) was studied on thrust force, supporting hole quality evaluation in terms of burr height, entrance, and inner diameters. The results showed that (Formula presented.) significantly influences the hole quality. In fact, as (Formula presented.) increases, the burr height decreases and the inner diameter approaches the nominal diameter. However, optimizing the hole geometry with high feed per tooth values increases the thrust forces, compromising tool life. In fact, a significant dependence of the thrust force on both cutting parameters was found. In this scenario, increasing (Formula presented.) can mitigate the high thrust forces by inducing material softening. The study results improve precision manufacturing by refining parameters, ensuring the quality and reliability of magnesium-based microcomponents

Heterogeneity in clinical practices for post-cardiotomy extracorporeal life support: A pilot survey from the PELS-1 multicenter study

Background: High-quality evidence for post-cardiotomy extracorporeal life support (PC-ECLS) management is lacking. This study investigated real-world PC-ECLS clinical practices. Methods: This cross-sectional, multi-institutional, international pilot survey explored center organization, anticoagulation management, left ventricular unloading, distal limb perfusion, PC-ECLS monitoring, and transfusion practices. Twenty-nine questions were distributed among 34 hospitals participating in the Post-cardiotomy Extra-Corporeal Life Support Study. Results: Of the 32 centers [16 low-volume (50%); 16 high-volume (50%)] that responded, 16 (50%) had dedicated ECLS specialists. Twenty-six centers (81.3%) reported using additional mechanical circulatory supports. Anticoagulation practices were highly heterogeneous: 24 hospitals (75%) reported using patients bleeding status as a guide, without a specific threshold in 54.2% of cases. Transfusion targets ranged from 7 to 10 g/dL. Most centers used cardiac venting on a case-by-case basis (78.1%) and regular distal limb perfusion (84.4%). Nineteen (54.9%) centers reported dedicated monitoring protocols, including daily echocardiography (87.5%), Swan-Ganz catheterization (40.6%), cerebral near-infrared spectroscopy (53.1%), and multimodal assessment of limb ischemia. Inspection of the circuit (71.9%), oxygenator pressure drop (68.8%), plasma free hemoglobin (75%), d-dimer (59.4%), lactate dehydrogenase (56.3%), and fibrinogen (46.9%) are used to diagnose hemolysis and thrombosis. Conclusions: This study shows remarkable heterogeneity in clinical practices for PC-ECLS management. More standardized protocols and better implementation of the available evidence are recommended

Characteristics and Outcomes of Prolonged Venoarterial Extracorporeal Membrane Oxygenation after Cardiac Surgery:The Post-Cardiotomy Extracorporeal Life Support (PELS-1) Cohort Study

OBJECTIVES: Most post-cardiotomy (PC) extracorporeal membrane oxygenation (ECMO) runs last less than 7 days. Studies on the outcomes of longer runs have provided conflicting results. This study investigates patient characteristics and short- and long-term outcomes in relation to PC ECMO duration, with a focus on prolonged (&gt; 7 d) ECMO. DESIGN: Retrospective observational cohort study. SETTING: Thirty-four centers from 16 countries between January 2000 and December 2020. PATIENTS: Adults requiring post PC ECMO between 2000 and 2020. INTERVENTIONS: None. MEASUREMENTS AND MAIN RESULTS: Characteristics, in-hospital, and post-discharge outcomes were compared among patients categorized by ECMO duration. Survivors and nonsurvivors were compared in the subgroup of patients with ECMO duration greater than 7 days. The primary outcome was in-hospital mortality. Two thousand twenty-one patients were included who required PC ECMO for 0-3 days (n = 649 [32.1%]), 4-7 days (n = 776 [38.3%]), 8-10 days (n = 263 [13.0%]), and greater than 10 days (n = 333 [16.5%]). There were no major differences in the investigated preoperative and procedural characteristics among ECMO duration groups. However, the longer ECMO duration category was associated with multiple complications including bleeding, acute kidney injury, arrhythmias, and sepsis. Hospital mortality followed a U-shape curve, with lowest mortality in patients with ECMO duration of 4-7 days (n = 394, 50.8%) and highest in patients with greater than 10 days ECMO support (n = 242, 72.7%). There was no significant difference in post-discharge survival between ECMO duration groups. In patients with ECMO duration greater than 7 days, age, comorbidities, valvular diseases, and complex procedures were associated with nonsurvival. CONCLUSIONS: Nearly 30% of PC ECMO patients were supported for greater than 7 days. In-hospital mortality increased after 7 days of support, especially in patients undergoing valvular and complex surgery, or who had complications, although the long-term post-discharge prognosis was comparable to PC ECMO patients with shorter support duration.</p

P44 PREDICTORS OF MORTALITY AFTER ACUTE TYPE A AORTIC DISSECTION REPAIR IN PATIENTS OF 70 YEARS OF AGE OR OLDER

Abstract Objectives The impact of age on outcomes of acute type A aortic dissection remains controversial. We sought to investigate 30–day and follow–up outcomes of acute type A aortic dissection repair in elderly patients. Survival anlysis was performed and independent risk factors for mortality were searched. Methods During a 21–year period (2000–2021), 102 patients of 70 years of age or older were emergently treated for acute type A aortic dissection at our institution. (mean age 75.1 ± 3.8 years, 53.9% male) Preoperative characteristics are displayed in Table I. Results Overall 30–day mortality (including operative mortality) was 21.6%. Mortality increased among patients presenting with atrial fibrillation (adjusted odds ratio 10.33, P = 0.02) and visceral malperfution (adjusted odds ratio 70.88, P = 0.005). Survival at 1, 5 and 10 years was 70.2 ± 4.6%, 50.9 ± 5.6% and 24.1 ± 5.6%, respectively (Figure 1). The need to perform concomitant coronary artery bypass grafting was the only independent risk factor for mortality during follow–up. (adjusted odds ratio 2.21, P = 0.04) Conclusions Thirty –day and follow–up mortality were extremely satisfactory in elderly patients undergoing acute type A dissection repair. We could detect significant disease and surgery–related risk factors for death. Patients presenting with atrial fibrillation or visceral malperfusion had the poorest 30–day outcome. The need to perform concomitant coronary artery bypass grafting, significantly increased the mortality during follow–up. </jats:sec