Fail-safe robustness of critical load carrying structures is an important design philosophy for aerospace industry. The basic idea is that a structure should be designed to survive normal loading conditions when partial damage occurred. Such damage is quantified as complete failure of a structural member, or a partial damage of a larger structural part. In the context of topology optimization fail-safe consideration was first proposed by Jansen et al. Struct Multidiscip Optim 49(4):657-666, (2014). While their approach captures the essence of fail-safe requirement, it has two major shortcomings: (1) it involves analysis of a very large number of FEA models at the scale equal to the number of elements; (2) failure was introduced in generic terms and therefore the fundamental aspects of failure test of discrete members was not discussed. This paper aims at establishing a rigorous framework for failsafe topology optimization of general 3D structures, with the goal to develop a computationally viable solution for industrial applications. We demonstrate the effectiveness of the proposed approach on several examples including a 3D example with over three hundred thousand elements.
Introduction:Recombinant FVIIa (rFVIIa) is widely used to manage bleeding risk during and after surgery in patients with haemophilia complicated by inhibitors. In the postoperative period, rFVIIa must be delivered frequently and regularly to maintain haemostasis, considering its short half-life. Preparation and manual administration of bolus doses of rFVIIa at regular intervals may place a strain on available nursing resources. A programmable mini-pump may offer an approach to facilitate regular administration of bolus doses of rFVIIa at specified intervals.
Aim:To investigate if a mini-pump is a practical and effective way to deliver rFVIIa in the postoperative period.
Methods:It was first necessary to establish that rFVIIa remains stable and sterile in the mini-pump reservoir for an extended period. Four days after loading the minipump under sterile conditions no evidence of bacterial or fungal growth was observed and in vitro procoagulant activity of rFVIIa remained stable. The mini-pump was used to deliver rFVIIa as bolus doses to two patients with inhibitors who had undergone surgery. Nurses were asked to report their satisfaction with the use of the mini-pump using a specific questionnaire.
Results:Haemostasis was evaluated as excellent in both cases; nurses were satisfied with use of the mini-pump.Conclusion: This pilot study shows that intermittent delivery of rFVIIa at fixed intervals using an automated mini-pump offers accurate and reliable administration in the postoperative setting. This approach may reduce burden on nursing staff, potentially minimize the risk of human error and avoid delay in administration of rFVIIa. K E Y W O R D S automated infusion, congenital haemophilia with inhibitors, eptacog alfa (activated), rFVIIa, surgery 1 | INTRODUC TI ON In people with moderate or severe haemophilia, orthopaedic complications can begin early in life and patients with inhibitors have been shown to exhibit greater orthopaedic complications and a more substantial impact on quality of life than patients without. 1,2Before the availability of bypassing agents, surgery in people with haemophilia complicated by inhibitors was considered hazardous. 3
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