Respiratory airway resistance monitoring in mechanically ventilated patients

Physiological models of respiratory mechanics can be used to optimise mechanical ventilator settings to improve critically ill patient outcomes. Models are generally generated via either physical measurements or analogous behaviours that can model experimental outcomes. However, models derived solely from physical measurements are infrequently applied to clinical data

Fabrication of a compliant phantom of the human aortic arch for use in Particle Image Velocimetry (PIV) experimentation

Compliant phantoms of the human aortic arch can mimic patient specific cardiovascular dysfunctions in vitro. Hence, phantoms may enable elucidation of haemodynamic disturbances caused by aortic dysfunction. This paper describes the fabrication of a thin-walled silicone phantom of the human ascending aorta and brachiocephalic artery. The model geometry was determined via a meta-analysis and modelled in SolidWorks before 3D printing. The solid model surface was smoothed and scanned with a 3D scanner. An offset outer mould was milled from Ebalta S-Model board. The final phantom indicated that ABS was a suitable material for the internal model, the Ebalta S-Model board yielded a rough external surface. Co-location of the moulds during silicone pour was insufficient to enable consistent wall thickness. The resulting phantom was free of air bubbles but did not have the desired wall thickness consistency

A Novel Fabrication Method for Compliant Silicone Phantoms of Arterial Geometry for Use in Particle Image Velocimetry of Haemodynamics

Cardiovascular diseases (CVDs) are one of the leading causes of death globally. In-vitro measurement of blood flow in compliant arterial phantoms can provide better insight into haemodynamic states and therapeutic procedures. However, current fabrication techniques are not capable of producing thin-walled compliant phantoms of complex shapes. This study presents a new approach for the fabrication of compliant phantoms suitable for optical measurement. Two 1.5× scaled models of the ascending aorta, including the brachiocephalic artery (BCA), were fabricated from silicone elastomer Sylgard-184. The initial phantom used the existing state of the art lost core manufacturing technique with simple end supports, an acrylonitrile butadiene styrene (ABS) additive manufactured male mould and Ebalta-milled female mould. The second phantom was produced with the same method but used more rigid end supports and ABS male and female moulds. The wall thickness consistency and quality of resulting stereoscopic particle image velocimetry (SPIV) were used to verify the fidelity of the phantom for optical measurement and investigation of physiological flow fields. However, the initial phantom had a rough surface that obscured SPIV analysis and had a variable wall thickness (range = 0.815 mm). The second phantom provided clear particle images and had a less variable wall thickness (range = 0.317 mm). The manufacturing method developed is suitable for fast and cost-effective fabrication of different compliant arterial phantom geometries

COVID-19 and cardiac rehabilitation

The British Association for Cardiovascular Prevention and Rehabilitation (BACPR), the British Cardiovascular Society (BCS) and the British Heart Foundation (BHF) have issued a joint position statement ‘Retention of cardiac rehabilitation services during the COVID-19 pandemic’

Liberal warriors and the violent colonial logics of “partnering and advising"

Building on the feminist literature that traces the (re)production of militarized masculinities in and through military interventions, this article details some of the ways British soldiering subjects are being shaped in today's counterinsurgency context. Required now to be both nation builders and war fighters, contemporary soldiers are a “softer,” less masculinized subjectivity, and what Alison Howell has termed “liberal warriors.” British troops with their long history of colonialism and frequent overseas military campaigns are understood to be particularly suited to this role. Taking the British military's involvement in the “partnering and advising” of the Afghan National Army (ANA), this article pays attention to the interlocking gendered, raced, and sexualized discourses through which the British/Afghan encounter is experienced. Exploring first British troops' preoccupation with the perceived femininity and homosexuality of their Afghan counterparts, and second, Afghan hypermasculinity as demonstrated by the characterizations of their violent and chaotic fighting tactics, colonial logics are revealed. While British liberal warriors come to know “who they are” through these logics, (mis)represented Afghan soldiers are rendered increasingly vulnerable to the very “real,” very material violences of war

In-vitro particle image velocimetry assessment of the endovascular haemodynamic features distal of stent-grafts that are associated with development of limb occlusion

Aneurysms are common vascular diseases which affect normal haemodynamics in the aorta. Endovascular aortic repair (EVAR) using stent-grafts is a common treatment that excludes the aneurysm from the circulation, preventing further growth and eventual rupture. However, complications such as endoleak, dislocation or limb occlusion have been reported after EVAR. This study hypothesized that the compliance mismatch between the graft and parent artery causes haemodynamic disturbances at the distal edge of the graft. Therefore, the potential for the graft to cause limb occlusion was assessed. A compliant phantom was fabricated. A circulatory loop was developed to run the fluid and generate a physiological flow waveform. Particle Image Velocimetry was utilised to capture fluid dynamics in the replica. The result showed a low velocity region at the graft trailing edge wall. The low velocity boundary layer thickness decreased downstream of the graft. A flow recirculation was initiated and increased in size during the mid-acceleration at the low velocity region. Shear stresses fluctuated at the trailing edge of the graft which is a risk factor for intimal thickening followed by graft or limb occlusion. It was concluded that this haemodynamic behaviour was due to the graft and parent artery compliance mismatch

Haemodynamic frailty – A risk factor for acute kidney injury in the elderly

Clinical frailty in the elderly is defined by a composite measure of functional psychomotor decline. Herein, we develop the concept of haemodynamic frailty (HDF), a state of increased predisposition to disease prevalent in the elderly and characterised by impairment of the network of compensatory responses governing the defence of circulatory volume and adaptive haemodynamic function. We review the factors predisposing the elderly to HDF, with a focus on the impaired capacity to sustain total body water balance. As a component of HDF, dehydration generates vulnerability to diseases caused by tissue hypoperfusion, including acute kidney injury. We provide a detailed mechanistic explanation of how dehydration and depletion of the intravascular volume impacts on renal blood flow to become an important element of the heightened risk of acute kidney injury (AKI) in the elderly. We bring these mechanistic considerations into the clinical context with reference to examples of how pre-renal (haemodynamic) and intrinsic (involving renal parenchymal damage) AKI risk is elevated in the setting of dehydration. Finally, we present HDF as a state of opportunity to prevent disease, for which diagnostic and interventional standards need to be refined. Further prospective studies are warranted to help clarify the clinical utility of assessing and managing HDF with regard to the mitigation of AKI risk in the elderly

Randomized clinical trial of therapeutic music video intervention for resilience outcomes in adolescents/young adults undergoing hematopoietic stem cell transplant: a report from the Children's Oncology Group

BACKGROUND: To reduce the risk of adjustment problems associated with hematopoietic stem cell transplant (HSCT) for adolescents/young adults (AYAs), we examined efficacy of a therapeutic music video (TMV) intervention delivered during the acute phase of HSCT to: 1) increase protective factors of spiritual perspective, social integration, family environment, courageous coping, and hope-derived meaning; 2) decrease risk factors of illness-related distress and defensive coping; and 3) increase outcomes of self-transcendence and resilience. METHODS: This was a multisite randomized, controlled trial (COG-ANUR0631) conducted at 8 Children's Oncology Group sites involving 113 AYAs aged 11-24 years undergoing myeloablative HSCT. Participants, randomized to the TMV or low-dose control (audiobooks) group, completed 6 sessions over 3 weeks with a board-certified music therapist. Variables were based on Haase's Resilience in Illness Model (RIM). Participants completed measures related to latent variables of illness-related distress, social integration, spiritual perspective, family environment, coping, hope-derived meaning, and resilience at baseline (T1), postintervention (T2), and 100 days posttransplant (T3). RESULTS: At T2, the TMV group reported significantly better courageous coping (Effect Size [ES], 0.505; P = .030). At T3, the TMV group reported significantly better social integration (ES, 0.543; P = .028) and family environment (ES, 0.663; P = .008), as well as moderate nonsignificant effect sizes for spiritual perspective (ES, 0.450; P = .071) and self-transcendence (ES, 0.424; P = .088). CONCLUSIONS: The TMV intervention improves positive health outcomes of courageous coping, social integration, and family environment during a high-risk cancer treatment. We recommend the TMV be examined in a broader population of AYAs with high-risk cancers