Warfarin doses in the initiation phase among patients with heart valve replacement and atrial fibrillation in Hospital Pulau Pinang

The use of warfarin is essential in patients having atrial fibrillation (AF), aortic valve replacement (AVR) and mitral valve replacement (MVR). However, the use of warfarin may bring major adverse effects such as bleeding and it has dose related side effects. Due to higher incidence of bleeding in initial phase of warfarin therapy and reported fluctuation of dose in initial phase of warfarin therapy after heart valve surgery, this study was conducted to evaluate the changes in warfarin doses among patients after heart valve surgery and atrial fibrillation. All patients having atrial fibrillation, aortic valve replacement and mitral valve replacement who were initiated warfarin therapy in year 2008 till 2010 in Hospital Pulau Pinang was selected as samples. A total of 137 patients were included for this study. Data collected included patient’s age. race, gender, warfarin initiation date, warfarin indication, warfarin dose and INR value for 1st till 12th weeks of warfarin initiation. Statistical analysis was performed using repeated measures ANOVA and repeated measures ANCOVA. Heart valve replacement patients (AVR or MVR) showed increasing trend in warfarin doses during the initial phase of warfarin therapy. This trend was not observed in Al-' patients. The dose of warfarin warfarin initiation for AVR and MVR group (p-value <0.001) but there was no significant difference in AF group. The dose of warfarin was significantly different among AVR and AF patients for first 5 weeks of warfarin initiation. Indications (p-value= 0.036) and race (p-value=0.016) were found to be significantly affecting warfarin doses in the initial phase of warfarin therapy but not gender (p-value =0.122) and age (p-value =0.280). Overall, the mean dose of warfarin required was lower compared to western countries. Monitoring should be frequent for patients with heart valve replacement during the initial 3 months period of warfarin therapy

Warfarin doses in the initiation phase among patients with heart valve replacement and atrial fibrillation in Hospital Pulau Pinang

The use of warfarin is essential in patients having Atrial Fibrillation (AF), Aortic Valve Replacement (AVR) and Mitral Valve Replacement (MVR). However, the use of warfarin may bring major adverse effects such as bleeding and it has dose related side effects. Due to higher incidence of bleeding in initial phase of warfarin therapy and reported fluctuation of dose in initial phase of warfarin therapy after heart valve surgery, this study was conducted to evaluate the changes in warfarin doses among patients after heart valve surgery and atrial fibrillation. All patients having atrial fibrillation, aortic valve replacement and mitral valve replacement who were initiated warfarin therapy in year 2008 till 2010 in Hospital Pulau Pinang was selected as samples. A total of 137 patients were included for this study. Data collected included patient’s age. race, gender, warfarin initiation date, warfarin indication, warfarin dose and INR value for 1st till 12th weeks of warfarin initiation. Statistical analysis was performed using repeated measures ANOVA and repeated measures ANCOVA. Heart valve replacement patients (AVR or MVR) showed increasing trend in warfarin doses during the initial phase of warfarin therapy. This trend was not observed in Al-' patients. The dose of warfarin warfarin initiation for AVR and MVR group (p-value <0.001) but there was no significant difference in AF group. The dose of warfarin was significantly different among AVR and AF patients for first 5 weeks of warfarin initiation. Indications (p-value =0.036) and race (p-value =0.016) were found to be significantly affecting warfarin doses in the initial phase of warfarin therapy but not gender (p-value =0.122) and age (p-value =0.280). Overall, the mean dose of warfarin required was lower compared to western countries. Monitoring should be frequent for patients with heart valve replacement during the initial 3 months period of warfarin therapy

Design and 3D Printing of Scaffolds and Tissues

A growing number of three-dimensional (3D)-printing processes have been applied to tissue engineering. This paper presents a state-of-the-art study of 3D-printing technologies for tissue-engineering applications, with particular focus on the development of a computer-aided scaffold design system; the direct 3D printing of functionally graded scaffolds; the modeling of selective laser sintering (SLS) and fused deposition modeling (FDM) processes; the indirect additive manufacturing of scaffolds, with both micro and macro features; the development of a bioreactor; and 3D/4D bioprinting. Technological limitations will be discussed so as to highlight the possibility of future improvements for new 3D-printing methodologies for tissue engineering

A preliminary investigation on cross-foldable design in 4D printing

In 4D printing, a printed smart structure would fold or unfold upon an external stimulus. In prior research, the hinges in the smart structure always fold or unfold individually with no crossing or overlap. The design complexity of the smart structure is increased by increasing the total number of hinges. In this research, cross-folding is investigated. Here cross-folding is defined as two overlapping folds in a single hinge. In particular, this research investigates the effect of thickness on cross-folding smart structures. It is found that hinge thickness affects the repeatability of cross-folding. A hinge with a thickness of 0.5 mm could be cross-folded three times prior to fracture whilst a hinge with a thickness of 0.3 mm could be cross-folded only once prior to fracture. A hinge with a thickness of 0.1 mm could not even be cross-folded without cracking. The introduction of a physical hole in the centre of the folding/unfolding line provided stress relief and prevented fracture.NRF (Natl Research Foundation, S’pore)Published versio

Design and 4D Printing of Cross-Folded Origami Structures: A Preliminary Investigation

In 4D printing research, different types of complex structure folding and unfolding have been investigated. However, research on cross-folding of origami structures (defined as a folding structure with at least two overlapping folds) has not been reported. This research focuses on the investigation of cross-folding structures using multi-material components along different axes and different horizontal hinge thickness with single homogeneous material. Tensile tests were conducted to determine the impact of multi-material components and horizontal hinge thickness. In the case of multi-material structures, the hybrid material composition has a significant impact on the overall maximum strain and Young’s modulus properties. In the case of single material structures, the shape recovery speed is inversely proportional to the horizontal hinge thickness, while the flexural or bending strength is proportional to the horizontal hinge thickness. A hinge with a thickness of 0.5 mm could be folded three times prior to fracture whilst a hinge with a thickness of 0.3 mm could be folded only once prior to fracture. A hinge with a thickness of 0.1 mm could not even be folded without cracking. The introduction of a physical hole in the center of the folding/unfolding line provided stress relief and prevented fracture. A complex flower petal shape was used to successfully demonstrate the implementation of overlapping and non-overlapping folding lines using both single material segments and multi-material segments. Design guidelines for establishing cross-folding structures using multi-material components along different axes and different horizontal hinge thicknesses with single or homogeneous material were established. These guidelines can be used to design and implement complex origami structures with overlapping and non-overlapping folding lines. Combined overlapping folding structures could be implemented and allocating specific hole locations in the overall designs could be further explored. In addition, creating a more precise prediction by investigating sets of in between hinge thicknesses and comparing the folding times before fracture, will be the subject of future work.NRF (Natl Research Foundation, S’pore)Published versio

3D printing of smart materials: a review on recent progresses in 4D printing

Additive manufacturing (AM), commonly known as three-dimensional (3D) printing or rapid prototyping, has been introduced since the late 1980s. Although a considerable amount of progress has been made in this field, there is still a lot of research work to be done in order to overcome the various challenges remained. Recently, one of the actively researched areas lies in the additive manufacturing of smart materials and structures. Smart materials are those materials that have the ability to change their shape or properties under the influence of external stimuli. With the introduction of smart materials, the AM-fabricated components are able to alter their shape or properties over time (the 4th dimension) as a response to the applied external stimuli. Hence, this gives rise to a new term called ‘4D printing’ to include the structural reconfiguration over time. In this paper, recent major progresses in 4D printing are reviewed, including 3D printing of enhanced smart nanocomposites, shape memory alloys, shape memory polymers, actuators for soft robotics, self-evolving structures, anti-counterfeiting system, active origami and controlled sequential folding, and some results from our ongoing research. In addition, some research activities on 4D bio-printing are included, followed by discussions on the challenges, applications, research directions and future trends of 4D printing

Paediatric COVID-19 mortality: a database analysis of the impact of health resource disparity

Background The impact of the COVID-19 pandemic on paediatric populations varied between high-income countries (HICs) versus low-income to middle-income countries (LMICs). We sought to investigate differences in paediatric clinical outcomes and identify factors contributing to disparity between countries.Methods The International Severe Acute Respiratory and Emerging Infections Consortium (ISARIC) COVID-19 database was queried to include children under 19 years of age admitted to hospital from January 2020 to April 2021 with suspected or confirmed COVID-19 diagnosis. Univariate and multivariable analysis of contributing factors for mortality were assessed by country group (HICs vs LMICs) as defined by the World Bank criteria.Results A total of 12 860 children (3819 from 21 HICs and 9041 from 15 LMICs) participated in this study. Of these, 8961 were laboratory-confirmed and 3899 suspected COVID-19 cases. About 52% of LMICs children were black, and more than 40% were infants and adolescent. Overall in-hospital mortality rate (95% CI) was 3.3% [=(3.0% to 3.6%), higher in LMICs than HICs (4.0% (3.6% to 4.4%) and 1.7% (1.3% to 2.1%), respectively). There were significant differences between country income groups in intervention profile, with higher use of antibiotics, antivirals, corticosteroids, prone positioning, high flow nasal cannula, non-invasive and invasive mechanical ventilation in HICs. Out of the 439 mechanically ventilated children, mortality occurred in 106 (24.1%) subjects, which was higher in LMICs than HICs (89 (43.6%) vs 17 (7.2%) respectively). Pre-existing infectious comorbidities (tuberculosis and HIV) and some complications (bacterial pneumonia, acute respiratory distress syndrome and myocarditis) were significantly higher in LMICs compared with HICs. On multivariable analysis, LMIC as country income group was associated with increased risk of mortality (adjusted HR 4.73 (3.16 to 7.10)).Conclusion Mortality and morbidities were higher in LMICs than HICs, and it may be attributable to differences in patient demographics, complications and access to supportive and treatment modalities