Suboptimal Control of Interconnected Power Systems

Electrical Engineerin

Cardiopulmonary interactions and exercise capacity in patients with a Fontan circulation

Children born with a functionally single ventricle who undergo a Fontan completion have altered haemodynamics associated with increased morbidity. They have significantly impaired lung function and reduced exercise capacity. This thesis aims to provide a more in-depth understanding of the altered cardiopulmonary interaction, abnormal pulmonary function and exercise intolerance in children and adults with a Fontan circulation. Chapter 1 provides a summary of the evolution of the Fontan circulation, and critically reviews the current literature on cardiopulmonary interaction in the normal and Fontan circulations. In Chapter 3 we sought to further characterise the abnormalities of lung function in the Fontan cohort and gain a better understanding of underlying aetiology through detailed lung function testing. In Chapter 4 we assessed the benefits of inspiratory muscle training on exercise capacity. In Chapter 5 we explore other parameters of exercise capacity, oxygen pulse slope, in patients with a Fontan circulation. In Chapter 6 we established Fontan-specific normative data for maximal workload, and oxygen uptake at anaerobic threshold and peak exercise. This thesis characterises the impaired lung function and abnormal exercise capacity in patients with a Fontan circulation. It provides a better understanding of the impaired respiratory function, haemodynamic responses to exercise, and altered cardiopulmonary interactions, in Fontan patients

Scaling Peak Oxygen Consumption for Body Size and Composition in People With a Fontan Circulation

This is the final version. Available on open access from Wiley via the DOI in this recordBACKGROUND: Peak oxygen consumption (peak ̇ VO2) is traditionally divided (“ratio- scaled”) by body mass (BM) for clinical interpretation. Yet, it is unknown whether ratio- scaling to BM can produce a valid size- independent expression of peak VO2 in people with a Fontan circulation. Furthermore, people with a Fontan circulation have deficits in lean mass, and it is unexplored whether using different measures of body composition may improve scaling validity. The objective was to assess the validity of different scaling denominators (BM, stature, body surface area, fat- free mass, lean mass, and appendicular lean mass using ratio and allometric scaling). ̇ METHODS AND RESULTS: Eighty- nine participants (age: 23.3±6.7 years; 53% female) with a Fontan circulation had their cardiorespiratory fitness and body composition measured by cardiopulmonary exercise testing and dual- energy x- ray absorptiometry. Ratio and allometric (log- linear regression) scaling was performed and Pearson correlations assessed scaling validity. Scaling denominators BM (r=−0.25, P=0.02), stature (r=0.46, P<0.001), and body surface area (0.23, P=0.03) were significantly correlated with their respective ratio- scaled expressions of peak ̇ VO2, but fat- free mass, lean mass, or appendicular Downloaded from http://ahajournals.org by on December 14, 2022 lean mass were not (r≤0.11; R2=1%). Allometrically expressed peak denominator (r=≤0.23; R2=≤4%). ̇ ̇ VO2 resulted in no significant correlation with any scaling CONCLUSIONS: The traditional and accepted method of ratio- scaling to BM is invalid because it fails to create a size- independent expression of peak VO2 in people with a Fontan circulation. However, ratio- scaling to measures of body composition (fat- free mass, lean mass, and appendicular lean mass) and allometric techniques can produce size- independent expressions of peak ̇ VO2 in people with a Fontan circulation.Canon Medical Systems UK Ltd.University of ExeterMedical Research Future Fun

Azithromycin in periodontal treatment: More than an antibiotic

R. Hirsch, H. Deng, M. N. Laohacha

The role of bacterial and non-bacterial toxins in the induction of changes in membrane transport: implications for diarrhea

Bacterial toxins induce changes in membrane transport which underlie the loss of electrolyte homeostasis associated with diarrhea. Bacterial- and their secreted toxin-types which have been linked with diarrhea include: (a) Vibrio cholerae (cholera toxin

O2 pulse slope correlates with stroke volume during exercise in patients with a Fontan circulation

Background Peak oxygen pulse (O2pulse=oxygen consumption/heart rate) is calculated by the product of stroke volume (SV) and oxygen extraction. It has been shown to be reduced in patients with a Fontan circulation. However, in the Fontan population, it may be a poor marker of SV. We propose that the slope of the O2 pulse curve may be more reflective of SV during exercise.Methods We analysed cardiopulmonary exercise test data in 22 subjects with a Fontan circulation (cohort A) and examined the association between peak SV during exercise (aortic flow measured on exercise cardiac MRI), and O2 pulse parameters (absolute O2 pulse and O2 pulse slopes up to anaerobic threshold (AT) and peak exercise). In a separate Fontan cohort (cohort B, n=131), associations between clinical characteristics and O2 pulse kinetics were examined.Results In cohort A, peak aortic flow was moderately and significantly associated with O2pulseslopePEAK (r=0.47, p=0.02). However, neither absolute O2pulseAT nor O2pulsePEAK was significantly associated with peak aortic flow. In cohort B, O2pulseslopePEAK and O2pulseslopeAT were not significantly associated with clinical parameters, apart from a weak association with forced vital capacity.Conclusion The slope of the O2 pulse curve to peak exercise may be more reflective of peak SV in the Fontan population than a single peak O2 pulse value

Inspiratory Muscle Training Is Associated With Improved Inspiratory Muscle Strength, Resting Cardiac Output, and the Ventilatory Efficiency of Exercise in Patients With a Fontan Circulation

BACKGROUND: Patients with a Fontan circulation have reduced exercise capacity and respiratory muscle strength. Inspiratory muscle training (IMT) improves exercise capacity and quality of life in adults with heart failure. We assessed whether 6 weeks of a home-based program of IMT improves inspiratory muscle strength and the ventilatory efficiency of exercise in adolescent patients with a Fontan circulation. METHODS AND RESULTS: Twenty-three adolescent participants (aged 16±2 years) with a Fontan circulation underwent 6 weeks of IMT for 30 minutes daily. Respiratory muscle strength (maximal inspiratory pressure and expiratory pressure), lung function, and exercise capacity (cardiopulmonary exercise testing) were assessed. Fourteen of 23 participants also underwent exercise cardiac magnetic resonance imaging to examine the effects of IMT on cardiac output and systemic and pulmonary blood flow. Six weeks of IMT improved maximal inspiratory pressure by 36±24 cm H2O (61±46%) with no change in maximal expiratory pressure. Ventilatory efficiency of exercise improved after 6 weeks of IMT (from 34.2±7.8 to 32.2±5.6, P=0.04). In those who underwent exercise cardiac magnetic resonance imaging, IMT increased resting cardiac output (from 4.2±1.2 to 4.5±1.0 L/min, P=0.03) and ejection fraction (from 50.1±4.3 to 52.8±6.1%, P=0.03). CONCLUSIONS: Six weeks of IMT is associated with improved inspiratory muscle strength, ventilatory efficiency of exercise, and resting cardiac output in young Fontan patients. IMT may be a simple beneficial addition to the current management of Fontan patients, potentially reducing exercise intolerance and long-term morbidity and mortality