Resham Baruah

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For disease states characterized by oscillatory ventilation, an ideal dynamic therapy would apply a counteracting oscillation in ventilation. Modulating respiratory gas transport through the circulation might allow this. We explore the ability of repetitive alternations in heart rate, using a cardiac pacemaker, to elicit oscillations in respiratory(More)
BACKGROUND Alternation of heart rate between 2 values using a pacemaker generates oscillations in end-tidal CO(2) (et-CO(2)). This study examined (a) whether modulating atrioventricular delay can also do this, and (b) whether more gradual variation of cardiac output can achieve comparable changes in et-CO(2) with less-sudden changes in blood pressure. (More)
BACKGROUND The AV delay optimization of biventricular pacemakers (cardiac resynchronization therapy) may maximize hemodynamic benefit but consumes specialist time to conduct echocardiographically. Noninvasive BP monitoring is a potentially automatable alternative, but it is unknown whether it gives the same information and similar precision (signal/noise(More)
BACKGROUND Hemodynamic optimization of cardiac resynchronization therapy (CRT) can be achieved reproducibly and--with bulky, nonimplantable equipment--noninvasively. We explored whether a simple photoplethysmogram signal might be used instead. METHOD Twenty patients (age 65 ± 12) with CRT underwent automatic atrioventricular (AV) delay optimization, using(More)
OBJECTIVES This study targeted carbon dioxide (CO(2)) oscillations seen in oscillatory ventilation with dynamic pre-emptive CO(2) administration. BACKGROUND Oscillations in end-tidal CO(2) (et-CO(2)) drive the ventilatory oscillations of periodic breathing (PB) and central sleep apnea in heart failure (HF). METHODS Seven healthy volunteers simulated PB,(More)
BACKGROUND Effective regurgitant orifice area (EROA) in mitral regurgitation (MR) is difficult to quantify. Clinically it is measured using the proximal isovelocity surface area (PISA) method, which is intrinsically not automatable, because it requires the operator to manually identify the mitral valve orifice. We introduce a new fully automated algorithm,(More)
Increased chemosensitivity to hypoxia and hypercapnia, together with a prolonged circulatory time, are the main determinants of Cheyne-Stokes (C-S) respiration in heart failure. To evaluate the effect of acetazolamide, a carbonic anhydrase inhibitor, on chemosensitivity and respiratory dynamics in patients with heart failure with C-S respiration, 12(More)
BACKGROUND The right ventricle (RV) may be selectively impaired following coronary artery bypass graft (CABG) surgery. We tested this hypothesis in two study parts: a prospective cohort undergoing CABG, and a retrospective cross-sectional cohort of heart-failure patients with and without a history of CABG. METHODS In the prospective study, 20 patients(More)
We examine the potential to treat unstable ventilatory control (seen in periodic breathing, Cheyne-Stokes respiration, and central sleep apnea) with carefully controlled dynamic administration of supplementary CO(2), aiming to reduce ventilatory oscillations with minimum increment in mean CO(2). We used a standard mathematical model to explore the(More)
BACKGROUND Clinicians are sometimes advised to make decisions using thresholds in measured variables, derived from prognostic studies. OBJECTIVES We studied why there are conflicting apparently-optimal prognostic thresholds, for example in exercise peak oxygen uptake (pVO2), ejection fraction (EF), and Brain Natriuretic Peptide (BNP) in heart failure(More)