Navegando por Palavras-chave "stroke volume"

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    Haemodynamic effects of proportional assist ventilation during high-intensity exercise in patients with chronic obstructive pulmonary disease
    (Wiley-Blackwell, 2010-11-01) Carrascossa, Claudia R. [UNIFESP]; Oliveira, Cristino C. [UNIFESP]; Borghi-Silva, Audrey [UNIFESP]; Ferreira, Eloara M. V. [UNIFESP]; Maya, Joyce [UNIFESP]; Queiroga, Fernando [UNIFESP]; Berton, Danilo C. [UNIFESP]; Nery, Luiz E. [UNIFESP]; Alberto Neder, J. [UNIFESP]; Universidade Federal de São Paulo (UNIFESP); Universidade Federal de São Carlos (UFSCar)
    Background and objective: Proportional assist ventilation (PAV) has been proposed as a more physiological modality of non-invasive ventilation, thereby reducing the potential for deleterious cardio-circulatory effects during exercise, in patients with COPD. We therefore evaluated whether PAV modulates the kinetic and 'steady-state' haemodynamic responses to exercise in patients with moderate-to-severe COPD.Methods: Twenty patients underwent constant-load (75-80% peak work rate) cycle ergometer exercise testing to the limit of tolerance (T(lim)), while receiving PAV or breathing spontaneously. Stroke volume (SV), heart rate (HR) and cardiac output (CO) were monitored by impedance cardiography.Results: Compared with unassisted breathing, PAV increased T(lim) in 8/20 patients (median improvement 113% (range 8 to 212) vs -20% (range -40 to -9)). PAV had no significant effects on 'steady-state' haemodynamic responses either in patients with or those without increased T(lim) (P > 0.05). However, at the onset of exercise, SV kinetics were slowed with PAV, in 13/15 patients with analysable data. HR dynamics remained unaltered or failed to accelerate sufficiently in nine of these patients, thereby slowing CO kinetics (T(1/2) 61 s (range 81-30) vs 89 s (range 100-47)). These deleterious effects were not, however, associated with PAV-induced changes in T(lim) (P > 0.05).Conclusions: PAV slowed the SV and CO kinetics at the onset of high-intensity exercise in selected patients with moderate-to-severe COPD. However, these adverse effects of PAV disappeared during the stable phase of exercise, and were not related to the ergogenic potential of PAV in this patient population.
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    Heart stroke volume, cardiac output, and ejection fraction in 265 normal fetus in the second half of gestation assessed by 4D ultrasound using spatio-temporal image correlation
    (Informa Healthcare, 2011-09-01) Simioni, Christiane [UNIFESP]; Machado Nardozza, Luciano Marcondes [UNIFESP]; Araujo Junior, Edward [UNIFESP]; Rolo, Liliam Cristine [UNIFESP]; Zamith, Marina [UNIFESP]; Caetano, Ana Carolina [UNIFESP]; Moron, Antonio Fernandes [UNIFESP]; Universidade Federal de São Paulo (UNIFESP)
    Objectives. the aim of this study was to establish nomograms for fetal stroke volume (SV), cardiac output (CO), and ejection fraction (EF) using four-dimensional ultrasound with spatio-temporal image correlation (STIC) modality.Methods. the fetal heart was scanned using STIC modality, starting with classic four-chamber view plane, during fetal quiescence with abdomen uppermost, at an angle of 20-30 degrees, without color Doppler flow mapping. in post-processing virtual organ, computer-aided analysis technique was used to obtain a sequence of six sections of each ventricular volume in end-systolic volume (ESV) and end-diastolic volume (EDV). the SV (SV = EDV-ESV), CO (CO = SV x fetal heart rate), and EF (EF = SV/EDV) for each ventricle were then calculated. Intra- and interobserver agreement were then calculated.Results. Two hundred sixty-five fetuses, ranging in gestational age (GA) from 20 to 34(+6) weeks, were included in the study. the left and right SV and CO increased exponentially with gestation and EF remained fairly stable through gestational. Mean left and right SV increased from 0.211 ml and 0.220 ml at 20 weeks to 1.925 ml and 2.043 ml, respectively, at 34 weeks. Mean left and right CO increased from 30.25 ml/min and 31.52 ml/min at 20 weeks to 268.49 ml/min and 287.80 ml/min, respectively, at 34 weeks. Both left and right mean EF remained constant at around 0.63 with advancing GA. Nomograms were created for LSV, RSV, LCO, RCO, LEF, and REF vs. gestational age. Intra- and interobserver agreement reached 95%.Conclusions. Four-dimensional ultrasound using STIC represents a simple and reproducible method for estimating fetal cardiac function. STIC seems to overcome many of the pitfalls of conventional ultrasound methods and has the potential to become the method of choice.