The purpose of this study was to explore the efficacy of two existing pulse contour analysis (PCA) models for estimating cardiac stroke volume from the arterial pressure waveform during kicking ergometer exercise and head-up tilt manoeuvres. Secondly, one of the existing models was modified in an attempt to enhance its performance. In part I, seven healthy young adults repeated two submaximal exercise sessions on a kicking ergometer, each with three different sets of steady-state cardiac output comparisons (pulsed Doppler vs. pulse contour). Across all exercise trials regression results were found to be PCA = 1. 23 x Doppler-1. 38 with an r2 = 0. 51. In part II, eight young and eight older male healthy subjects participated in a head-up tilt experiment. Cardiac output comparisons were again performed during the supine and tilt conditions using pulsed Doppler and pulse contour cardiac output. Regression results revealed that PCA performed best during supine conditions and preferentially on the older subjects. In all instances, impedance-calibrated pulse contour analysis will provide reasonable beat-by-beat cardiac output within very narrow confines and will result in a progressively more significant bias as cardiovascular dynamics change. In addition, it appears that heart rate variability negatively influences beat-by-beat pulse contour cardiac output results, further limiting application of existing models.

The purpose of this study was to explore the efficacy of two existing pulse contour analysis (PCA) models for estimating cardiac stroke volume from the arterial pressure waveform during kicking ergometer exercise and head-up tilt manoeuvres. Secondly, one of the existing models was modified in an attempt to enhance its performance. In part I, seven healthy young adults repeated two submaximal exercise sessions on a kicking ergometer, each with three different sets of steady-state cardiac output comparisons (pulsed Doppler vs. pulse contour). Across all exercise trials regression results were found to be PCA = 1. 23 x Doppler-1. 38 with an r2 = 0. 51. In part II, eight young and eight older male healthy subjects participated in a head-up tilt experiment. Cardiac output comparisons were again performed during the supine and tilt conditions using pulsed Doppler and pulse contour cardiac output. Regression results revealed that PCA performed best during supine conditions and preferentially on the older subjects. In all instances, impedance-calibrated pulse contour analysis will provide reasonable beat-by-beat cardiac output within very narrow confines and will result in a progressively more significant bias as cardiovascular dynamics change. In addition, it appears that heart rate variability negatively influences beat-by-beat pulse contour cardiac output results, further limiting application of existing models.

Orientador: Francisco José Teixeira-Neto / Resumo: Introdução e objetivos: Mensurações do débito cardíaco (DC) pela técnica termodiluição transpulmonar (DCTP) e pela análise de contorno de pulso com calibração pela técnica transpulmonar (DCACP) são alternativas menos invasivas em comparação ao DC fornecido pela técnica de termodiluição de artéria pulmonar (DCP). Entretanto, instabilidades hemodinâmicas podem alterar o desempenho destes métodos. A Fase I do estudo objetivou avaliar se a utilização de 10 mL de indicador térmico (solução fisiológica a ≤ 5oC) para o DCTP (artéria femoral) promoveria melhor concordância e habilidade em detectar alterações no DCP em comparação a 5 mL de indicador. Na Fase II, objetivou-se verificar se alterações na resistência vascular sistêmica (RVS) influenciariam a concordância e a habilidade em detectar tendências entre o DCACP e o DCP. Métodos: Em 8 cães adultos (20,8–31,5 kg), mensurações simultâneas em triplicata do DCTP e DCP foram obtidas utilizando 5 e 10 mL de indicador térmico durante anestesia com isoflurano associado ou não com a infusão contínua intravenosa de remifentanil (0,3 e 0,6 μg/kg/min) ou de dobutamina (2,5 e 5,0 μg/kg/min) (Fase I). Durante a Fase II, o DCACP e o DCP foram mensurados simultaneamente (triplicata) antes e durante alterações na RVS induzidas pela infusão contínua de fenilefrina (1,0 μg/kg/min) ou de nitroprussiato (1,0 μg/kg/min). A acurácia e a precisão da concordância entre métodos foram estudadas pela análise de Bland-Altman para medidas múltiplas (Fase I) ... (Resumo completo, clicar acesso eletrônico abaixo) / Abstract: Background and objectives: Cardiac output (CO) measurements by transpulmonary thermodilution (TPTDCO) and by pulse contour analysis calibrated with transpulmonary thermodilution (PCACO) are less invasive alternatives to pulmonary artery thermodilution (PATDCO). However, hemodynamic instability could affect the performance of these methods. The objective of Phase I of the study was to determine if the use of 10 mL of thermal indicator (physiological saline at ≤ 5oC) for TPTDCO (measured in the femoral artery) would improve the agreement and trending ability with PATDCO in comparison to 5 mL of indicator. During Phase II, the aim was to verify if changes in systemic vascular resistance (SVR) would alter the agreement and trending ability between PCACO and PATDCO. Methods: In eight adult dogs (20.8–31.5 kg), simultaneous TPTDCO and PATDCO measurements (averaged from 3 repetitions) using 5 and 10 mL of thermal indicator were obtained during isoflurane anesthesia combined or not with intravenous remifentanil (0.3 e 0.6 μg/kg/min) or dobutamine (2.5 e 5.0 μg/kg/min) (Phase-1). During Phase-2, triplicate PCACO and PATDCO measurements were recorded before and during phenylephrine (1.0 μg/kg/min) or nitroprusside (1.0 μg/kg/min) induced changes in SVR. The accuracy and precision of agreement was evaluated by the Bland-Altman method for multiple measurements (Phase I) and for single measurements per subject (Phase 2). The ability of the test methods (PCACO and TPTDCO) to detect changes... (Complete abstract click electronic access below) / Doutor