Subject(s)
Humans , Heart , Cardiac Output , Reproducibility of Results , Healthy Volunteers , Monitoring, PhysiologicABSTRACT
FUNDAMENTO: A ressonância magnética cardíaca é considerada o método padrão-ouro para o cálculo de volumes cardíacos. A bioimpedância transtorácica cardíaca avalia o débito cardíaco. Não há trabalhos que validem essa medida comparada à ressonância. OBJETIVO: Avaliar o desempenho da bioimpedância transtorácica cardíaca no cálculo do débito cardíaco, índice cardíaco e volume sistólico, utilizando a ressonância como padrão-ouro. MÉTODOS: Avaliados 31 pacientes, com média de idade de 56,7 ± 18 anos, sendo 18 (58%) do sexo masculino. Foram excluídos os pacientes cuja indicação para a ressonância magnética cardíaca incluía avaliação sob estresse farmacológico. A correlação entre os métodos foi avaliada pelo coeficiente de Pearson, e a dispersão das diferenças absolutas em relação à média foi demonstrada pelo método de Bland-Altman. A concordância entre os métodos foi realizada pelo coeficiente de correlação intraclasses. RESULTADOS: A média do débito cardíaco pela bioimpedância transtorácica cardíaca e pela ressonância foi, respectivamente, 5,16 ± 0,9 e 5,13 ± 0,9 L/min. Observou-se boa correlação entre os métodos para o débito cardíaco (r = 0,79; p = 0,0001), índice cardíaco (r = 0,74; p = 0,0001) e volume sistólico (r = 0,88; p = 0,0001). A avaliação pelo gráfico de Bland-Altman mostrou pequena dispersão das diferenças em relação à média, com baixa amplitude dos intervalos de concordância. Houve boa concordância entre os dois métodos quando avaliados pelo coeficiente de correlação intraclasses, com coeficientes para débito cardíaco, índice cardíaco e volume sistólico de 0,78, 0,73 e 0,88, respectivamente (p < 0,0001 para todas as comparações). CONCLUSÃO: A bioimpedância transtorácica cardíaca mostrou-se acurada no cálculo do débito cardíaco quando comparada à ressonância magnética cardíaca.
BACKGROUND: Cardiac magnetic resonance imaging is considered the gold-standard method for the calculation of cardiac volumes. Transthoracic impedance cardiography assesses the cardiac output. No studies validating this measurement, in comparison to that obtained by magnetic resonance imaging, are available. OBJECTIVE: To evaluate the performance of transthoracic impedance cardiography in the calculation of the cardiac output, cardiac index and stroke volume using magnetic resonance imaging as the gold-standard. METHODS: 31 patients with a mean age of 56.7 ± 18 years were assessed; of these, 18 (58%) were males. Patients whose indication for magnetic resonance imaging required pharmacologic stress test were excluded. Correlation between methods was assessed using the Pearson's coefficient, and dispersion of absolute differences in relation to the mean was demonstrated using the Bland-Altman's method. Agreement between methods was analyzed using the intraclass correlation coefficient. RESULTS: The mean cardiac output by transthoracic impedance cardiography and by magnetic resonance imaging was 5.16 ± 0.9 and 5.13 ± 0.9 L/min, respectively. Good agreement between methods was observed for cardiac output (r = 0.79; p = 0.0001), cardiac index (r = 0.74; p = 0.0001) and stroke volume (r = 0.88; p = 0.0001). The analysis by the Bland-Altman plot showed low dispersion of differences in relation to the mean, with a low amplitude of agreement intervals. Good agreement between the two methods was observed when analyzed by the intraclass correlation coefficient, with coefficients for cardiac output, cardiac index and stroke volume of 0.78, 0.73 and 0.88, respectively (p < 0.0001 for all comparisons). CONCLUSION: Transthoracic impedance cardiography proved accurate in the calculation of the cardiac output in comparison to cardiac magnetic resonance imaging.
Subject(s)
Adult , Aged , Female , Humans , Male , Middle Aged , Cardiac Output/physiology , Cardiography, Impedance/standards , Magnetic Resonance Imaging/standards , Heart Failure/diagnosis , Hemodynamics/physiology , Stroke VolumeABSTRACT
BACKGROUND: Determining the precise magnitude, duration, and mechanism of hypotension caused by intravenous amiodarone could potentially increase the safety of drug administration to critically ill patients. The objective of this study was to characterize the immediate cardiovascular actions of an intravenous loading dose of amiodarone administered using echocardiographic and hemodynamic measurements. METHODS: In a prospective double-blind trial, 20 patients undergoing off-pump coronary artery bypass graft surgery were randomly assigned to receive intravenous amiodarone (n = 10) or placebo (n = 10). Heart rate (HR), arterial blood pressure (systolic, diastolic, mean; SAP, DAP, MAP), pulmonary artery pressure (systolic, diastolic, mean; PSAP, PDAP, PMAP), cardiac output (CO), central venous pressure (CVP), left ventricular ejection fraction (LVEF) were measured. RESULTS: HR, SAP, DAP, MAP, PSAP, PDAP, PMAP, CO by thermodilution method, CVP, LVEF by echocardiographic measurements was not significantly different in both group. Hypotension requiring intervention occurred in 2 of 10 patients after amiodarone administration and in none of 10 patients after placebo. CONCLUSIONS: Hypotension requiring intervention occurred 20% after amiodarone administration, the cause of these hypotension were thought to be arterial dilatation but was not associated with decreased cardiac output or left ventricular ejection fraction and corrected successfully by intravenous administration of phenylephrine.