Transthoracic echocardiographic assessment of cardiac output in mechanically ventilated critically ill patients by intensive care unit physicians / Avaliação ecocardiográfica transtorácica do débito cardíaco feita por médicos da unidade de terapia intensiva em pacientes críticos sob ventilação mecânica

Abstract Background and objectives: Transthoracic echocardiography may potentially be useful to obtain a prompt, accurate and non-invasive estimation of cardiac output. We evaluated whether non-cardiologist intensivists may obtain accurate and reproducible cardiac output determination in hemodynamically unstable mechanically ventilated patients. Methods: We studied 25 hemodynamically unstable mechanically ventilated intensive care unit patients with a pulmonary artery catheter in place. Cardiac output was calculated using the pulsed Doppler transthoracic echocardiography technique applied to the left ventricular outflow tract in apical 5 chamber view by two intensive care unit physicians who had received a basic Transthoracic Echocardiography training plus a specific training focused on Doppler, left ventricular outflow tract and velocity-time integral determination. Results: Cardiac output assessment by transthoracic echocardiography was feasible in 20 out of 25 enrolled patients (80%) and showed an excellent inter-operator reproducibility (Pearson correlation test r = 0.987; Cohen's K = 0.840). Overall, the mean bias was 0.03 L.min-1, with limits of agreement -0.52 and +0.57 L.min-1. The concordance correlation coefficient (ρc) was 0.986 (95% IC 0.966-0.995) and 0.995 (95% IC 0.986-0.998) for physician 1 and 2, respectively. The value of accuracy (Cb) of COTTE measurement was 0.999 for both observers. The value of precision (ρ) of COTTE measurement was 0.986 and 0.995 for observer 1 and 2, respectively. Conclusions: A specific training focused on Doppler and VTI determination added to the standard basic transthoracic echocardiography training allowed non-cardiologist intensive care unit physicians to achieve a quick, reproducible and accurate snapshot cardiac output assessment in the majority of mechanically ventilated intensive care unit patients.

Resumo Justificativa e objetivos: A ecocardiografia transtorácica pode ser potencialmente útil para obter uma estimativa rápida, precisa e não invasiva do débito cardíaco. Avaliamos se os intensivistas não cardiologistas podem obter uma determinação precisa e reprodutível do débito cardíaco em pacientes mecanicamente ventilados e hemodinamicamente instáveis. Métodos: Avaliamos 25 pacientes em unidade de terapia intensiva, mecanicamente ventilados, hemodinamicamente instáveis, com cateteres de artéria pulmonar posicionados. O débito cardíaco foi calculado com a técnica de ecocardiografia transtorácica com Doppler pulsátil aplicada à via de saída do ventrículo esquerdo no corte apical (5-câmaras) por dois médicos intensivistas que receberam treinamento básico em ecocardiografia transtorácica e treinamento específico focado em Doppler, via de saída do ventrículo esquerdo e determinação da integral de tempo-velocidade. Resultados: A avaliação do débito cardíaco pelo ecocardiograma transtorácico foi factível em 20 dos 25 pacientes inscritos (80%) e mostrou excelente reprodutibilidade entre operadores (teste de correlação de Pearson r = 0,987; K de Cohen = 0,840). No geral, o viés médio foi de 0,03 L.min-1, com limites de concordância de -0,52 e +0,57 L.min-1. O coeficiente de correlação de concordância (ρc) foi 0,986 (95% IC 0,966-0,995) e 0,995 (95% IC 0,986-0,998) para os médicos 1 e 2, respectivamente. O valor de precisão (Cb) da mensuração de COTTE foi de 0,999 para ambos os observadores. O valor de precisão (ρ) da mensuração de COTTE foi de 0,986 e 0,995 para os observadores 1 e 2, respectivamente. Conclusões: Um treinamento específico focado na determinação do Doppler e VTI, adicionado ao treinamento padrão em ecocardiografia transtorácica básica, permitiu que médicos não cardiologistas da unidade de terapia intensiva obtivessem uma avaliação rápida, reprodutível e precisa do débito cardíaco instantâneo na maioria dos pacientes mecanicamente ventilados em unidade de terapia intensiva.

[Transthoracic echocardiographic assessment of cardiac output in mechanically ventilated critically ill patients by intensive care unit physicians]. / Avaliação ecocardiográfica transtorácica do débito cardíaco feita por médicos da unidade de terapia intensiva em pacientes críticos sob ventilação mecânica.

BACKGROUND AND OBJECTIVES: Transthoracic echocardiography may potentially be useful to obtain a prompt, accurate and non-invasive estimation of cardiac output. We evaluated whether non-cardiologist intensivists may obtain accurate and reproducible cardiac output determination in hemodynamically unstable mechanically ventilated patients. METHODS: We studied 25 hemodynamically unstable mechanically ventilated intensive care unit patients with a pulmonary artery catheter in place. Cardiac output was calculated using the pulsed Doppler transthoracic echocardiography technique applied to the left ventricular outflow tract in apical 5 chamber view by two intensive care unit physicians who had received a basic Transthoracic Echocardiography training plus a specific training focused on Doppler, left ventricular outflow tract and velocity-time integral determination. RESULTS: Cardiac output assessment by transthoracic echocardiography was feasible in 20 out of 25 enrolled patients (80%) and showed an excellent inter-operator reproducibility (Pearson correlation test r=0.987; Cohen's K=0.840). Overall, the mean bias was 0.03L.min-1, with limits of agreement -0.52 and +0.57L.min-1. The concordance correlation coefficient (ρc) was 0.986 (95% IC 0.966-0.995) and 0.995 (95% IC 0.986-0.998) for physician 1 and 2, respectively. The value of accuracy (Cb) of COTTE measurement was 0.999 for both observers. The value of precision (ρ) of COTTE measurement was 0.986 and 0.995 for observer 1 and 2, respectively. CONCLUSIONS: A specific training focused on Doppler and VTI determination added to the standard basic transthoracic echocardiography training allowed non-cardiologist intensive care unit physicians to achieve a quick, reproducible and accurate snapshot cardiac output assessment in the majority of mechanically ventilated intensive care unit patients.