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Heart rate variation as a marker of fluid responsiveness in patients with septic shock
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A ressuscitação com fluidos é um dos pilares do tratamento do choque séptico. O seu objetivo é aumentar o volume intravascular, aumentando o débito cardíaco (DC) e, consequentemente, melhorando a hipotensão e hipóxia tecidular. Esta deve basear-se na avaliação da fluidorresponsividade, só se devendo administrar fluídos se os benefícios antecipados ultrapassarem o risco de sobrecarga de volume. Pusemos a hipótese de que a variação da frequência cardíaca (FC), entre antes e depois de uma prova de fluidos, poderia ser um marcador de fluidorresponsividade.
Realizámos um estudo prospetivo observacional num hospital universitário terciário numa coorte de doentes admitidos na Unidade de Cuidados Intensivos (UCI) que se encontravam nas primeiras 24h após reconhecimento de choque séptico, definido como hiperlactacidemia e dependência de vasopressores associados a infeção presumida ou declarada. A fluidorresponsividade foi avaliada por ecocardiografia após uma prova de fluidos (infusão de 500 mL de cristalóides em 30 min). Um aumento de 10% no integral de velocidade-tempo no trato de saída do ventrículo esquerdo (LVOT-VTI, do inglês left ventricular outflow tract velocity time integral) foi usado em substituição de um aumento do volume sistólico. Foram obtidas medições de LVOT-VTI e velocidade de pico e outras variáveis, incluindo FC, antes e depois da administração de fluídos.
Foram incluídos 30 doentes no estudo, tendo 4 sido excluídos da análise por má janela acústica ecográfica. Em doentes respondedores não se verificou correlação significativa entre ΔLVOT-VTI% e ΔFC% (p=0,533), pelo que a ΔFC não parece ser um marcador adequado de fluidorresponsividade. Também não se encontrou correlação entre ΔLVOT-VTI% e Δvelocidade de pico% (p=0,070) nem entre ΔLVOT-VTI% e ΔDC% (p=0,213) em respondedores. Embora a variação do volume sistólico seja uma variável validada para prever fluidorresponsividade em doentes em choque séptico, a sua aplicabilidade é limitada e os nossos dados sugerem que é apenas útil numa pequena percentagem dos doentes em UCI (39,3%).
Fluid resuscitation is a basilar stone in septic shock treatment. Its main goal is to increase intravascular volume, hence increasing cardiac output (CO), which will ultimately improve hypotension and tissue hypoxia. Fluid administration should only occur when hemodynamic benefits likely outweigh the risks of fluid overload and should be based on fluid responsiveness assessment. We hypothesized that heart rate (HR) variation between before and after a fluid challenge could be a marker of fluid responsiveness. We performed a prospective observational study in a tertiary universitary hospital in a cohort of patients in the first 24h after septic shock recognition admitted to the Intensive Care Unit (ICU). Septic shock was identified by hiperlactacidemia and vasopressor dependence associated with presumed or declared infection. A fluid challenge (500 mL crystalloid infusion in 30 min) was performed. Fluid responsiveness was evaluated by echocardiography and a 10% increase in the left ventricular outflow tract velocity time integral (LVOT-VTI) was used as a surrogate of systolic volume increase. Averages of three LVOT-VTI and peak velocity measures collected before and after volume expansion were used. Other data was also collected, including heart rate prior and after fluid administration. A total of 30 patients were enrolled in this study but 4 were excluded from the analysis due to poor acoustic echocardiographic window. In responsive patients, there was no significant correlation between ΔLVOT-VTI% and ΔHR% (p=0,533), therefore ΔHR does not seem to be an adequate marker of fluid responsiveness. We also found no correlation between ΔLVOT-VTI% and Δpeak velocity% (p=0,070) nor between ΔLVOT-VTI% and ΔCO% (p=0,213) in responsive patients. Furthermore, albeit systolic volume variation is a validated variable to predict fluid responsiveness in patients in septic shock, its applicability is limited, and our data suggests it may be of little use in a large percentage of the ICU population (39,3%).
Fluid resuscitation is a basilar stone in septic shock treatment. Its main goal is to increase intravascular volume, hence increasing cardiac output (CO), which will ultimately improve hypotension and tissue hypoxia. Fluid administration should only occur when hemodynamic benefits likely outweigh the risks of fluid overload and should be based on fluid responsiveness assessment. We hypothesized that heart rate (HR) variation between before and after a fluid challenge could be a marker of fluid responsiveness. We performed a prospective observational study in a tertiary universitary hospital in a cohort of patients in the first 24h after septic shock recognition admitted to the Intensive Care Unit (ICU). Septic shock was identified by hiperlactacidemia and vasopressor dependence associated with presumed or declared infection. A fluid challenge (500 mL crystalloid infusion in 30 min) was performed. Fluid responsiveness was evaluated by echocardiography and a 10% increase in the left ventricular outflow tract velocity time integral (LVOT-VTI) was used as a surrogate of systolic volume increase. Averages of three LVOT-VTI and peak velocity measures collected before and after volume expansion were used. Other data was also collected, including heart rate prior and after fluid administration. A total of 30 patients were enrolled in this study but 4 were excluded from the analysis due to poor acoustic echocardiographic window. In responsive patients, there was no significant correlation between ΔLVOT-VTI% and ΔHR% (p=0,533), therefore ΔHR does not seem to be an adequate marker of fluid responsiveness. We also found no correlation between ΔLVOT-VTI% and Δpeak velocity% (p=0,070) nor between ΔLVOT-VTI% and ΔCO% (p=0,213) in responsive patients. Furthermore, albeit systolic volume variation is a validated variable to predict fluid responsiveness in patients in septic shock, its applicability is limited, and our data suggests it may be of little use in a large percentage of the ICU population (39,3%).
Descrição
Trabalho Final do Curso de Mestrado Integrado em Medicina, Faculdade de Medicina, Universidade de Lisboa, 2023
Palavras-chave
Choque séptico Fluidorresponsividade Frequência cardíaca Medicina intensiva