Description
Le dysfonctionnement cardiaque est fréquent en cas de sepsis et de choc septique, nécessitant une évaluation rigoureuse pour une prise en charge optimale. L'échocardiographie est la pierre angulaire de l'évaluation de la fonction myocardique, notamment de la fraction d'éjection et du débit cardiaque. Elle permet de détecter une dilatation ventriculaire, une diminution de la contractilité ou d'autres anomalies.
Des biomarqueurs comme les troponines et le peptide natriurétique de type B (BNP) aident à identifier les lésions et le stress myocardiques. La surveillance hémodynamique, à l'aide d'outils tels que les cathéters artériels pulmonaires ou l'analyse du contour du pouls, fournit des informations sur le débit cardiaque et la résistance vasculaire systémique. L'identification précoce d'un dysfonctionnement cardiaque permet des interventions sur mesure.
Résumé
- The speaker discusses the use of echocardiography (Echo) in managing septic shock, emphasizing its value in hemodynamic assessment and support. While Echo is beneficial for measuring cardiac output, stroke volume, and ventricular function, definitive studies proving its impact on mortality benefits in sepsis are lacking. Its advantages include being non-invasive, rapid availability, high diagnostic yield, and monitoring abilities, allowing for flexible use and handling of specific cardiac issues related to sepsis.
- In early septic shock, Echo can help recognize a failing cardiovascular system by identifying defective volume, vascular tone problems, or pump failure. Common findings include hypovolemia and biventricular hyperkinesia. Repeated assessments are crucial during hemodynamic iterations, enabling early recognition and correction of factors, requiring integration of other clinical data like arterial pressures and lactates. The goal is to assess cardiac output, volume status, volume responsiveness, LV and RV systolic function, systemic arterial resistances, and LV filling pressures.
- For low output states, Doppler sampling of the left ventricular outflow tract (LVOT) is performed, but the aortic valve must be intact. Measurements are typically done through the five-chamber view in transthoracic echo or deep transgastric views in transesophageal echo. The time velocity integral of blood exiting the LV is multiplied by the calculated cross-sectional area of the LVOT. Normal cardiac index values aren't always adequate in septic shock due to peripheral flow distribution variations, and current methods are often semi-quantitative rather than precise.
- Inadequate central blood volume, despite resuscitation, can be identified by a small left ventricular end-diastolic area, particularly on the parasternal short axis view. Volume responsiveness is tested using metrics like Delta Vpeak, IVC distensibility index, SVC collapsibility index, and response to passive leg raising (PLR). However, accuracy depends on the patient being passively mechanically ventilated and in sinus rhythm. LV systolic dysfunction is assessed qualitatively or quantitatively, and sequential determination of ejection fraction and fractional area change is performed.
- RV systolic dysfunction, present in about one-third of septic shock patients, can occur alone or as part of biventricular dysfunction. It is assessed semi-quantitatively, appreciating RV dilation. Management involves inotropic administration, vasopressors, and low plateau pressure ventilation; in some cases, inhaled nitric oxide or pronation may be needed. Assessing diastolic function and filling pressures is also crucial, utilizing mitral annulus tissue Doppler and mitral inflow propagation velocity.
- Transesophageal echo aids in diagnosing cardiac sources of sepsis, demonstrating a higher sensitivity for small vegetations. However, limitations include a lack of robust outcome data, frequent value estimations rather than precise measurements, and the need for integration with other monitoring devices like pulse contour cardiac output monitors, PA catheters, or PiCCO. Despite having potential diagnostic capability and monitoring accuracy, the speaker stresses the need for more extensive outcome studies focused on mortality related to echo in septic shock.
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