Abstract
BackgroundEchocardiography is increasingly used for haemodynamic evaluation and titration of therapy in intensive care, warranting reliable and reproducible measurements. The aim of this study was to evaluate the observer dependence of echocardiographic findings of left ventricular (LV) diastolic and systolic dysfunction in patients with septic shock.MethodsEchocardiograms performed in 47 adult patients admitted with septic shock to a general intensive care unit (ICU) were independently evaluated by one cardiologist and one intensivist for the following signs: decreased diastolic tissue velocity of the base of the LV septum (é), increased early mitral inflow (E) to é ratio (E/é), decreased LV ejection fraction (EF) and decreased LV global longitudinal peak strain (GLPS). Diastolic dysfunction was defined as é <8.0 cm/s and/or E/é ≥15 and systolic dysfunction as EF <50% and/or GLPS > −15%. Ten randomly selected examinations were re-analysed two months later. Pearson’s r was used to test the correlation and Bland-Altman plots to assess the agreement between observers. Kappa statistics were used to test the consistency between readers and intraclass correlation coefficients (ICC) for inter- and intraobserver variability.ResultsIn 44 patients (94%), image quality was sufficient for echocardiographic measurements. The agreement between observers was moderate (k = 0.60 for é, k = 0.50 for E/é and k = 0.60 for EF) to good (k = 0.71 for GLPS). Pearson’s r was 0.76 for é, 0.85 for E/é, 0.78 for EF and 0.84 for GLPS (p < 0.001 for all four). The ICC between observers for é was very good (0.85; 95% confidence interval (CI) 0.73-0.92), good for E/é (0.70; 95% CI 0.45 – 0.84), very good for EF (0.87; 95% CI 0.77 – 0.93), excellent for GLPS (0.91; 95% CI 0.74 – 0.95), and very good for all measures repeated by one of the observers. On Bland-Altman analysis, the mean differences and 95% limits of agreement for é, E/é, EF and GLPS were −0.01 (0.04 – 0.07), 2.0 (−14.2 – 18.1), 0.86 (−16 – 14.3) and 0.04 (−5.04 – 5.12), respectively.ConclusionsModerate observer-related differences in assessing LV dysfunction were seen. GLPS is the least user dependent and most reproducible echocardiographic measurement of LV function in septic shock.Electronic supplementary materialThe online version of this article (doi:10.1186/s12947-015-0015-6) contains supplementary material, which is available to authorized users.
Highlights
Echocardiography is increasingly used for haemodynamic evaluation and titration of therapy in intensive care, warranting reliable and reproducible measurements
Patients who by the treating physician were not expected to survive longer than 24 hours, in whom intensive care treatment was partly withheld from admission, or who due to language barriers or mental inability were not expected to be able to give consent even after recovery, were excluded
Two patients died before echocardiography could be undertaken and in one patient, images were lost in the storage process
Summary
Echocardiography is increasingly used for haemodynamic evaluation and titration of therapy in intensive care, warranting reliable and reproducible measurements. Cardiac dysfunction is a well-known complication of septic shock. It was first described using radionuclide cineangiography [1], and has been studied further since the introduction of echocardiography in intensive care clinical practice. Numerous studies have described diastolic as well as systolic dysfunction, or a combination of the two, in septic shock, using a variety of different echocardiographic parameters [2,3,4,5,6]. Echocardiographic assessment is often complicated by tachycardia, high levels of catecholamines and difficulties in image
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