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Tissue Doppler of Early Mitral Filling Correlates With Simulated Volume Loss in Healthy Subjects
Author(s) -
Moore Christopher L.,
Tham Edward T.,
Samuels Kathleen J.,
McNamara Robert L.,
Galante Nicholas J.,
Stachenfeld Nina,
Shelley Kirk,
Dziura James,
Silverman David G.
Publication year - 2010
Publication title -
academic emergency medicine
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 1.221
H-Index - 124
eISSN - 1553-2712
pISSN - 1069-6563
DOI - 10.1111/j.1553-2712.2010.00906.x
Subject(s) - medicine , hypovolemia , preload , doppler effect , cardiology , intravascular volume status , inferior vena cava , doppler imaging , blood pressure , ultrasound , doppler ultrasound , nuclear medicine , hemodynamics , radiology , diastole , physics , astronomy
Objectives: The accurate noninvasive assessment of preload in emergency department (ED) patients remains elusive. Point‐of‐care ultrasound (US) imaging, particularly evaluation of the inferior vena cava (IVC), has been shown to be qualitatively helpful. Doppler and tissue Doppler are now routinely available on ED US equipment, but few studies have looked at the correlation of dynamic changes in these parameters in a controlled model of hypovolemia. Our objective was to examine the correlation of Doppler parameters to simulated volume loss in healthy subjects using a lower‐body negative pressure (LBNP) model and to compare these measurements to commonly used IVC measurements of preload. Methods: Twelve paid volunteers with no known cardiovascular disease between the ages of 23 and 31 years old (mean ± SD = 25.5 ± 2.5 years old) were recruited. Hypovolemia was simulated using graduated LBNP levels with measurements taken at 0, −30, and −60 mm Hg and lower pressures as tolerated. Vital signs were monitored in all patients. US measurements recorded at each negative pressure level included IVC maximum (IVC max ) and minimum (IVC min ) dimensions; early (E) and late (A) transmitral filling velocities using pulsed‐wave spectral Doppler; and early (E′) and late (A′) tissue Doppler velocities at the septal ( sep ) and lateral ( lat ) mitral annulus, using pulsed‐wave tissue Doppler. Results: Lower‐body negative pressure correlated significantly and positively within subjects for all US parameters except for the A filling wave. E′ lat and E′ sep showed the strongest correlation with R 2 values of 0.749 (95% confidence interval [CI] = 0.577 to 0.854) and 0.738 (95% CI = 0.579 to 0.875) respectively, followed by A′ sep 0.674 (95% CI = 0.416 to 0.845), IVC max 0.638 (95% CI = 0.425 to 0.806), A′ lat 0.547 (95% CI = 0.280 to 0.802), IVC min 0.512 (95% CI = 0.192 to 0.777), and E 0.478 (95% CI = 0.187 to 0.762). Ratios correlated only moderately with LBNP level, including E/ E′ lat R 2 of 0.430 (95% CI = 0.131 to 0.706), E/ E′ sep 0.416 (95% CI = 0.183 to 0.686), and IVC collapsibility index (IVC CI ) 0.201 (95% CI = 0.003 to 0.681). Vital signs, including heart rate and blood pressure, did not vary significantly with LBNP levels. Conclusions: In this pilot study of healthy subjects, tissue Doppler assessment of early diastolic filling correlated most strongly with simulated hypovolemia. ACADEMIC EMERGENCY MEDICINE 2010; 17:1162–1168 © 2010 by the Society for Academic Emergency Medicine