Study objective: We hypothesized that a dynamic left
ventricular (LV) evaluation during a loading challenge might enhance
diagnostic capabilities of routine transesophageal echocardiography in
critically ill patients and selection of therapeutic options against
circulatory failure, particularly the choice between volume expansion
and vasoactive agent infusion.
clinical study in a group of 26 patients requiring hemodynamic support
by vasoactive infusion because of low systemic arterial pressure
(< 90 mm Hg by invasive monitoring) during mechanical
Setting: University hospital ICU.
Patients: Patients required respiratory support for an
episode of acute respiratory failure of various causes or for an
episode of coma. They were studied by transesophageal echocardiography
during mechanical ventilation in the controlled mode, before and during
a loading challenge made using the legs compartment of medical
antishock trousers inflated at 80 mm Hg.
A short-axis view of the left ventricle was obtained by a transgastric
approach, and end-diastolic and end-systolic areas were measured. LV
stroke area (LVSA) and LV fractional area contraction (LVFAC) were
Results: Changes in LV
echocardiographic measurements permitted separation of the patients
into two groups. In nine patients (group 1), LVSA, used as an index of
stroke output, was significantly increased during the challenge,
together with a significant increase in LV end-diastolic area,
suggesting preload improvement by the challenge. Conversely, in 17
patients (group 2), LVSA was significantly reduced by the challenge,
together with a significant decrease in LVFAC, suggesting a negative
effect of increased afterload by the challenge.
Conclusion: Study of the changes in LV dimensions during
loading challenge in hemodynamically unstable patients was used to
evaluate the balance between the adequacy of preload and the ability of
the heart to pump against an increased load, and might thus guide