The use of transesophageal echocardiography for preload assessment in critically ill patients

IV volume is often administered to patients in an intensive care unit (ICU) to improve cardiovascular function. We investigated the relationship betwe en stroke volume (SV) and left ventricular (LV) size by using transesophage al echocardiography (TEE) in a population of 20 ICU patients and 21 postope rative cardiac surgical patients. We also examined whether LV end diastolic area (EDA), by TEE, could identify patients who increased SV by 20% or mor e (responders) after 500 mL of pentastarch administration. There was only a modest relationship (r = 0.60) between the EDA and the SV in all patients. No relationship could be found between the pulmonary capillary wedge press ure (PCWP) and the EDA in all patients. Both responder and nonresponder PCW P increased significantly after volume administration. Only responder EDA i ncreased significantly after volume administration. Responders had signific antly lower EDA (15.3 +/- 5.4 cm(2)) and PCWP (12.2 +/- 2.2 mmHg) when comp ared with nonresponders (20.2 +/- 4.8 cm(2)) and 15.9 +/- 3.1 mm Hg, respec tively). Pew ICU patients and only those with a small EDA responded to volu me administration. It was not possible to identify an overall optimal LV ED A below which most patients demonstrate volume-recruitable increases in SV. Implications: In a ventilated intensive care unit and cardiac surgical pop ulation, transesophageal echocardiography and pulmonary artery catheter are sensitive in detecting changes in preload after volume administration. Few patients demonstrate volume-recruitable increases in stroke volume when co mpared to cardiac surgical patients. It is not possible to establish an ove rall end diastolic threshold below which a large proportion of ventilated p atients respond to volume administration.