Subjective assessment of left ventricular preload using transesophageal echocardiography: Corresponding pulmonary artery occlusion pressures

Objective: To record pulmonary artery occlusion pressures (PAOPs) in patients whose left ventricular preload reserve was subjectively determined using transesophageal echocardiography (TEE). Design: Prospective, blinded, nonrandomized. Setting: University hospital. Participants: Twenty-three patients with well-preserved left ventricular function during nonemergent cardiac surgery. Interventions: After separation from cardiopulmonary bypass, patients received repeated boluses of fluid volume through the aortic inflow cannula while being monitored with TEE. The endpoint for this fluid administration was a plateau in left ventricular fractional area change and enddiastolic area. This point at which additional fluid failed to cause noticeable increases in left ventricular end-diastolic area and fractional area change was defined as the preload reserve volume. After reaching the preload reserve volume, the PAOP was measured, as were the systolic blood pressure, left ventricular fractional area change, and end-diastolic area. Measurements and Main Results: The mean PAOP for all patients at the time of achieving preload reserve volume was 18.6 ± 2.9 mmHg. In 8 patients, the PAOP corresponding to preload reserve volume was elevated (20 to 25 mmHg). The remaining 15 patients had PAOPs ranging from 13 to 19 mmHg. When these 2 groups were compared with respect to left ventricular end-diastolic area, fractional area change, and systolic blood pressure, there were no significant differences between groups. The left ventricular wall thickness was significantly greater, however, in the group with elevated PAOP (1.37 ± 0.04 cm) when compared with the group with normal ventricular filling pressures (1.05 ± 0.15 cm) (p = 0.001). Conclusions: In patients with well-preserved left ventricular function and normal wall thickness, preload reserve volumes subjectively determined by TEE corresponded to a range of filling pressures historically targeted to maximize cardiac performance (13 to 19 mmHg). In a subset of patients with increased wall thickness, however, subjective determination of preload reserve was associated with filling pressures that were higher than traditionally considered optimal (20 to 25 mmHg). Similarities in left ventricular fractional area change and end-diastolic area between these 2 groups suggest that patients with elevated filling pressures had decreased ventricular compliance and were managed correctly with higher than usual PAOPs.