Introduction :
The pulmonary artery catheter (PAC) has historically been used to measure the pulmonary capillary wedge pressure (PCWP)1. This measurement is considered as a surrogate of left atrial pressure (LAP) and, by extension, left ventricular end‐diastolic pressure. Various studies have shown that PCWP and LAP correlate well in patients with cardiovascular disease2,3. Estimation of LAP is a core component of the evaluation of left ventricular diastolic function4. Elevated left ventricular filling pressures predict long‐term adverse outcomes, even in patients with normal ejection fractions5. A restrictive diastolic filling pattern predicts major morbidity and mortality in patients undergoing cardiac surgery6.
The use of the PAC has been questioned in the perioperative period with some studies unable to clearly demonstrate clinical benefit. This has resulted in declining use in the perioperative period7. Alternative methods like echocardiography has been used for the noninvasive estimation of PCWP and LAP. Transthoracic echocardiography (TTE) is non-invasive and is therefore of considerable appeal as a measurement tool. Various Doppler measurements have been made in healthy patients and in different disease states, and their correlation and agreement with PCWP is reasonable. Transesophageal echocardiography (TEE) is used routinely in cardiac surgery for the evaluation of hemodynamic conditions, left ventricular function and valvular function. Few studies8,9 were attempted to validate correlation and agreement of Doppler measurements using TEE and PCWP in anaesthetised patients receiving mechanical ventilation. It should not be assumed that TTE validation will automatically apply to patients using TEE, although successful validation would be of great clinical benefit and reduce reliance on the pulmonary artery catheter.