Oesophageal or transgastric views for estimating mean pulmonary artery pressure with transoesophageal echocardiography

BACKGROUND: Recent data suggest that in cardiac surgical patients, the pulmonary artery acceleration time (PAT) is useful for estimating mean pulmonary artery pressure (MPAP) noninvasively with transoesophageal echocardiography (TOE). The pulmonary valve can be visualised from multiple echocardiographic windows, but it is unclear which, if any, view correlates best with MPAP. OBJECTIVE(S): To compare the PAT measured with TOE from oesophageal and transgastric views with MPAP obtained invasively with a pulmonary artery catheter. DESIGN: A prospective observational study. SETTING: St. Vincent's Hospital, Melbourne, a university tertiary referral centre in Australia. PATIENTS: Sixty-three patients having cardiac surgery were included in our study. All patients had insertion of both a TOE probe and pulmonary artery catheter; this is the routine standard of care in our centre. INTERVENTION(S): Nil. MAIN OUTCOME MEASURES: During a period of haemodynamic stability, the PAT was measured first from an oesophageal view and then immediately after from a transgastric view. The results were then compared with the invasively measured MPAP. RESULTS: Simultaneous measurements of MPAP and PAT were taken in 63 patients. In two patients, these measurements were not possible in the transgastric position due to an inability to visualise the right ventricular outflow tract and pulmonary valve. A Bland-Altman analysis of the PAT measured from the upper oesophageal and transgastric views showed a mean difference of 1 ms and limits of agreement of -18 to 16 ms. The area under the receiver operating curves for predicting pulmonary hypertension with PAT were upper oesophageal view 0.99 [95% confidence interval (CI), 0.98 to 1.00] and transgastric view 0.99 (95% CI, 0.97 to 1.00). The agreement between the results from these two views in the diagnosis of pulmonary hypertension (defined as PAT < 107 ms) was 93.4% with a kappa of 0.85 (95% CI, 0.59 to 1.00). There is an inverse curvilinear relationship between PAT and MPAP. Using a cut-off of 107 ms, the upper oesophageal view predicted pulmonary hypertension (defined as MPAP > 25 mmHg) with a sensitivity of 94.7% and specificity of 97.6%. The transgastric view predicted pulmonary hypertension with a sensitivity of 89.4% and specificity of 95.2%. CONCLUSION: Oesophageal and transgastric measurements of PAT have close agreement and a similar high ability to discriminate between people with and without pulmonary hypertension. The transgastric measurement was unobtainable in a small percentage of patients and required more probe manipulation. We would recommend PAT measurement in the upper oesophageal view.