Comparison of transesophageal and transthoracic contrast echocardiography for detection of an intrapulmonary shunt in liver disease.

Study Objectives: Contrast transthoracic echocardiography (TTE) is currently used to identify intrapulmonary shunt (IPS) in patients with end-stage liver disease. The aim of this study was to compare the use of contrast TTE and transesophageal echocardiography (TEE) in detecting IPS.
Design: Thirty-seven consecutive outpatients with severe liver disease awaiting liver transplantation underwent contrast TEE and TTE. The IPS was assessed semiquantitatively in four grades with TEE and as positive or negative with TTE.
Setting: ICU.
Interventions: Patients underwent contrast TEE after pharyngeal anesthesia alone followed by contrast TTE. Contrast echocardiography was performed with a modified fluid gelatin solution.
Results: Overall detection rate of an IPS was 51% with TEE and 32% with TTE (p < 0.001). Four patients had an IPS detected with TEE but not with TTE. Quality of imaging was poor in 22% with TTE and 0% with TEE (p < 0.001). A PaO2 < 80 mm Hg or a dyspnea was associated with an IPS in 56% and 50% of patients with TEE and in 33% and 25% with TTE, respectively.
Conclusion: Contrast-enhanced TEE is superior to TTE for detecting an IPS in patients with severe liver disease awaiting liver transplantation. The use of gelatin contrast solution allows an early detection of IPS. Because of the high sensitivity of TEE, all patients suspected of hepatopulmonary syndrome should undergo TEE in search of an IPS if TTE is normal.