A new method to estimate regional pulmonary blood flow using transesophageal echocardiography

We report a novel method to estimate regional blood flow in the atelectatic lung using transesophageal echocardiography in an experimental dog model. To verify the efficacy of the method, we investigated the ability of this experimental model to detect changes in regional pulmonary blood flow.

Fourteen anesthetized and ventilated mongrel dogs were randomized into an isoproterenol group (n = 7) or a dopamine group (n = 7). To produce an atelectatic lesion, 60 mL/kg of saline was infused into the left pleural space. The velocity time integral (VTI) derived from pulse Doppler was evaluated as an index of blood flow in the atelectatic lesion. To investigate the response of the method to changes in blood flow, the VTI and the shunt fraction (Qs/Qt) were measured during systemic administration of isoproterenol 0.05 microg x kg(-1) x min(-1) (as a pulmonary vasodilator) and dopamine 10 microg x kg(-1) x min(-1) (as a pulmonary vasoconstrictor).

Both VTI and Qs/Qt were increased significantly by isoproterenol administration. There was a significant correlation between the percentage changes of VTI and Qs/Qt with isoproterenol administration (r2 = 0.50, P < 0.001). Both VTI and Qs/Qt were unchanged during administration of dopamine.

Transesophageal echocardiography may be useful in detecting changes in regional pulmonary blood flow in an atelectatic lesion.