Imbalances in regional lung ventilation: a validation study on electrical impedance tomography - Victorino, JA; Borges, JB; Okamoto, VN; Matos, GF; Tucci, MR; Caramez, MP; Tanaka, H; Sipmann, FS; Santos, DC; Barbas, CS; Carvalho, CR; Amato, MB (Am J Respir Crit Care Med, 2004)