Thirteen patients were included in 11 EIT studies; good-quality EIT signals were obtained from nine patients. Descriptive data, ventilator settings and baseline data of respiratory system mechanics and gas exchange are summarized in Table 1 . Although three patients were born prematurely (one at 32 weeks and two at 36 weeks' gestation), none of the patients had chronic lung disease. Hyperinflation was present in 10 patients, four of these patients also had infiltrates. Ten patients had hypercapnia (PaCO 2 >45 mmHg) and seven infants had PaO 2 /FiO 2 less than 200 at baseline (T = 0). Tidal volume remained constant throughout the experiment (Figure 1 ). Leakage around the uncuffed endotracheal tube was less than 5% in all patients.