Body and head position effects on regional lung ventilation in infants: an electrical impedance tomography study

Objective: To determine the effects of body and head positions on the spatial distribution of ventilation in nonintubated spontaneously breathing and mechanically ventilated infants using electrical impedance tomography (EIT). Design and setting: Prospective study in a neonatal intensive care unit. Patients: Ten spontaneously breathing (gestational age 38 weeks, postnatal age 13 days) and ten mechanically ventilated infants (gestational age 35 weeks, postnatal age 58 days). Interventions: Supine and prone postures with different head positions (midline and rotated to the left and right side). Measurements and results: The distribution of ventilation in the chest cross-section was repeatedly determined from EIT data in each body/head position studied. During spontaneous breathing the tidal volumes in the left lung region were reduced in the supine posture with the head turned to the left as well as in the prone posture with the head rotated to either side when compared with the supine posture with the head in the midline position. During mechanical ventilation the tidal volumes in the left lung region were unaffected by the body and head position except for the prone posture combined with the leftward head rotation which reduced them. In both types of ventilation the tidal volumes in the right lung region were unaffected by the change in body/head position. Conclusion: The results indicate that the spatial distribution of ventilation is influenced by the body and head position in spontaneously breathing infants. Prone posture with the leftward head rotation has the most prominent effect which is detectable even during mechanical ventilation.