Infant sleeping position and inspiratory pressures in the upper airways and oesophagus.

Inspiratory pressures were measured at three levels in the upper airways and in the oesophagus in different sleeping positions. Thirty one consecutive healthy infants were examined at the age of 1-3 days, 25 of these at 6 weeks, and 23 at 12 weeks. Oxygen saturation, an electrocardiogram, transthoracic impedance, nasal airflow, and inspiratory pressure in the epipharynx, oropharynx, hypopharynx, and in the intrathoracic part of the oesophagus were measured. There was no significant change in the heart rate, oxygen saturation, or respiratory rate in the four sleeping positions. The peak negative inspiratory pressures obtained from the oesophagus (PES) were significantly lower in the supine head straight compared with the supine head turned and the prone positions. At 6 weeks, the only significant difference was between the supine head straight and the prone positions. The PES is less negative at all ages in the supine head straight than in all other sleeping positions, but this does not reach statistical significance.