The prone position is associated with a decrease in respiratory system compliance in healthy anaesthetized infants

Ten healthy (ASA I or II) anaesthetized infants undergoing clubfoot surgery were studied. General anaesthesia included rocuronium, nitrous oxide and i soflurane. Volume controlled ventilation (12 ml.kg(-1)) was delivered via a coaxial Mapleson-D (Bain) system and a Datex AS/3 ventilator. Pulmonary me chanics were measured sequentially in the supine and prone positions using a Bicore CP-100 pulmonary function monitor. Subjects had a mean age of 6 (/- 2) months and a mean weight of 8.3 (+/- 1.4) kg. Dynamic compliance (C-D YN) and static compliance (C-STAT) were both significantly lower in the pro ne position than in the supine position (P < 0.0005). Mean C-DYN decreased from 14.9 +/- 4.9 ml.cmH(2)O(-1) (supine) to 11.6 +/- 3.5 ml.cmH(2)O(-1) (p rone). Mean C-STAT decreased from 10.2 +/- 2.8 ml.cmH(2)O(-1) (supine) to 8 .9 +/- 2.3 ml.cmH(2)O(-1) (prone). No clinically significant differences in gas exchange were noted, however, on repositioning.