[Tube wall herniation in an Ulmer system as a cause of an intraoperative ventilation disorder]

We report an intraoperative complication caused by nitrous oxide diffusion through the inner layer of a tube of the Ulmer breathing system, which has been developed for ventilation of small children and neonates (Fig. 2a). About 40 min after intubation and mechanical ventilation with oxygen, nitrous oxide, and halothane a sudden rise in PETCO2 was noticed (Fig. 1). Auscultation of both lungs revealed no pathological finding; suction through the endotracheal tube was possible with no indication of endotracheal tube herniation. After reconnection to the ventilator, PETCO2 values again increased. Thorough inspection of the tubes of the Ulmer breathing system revealed a herniation that nearly occluded the lumen (Fig. 2b). After changing the anesthetic system, the operation and anesthesia were continued uneventfully.