Ventilation with xenon/oxygen mixtures: animal study at the University of Ulm

Relevance of increased pulmonary resistance due to higher density and viscosity of xenon/oxygen mixtures in comparison to nitrogen/oxygen has been investigated in an animal study at the University of Ulm, Germany. Dr. Schmidt, Dr. Marx, Dr. Papp-Jambor, Dr. Reinelt (University Hospital Ulm) and Prof. Dr. Schirmer (German Heart Center, Bad-Oeynhausen, Germany) have randomly assigned 14 pigs (German Landrace) to receive either 75% xenon in oxygen (75 animals) or 75% nitrogen in oxygen mixtures (25 animals) under condition of normo-, hypo- and hyperventilation.

Xenon, the only inert gas having anaesthetic properties under atmospheric pressures, is regarded to be close to the ideal inhalation anaesthetic. One of the advantages of xenon anaesthesia seems to be the absence of adverse effects on the central nervous system. All hemodynamic parameters remained stable during the experiments.

The main finding of their study was that during xenon anaesthesia with normoventilation or hyperventilation significant higher pressures were measured in the ventilator system as compared with the pressures in the bronchial system and as compared with nitrogen/oxygen ventilation. Furthermore, ventilator pressures did not correspond to pressures measured in the bronchial system which may be explained by the higher density and viscosity of xenon leading to reduction of pressure along the endotracheal tube.

From their study results, the authors conclude that a potential risk of elevated pressures in the ventilator during xenon ventilation is not the impairment of the bronchial system but possible hypoventilation using small volumes in pressure controlled ventilation or during volume controlled ventilation with no volume compensation available.