Influence of xenon on pulmonary mechanics and lung aeration in patients with healthy lungs.

Abstract

The anaesthetic xenon shows potent organ-protective properties. Due to high density and dynamic viscosity, peak inspiratory pressure (P_max) increases during xenon application. Thus, barotrauma may counteract organ protection. Accordingly, we investigated the influence of xenon on lung mechanics and lung aeration in patients with normal and reduced thoracic wall compliance. After registration and ethical approval, 20 patients free of pulmonary disease undergoing routine xenon-based anaesthesia were mechanically ventilated. The primary outcome variable transpulmonary pressure (P_tp) was determined from plateau pressure and intraoesophageal pressure before and after xenon wash-in. We recorded P_max, and calculated airway resistance (R_AW), and static (C_stat) and dynamic (C_dyn) respiratory compliances. Finally, lung aeration was quantified by electrical impedance tomography-derived centre of ventilation index (CVI) and global inhomogeneity index (GI) in the awake state, before and during xenon. Xenon increased P_max [20.8 (SD 3) vs 22.6 (3) cm H₂O, P<0.001] and R_AW [0.9 (0.2) vs 1.4 (0.3) cm H₂O litre^-1 s, P<0.001], without affecting P_tp [1.5 (4) vs 2.0 (4) cm H₂O, P=0.15]. While C_stat remained unchanged, C_dyn was reduced [33.9 (7) vs 31.2 (6) ml (cm H₂O)^-1, P<0.001). A ventral tidal volume shift after anaesthesia induction [CVI 0.53 (0.03) vs 0.59 (0.04), P<0.001] was unaltered during xenon [CVI 0.59 (0.04), P=0.29]. Homogeneity of lung aeration was also unchanged during xenon [GI 0.37 (0.03) vs 0.37 (0.03), P=0.99]. There were no clinically meaningful differential BMI-related effects. Xenon increases calculated airway resistance and peak inspiratory pressure without affecting transpulmonary pressure, independent of BMI. NCT02682758.