Feasibility of forced oscillatory assessment of respiratory mechanics across a laryngeal mask airway in rabbits

Andre Dos Santos Rocha, Roberta Südy, Gergely H. Fodor, Walid Habre, Ferenc Peták

Research output: Contribution to journalArticle


Objectives: The forced oscillation technique (FOT) is the method of choice for assessment of respiratory tissue mechanics. A laryngeal mask airway (LMA) is increasingly used to secure the airways in subjects under sedation or general anesthesia. While FOT is routinely performed using an endotracheal tube (ETT), the accuracy of information about airway and tissue mechanics obtained with FOT using a LMA has not been characterized. Therefore, we compared the mechanical parameters obtained with FOT using LMA and ETT in rabbits. Approach: FOT was performed through a LMA at normal and reduced oscillatory amplitudes in anesthetized and mechanically ventilated rabbits (n = 9) at positive end-expiratory pressures (PEEP) of 3 and 6 cmH2O. These measurements were repeated at normal amplitude for the same animal using an ETT. Airway resistance, inertance, respiratory tissue damping (G) and elastance (H) were measured under each condition by FOT. The potential bias of the distensible upper airways when FOT was applied using LMA was assessed with a simulation study. Main results: Values of parameters reflecting airway mechanics were significantly higher when measured using LMA at both PEEPs and oscillatory amplitudes than with ETT. Conversely, regardless of the condition, there was a correlation (r = 0.89 both at normal and reduced amplitudes; p  < 0.0001) with good agreement (mean bias of 8.8 cmH2O/l and 11.3 cmH2O/l) in H, whereas G was systematically lower when obtained with LMA than with ETT at PEEP 3 (21.1% ± 7.2% and 9.6% ± 6.9% at normal and reduced oscillatory amplitudes, respectively) and 6 cmH2O (15.1% ± 8.2%, 1.6% ± 9.4%, p  < 0.05 for all). Significance: Mechanical properties of the airways and the respiratory tissues, particularly for respiratory tissue stiffness, can be reliably assessed using LMA. However, the involvement of a longer laryngo-tracheo-bronchial pathway when using LMA should be considered for airway resistance and inertance, whereas upper airway shunting may affect the assessment of respiratory tissue damping.

Original languageEnglish
Article number065001
JournalPhysiological measurement
Issue number6
Publication statusPublished - Jun 28 2019



  • airway device
  • lung function
  • oscillometry
  • respiratory impedance
  • upper airway shunt

ASJC Scopus subject areas

  • Biophysics
  • Physiology
  • Biomedical Engineering
  • Physiology (medical)

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