The main objective is to investigate the mechanical properties of the airways and respiratory tissues. Our current projects are focused on the study of the upper airway collapsibility in sleep apnea, and on respiratory mechanics monitoring in patients subjected to non-invasive mechanical ventilation. The clinical aims of this research are to achieve better non-invasive diagnostic techniques of these diseases and to optimize their treatment by means of ventilatory support.

Assessing the mechanical properties of the respiratory system during non-invasive ventilation and during sleep is particularly challenging since only methods that are non-invasive and that do not require patient cooperation can be used. We investigate respiratory mechanics by combining conventional techniques with novel approaches such as the Forced Oscillation Technique (FOT). Depending on the hypothesis to be tested, the studies are carried out on animals, on healthy subjects or on patients with different respiratory diseases. Data interpretation is carried out by means of models featuring respiratory mechanics including parameters of pathophysiologic interest.

Non-invasive mechanical ventilation is commonly applied in patients requiring artificial breathing support owing to acute or chronic respiratory failure. Our approach to assess respiratory mechanics in obstructive and restrictive patients subjected to non-invasive mechanical ventilation is focused on the application of FOT. We have recently shown that FOT provides a reliable estimation of the respiratory system resistance in patients subjected to ventilatory support through a nasal/face mask, and that this technique is easily simplified by application of the forced oscillation by means of the ventilator.

Sleep apnea is a highly prevalent disease characterized by recurrent upper airway closure during sleep. Our lab has shown that FOT allows an easy characterization of the degree of airway obstruction along the breathing cycle during sleep, and that the technique is helpful in diagnosing sleep apnea and in titrating the treatment with continuous positive airway pressure (CPAP). We analyze and optimize the methods for the assessment of sleep disturbances by means of simplified sensors (pulse oximeters, thermistors, nasal prongs). We also develop methods for evaluating the performance of automatic CPAP devices.

Forced Oscillation Setup

FOT is a method for non-invasively assessing respiratory mechanics without patient cooperation. FOT is based on the application of a small pressure oscillation (~1 cm H2O) at the mouth while the patient is spontaneously breathing.The oscillation pressure is generated by a loudspeaker-in-box assembly. Pressure and flow are measured at the patient's airway opening by means of a pressure sensor and a pneumotachograph. A low resistance leak open to the atmosphere is placed in the proximity of the patient to reduce the dead space during the measurement. The FOT device includes the circuitry required to drive the loudspeaker and record the signals. The oscillatory resistance and reactance of the patient's respiratory system are derived by Fourier analysis of the pressure and flow signals recorded at the airway opening. As forced oscillation can be applied at different frequencies, patient mechanics can be assessed over a wide frequency band, which is of particular interest to investigate the mechanical properties of the respiratory system with models featuring airways and tissue viscolasticity. Given that FOT measurements do not require patient cooperation, the technique is suitable for assessing respiratory mechanics during normal breathing in infants, children and the elderly or in special clinical applications such as mechanical ventilation and sleep monitoring.