Regional Lung Opening and Closing Pressures in Patients With Acute Lung Injury

Measurement of Regional Lung Opening and Closing Pressures in Patients With Acute Lung Injury Using Electrical Impedance Tomography

The purpose of this study is the measurement of regional opening and closing pressures of lung tissue by electrical impedance tomography in lung healthy and patients with acute lung injury. These values might help the setting of positive endexpiratory pressure during artificial ventilation to avoid the cyclic opening and closing of alveoli.

During artificial ventilation the cyclic opening and closing of alveoli during artificial ventilation results in patients with acute lung injury (ALI) in a higher mortality. A positive endexpiratory pressure (PEEP) is applied with the intention to avoid these cyclic opening and closing of alveoli. The distribution of ventilation in patients with ALI is extremely inhomogeneous, consequently there are different regional opening pressures needed to open up the alveoli and avoid closing. Finding the best level of PEEP in patients with injured lungs to avoid atelectasis and alveolar strain induced by inadequately high or low PEEP levels is a challenge. The purpose of this study is to develop a protocol for measuring regional opening and closing pressures using the method of electrical impedance tomography in lung healthy and ALI patients. A ventilator setting guided by regional opening and closing pressures might help reducing the impairment of the lung by artificial ventilation.

electrical impedance tomography, EIT, acute lung injury, regional lung opening pressure, regional lung closing pressure

In all patients a standard low flow pressure volume manoeuvre is applied by a respirator with a constant gas flow of 4 l/min starting at a zero end-expiratory pressure up to a tidal volume of 2 l or until a maximum airway pressure of 35 cm H2O was reached.

For the measurement of regional opening pressures in lung healthy and acute lung injury an inspiratory low flow manoeuvre with synchronous measurement of regional ventilation and airway pressure is performed. The regional opening pressures are defined as the airway pressure to the point were the regional lung areas open up.

For the measurement of regional closing pressures in lung healthy and acute lung injury an expiratory low flow manoeuvre with synchronous measurement of regional ventilation and airway pressure is performed. The regional closing pressures are defined as the airway pressure to the point were the regional lung areas start closing.

Inclusion Criteria: artificial ventilation acute lung injury / healthy lung (control group) Exclusion Criteria: pregnancy Cerebral trauma / surgery Age < 18 years instable cardiovascular disease instable chest wall

University Medical Center of Schleswig-Holstein, Campus Kiel, Department of Anesthesiology and Intensive Care Medicine

Department of Anesthesiology and Intensive Care Medicine, University Medical Center of Schleswig-Holstein, Campus Kiel

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