• Vittorio Antonaglia, Sara Pascotto, Loredana De Simoni, and Walter A Zin.
• Istituto di Anestesia, Rianimazione e Terapia Antalgica, Laboratorio di Biomeccanica Respiratoria, Università degli Studi di Trieste, Trieste, Italy. v.antonaglia@libero.it
• J Clin Monit Comput. 2006 Aug 1;20(4):243-9.

ObjectivesThe application of sighs during baseline ventilation was found to improve alveolar recruitment and oxygenation in patients with acute respiratory distress syndrome (ARDS). The present investigation evaluates if respiratory mechanics can be modified by a sigh.MethodsTen consecutive patients with acute lung injury (ALI) admitted to the University Hospital Intensive Care Unit the were studied during mechanical ventilation. Three sighs were administered to sedated-paralyzed patients during the measurement period. Respiratory mechanics were studied in regular breaths immediately before and after a sigh provided that a steady-state had been reached and by the airway pressure-time curve profile to evaluate the lung recruitment. Viscoelastic constants (elastic, resistive, and time), as well as elastance and resistances, were determined by the single breath method. Arterial blood gases were also determined pre- and post-sigh.ResultsElastic and resistive components of viscoelasticity decreased after a sigh (20 and 21%, respectively). As a result, the pressure required to overcome viscoelasticity and mechanical inhomogeneities also decreased in these patients (17%). The mechanical changes were associated with alterations in PaO(2).ConclusionsThe sigh is useful to diminish viscoelastic impedance in ALI patients, thus allowing a smaller inflation pressure. Under the present experimental conditions it seems that viscoelastic mechanical alterations precede their elastic and resistive counterparts.

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