4. Pelosi, et al10 studied the effect of three consecutive 'sigh' breaths (one with plateau pressure of 45 cm H2O but of normal duration) in 10 adults with ARDS. After 1 hour of 3 sigh breaths per minute, end-expiratory lung volume (measured by He dilution) increased from 1.49±0.58 to 1.91±0.67 L, and an increase in PaO2 from 92.8±18.6 to 137.6±23.9 mm Hg, compared with the same ventilator settings without sigh breaths. Lung elastance and ventilation also increased. No adverse effects were noted.