Mechanical ventilationMechanical ventilation is often a life-saving intervention, but it may Gemcitabine IC50 cause or exacerbate lung damage in patients with ALI/ARDS. Arterial oxygenation is frequently used as an intervention target for mechanical ventilation. Although hypoxia is a major concern to the clinician, hyperoxia is also highly toxic but may be overlooked at bedside. de Jonge and coworkers [8] investigated the relationship between FiO2 administered, PaO2 levels achieved and hospital mortality in 36,307 consecutive patients admitted to 50 Dutch ICUs treated with mechanical ventilation. The authors demonstrated that the achieved PaO2 values in the ICU patients were higher than those recommended in the literature. The mortality rate was linearly related to FiO2.

Both low PaO2 and high PaO2 during the first 24 hours after ICU admission were associated with hospital mortality, forming a U-shaped curve. This study suggests that hyperoxia might have been overlooked in the ICU, and optimizing oxygenation targets may help to improve outcomes.In patients with pulmonary shunts, increases in FiO2 have a minimal effect on arterial oxygenation. One approach to increase PaO2 is to perform recruitment manoeuvres. Constantin and coworkers [9] compared two recruitment manoeuvres in 19 patients with ARDS using a randomized crossover design. The recruitment manoeuvres were applied based on pulmonary mechanics in each patient, beginning with either continuous positive airway pressure or extended sigh. Both recruitment manoeuvres increased oxygenation, but the increase in PaO2/FiO2 was significantly greater with extended sigh than with continuous positive airway pressure.

The investigators also used lung computed tomography (CT) scans and pressure-volume curves to examine the impact of the recruitment manoeuvres.Several studies examined the utility of monitoring end-expiratory lung volume (EELV) to help to optimize ventilatory settings or predict the effects of lung recruitment manoeuvres in ALI/ARDS. The application of positive end-expiratory pressure (PEEP) can lead to increased EELV as a result of recruitment or further distension of already ventilated alveoli. Koefoed-Nielsen and coworkers [10] examined whether the measurement of EELV combined with the use of pressure-volume curves would be helpful in predicting changes in lung mechanics in response to recruitment manoeuvres. They speculated Anacetrapib that EELV measurement could determine whether lung volume is reduced in clinical situations with low respiratory system compliance and low PaO2/FiO2 ratios, whereas an analysis of pressure-volume curves could predict whether recruitment manoeuvres and increased PEEP would be effective.