What's to be learned from 10 patients in one pediatric ICU?

Treatment strategies for patients with acute lung injury (ALI) and ARDS have improved markedly in the past 2 decades.1,2 Despite these improvements, mortality and morbidity remain high in affected patients, and the optimal ventilation strategy for these patients remains controversial.3 There is general consensus, based primarily on adult studies, that low-tidal-volume strategies are associated with improved survival4; however, such strategies are not successful in all patients, and may also be associated with progressive lung collapse. Moreover, derecruitment itself may perpetuate lung injury, further exacerbating the initial insult.5 Various recruitment maneuvers have been proposed as adjuncts to low-tidal-volume ventilation, to improve pulmonary function in patients with ALI and ARDS; however, few data exist to either support or refute their effectiveness.6,7 Multiple studies have demonstrated short-term recruitment maneuver benefits in lung inflation, oxygenation, ventilation, and lung compliance, but data for longerterm benefit are lacking.8-10 Indeed, there is no evidence that recruitment maneuvers improve survival. There are several real and potential benefits associated with successful application of recruitment maneuvers. First, repetitive collapse of vulnerable lung units is a source of lung injury, and successful permanent recruitment of such units would serve to improve pulmonary function and reduce ongoing injury. Several studies in pediatric patients have shown improvements in oxygenation for 6–12 hours following recruitment maneuvers.9,11 Second, given that the mortality for ALI/ARDS remains stubbornly high despite current practices, recruitment maneuvers followed by optimization of PEEP could represent a means of improving outcomes in targeted populations. Recruitment maneuvers also raise concerns. First, shear injury may not be a ubiquitous cause of ALI/ARDS, and therefore strategies designed to minimize such injury would be ineffective except in specific cases. Second, even if recruitment maneuvers are helpful, it is not clear which recruitment method is most effective, nor what the optimal protocol for application should be.12 Third, recruitment maneuvers are potentially a source of direct injury, including pneumothorax, subcutaneous emphysema, and hemodynamic instability.13 Finally, it is not clear that the changes brought about by successfully applied recruitment maneuvers are important drivers of improved outcomes.