Clinical meaning
The nurse managing ARDS must understand lung-protective ventilation principles, recruitment maneuvers, and rescue therapies. The injured ARDS lung is heterogeneously affected: dependent (posterior/basilar) regions are consolidated and fluid-filled, non-dependent (anterior/apical) regions remain relatively aerated, and a border zone between them is atelectatic but recruitable. This creates the concept of a baby lung -- only 20-30% of the lung is available for ventilation. Delivering standard tidal volumes (10-12 mL/kg) to this small aerated volume causes overdistension (volutrauma), releases inflammatory mediators (biotrauma), and injures the alveolar-capillary membrane further. The ARDSNet protocol addresses this: tidal volume 6 mL/kg IBW, plateau pressure below 30 cmH2O, respiratory rate up to 35 to compensate for lower tidal volume, permissive hypercapnia (accept PaCO2 up to 55 as long as pH above 7.25), and FiO2/PEEP ladder. The driving pressure (plateau pressure minus PEEP) may be the most important predictor of mortality: driving pressure above 15 cmH2O is associated with increased mortality. The nurse implements this protocol, monitors ventilator mechanics, performs daily spontaneous breathing trials when appropriate, manages prone positioning, and recognizes complications. Rescue therapies for refractory hypoxemia include high PEEP strategy, inhaled nitric oxide (selective pulmonary vasodilator, improves V/Q matching), inhaled epoprostenol (prostacyclin analogue, similar mechanism to iNO but less expensive), neuromuscular blockade, and ECMO for the most severe cases.