However, prolonging mechanical ventilation to more than 6 h in the current experimental models would also have some limitations: (1) only changes in IL-6 protein levels were observed, since protein synthesis of PCIII and caspase-3 requires more than 6 h, and (2) keeping small animals with ALI alive for 6 h requires administration of larger volumes of fluids, sometimes vasoactive drugs (for example, noradrenaline) to keep MAP higher than 70 mmHg, and bicarbonate to counteract intense metabolic acidosis. Here, CASP3 is linked to acute respiratory distress syndrome.