Objective: To explore better ventilation strategies above lower-tidal-volume (LTV) strategy to protect lung function and improve outcome in acute respiratory distress syndrome (ARDS).
Methods: Thirty ARDS patients were enrolled in Department of Critical Care Medicine of Peking Union Medical College Hospital from July, 2004 to June, 2005. They were randomly allocated into two groups, LTV group and individual ventilation (IV) group. Patients received 6 ml/kg tidal volume (V(T)) and high positive end-expiratory pressure (PEEP) in LTV group. In IV group, static pressure-volume (P-V) curve was measured daily, and PEEP and V(T) were set based on P-V variation, and the open-lung potential was evaluated before recruitment maneuvers. The clinical effect, the degree of lung injury and other outcome indicators in two groups were assessed.
Results: The mortality rate in 28 days of IV group (35.7%) was lower than that of LVT group (57.2%, chi(2) = 1.265, P > 0.05). The serum surfactant-associated protein D (SP-D) expression in the third and the seventh day of IV group [154 (91 - 217), 149 (91 - 206) mg/L] were higher than those before enrollment [140 (80 - 200) mg/L]; and the IL-8 expression in the third and the seventh day of IV group [179 (122 - 236), 210 (100 - 321) ng/L] were higher than those before enrollment [210 (132 - 289) ng/L]; but all showed no significant difference [chi(2) = 1.265, Z = 1.079, 1.741, -0.879, 0.471, respectively, all P > 0.05]. The free-ICU days in 28 days and free-organ-dysfunction days of IV group [11 (5 - 16) d, 13 (6 - 18) d] were significantly higher than that of LTV group [3 (0 - 8) d, 3 (0 - 7) d, Z = -2.277, -2.372 respectively, all P < 0.05]. The PEEP, V(T), partial pressure of carbon dioxide in arterial blood (PaCO2), the plateau pressure (Pplat) of initial 3 days after enrollment in IV group [(11 +/- 2) cm H2O (1 cm H2O = 0.098 kPa), (511 +/- 66) ml, (37 +/- 5) mm Hg (1 mm Hg = 0.133 kPa), (21 +/- 5) cm H2O] were significant different with those of LTV group [(16 +/- 3) cm H2O, (407 +/- 58) ml, (47 +/- 8) mm Hg, (26 +/- 4) cm H2O, t = -8.019, 6.501, -4.311, -4.823, all P < 0.01].
Conclusions: Compared with LTV and high PEEP therapy, IV strategies are feasible for decreasing PEEP and Pplat, increasing tidal compliance and V(T), and avoiding CO2 retention. It also increased free-ICU days and free-organ-dysfunction days.