Effects of Permissive Hypercapnia on Pulmonary Mechanics and Hemodynamics during Mechanical Ventilation in Severe Acute Respirat

Objectives: To evaluate effects of permissive hypercapnia (PHC) on pulmonary mechanics and hemodynamics in patients with severe acute respiratory distress syndrome (ARDS). Methods: We observed the influence of different tidal volume (VT) on pulmonary mechanics and hemodynamics in 10 patients with severe ARDS. Results: PHC was induced by decreasing VT from 10 – 12 ml/kg (routine VT) to 6 – 8 ml/kg (small VT). Arterial oxygen pressure and saturation remained unchanged, but pulmonary venous admixture was increased (p < 0.05). Airway plateau pressure and mean pressure were also decreased markedly. C20/C, which reflects lung overdistention, was increased significantly. Mean arterial pressure, central venous pressure, pulmonary arterial pressure were not changed, while systemic vascular resistance index was decreased markedly (p < 0.05). Cardiac index (CI) and oxygen delivery (DO2) were increased (p < 0.05), while oxygen consumption remained unchanged. Conclusions: PHC, which was induced by small VT, might prevent lung overdistention and led to an increase in CI and DO2.