[The effects of different tidal volume ventilation on right ventricular function in critical respiratory failure patients]

Objective: To observe and explore the effects of different tidal volume (VT) ventilation on right ventricular (RV) function in patients with critical respiratory failure. Methods: Consecutive respiratory failure patients who were treated with invasive ventilator over 24 h in the Department of Critical Care Medicine at the Fourth Hospital of Hebei Medical University from June to December in 2015 were enrolled in this study.Clinical data including patients' vital signs, ventilator parameters and RV echocardiography were collected within 6 h (D0), day1(D1), day2 (D2) and day3 (D3) after ventilation started.According to the VT, patients with acute respiratory distress syndrome (ARDS) were assigned to low VT group [S6, ≤6 ml/kg predicted body weight (PBW)] and high VT group (L6, >6 ml/kg PBW), while non-ARDS patients were also assigned to low VT group (S8, ≤8 ml/kg PBW) and high VT group (L8, >8 ml/kg PBW). Results: A total of 84 patients were enrolled in this study.44.2% ARDS patients and 58.5% non-ARDS patients were in low VT groups.After ventilation, tricuspid annulus plane systolic excursion(TAPSE)decreased progressively in S6 [from 18.30(16.70, 20.70) mm to 17.55(15.70, 19.50) mm, P=0.001], L6 [from 19.50(17.00, 21.00) mm to 16.30(15.00, 18.00) mm P=0.001], S8[from 18.00(16.00, 21.00) mm to 16.50(15.50, 18.00) mm, P=0.001] and L8 [from 19.00(17.50, 21.50) mm to 16.35(15.15, 17.00) mm, P=0.001] groups.However, TAPSE decreased less in small VT groups (S6 and S8) than those of in large VT groups (S8 and L8) without significant differences.There were not statistical differences between different VT groups in terms of ventilation days, including right ventricle area/left ventricle area (RV(area)/LV(area)), TAPSE, peak mitral flow velocity of the early rapid filling wave (E), peak mitral flow velocity of the late rapid filling wave (A), early diastolic velocity of the tricuspid annulus (e'), pulmonary artery systolic pressure, inferior vena cava diameter (all P>0.05). Compared to L6 group, low VT (S6 group) resulted in decreased mortality at 28 days [1/19 vs 37.5%(9/24), P=0.014]. There were not statistical differences between different VT groups in terms of ventilation days, length of intensive care unit stay, length of hospital stay (all P>0.05). Logistic regression analysis showed that VT could be the independent factor of TAPSE (OR=1.104, 95%CI 0.100-1.003, P=0.049). Conclusions: Positive pressure mechanical ventilation resulted in RV systolic dysfunction .Lower VT may have the protective effect on RV function. Trial registration: Chinese Clinical Trial Registry, ChiCTR-POC-15007563.