[Value of lung ultrasound examination in making decision of severe acute respiratory distress syndrome receiving prone ventilation].

Objective: To investigate the ideal persistence time of prone position ventilation in patients with severe acute respiratory distress syndrome (ARDS).
Methods: Collect 78 cases of severe ARDS admitted to the ICU unit of Sichuan Provincial People's Hospital from October 2012 to June 2014, all the ARDS patients needed to receive 8 h/day prone position continuous 5 day. For each of the prone position ventilation, ultrasound patterns were recorded and the aeration scores were calculated at the beginning of the prone position (T0) and 2 h (T1), 4 h (T2), 6 h (T3), 8 h (T4) later. The correlation of the aeration score variation (ASV) and the arterial blood gas indexes (pH, PaO(2), PaCO(2), PaO(2)/FiO(2)) were recorded also. The adverse reactions, ventilator situation and oxygen fraction after 7 days, 28-day mortality were monitored.
Results: The aeration score of the lung at T1, T2, T3, T4 was significantly reduced than T0 all, the ventilation situation of mainly areas was improved after 2 h PPV (P < 0.05), 4 h later it was not distinguished (P > 0.05); the value of PaO(2), PaO(2)/FiO(2) was greater at T1, T2, T3, T4 than T0 (P < 0.05), the value of the oxygen fraction was significant increased at T2 than T1 (t = 2.840, P < 0.05); the number of patients with oxygen fractions > 300 mmHg after 5 days PPV was 65 (83.3%); there were 30 (38.5%) patients free of mechanical ventilation after 7 days; the 28-day mortality was 7 (8.97%).
Conclusion: In patients with severe ARDS, applicating 2-4 hours validity of prone position ventilation significantly improves the pulmonary ventilation, more than 4 h PPV do not better for patients probably.