Pressure-controlled inverse ratio ventilation as a rescue therapy for severe acute respiratory distress syndrome

Purpose: Low tidal volume ventilation improves the outcomes of acute respiratory distress syndrome (ARDS). However, no studies have investigated the use of a rescue therapy involving mechanical ventilation when low tidal volume ventilation cannot maintain homeostasis. Inverse ratio ventilation (IRV) is one candidate for such rescue therapy, but the roles and effects of IRV as a rescue therapy remain unknown. Methods: We undertook a retrospective review of the medical records of patients with ARDS who received IRV in our hospital from January 2007 to May 2014. Gas exchange, ventilation, and outcome data were collected and analyzed. Results: Pressure-controlled IRV was used for 13 patients during the study period. Volume- controlled IRV was not used. IRV was initiated on 4.4 ventilation days when gas exchange could not be maintained. IRV significantly improved the PaO2/FiO(2) from 76 +/- 27 to 208 +/- 91 mmHg without circulatory impairment. The mean duration of IRV was 10.5 days, and all survivors were weaned from mechanical ventilation and discharged. The 90-day mortality rate was 38.5 %. Univariate analysis showed that the duration of IRV was associated with the 90-day mortality rate. No patients were diagnosed with pneumothorax. Conclusions: Pressure-controlled IRV provided acceptable gas exchange without apparent complications and served as a successful bridge to conventional treatment when used as a rescue therapy for moderate to severe ARDS.