PURPOSE:Low tidal volume assist-control (A-C) ventilation is considered the standard mode of ventilation in patients with ARDS. However, many patients will develop worsening oxygenation for which Airway pressure release ventilation (APRV) could be an acceptable rescue ventilatory mode.
METHODS:We designed an observational, prospective, open-label cohort study to test the hypothesis that APRV would improve oxygenation (FiO2/PaO2) and decrease dead space ventilation (Vd/Vt)when measured with the end-tidal C02. Data were recorded at baseline on A/C (T0) and 2 hours (T1), 10 hours (T2) and at 24–30 hours (T3) after change to APRV. Mean differences calculated from a paired T test were done between T0 and T3.
RESULTS:19 enrolled patients had pneumonia. The baseline SOFA score was 10.5 (± 40). 9 patients died (47%). The baseline mean Pa02/Fi02 was 163 (± 82) with a PaC02 of 42 (± 9.7) and a Vd/Vt of 69% (± 2.4%). The median follow-up time was 25 hours (IQR 21–33). The Pa02/Fi02 at T3 was 230 (± 112) with a mean increase of 67 (± 136) (p=0.04). The PaC02 remained stable during this period. The Vd/Vt at T3 (available in 15 patients) was 55% (± 9), a decrease of 13%(± 11%) (p=0.0003). There was no difference in the change of Pa02/FI02 at T3 between survivors (52 ± 106) and non-survivors (46 ± 72) [p=0.87].
CONCLUSION:APRV improved oxygenation and decreased dead space ventilation in patients with refractory ARDS. Blood pressure remained stable without the need of vasopressors and with decreased in the sedation requirements.
CLINICAL IMPLICATIONS:The oxygenation surrogate end-points did not correlate with survival. Additional studies are required to determine the effects of APRV on patient outcomes such as; mortality, ventilator free days, length of ICU stay.
DISCLOSURE:Enrique Machare Delgado, No Financial Disclosure Information; No Product/Research Disclosure Information