PURPOSE: EVLW plays an important role in the pathophysiology of ALI/ARDS and correlates negatively with oxygenation and mortality. Several studies have shown that the addition of PEEP reduces EVLW in the setting of ALI/ARDS. The mechanism of this benefit is not clearly understood. Our trial is testing the hypothesis that APRV reduces the EVLW (primary endpoint) in ALI/ARDS patients through the increase in mean airway pressure (mPaw) paralleling the improvement in oxygenation (secondary endpoint).
METHODS: A pilot study to test the effect of APRV on the EVLW in patients with ALI/ARDS compared to conventional mechanical ventilation. EVLW was measured by the thermodilution method using the PiCCO2 (Pulsion medical system). Measurements were done on conventional ventilation, after 1 and 6 hours from switching to APRV. APRV was set and weaned according to a specific protocol; the P High was set to equal the plateau pressures. Six patients with the diagnosis of ALI/ARDS < 96 hours were enrolled during a 3 months period.
RESULTS: The reported results are: EVLW (ml/kg), mPaw (cmH2O), PaO2/FiO2, mPaw/EVLW index. Results are reported in mean ± SD. Correlation coefficient between variables was calculated. EVLW was reduced by 24 % (19.6 ± 7.5 to 15 ± 4.1) in 1 hour and 11 % (17.5 ± 6) in 6 hours. mPaw was increased by 68 % (15.8 ± 5.5 to 26.5 ± 4.7) in 1 hour and 55 % (24.5 ± 3.8) in 6 hours. PaO2/FiO2 was increased by 47 % (163.6 ± 67.6 to 239.8 ± 132.4) in 1 hour and 58% (257.9 ± 165.3) in 6 hours. mPaw/EVLW was increased by 114 % (0.87 ± 0.08 to 1.86 ± 0.2) in 1 hour and 76% (1.53 ± 0.26) in 6 hours. Strong relation was found between mPaw and EVLW (- 0.99), EVLW and PaO2/FiO2 (- 0.96), mPaw/EVLW index and PaO2/FiO2 (0.87).
CONCLUSIONS: APRV reduced EVLW, and improved PaO2/FiO2.
CLINICAL IMPLICATIONS: Mean airway pressure plays an important role in the reduction of EVLW and improvement in oxygenation during APRV.
DISCLOSURE: The following authors have nothing to disclose: Mohamed Abou El Fadl, Hany Farag, Kameron Ferdowsali, Aanchal Kapoor, Ehab Daoud
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