Introduction: According with current literature(Hernandes A et al,DOI:10.2147/COPD.S339498;Zikyri A et al, DOI:10.2147/COPD.S152574), use of long-term NIV in COPD patients is related with improvement in diaphragm strength and increasing of forced vital capacity(FVC).

Aims: Our aim is to assess if FVC improvement during NIV could be found in AE-COPD with ARF, considering the predictive role diaphragm ultrasound(DUS) on NIV outcome and reliability of thickness fraction(TF) & its variation(?TDI) as work of breathing(WoB) surrogate measurement(Brochard L et al,DOI:10.1007/s00134-012-2547-7).

Methods: We enrolled 13 subjects (9 m+4 f), aged 68±7 y.o, admitted to our RICU for AE-COPD & Hypercapnic ARF. FVC performed in stable condition within previous 3 months was an inclusion criteria.All patients had a basal blood gas. NIV was applied to each patient with mean PSupport 10±3 & mean PEEP 8±3cmH2O. For each patient, the baseline pCO2 was compared with pCO2 value after 3 hrs of NIV. CVF was tested after 3 days of NIV, and compared with basal one. We also performed for each patient DUS to evaluate TF before and after NIV. Data were evaluated by paired t test.Value of p<0.05 was taken as statistically significant.

Results: After 3 days of NIV, FVC and ?TDI were significativly improved from basal value. FVC increased from 42.3±13.4% to 49.7±16.2% after NIV, with P value=0.02. TF after 3 days improved from basal 2.32±0.52 cm to 3.82±0.63 cm after NIV, with P>0.008.

Conclusion: Data suggests that NIV in AECOPD determines a decrease of lung hyperinflaction, with significant improvement in FVC & diaphragm TF, in reduction of WoB and arterial CO2.