Comparison of ventilation modes for acute respiratory acidosis in COPD: a retrospective study

Abstract

Spontaneous/timed (ST) non-invasive ventilation (NIV) is commonly employed in patients with acute type 2 respiratory failure (T2RF) secondary to COPD. Use of average volume assured pressure support (AVAPS) is increasing. Differences in outcomes between ST and AVAPS are unclear. Aim: To determine the effect of two modes of NIV (ST and AVAPS) on pH, PaCO2 and length of hospital stay (LoS) in patients with acute T2RF secondary to COPD. Methods: Data were collected retrospectively from patients admitted to hospital with T2RF, requiring NIV, secondary to COPD exacerbation between Sep 2015 and Dec 2016. Results: 34 patients were included (ST n=19 AVAPS n=15). pH normalisation occurred within 12h-post NIV in 79% of patients on ST and 73% on AVAPS (p=0.33), with significant reductions in PaCO2 in both groups(table 1). There was a trend towards reduced LoS in patients on AVAPS (Median(IQR) ST 10(6,15) vs 8(5,12) days, median(95%CI) between-group differences 3(-1 to 6) days, p=0.32). Conclusion: AVAPS is as effective as S/T in treating T2RF secondary to COPD and may help to reduce LoS