This Figure shows the results from one of the first studies that assessed noninvasive HMV after acidotic respiratory failure in COPD patients.^[15] The graph shows the probability of a recurrent acute hypercapnic respiratory failure in the control group receiving sham NIV (continuous positive airway pressure [CPAP] with a pressure of 5.0 cmH₂O) compared to NIV using a mean IPAP of 15 cmH₂O. It is clear that the probability of recurrent acute hypercapnic respiratory failure was lower in the group receiving NIV compared with the control group.