“…[31][32][33]35,37,40 Studies comparing incentive spirometry for PPC prevention after cardiac/thoracic surgery also include a trial with no intervention as the control, 48 and studies that compared incentive spirometry to other techniques. 44,45,47,48,51,52,54,55,58,60 The majority of these trials reported no difference between incentive spirometry and the comparator. 44,47,48,51,52,54,58,60 This creates one of the challenges in evaluating the evidence on incentive spirometry in PPC prevention.…”