Study	Reason for exclusion
Carmini 2000	Intervention group: incentive spirometer plus another respiratory technique
Cattano 2010	Another question (to evaluate the systematic use of incentive spirometer)
Dronkers 2008	Intervention group: incentive spirometer plus another respiratory technique
Gale 1977	Clinical situation: cardiac surgery
Genç 2004	Intervention group: incentive spirometer plus another respiratory technique such as forced expiration and coughing techniques
Indihar 1982	Quasi‐randomized controlled trial
Kundra 2010	Preoperative incentive spirometer versus postoperative incentive spirometer
Lederer 1980	The study compared the use of three types of deep‐breathing devices
Minschaert 1982	Intervention group: incentive spirometer plus chest physical therapy
Pereira 2000	Cohort study
Pfenninger 1977	Case series
Sleszynski 1993	Quasi‐randomized controlled trial
Vilaplana 1990	Patients with chest and oesophageal surgery
Westwood 2007	Non‐randomized controlled trial