Presently , the evidence does not support the use of IS for decreasing the incidence of PPCs following cardiac or upper abdominal surgery
OBJECTIVE To systematic ally review the evidence examining the use of incentive spirometry ( IS ) for the prevention of  postoperative pulmonary complications ( PPCs ) .
Breath-stacking increases the depth and duration of chest expansion by incentive spirometry.
Although the objective of incentive spirometry is to achieve and hold high lung volumes , many patients with pain or weakness are unable to sustain the effort needed to perform effective exercises . We question ed whether using a one-way valve to prevent exhalation would allow rest between inspiratory efforts and cause volume to cumulate during successive tidal efforts , improving both the depth and duration of the inspiratory maneuver . We studied 26 cooperative but naive patients recovering from surgery , trauma , or critical illness whose pain or weakness impaired ability to achieve and sustain deep inspiration . All subjects breathed via mouthpiece from a spirometer prefilled with 100 % oxygen . Three different maneuvers were performed in r and om order by all subjects : ( 1 ) st and ard inspiratory capacity without valve or inspiratory hold , ( 2 ) inspiratory capacity ( IC ) with breathholding aided by a one-way valve , and ( 3 ) uncoached breath-stacking , during which successive tidal breaths were cumulated by one-way valving . A fourth maneuver was added in the last 13 subjects studied : an initial coached IC effort with subsequent valved stacking of tidal efforts . When compared with IC , " breath stacking " ( valved ) maneuvers increased inspired volume by an average of 15 to 20 % ( p less than 0.05 ) . More importantly , there was a severalfold increase in the time over which high lung volume was sustained ( p less than 0.001 ) . Our results indicate that one-way valving helps to achieve and sustain deep inspiration , even in uncoached patients
Presently , the evidence does not support the use of IS for decreasing the incidence of PPCs following cardiac or upper abdominal surgery
OBJECTIVE To systematic ally review the evidence examining the use of incentive spirometry ( IS ) for the prevention of  postoperative pulmonary complications ( PPCs ) .