The efficacy of postoperative incentive spirometry is influenced by the device-specific imposed work of breathing

Study objectives: The study evaluated the impact of the additional imposed work of breathing (WBimp) generated by two different spirometers on postope rative incentive spirometry performance in patients at high risk and modera te risk for postoperative pulmonary complications (PPCs). Additionally, we investigated whether maximal inspiratory pressure (PImax) is an easy estima te of the WBimp imposed by incentive spirometers. Design: Prospective, randomized, single-blind clinical trial. Setting: ICU of a university hospital. Interventions and measurements: Thirty male patients were assigned to a gro up at high risk for PPCs (group A; inspiratory capacity [IC], < 1.6 L) or t o a group at moderate risk for PPCs (group B; IC, 1.6 to 2.5 L) after upper -abdominal, thoracic, or two-cavity surgery, On the first or second postope rative day WBimp, IC, and PImax were recorded without spirometers (baseline ) and during incentive spirometry with the Mediflo spirometer (Medimex; Ham burg, Germany) thigh WBimp) and the Coach spirometer (Kendall; Neustadt, Ge rmany) (low WBimp) using a pneumotachograph. In group A, the baseline and t he ICs for both spirometers only differed slightly. In group B, the IC was significantly reduced for the Mediflo (p < 0.05), which imposed a WBimp twi ce as high as the Coach (p < 0.01), PImax was significantly increased for b oth the Mediflo and the Coach (p <less than> 0.01). PImax was positively co rrelated with WBimp (r = 0.8). Conclusions: Incentive spirometers differ considerably in their additional Wbimp with a potential impact on the efficacy of postoperative incentive sp irometry performance. PImax might be an easy clinical estimate for the WBim p during incentive spirometry, Incentive spirometers with low WBimp permit increased maximal sustained inspiration and, thus, enhanced incentive spiro metry performance, and, therefore, it might be more suitable for use in pos toperative respiratory care.