title: Reduction in cardiorespiratory fitness after lung resection is not related to the number of lung segments removed.
abstract: OBJECTIVE
  To evaluate the effect of lung cancer surgery on cardiorespiratory fitness (CRF), and to assess the agreement between the predicted postoperative (ppo) V̇O2peakand actually measured postoperative peak oxygen uptake (V̇O2peak).
  
  
  METHODS
  Before and 4-6 weeks after lung cancer surgery, 70 patients (35 women) underwent measurements of pulmonary function and CRF via a cardiopulmonary exercise test. In addition, the 23 non-exercising patients underwent measurements after 6 months. The ppo V̇O2peakcalculated from the number of functional segments removed was compared with the actually measured postoperative values of V̇O2peakfor accuracy and precision.
  
  
  RESULTS
  After surgery, the V̇O2peakdecreased from 23.9±5.8 to 19.2±5.5 mL/kg/min (-19.6±15.7%) (p<0.001). The breathing reserve increased by 5% (p=0.001); the oxygen saturation remained unchanged (p=0.30); the oxygen pulse decreased by -1.9 mL/beat (p<0.001); the haemoglobin concentration decreased by 0.7 g/dL (p=0.001). The oxygen pulse was the strongest predictor for change in V̇O2peak; adjusted linear squared: r2=0.77. Six months after surgery, the V̇O2peakremained unchanged (-3±15%, p=0.27). The ppo V̇O2peak(mL/kg/min) was 18.6±5.4, and the actually measured V̇O2peakwas 19.2±5.5 (p=0.24). However, the limits of agreement were large (CI -7.4 to 8.2). The segment method miscalculated the ppo V̇O2peakby more than ±10 and ±20% in 54% and 25% of the patients, respectively.
  
  
  CONCLUSIONS
  The reduction in V̇O2peakand lack of improvement 6 months after lung cancer surgery cannot be explained by the loss of functional lung tissue. Predicting postoperative V̇O2peakbased on the amount of lung tissue removed is not recommendable due to poor precision.
  
  
  BACKGROUND
  NCT01748981.
authors.affiliation: Department of Pulmonary Medicine, Oslo University Hospital, Oslo, Norway; Department of Sports Medicine, Norwegian School of Sport Sciences, Oslo, Norway.
authors.forename: Elisabeth
authors.initials: E
authors.lastname: Edvardsen
authors.affiliation: Department of Sports Medicine , Norwegian School of Sport Sciences , Oslo , Norway.
authors.forename: Sigmund A
authors.initials: SA
authors.lastname: Anderssen
authors.affiliation: Department of Pulmonary Medicine , Oslo University Hospital , Oslo , Norway.
authors.forename: Fredrik
authors.initials: F
authors.lastname: Borchsenius
authors.affiliation: Department of Pulmonary Medicine , Oslo University Hospital , Oslo , Norway.
authors.forename: Ole Henning
authors.initials: OH
authors.lastname: Skjønsberg
keywords: Aerobic fitness; Cancer; Exercise physiology; Lungs; Surgery