Predicted versus observed FEV1 and DLCO after major lung resection: a prospective evaluation at different postoperative periods.

BACKGROUND

The objective of this study was to prospectively assess the agreement between predicted and observed postoperative values of forced expiratory volume in 1 second (FEV1) and carbon monoxide lung diffusion capacity (DLCO) after major lung resection.

METHODS

Two hundred consecutive patients undergoing lobectomy or pneumonectomy for lung cancer in a single center were prospectively evaluated with complete preoperative and repeated postoperative measurements of FEV1 and DLCO. Predicted postoperative (ppo) values were compared with the observed postoperative values. The precision of ppoFEV1 and ppoDLCO at 3 months was subsequently evaluated by plotting the cumulative predicted postoperative values against the observed ones.

RESULTS

After lobectomy, observed values were 11% lower at discharge (p < 0.0001), and 6% higher at 3 months (p < 0.0001), compared with ppoFEV1. No differences were noted at 1 month. Observed DLCO values were 12% lower than predicted at discharge (p < 0.0001) and 10% higher than predicted at 3 months (p < 0.0001), without differences noted at 1 month. After pneumonectomy, no differences were noted between predicted and observed values of FEV1 at every evaluation time, and of DLCO at discharge and 1 month. However, the observed DLCO value was 17% higher than predicted at 3 months (p = 0.002). Plots of predicted and observed postoperative values at 3 months showed that ppoFEV1 predicted worse at lower levels of ppoFEV1, and ppoDLCO was constantly lower than the observed values at every ppoDLCO levels.

CONCLUSIONS

Given the imprecision of the prediction of postoperative function, particularly of gas exchange determinants and after pneumonectomy, and at low ppoFEV1 levels, the use of ppoFEV1 and ppoDLCO for risk stratification needs to be reconsidered.