Lung Scanning and Exercise Testing for the Prediction of Postoperative Performance in Lung Resection Candidates at Increased Risk for Complications

Objective

To analyze the value of preoperative lung scanning and exercise testing for the prediction of postoperative complications and of the short- as well as long-term performance in lung resection candidates at increased risk for complications.

Design

Prospective clinical trial.

Setting

Clinical pulmonary function laboratory in a university teaching hospital.

Patients

Twenty-five (mean age, 63 years; 17 men) of 84 consecutive lung resection candidates were considered at increased risk for postoperative complications due to impaired pulmonary function (FEV₁ <2 L or diffusion of carbon monoxide [DCO] <50% predicted, or FEV₁ and DCO ≤80% predicted combined with New York Heart Association dyspnea index ≥2).

Interventions

Candidates underwent radionuclide ventilation/perfusion scans and exercise testing to predict postoperative (=ppo) values for FEV₁, DCO, and maximal O₂ uptake ( $\dot{\text{V}}$o₂max). They all underwent thoracotomy for neoplastic lesions; 7 had pneumonectomies, 18 lobectomies. Six patients had postoperative complications (within 30 days), of whom three died. Three and 6 months postoperatively, pulmonary function tests and $\dot{\text{V}}$o₂max were repeated.

Measurements and results

In the 22 survivors, the observed values were then compared with the predicted values. At 3 months, there were excellent correlations (absolute/predicted values): for FEV₁ r=0.78 and 0.81; for DCO, r=0.77 and 0.74; and for $\dot{\text{V}}$o₂max, r=0.71 and 0.83. The means of FEV₁ and $\dot{\text{V}}$o₂max did not differ from the predicted values, whereas the predicted DCO was lower than the observed value (mL/min/mm Hg: 15.1 vs 17.9; percent predicted: 59.6 vs 70.9) (p<0.05). At 6 months, correlations remained very good for FEV₁ (r=0.81 and 0.84) and for DCO (r=0.76 and 0.74), but had decreased for $\dot{\text{V}}$o₂max to 0.56 and 0.65, respectively. All means were higher than predicted (p<0.05) owing to recovery in the lobectomy group. Patients with postoperative complications (group B) had a lower preoperative $\dot{\text{V}}$o₂max in percent predicted (62.8±7.5% vs 84.6±19.7%) (p<0.01) and also a lower $\dot{\text{V}}$o₂max-ppo (10.6±3.6 vs 14.8±3.5 mL/kg/min and 44.3±13.5 vs 68.0±20.7% predicted) (p<0.05) than patients without complications (group A). A $\dot{\text{V}}$o₂max-ppo <10 mL/kg/min was associated with a 100% mortality. Although FEV₁-ppo and DCO-ppo were lower in group B, the difference did not reach significance.

Conclusions

Radionuclide-based calculations of postoperative $\dot{\text{V}}$o₂max are predictive of operative morbidity and mortality: a $\dot{\text{V}}$o₂max-ppo of < 10 mL/kg/min may indicate inoperability. Further, short-term postoperative performance is accurately predicted by FEV₁-ppo and $\dot{\text{V}}$o₂max-ppo, but long-term function is underestimated after lobectomy. (CHEST 1995; 108:341-48)