Lung resection would be associated with lower jugular bulb oxygen saturation (SjvO2) values in patients with moderate to severe pulmonary dysfunction. We aimed to study the effects of lung resections on the postoperative changes in SjvO2, incidence of SjvO2 < 50%, pulmonary functions, cerebral blood flow equivalent (CBFE), and arterial to jugular difference in oxygen content (AjvDO2) in the patients with pulmonary dysfunction. Fifty-three patients scheduled for lung resection were allocated on the basis of forced vital capacity (FVC %) and forced expiratory volume in 1 second (FEV1%) into the following: good FVC and FEV1 (n = 14), mild (n = 14), moderate (n = 13), and severe (n = 12) pulmonary dysfunction groups. After lung resections, patients with pulmonary dysfunctions had significantly lower SjvO2, CBFE, FEV1, and FVC (P < .001), higher AjvDO2 (P < .001), and frequent episodes with SjvO2 < 50% (P < .03). Perioperative changes in FEV1 had a significant negative correlation with SjvO2 desaturation (P < .002). Patients with pulmonary dysfunction showed significant SjvO2 < 50% after lung resection, which is correlated to the perioperative changes in FEV1.