Changes in Cerebral Oxygenation in Patients With Pulmonary Dysfunction After Lung Resection

Surgery remains the treatment of choice for patients with resectable lung cancer. However, a significant proportion of patients undergoing lung resections have the associated condition COPD,1 which increases the risk of perioperative complications and death. New techniques in anesthesiology and critical care have enabled patients with COPD to have better outcomes following lung resections. Nowadays, patients with limited lung function, who would have been denied surgery according to the criteria proposed in the past, may undergo pulmonary resection with a low mortality rate.2

Lung resection results in loss of lung parenchyma including residual healthy lung tissue and in reduction in the pulmonary vascular bed. A decrease in residual pulmonary vascular bed after lung resection causes an increase in the right heart afterload, and in others, it would be associated with an increase in the right heart preload.3

The removal of lung parenchyma from patients with carcinoma of the lung, may lead to cardiopulmonary failure or death. A predicted postoperative forced expiratory volume in one second (FEV1) less than 0.8 to 1.0 liter is considered an indicative of a high risk of postoperative chronic ventilatory insufficiency. After pneumonectomy, FEV1 decreases by 29-35% and forced vital capacity (FVC) decreases by 27-44%. After lobectomy, FEV1 and FVC decrease to12-23% and 10-30%, respectively.4

After lobectomy in patients with normal pulmonary functions, there is a transient good maintenance of gas exchange for only 6-12hours, then it is followed with progressive deterioration in oxygen delivery and intra-pulmonary shunt fraction because of peripheral atelectasis 4-13 days after surgery.5 Other investigators reported a significant decrease in maximal oxygen uptake (VO2-Max) and maximal work rate (WR-Max) by 27% and 42%, respectively, 3 months after pneumonectomy, and by13% and 2%, respectively after lobectomy.

In patients with moderate-to-severe pulmonary dysfunction there is significant worsening of pulmonary gas exchange; especially during one-lung ventilation (OLV) which is the mandatory technique to facilitate thoracic surgery. This worsening is more marked in patients undergoing right thoracotomies after lung resection.6