Effects of Ketamine Infusion on Oxygenation in Patients with Chronic Obstructive Pulmonary Disease Undergoing Lung Cancer Surgery.

Ketamine changes respiratory mechanics, provides airway relaxation, and alleviates bronchospasm in patients with pulmonary disease. This study investigated the effect of a continuous infusion of ketamine during thoracic surgery on arterial oxygenation (PaO2/FiO2) and the shunt fraction (Qs/Qt) in patients with chronic obstructive pulmonary disease. Thirty patients older than 40 years, diagnosed with chronic obstructive pulmonary disease, and undergoing lobectomy were recruited for this study. Patients were allocated randomly to 1 of 2 groups. At the induction of anaesthesia, group K received intravenous (iv) 1 mg kg-1 ketamine as a bolus and followed by 0.5 mg kg-1 h-1 infusion until the end of the operation. Group S received the same amount of 0.9% saline as a bolus at induction and followed by a 0.5-mL kg-1 h-1 infusion of 0.9% saline until the end of the operation. PaO2 and PaCO2 values, FiO2 levels, PaO2/FiO2 ratio, peak airway pressure (Ppeak), plateau airway pressure (Pplat), dynamic compliance, and shunt fraction (Qs/Qt) were recorded during two-lung ventilation as a baseline and at 30 (one-lung ventilation, OLV-30) and 60 (OLV-60) minutes during one-lung ventilation. PaO2, PaCO2, PaO2/FiO2 values, and Qs/Qt ratio were similar between the 2 groups at OLV-30 minute (P = .36, P = .29, P = .34). However, at OLV-60 minute, PaO2, PaO2/FiO2 values were significantly increased, and Qs/Qt ratios were significantly decreased in group K than in group S (P = .016, P = .011, P = .016). Our data suggest that a continuous infusion of ketamine and desflurane inhalation in patients with chronic obstructive pulmonary disease during one-lung ventilation increase arterial oxygenation (PaO2/FiO2) and decrease shunt fraction.