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

Objective: 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 (PaO (2)/FiO (2)) and the shunt fraction (Q s/Q t) in patients with chronic obstructive pulmonary disease. Methods: 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. PaO (2) and PaCO (2) values, FiO 2 levels, PaO (2)/FiO (2) ratio, peak airway pressure (P peak), plateau airway pressure (P plat), dynamic compliance, and shunt fraction (Q s/Q t) 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. Results: PaO 2, PaCO (2), PaO (2)/FiO (2) values, and Q s/Q t ratio were similar between the 2 groups at OLV-30 minute (P =.36, P =.29, P =.34). However, at OLV-60 minute, PaO (2), PaO (2)/FiO (2) values were significantly increased, and Q s/Q t ratios were significantly decreased in group K than in group S (P =.016, P =.011, P =.016). Conclusions: 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 (PaO (2)/FiO (2)) and decrease shunt fraction.