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 (PaO2/FiO2) and the shunt fraction (Qs/Qt) 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. 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.

Results: 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).

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 (PaO2/FiO2) and decrease shunt fraction.