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.