The primary aim of the study is to demonstrate a reduction in circulating interleukin 6 levels at 4 and 24 hours after completion of lobectomy (either VATS or open). The null hypothesis (H0) is thus that there is no difference in circulating interleukin 6 levels when patients are given either ketamine or placebo (0.9% saline in equivalent volume). The alternative (two tailed) hypothesis (HA) if the null is disproved is that ketamine leads to significantly different levels of interleukin 6 at 4 and 24 hours after completion of surgery. We plan to randomize 40 patients to receive either ketamine or placebo, in a block of 4 randomization design stratified by whether surgery is performed by VATS or open lobectomy.