The objective of the PAIN-STOP trial is to assess the feasibility of a larger randomized controlled trial (RCT) evaluating NMDA antagonists and IV steroids, as compared to placebo, in decreasing the chances of clinically significant persistent post-surgical pain (PPSP) after video assisted thoracoscopic surgeries (VATS). This is a multi-centre randomized, controlled clinical trial with a 2 x 2 factorial design. The pilot phase of the trial will recruit 48 patients and follow them for 3 months. Patients will be randomized to one of four groups: 1) NMDA active + Steroid placebo; 2) Steroid active + NMDA placebo; 3) NMDA active + Steroid active; 4) NMDA placebo + Steroid placebo.