The trial aims to determine if IV ketamine reduces CPSP at 3 months post-surgery compared to placebo, with secondary objectives including acute pain severity, side effects, and quality of recovery. The trial protocol follows SPIRIT guidelines, using a distance model for follow-up, and includes measures of CPSP severity and patient wellbeing at 3 and 12 months. The primary endpoint was changed to 3 months post-surgery due to ICD-11 implementation, with 12 months becoming a secondary endpoint. The trial is multicenter, conducted in Australia, New Zealand, and Hong Kong, with a planned sample size of 4884 patients to detect a 15% reduction in CPSP incidence by ketamine.