BACKGROUND: Large language models (LLMs) show increasing potential for their use in healthcare for administrative support and clinical decision making. However, reports on their performance in critical care medicine is lacking. METHODS: This study evaluated five LLMs (GPT-4o, GPT-4o-mini, GPT-3.5-turbo, Mistral Large 2407 and Llama 3.1 70B) on 1181 multiple choice questions (MCQs) from the gotheextramile.com database, a comprehensive database of critical care questions at European Diploma in Intensive Care examination level. Their performance was compared to random guessing and 350 human physicians on a 77-MCQ practice test. Metrics included accuracy, consistency, and domain-specific performance. Costs, as a proxy for energy consumption, were also analyzed. RESULTS: GPT-4o achieved the highest accuracy at 93.3%, followed by Llama 3.1 70B (87.5%), Mistral Large 2407 (87.9%), GPT-4o-mini (83.0%), and GPT-3.5-turbo (72.7%). Random guessing yielded 41.5% (p <
0.001). On the practice test, all models surpassed human physicians, scoring 89.0%, 80.9%, 84.4%, 80.3%, and 66.5%, respectively, compared to 42.7% for random guessing (p <
0.001) and 61.9% for the human physicians. However, in contrast to the other evaluated LLMs (p <
0.001), GPT-3.5-turbo's performance did not significantly outperform physicians (p = 0.196). Despite high overall consistency, all models gave consistently incorrect answers. The most expensive model was GPT-4o, costing over 25 times more than the least expensive model, GPT-4o-mini. CONCLUSIONS: LLMs exhibit exceptional accuracy and consistency, with four outperforming human physicians on a European-level practice exam. GPT-4o led in performance but raised concerns about energy consumption. Despite their potential in critical care, all models produced consistently incorrect answers, highlighting the need for more thorough and ongoing evaluations to guide responsible implementation in clinical settings.