This paper investigates the effectiveness of an open-source large-scale language model (LLM) for extracting key events (reasons for admission, critical in-hospital events, and important follow-up actions) from medical record summaries, particularly discharge reports. To rigorously evaluate the accuracy and fidelity of LLM, we conduct comprehensive simulations and analyze the prevalence of hallucinations during the summarization process. While LLMs such as Qwen2.5 and DeepSeek-v2 successfully capture reasons for admission and events occurring during hospitalization, they are inconsistent in identifying follow-up recommendations.