Final answer:
Florence Nightingale's influence on 19th century nursing practice focused on improving sanitation and the patient environment to promote health, which led to significant reforms in military hospitals.
Step-by-step explanation:
The influence in question on nursing practice in the 19th century which was related to the improvement of the patient environment as a method of health promotion can be attributed to Florence Nightingale. Florence Nightingale is renowned for her work during the Crimean War, where she kept meticulous records, indicating that many deaths were due to preventable infectious diseases stemming from poor sanitation. Her analysis emphasized the need for improved hygiene practices and led to reforms in British military hospitals. This early form of epidemiological study played a pivotal role in changing the practice of nursing and highlighted the importance of a clean environment in health care.