# Flexible-Imaging-Fiber-Guided Intrratracheal Intubation in Rodents
###### Abstract  
Although experiments on intratracheal intubation for animals are essential for research, it remains challenging. This study aimed to validate an animal model using a flexible imaging guide system that can be conveniently and safely used as a new method to provide easy access to organs in small animals. PBS (Phosphate Buffered Saline) and PHMG (Polyhexamethylene guanidine) were administered by intratracheal intubation to 20 rodents (10 mice and 10 rats), and the changes in the lungs were observed. Results were verified using lung tissue histopathologic staining through the intratrachemically administered material, which confirmed that 100% of changes in lung tissue occurred in the PHMG-injected group, where intubation was facilitated using the flexible imaging guide. The drug was conveniently and safely administered. The flexible-imaging-fiber-guide-based intratracheal drug injectable system may be conveniently used by researchers. It allows drugs to be administered quantitatively, suggesting its potential wide use in drug development and toxicity evaluation. flexible imaging guide; intubation; PHMG +
Footnote †: journal: Medical Imaging  
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effects of exposure to PHMG-containing products and identify the factors contributing to the outbreak. One of the most significant studies was a case-control study investigating the association between exposure to humidifier disinfectants containing PHMG and lung injury. The previous study found a strong association between disinfectant exposure and lung injury, with risk increasing with increased exposure. The study identified that the disinfectants caused severe lung inflammation, leading to respiratory failure [3]. Other studies conducted by the task force investigated the toxicity of PHMG in animal models and the mechanism of PHMG-induced lung injury. These studies identified that PHMG exposure could cause significant damage to the lungs, liver, and kidneys [2]. The studies also recognized that the mechanism of PHMG-induced lung injury involved the activation of immune cells in the lungs, leading to severe inflammation and tissue damage [4]. The research conducted in Korea on PHMG has shown significant changes in regulations and guidelines for disinfectants and other products containing PHMG. The Korean government banned producing and selling humidifier disinfectants containing PHMG and other harmful chemicals [5]. The government also introduced stricter regulations on the use of disinfectants in public places such as schools and hospitals. Air pollution has several adverse health effects. Short-term exposure to air pollutants is closely related to respiratory diseases such as chronic obstructive pulmonary disease and cough [6]. However, to elucidate the causal relationship between harmful substances and diseases, there is a need for long-term research and support from experimental subjects [7; 8]. However, it is not possible to conduct research on respiratory diseases or their etiology by testing toxic substances directly on humans. Such studies should, therefore, be conducted in preclinical studies. The most challenging aspect of animal models is the precise and reproducible evaluation of lung disease or treatment by injecting multiple substances into the lungs. Research on disease diagnosis and treatment through establishing models of chronic obstructive pulmonary disease (COPD) is steadily increasing. COPD is the primary cause of morbidity and mortality worldwide and is characterized by chronic airway inflammation, mucus hypersecretion, airway remodeling, and emphysema, resulting in decreased lung function and dyspnea [9]. Gradual worsening of lung function due to aging and exposure to various harmful materials may progress to COPD [10]. Rodent models are widely used in research to investigate and establish a disease model for studying lung diseases, such as COPD. These animal models are widely used because they are economical and have good reproductive power [11]. These include inhalation and intratracheal intubation with drugs.