Advancements in Oral Hygiene Practices for the Prevention of Ventilator-Associated Pneumonia

: This review assesses the impact of oral hygiene interventions on preventing Ventilator-Associated Pneumonia (VAP) in ICU patients. It highlights the efficacy of chlorhexidine, povidone-iodine, sodium bicarbonate, and traditional Chinese medicine (TCM) in reducing the incidence of VAP by minimizing oral bacterial colonization. Chlorhexidine is notably effective at both high and low concentrations, while povidone-iodine offers strong bactericidal properties. Sodium bicarbonate shows potential, particularly for neonatal care, and TCM preparations emerge as beneficial with minimal side effects. Mechanical methods like toothbrushing and irrigation are also emphasized for their role in enhancing oral cleanliness. The review advocates for a multimodal oral care approach to significantly lower VAP risk, indicating a pressing need for standardized care protocols and further research to optimize preventive strategies in mechanically ventilated patients. Ventilator-Associated Pneumonia

Ventilator-Associated Pneumonia (VAP) emerges as a significant concern within intensive care, manifesting in patients who have been mechanically ventilated via intubation or tracheostomy for more than 48 hours, or within 48 hours following extubation.This condition is notably one of the more common complications faced in such settings [1] .The inhalation of bacteria from the oropharyngeal region, a common site for bacterial colonization, is identified as a key risk factor for the development of VAP.Adopting rigorous oral hygiene protocols has proven to be an effective preventative measure against bacterial colonization, thus mitigating the risk of VAP.This review delves into the efficacy of various oral hygiene approaches in combating VAP, intending to serve as a solid base for future clinical studies.

Chlorhexidine
Composed of chlorhexidine gluconate and metronidazole, chlorhexidine stands out as a potent antimicrobial agent effective against a broad spectrum of microorganisms.Its main component, chlorhexidine gluconate, is a powerful disinfectant, while metronidazole targets bacteria within the oral cavity [2] .Besides its role in combating oral odors, chlorhexidine has been instrumental in reducing the migration of bacteria to the lower respiratory tract, thus lowering infection risks [3] .Studies by Gao et al [4] have shown chlorhexidine's superiority over saline in decreasing VAP rates among critically ill patients.A meta-analysis by Guo et al [5] revealed the significant effectiveness of both high and low chlorhexidine concentrations in preventing VAP, with a preference for lower concentrations due to safety reasons.Further, research by Lu et al [6] indicated a 2% chlorhexidine solution's effectiveness over a 0.12% solution in VAP prevention.Wei et al [7] also confirmed that a 2% solution significantly reduces oral bacterial levels and consequently VAP incidences, highlighting the ongoing discussion on the optimal concentration for oral care.

Povidone-Iodine
Povidone-iodine, a combination of polyvinylpyrrolidone and iodine, exhibits potent bactericidal activity against most clinically relevant bacteria [8] .Huang et al [9] observed its significant effect in reducing VAP instances compared to saline and placebo in patients with head injuries.Similarly, Sun et al [10] found that gargling with povidone-iodine was more effective than compound borax solutions in VAP prevention, reducing oropharyngeal bacterial colonization.Ding et al [11] supported povidoneiodine's efficacy in lowering VAP occurrences among intubated patients.A meta-analysis by Emami et al [12] validated povidone-iodine's role in diminishing VAP rates and shortening ICU stays.

Sodium Bicarbonate
Sodium bicarbonate forms a mildly alkaline solution when dissolved, fostering an alkaline oral environment that hinders bacterial growth [13] .Although research predominantly focuses on neonatal care, with limited adult studies, Zheng et al [14] have shown that a 2.5% sodium bicarbonate solution effectively combats oral infections and VAP in ICU settings.Zhang et al [15] demonstrated its combined use with 0.9% saline in neonatal care significantly prevents VAP, suggesting its limited efficacy against Gram-negative bacteria, a gap filled by saline.

Traditional Chinese Medicine (TCM) Preparations
Incorporating TCM into oral care for its antibacterial properties and minimal side effects is gaining traction [16] .Zhu et al [16] compared chlorhexidine with TCM in ICU patients, finding TCM effective against oropharyngeal bacterial colonization and VAP caused by Gram-negative bacteria.Liao et al [17] , using San Huang Xie Xin Tang, reported reductions in VAP occurrences and improvements in oral health.Liang et al. [18] showed that TCM components like honeysuckle and baical skullcap effectively reduce oral complications and bacterial load.

Irrigation Method
The irrigation method, which uses water flow to cleanse the oral cavity of debris, secretions, and bacteria, has proven effective in VAP prevention.Gong Mingna's research [19] highlights the use of saline for mouth irrigation in tandem with suction, significantly reducing bacterial colonization and VAP incidents, and thereby shortening ICU stays.Zhang Zhiying's study [20] underscores the superior efficacy of irrigation over traditional cotton ball wiping in diminishing oral bacterial load and VAP occurrence, though it necessitates multiple personnel to ensure safety and efficacy.

Brushing with Irrigation
Employing toothbrushes, particularly when combined with chlorhexidine irrigation, stands out as a prime strategy for dental plaque control and VAP prevention [21] .Zeng Liming's findings [22] illustrate the benefits of this method in reducing oral bacterial content, enhancing oral health, and thereby lowering VAP rates.Xia Yu's comparison [23] further confirms the effectiveness of suction toothbrushing followed by irrigation, showcasing a notable decrease in VAP incidence in the study group.

Wiping Method
Traditional wiping, utilizing chlorhexidine-soaked cotton balls, swabs, or gauze, remains a cornerstone of oral care, effectively removing plaque and reducing bacterial proliferation [24] .Zhang Lixia's application [24] of this method has shown significant benefits in improving oral hygiene and decreasing VAP rates.Wang Yaning's approach [25] , comparing wet and dry-wet cotton ball wiping, highlights the dry-wet method's efficiency in clearing oral bacteria, underscoring the need for further investigation into the optimal wiping frequency.

Wiping Combined with Irrigation
Integrating wiping with irrigation offers a comprehensive approach to oral cleanliness, particularly effective in managing patients with substantial or sticky oral secretions.Li Hui's comparison [26] demonstrates the combined method's superiority in significantly reducing VAP incidence and hospitalization duration compared to wiping alone.Similarly, Sun Xiaowen's meta-analysis [27] supports the combined approach's enhanced effectiveness in improving oral hygiene and reducing VAP risk, suggesting a promising area for further clinical research and practice optimization.

Conclusion
Oral care in China is still in an exploratory phase, lacking unified guidelines.Identifying effective methods to clean the mouth, reduce bacterial colonization, and decrease VAP incidence remains a clinical priority.Currently, discussions on oral hygiene primarily focus on care methods and solutions, with a need for innovative approaches.As VAP can extend mechanical ventilation and hospitalization durations, increase medical costs, and mortality rates, continually exploring optimal oral hygiene strategies is crucial for improving patient outcomes.