Poor oral health and ventilator associated pneumonia (VAP); is there a link?

Abstract

In recent years, there has been significant research into the possible link between the oral microbiome and systemic disease. Respiratory disease has been one such area of interest, and several studies have now demonstrated there to be a clear link between the oral and lung microbiomes in both healthy and diseased lungs.

Ventilator associated pneumonia (VAP) is a specific condition where this link has been demonstrated. VAP is a parenchymal infection occurring in the lungs 48 hours after initiation of mechanical ventilation and has the potential to cause significant morbidity and mortality for patients.

There is now evidence to suggest that oral bacteria have the potential to transfer between the oral cavity and the lungs during mechanical ventilation. This, alongside evidence that patients’ oral health oftens worsens during mechanical ventilation resulting in colonisation of the oral cavity with potential respiratory pathogens, leads to the theory that the oral cavity may provide a reservoir for potential pathogens which could later transfer to the lungs resulting in VAP.

With this increasing recognition of the oral cavity as a source of potential respiratory pathogens, several measures have been implemented in ICU’s worldwide to prevent VAP including oral hygiene measures, oral decontamination, and oral suctioning amongst others.

One area, however, where there is currently limited knowledge is the oral health status of patients who are undergoing mechanical ventilation, and whether this has any impact on the likelihood of the oral cavity becoming colonised by potential respiratory pathogens and subsequent development of VAP. This topic is largely the focus of this thesis which consists of three main aspects.

Firstly, a scoping review was carried out to determine what is currently understood regarding the oral health of ICU patients and the assessment methods used. A systematic search of the literature was completed which included patients who were mechanically ventilated for at least 48 hours and were over 18 years old. The final review included 12 studies which met inclusion criteria and concluded that significant variation in assessment and reporting methods used in the included studies made direct comparison of results impossible and therefore there remains to be a poor overall understanding of the oral health of ICU patients in general.

The second aspect of research related to a point prevalence study carried out to determine current oral care methods and assessments used in UK ICUs over a 24 hour period. A national one-day point prevalence study was undertaken in 15 UK ICUs which used a questionnaire to survey the oral care provided to all patients admitted to ICU during that time. My participation in this study was largely relating to the data collection and analysis in one ICU (Belfast trust ICU) compared with results of the 2 overall study. A total of 195 patients were analysed overall in the 15 ICUs with 24 patients assessed in the Belfast trust ICU. Within the Belfast trust 100% of patients underwent oral assessment on admission although no formal protocol was in place for the unit. This compared to 35% of UK wide ICUs surveyed carrying out an assessment on admission despite 65% of ICUs having an assessment protocol in place. In the Belfast trust ICU, 100% of patients underwent oral care interventions within 24 hours compared to 73% of those in the UK wide studies. Methods of oral care varied significantly between units with toothbrushing being the most commonly specified method of oral care in the overall results (37.5%) and specifically in Belfast trust ICU (41%). Other methods of care included mouth rinsing and moisturising the oral cavity, chlorhexidine in various forms, and in 12% of Belfast trust responses (and 97% of overall results) an unspecified method of care was also used. The number of times oral care was carried out in the 24 hours study period varied greatly but was mostly commonly carried out more than four times per day. The overall results of this study demonstrated that both oral care method and frequency vary significantly between ICUs and highlights the need for more consistency in oral care protocols and methods to ensure compliance with those protocols that are in place.

The final aspect of this thesis was to develop a protocol for a single centre clinical study to be carried out in Belfast trust ICU which would aim to determine the baseline oral health of patients mechanically ventilated in the ICU, composition, and changes in their oral biofilm over the period of mechanical ventilation, and the impact of baseline oral health on this and on the incidence of VAP.

In conclusion, this work highlights that there is a limited appreciation of the oral health of patients in ICU. Furthermore, oral care measures and their frequency vary significantly between ICUs, which poses difficulty in assigning ‘routine care’ for proposed clinical trials across multiple ICUs. To enhance the data available on the link between oral care and VAP, a single centre clinical trial protocol was developed. Support for a link between patients’ baseline oral health and risk of VAP may allow oral health assessment at baseline to aid in determining a more effective individualised approach to oral care as a means of VAP prevention.

Date of Award	Dec 2023
Original language	English
Awarding Institution	Queen's University Belfast
Supervisor	Fionnuala Lundy (Supervisor), Ikhlas El Karim (Supervisor) & Danny McAuley (Supervisor)