Mechanical ventilation is often a requirement for patients in hospital intensive care units (ICUs). This may be because of a critical condition impairing their ability to breathe unassisted, or due to a requirement for these patients to be under sedation. Mechanical ventilation may be necessary in patients following trauma, recent surgery, brain injury, respiratory failure or after recreational drug usage.
As a consequence of the current COVID-19 pandemic, discussion of the use of ventilators has been prevalent in both local and global media (BBC News, 2020). Infection with COVID-19 may lead to respiratory complications and, in severe cases, patients may need to rely on mechanical ventilation to assist with breathing.
This article describes the consequences of poor oral health, the importance of oral hygiene for ventilated patients and the latest recommended approaches to oral hygiene care in ventilated patients for ICU nurses.
Consequences of poor oral health
The aim of providing good oral care is to decrease the microflora load present in a patient's oral cavity. Poor oral health has been linked to increased levels of hospital-acquired pneumonia (HAP), the leading type of hospital-acquired infection (Mehndiratta et al, 2016). Pneumonia is an inflammatory condition of the lung, usually caused by a bacterial infection. It primarily affects the alveoli, which can become filled with pus and fluid (pulmonary oedema). This limits oxygen intake and makes it painful for the individual to breathe (Leach, 2010; World Health Organization, 2019). Although there are several routes to lower airway colonisation, the primary mechanism by which microorganisms enter the lungs is through aspiration of contaminated oropharyngeal secretions (including dental plaque) (El-Rabbany et al, 2015). Patients lying supine in a hospital bed and older patients with decreased levels of consciousness are more likely to aspirate oral secretions (Mehndiratta et al, 2016). Poor oral health is also strongly associated with poor nutritional intake and malnutrition, which in turn can affect a patient's recovery. This can lead to longer hospital stays and, consequently, higher care costs (Gil-Montoya et al, 2008; El-Rabbany et al, 2015; Health Education England, 2016).
A subcategory of HAP is ventilator-associated pneumonia (VAP), which is defined as pneumonia that develops 48 hours or longer after mechanical ventilation is given by means of an endotracheal tube or tracheostomy (Rabello et al, 2018).
In mechanically ventilated patients, a reduction in oral immunity can occur because of critical illness and intubation; in other words, a reduction in the ability of the patient's oral cavity to resist harmful microorganism can occur. Prolonged mouth opening reduces saliva flow, which normally has protective buffering properties, and obstruction by the endotracheal tube can reduce accessibility for oral care. A combination of these factors results in an increase in oral bacteria, housed by the rapidly accumulating level of dental plaque. Once formed, this complex biofilm is relatively resistant to chemical control and must be disrupted mechanically for effective elimination.
The endotracheal tube that serves to deliver oxygen can act as a vehicle for pathogenic bacteria to spread into the lungs from the oral cavity. A deficient seal of the cuff to the endotracheal tube may also give rise to micro-aspiration of oropharyngeal secretions, which is a known contributor to the development of nosocomial pneumonia, especially in patients whose normal mechanisms for resisting infection may be compromised. VAP is a serious complication of mechanical ventilation. It is associated with a 10% mortality rate and can increase hospital stays by an average of 7–9 days per patient (Melsen et al, 2011). This can have major cost implications on a healthcare system. For example, in Canada alone, VAP has been estimated to account for around 17 000 ICU days per year (El-Rabbany et al, 2015). Good oral hygiene care for ventilated patients can reduce bacterial overgrowth and reduce the risk of VAP infection (Boltey et al, 2017).
Oral hygiene for ventilated patients
ICU patients will often be incapable of carrying out normal oral hygiene practices, such as toothbrushing, themselves. They are, therefore, entirely dependent on nurses for their oral hygiene needs. In England, it is generally accepted that ‘good, frequent oral care’ is paramount for these patients, and can be achieved using several methods in isolation or in combination, such as mouth rinses, gels and toothbrushing, as well as aspiration of secretions. However, no specific guidelines on oral hygiene care in ICU patients have been published, although several papers have made recommendations (Kumar and Rath, 2016; Yurdanur and Yagmur, 2016). In light of this, Health Education England published Mouth Care Matters in 2016, which aims to provide advice to health professionals so that they can support vulnerable patients with oral hygiene care. This document recommends that oral hygiene for ventilated patients should include the following:
In addition to the above suggestions, frequent suctioning of the oral cavity can remove secretions that may accumulate on the top of the cuff of the endotracheal tube and cause micro-aspiration. To minimise or prevent pressure areas on the lips, tongue and oral cavity, the oral tube should be regularly moved to the other side of the mouth (Health Education England, 2016).
The use of chlorhexidine mouthwash or gel
Chlorhexidine is an antiseptic agent with broad-spectrum activity against Gram-positive and Gram-negative organisms, facultative anaerobes, aerobes and yeast (Tran and Butcher, 2019). Until 2008, National Institute for Health and Care Excellence (NICE) guidelines recommended the inclusion of chlorhexidine as part of the oral hygiene regimen for all patients who are intubated and receiving mechanical ventilation. This led to the widespread use of oral chlorhexidine to decontaminate the oropharynx (Scottish Intensive Care Society Audit Group, 2012). However, chlorhexidine use presents with its own risks, such as oral mucosal lesions and anaphylaxis. Recent re-examination of the evidence brought into question the benefits of the effectiveness of chlorhexidine versus its risks. A study concluded that the use of chlorhexidine for cardiac surgery patients can prevent the incidence of VAP, but not for non-cardiac surgery patients (Klompas et al, 2014). In light of this evidence, NICE has withdrawn these VAP prevention recommendations, stating that ‘the recommended action on administering oral chlorhexidine is no longer supported by the evidence, and risks causing harm’ (NICE, 2008; Hellyer et al, 2016). Currently, individual hospital trusts are reviewing their policies on the use of chlorhexidine (Mehndiratta et al, 2016). Further studies will need to provide new insight into the risk–benefit balance of using chlorhexidine, or to explore alternative interventions with clearer evidence of benefit and risk (Tran and Butcher, 2019).
Conclusion
Clearer guidelines on oral hygiene care for ventilated patients are needed for ICU staff. As the COVID-19 pandemic continues to place an extraordinary burden on critical care, good oral health for ventilated patients may shorten hospital stays and reduce the incidence of hospital-acquired infections for these patients.