The multidisciplinary assessment and management of oral and respiratory secretions following severe acquired brain injury

Abstract

Managing oral and respiratory secretions after severe acquired brain injury (ABI) is complex and requires coordinated multidisciplinary assessment and intervention. Impairments in swallowing, coughing, posture and awareness contribute to secretion accumulation, increasing risks of aspiration and infection. This article outlines the pathophysiology of saliva and mucus changes in ABI, their clinical impact, and structured approaches to assessment including bedside indicators, dysphagia evaluation and tracheostomy-related considerations. Non-pharmacological, pharmacological and procedural treatments—ranging from airway clearance techniques to anticholinergics and salivary gland botulinum toxin—are reviewed. A pragmatic, individualised management pathway is proposed to optimise secretion control and support rehabilitation outcomes.

Introduction

Patients with acquired brain injury (ABI) can develop impairments in swallowing, postural control and awareness leading to excessive accumulation and/or production of secretions (consisting of saliva (sialorrhoea) and lower respiratory mucus). In the post-acute setting, excessive or poorly managed secretions are known to increase risk of aspiration [1], delay weaning from respiratory support [2] and impact on participation in rehabilitation.

There are a range of treatment options, focal and systemic, which may be employed. It is important for clinicians involved in the management of this patient group to have an understanding of their risks and benefits in the context of the different pathophysiological mechanisms which contribute to problematic secretions.

1. Pathophysiology

In considering airway secretions, it is important to identify the relative contributions of oral secretions (excess production or impaired clearance of saliva) and bronchial secretions (largely mucus i.e., lower airway secretions). Although in practice this can be difficult as they often occur concurrently, the approach to one secretion type may impact the other. Both should be considered for effective patient management. Table 1 outlines oral and respiratory secretion production, regulation and function.

Table 1: An overview of saliva and respiratory secretions.

2. Impact of Secretions Following ABI

2.1 Saliva

Observational studies suggest that posterior salivary aspiration occurs in around half of people with ABI and a tracheostomy [3], a retrospective review of chest infection incidence in severe TBI showed that over 80% of patients designated “nil by mouth” sustained a chest infection [4]. Posterior salivary loss resulting in airway penetration/aspiration can occur in the absence of obvious drooling. The aspiration of oral secretions, particularly those with a high bacterial load, is likely to be a contributing factor to the high incidence of chest infections in this population [1]. In the community setting, poor salivary control causes embarrassment and distress reducing participation in social engagements and activities [5], an increased care burden and perioral skin breakdown [6].

2.2 Respiratory Secretions

Regulation of respiratory mucus production involves a complex molecular pathway and a wide variety of stimuli will act to increase secretion acutely [7]. In the context of people with severe ABI this is likely to include factors such as infections, the presence of a tracheostomy or regular airway contact (such as suctioning). For those with reduced levels of conscious awareness, bulbar dysfunction or weak intercostal or trunk muscles, their ability to cough is likely to be impaired. Mucus viscosity is impacted by systemic levels of hydration and airflow. Thicker mucus leads to the formation of adherent mucus plaques and plugs in smaller airways [8] producing locally hypoxic conditions through airflow obstruction and inflammation [9], causing a vicious cycle of further obstruction and infection [10]. The lack of respiratory secretion clearance consequent to ABI means that this group are at risk of further chest infections.

3. Assessment

A determination of the relative contributions of oral and respiratory secretions and the likely benefit of any intervention is needed. A thorough assessment of a patient’s secretion management following severe ABI should include physiotherapy, speech and language therapy (SLT), nursing and medical input. It is important to consider:

• Bedside clinical indicators – issues are likely to be apparent at bedside. This may include:
  • Anterior drooling of saliva from the mouth (e.g., wet lips/chin/chest) – can be recorded using drooling severity and frequency scale (Figure 1) [11]
  • Visibly pooling saliva in the oral cavity
  • ‘Wet’ and gurgling voice when speaking or vocalising (such as groaning, yawning)
  • Audible ‘wet’ sound in upper airway during normal breathing
  • Visible changes to ventilation (e.g., increased respiratory rate or work of breathing)
  • Intermittent oxygen saturation drops
  • Frequency of coughing (where a cough reflex is present)
  • Effectiveness of cough (ability to mobilise secretions for them to be swallowed or expectorated/suctioned)
  • The frequency and nature of chest infections
• Suctioning – A review of suctioning needs should include:
  • Establishing the suctioning route – e.g., oral, naso- or oro-pharyngeal, or via tracheostomy, along with suction frequency
  • The volume of material suctioned and its appearance (colour and consistency) is helpful in determining if saliva or respiratory, or a combination
  • The prompt for the initiation of suctioning (e.g., audible secretions, patient request) is important to note. Caution should be used in the reliance on suctioning as an objective marker, as this is reliant on caregivers’ responsiveness and accurate recording of the intervention
• Dysphagia assessment – An assessment of swallowing will help to establish whether salivary issues are due to dysphagia, or hyper-salivation. While bedside assessment may give limited information on the process of swallowing, it can yield evidence about the frequency (or absence) of swallows. Cranial nerve assessment may be possible, either actively or by observation. Overt signs and symptoms of dysphagia may be limited in this population due to significant sensory impairment [12]. Instrumental assessment of swallow is recommended to provide objective clinical evidence. A fibre-optic endoscopic evaluation of swallowing (FEES) allows the direct visualisation of the pharynx, larynx and upper trachea and provides a more accurate picture of secretion management at a pharyngeal level [13].

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• Aspirate from subglottic port – for patients with a tracheostomy, establishing how much saliva is being removed via the subglottic port is a useful objective measure of saliva aspiration, and as such can be an effective outcome measure for interventions. The use of tracheostomy tubes with a subglottic port (Figure 2) should be considered where there are concerns around secretion management. Establishing a relationship between position of the patient and the volume of aspirate being cleared may indicate increased aspiration of saliva due to posterior loss into the airway. Port secretions should be visualised to determine whether they appear salivary or respiratory secretions (e.g., opaque/coloured, more viscous). If respiratory in appearance, this may indicate chest secretion that been coughed up past the cuff, or nasal secretions that have been aspirated.
• Tolerance of cuff deflation – for patients with a tracheostomy (Figure 2), tolerance of cuff deflation can be a useful indicator of their ability to manage their saliva [14]. If able to tolerate cuff deflation with no respiratory deterioration, then this suggests that they are adequately managing their saliva; however, caution should be applied due to the potential for reduced sensation and response to aspiration, masking clinical signs at bedside.
• Medication review – some medications (benzodiazepines, anti-seizure, opiates, muscle relaxants) depress swallow/laryngeal reflexes impeding pharyngeal clearance and increasing saliva burden. The impact of any medications should be explored in the context of patient presentation [15–17].
• Medical investigations – in the evaluation of respiratory secretions, there may be value in performing sputum culture to assess for micro-organisms involved with chronic infection which can stimulate mucus production. Imaging may be indicated in ruling out infection or establishing the presence of underlying lung disease relating to an increased production of mucus such as bronchiectasis. Imaging can also show gravity dependent consolidation suggestive of chronic salivary aspiration [18].

3. Non-pharmacological management

3.1 General measures

Initial physical assessment will demonstrate areas of potential intervention which should be addressed in the day-to-day management of patients with ABI and problematic secretions. A suggested initial approach to management is shown (Figure 3).

3.2 Respiratory physiotherapy and airway clearance techniques

Ensuring airway clearance is optimised is an important step in managing respiratory secretions in individuals post-ABI. As with any airway clearance plan, it is essential that the techniques utilised are specific to the individual’s need and circumstances [19,20]. Techniques chosen will depend on the individual’s ability to engage (level of awareness/cognition), their physical function and ongoing goals. This may include self-generated airway clearance techniques or assisted (e.g., manual techniques, suctioning and/or cough assist).

Removal of respiratory secretions through airway clearance techniques reduces secretion burden and prevents pooling in the upper airway when the patient is unable to clear effectively and independently.

3.3 Dysphagia intervention

The optimisation of swallowing is fundamental when dysphagia is contributing to secretion burden. Dysphagia rehabilitation is not always possible after ABI, associated with severity of the impairment, poor engagement or cognitive impairment. A common approach in functional swallowing rehabilitation involves giving an individual something to swallow – such as ice chips or teaspoons/sips of water [9]. The facilitation of a relatively bacteria-free bolus provides input to aid swallow sensorimotor function, can help clear thick oral secretions that are impeding swallow function, improve hydration and oral condition whilst minimising risk to chest status [21]. Such an approach requires careful individual risk/benefit analysis due to the potential risk of aspiration pneumonia [22]. Prior to any oral intake, oral care must be optimised due to risk of aspiration of oral bacteria which remains the highest risk factor for development of aspiration pneumonia [23].

A closely monitored proactive approach to dysphagia rehabilitation, with acceptance of some degree of risk and completed in tandem with general measures and pharmacological approaches, is required in optimising dysphagia, and saliva management, following ABI.

3.4 Tracheostomy considerations in secretion management

Patients with a cuffed tracheostomy experience difficulties due to both ABI-related dysphagia and laryngeal sensory dampening (caused by air bypassing the larynx due to cuff inflation) [24]. This bypassing of air from the larynx results in deconditioning of laryngeal function impacting the presence and effectiveness of protective airway responses such as cough and swallow [25]. Deflation of the cuff and application of a one-way valve to restore subglottic airflow and trans-laryngeal sensation should be commenced to optimise and rehabilitate the protective reflexes of swallowing and coughing [26,27]. If cuff deflation is not possible, above cuff airflow can be utilised. This involves applying a flow of air via the subglottic port of a tracheostomy tube. Although not as effective as cuff deflation in airflow restoration, this has yielded positive outcomes on laryngeal function [28], including with patients who are unable to participate [29]. The presence of a tracheostomy, where cuff is deflated, should not preclude the concurrent use of dysphagia rehabilitation techniques. These should be used appropriately to expedite dysphagia rehabilitation.

4. Pharmacological therapies

4.1 Anticholinergic agents

Anticholinergic agents act both on salivary and bronchogenic secretions by antagonism of muscarinic receptors (M3). Within the airways, submucosal gland blockade reduces mucus and water secretion [30]. There is a need to consider the potential impact of such medications on thickening respiratory secretions when these are difficult to clear. Anticholinergic drugs are also used as bronchodilators, through their action on smooth muscle, improving secretion clearance from the lower airways [31].

Anticholinergic medications used include glycopyrronium [32], hyoscine and atropine [33] (Table 2). There is no specific evidence regarding the relative superiority of any agent in the management of either saliva [34] or bronchial respiratory secretions [35] and their use is off-license for this group. There are a number of side effects associated with the use of anticholinergic medication (table 3) [36] which are a particular concern after an ABI. It is preferable to use agents that are less likely to cross the blood brain barrier. For this reason, glycopyrronium is recommended by the NICE guidelines for the management of sialorrhoea in Parkinson’s disease [37].

4.2 Botulinum toxin injections to salivary glands

Saliva production is controlled by the parasympathetic nervous system (Figure 4). Salivary gland injection of botulinum toxin (BONT) causes a blockade in stimulation of salivary secretion reducing saliva production with minimal systemic side effects and is recommended in the treatment of chronic sialorrhoea [38]. The main risks are procedural (bleeding, bruising, and pain), or local or distant spread of the BONT [39]. The treatment wears off after around four months but can be repeated [40]. A flow diagram shows the suggested pathway for the use of anticholinergic medication and intra-salivary BONT in managing salivary secretion (Figure 5).

Although salivary gland BONT is considered in the management of sialorrhoea when anticholinergic medications have not been tolerated, there is increasing evidence and collective practical experience to suggest that salivary gland BONT should be considered earlier in the pathway [41]. While there is limited evidence for the use of BONT specifically following ABI, available literature suggests effectiveness [42].

Injections are performed anatomically or using ultrasound guidance into both the parotid and submandibular glands (Figure 6) [43]. Ultrasound guided procedures may offer benefits to both clinical effectiveness and safety.

The risk of dysphagia (as an adverse treatment outcome) may be less of an issue where people are exclusively gastrostomy fed. If worsening dysphagia occurs in this scenario, it will be un-impactful and short lived. Dry mouth symptoms (if they occur) can usually be managed by reducing other anticholinergics, diligent oral care, and a dose-reduction on repeat BONT treatments.

4.3 Mucolytics and expectorants

Airway clearance techniques for respiratory secretions can be enhanced by the use of inhaled or systemic medications such as mucolytics and expectorants. Research on the action and effectiveness of these medications is mainly in chronic respiratory conditions (cystic fibrosis, non-CF bronchiectasis, COPD) with no evidence for their use within the setting of ABI. Decisions around which to use will be based on patient presentation and may involve a combination of these medications or by progressing through them in a hierarchical manner. The modes of action, routes of delivery and doses of medications used in the management of respiratory mucus are shown (Table 3).

Once initiated, the effects of medications should be monitored and adjusted according to response. Clinically, in practice, it may be noted that too frequent use, or too high a concentration of mucolytics, may result in more profuse watery secretions that become difficult to clear effectively. These secretions can pool in the upper airways when cough and swallow are less effective and need to be distinguished from saliva.

4.4 Antibiotics

Inefficient chest clearance and aspiration from ineffective swallow engender risk of repeat chest infections and airway colonisation of bacteria. The presence of bacteria, inflammation and increased mucus load can further impact the presentation and management of airway secretions. There is no evidence base for the management of this issue, but treating bacterial colonisation with nebulised antibiotics may theoretically reduce secretion burden. This should be done in consultation with microbiology advice. There have been some studies looking at the use of nebulised antibiotic therapy to reduce bacterial load in individuals with neurological impairment which suggest this treatment may reduce infection frequency [44,45].

4.5 Longer-term options

Ongoing issues with sialorrhoea not responding to conservative or pharmacological interventions may require other approaches. These include surgical management (duct ligation or saliva gland excision) [46] and radiotherapy [47]. As such interventions are likely to be irreversible, they need to be considered within an individual’s overall treatment goals and disease trajectory. There may be a case that such interventions carry less risk than the need for prolonged anti-cholinergic treatment or repeated intra-salivary BONT injections.

5. Conclusions and clinical takeaways

• Management of secretions after ABI must be multimodal and based around the identification of the aetiology of the secretions (primarily saliva vs. lower airway mucus).
• The assessment of cough effectiveness and swallowing, oral hygiene, tracheostomy care and targeted physiotherapy/humidification are essential first steps.
• Where saliva management issues relate to dysphagia, early management must include optimisation of swallow function wherever possible.
• Secretion management for patients with tracheostomies must consider laryngeal optimisation by establishing sub-glottic airflow, ideally via cuff deflation with one-way valve placement.
• Pharmacologic options (anti-cholinergics, mucolytics and expectorants) can be considered with close monitoring of response.
• Botulinum toxin treatment may reduce the need for systemic medications and be useful earlier in the treatment pathway.

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