Secretion Management: Airway Clearance Techniques (ACT) 

Coughing is the main strategy utilised for secretion clearance, other than huffing or nose blowing. An effective cough has 4 main stages:

1. maximal inspiratory volume
2. glottis closure to increase intrathoracic pressure
3. fast and forceful abdominal/intercostal muscle contraction
4. rapid glottal opening to expel the inspired volume at a high flow rate

Spirometry is a very objective assessment tool for measuring cough effectiveness for airway clearance. A vital capacity (VC) >1.5L and sufficient forced expiratory effort is required to generate a peak cough flow (PCF) >160-270L/min for an effective cough.

Following a SCI, there is often respiratory muscle weakness (abdominal, intercostal and diaphragm muscles) plus compliance changes to the lung and chest wall. This results in a reduction in VC and PCF for expelling central airway debris and secretions. If significant enough, other strategies must be utilised to effect a cough and ultimately prevent retention of secretions and the risk of atelectasis, pneumonias and potentially acute respiratory failure.

If the SCI is above T6, there is also an additional autonomic dysfunction with the loss of sympathetic nervous system control and predominance of parasympathetic nervous system activity. This further impacts airway clearance and results in:

• decreased pulmonary surfactant production
• increased pulmonary secretion production
• airway bronchospasm
• cardiovascular effects including increased risk of pulmonary embolus and pulmonary oedema

While developing a secretion management plan is crucial, it is important to first:

• complete a comprehensive respiratory function assessment
• develop a ventilation management and lung volume inflation/recruitment plan
• have a multidisciplinary approach to management and intervention

SECRETION MANAGEMENT

Overall, a secretion management plan should employ a range of mostly treatments, including

• hydration: maintain adequate oral or intravenous hydration using caution not to create pulmonary fluid overload
• humidification: supply humidified room air or oxygen
• medications: administering bronchodilators such as ipratropium or salbutamol, followed by mucolytic agents or nebulised saline to reduce mucous viscosity
• NIV or invasive ventilation as indicated

Complimentary physiotherapy interventions should also be incorporated, starting with lung volume inflation/recruitment techniques and followed by airway clearance techniques. ACTs can be considered to have two main strategies:

1. peripheral ACT: sputum mobilization
2. proximal ACT: cough augmentation

All ACT strategies should be assessed and completed by a physiotherapist, or clinicians/carers who have been adequately trained by a physiotherapist.

A range of ACT strategies are often used in combination, unless contra-indicated or not tolerated by a person with SCI. Seek medical clearance to introduce into treatments.

Peripheral ACT strategies are utilized before proximal ACT to improve ventilation around airways with secretions and mobilise the sputum to move proximally. These strategies also benefit from pre-administration of medications to relax airway bronchospasm and reduce sputum tenacity.

Proximal ACT strategies are completed after this, to stimulate or augment the individual with SCI’s cough effort: clearing only upper airways around the trachea. Further lung volume inflation/recruitment techniques will need to be employed at the end of a treatment session to ensure cough-induced atelectasis is reversed.

If acutely unwell, a full treatment session can be very fatiguing for a person with SCI, so frequent treatment sessions should be planned to be efficient:

• minimise the energy demand of treatment
• cluster treatment sessions with cares so that there is deliberate rest time given

PERIPHERAL ACT: Sputum Mobilisation

• Postural Drainage Positioning
• Intermittent Positive Pressure Breathing (IPPB)
• Percussion and Vibration

Postural Drainage Positioning

This conventional physiotherapy technique uses variable body positions and the influence of gravity to improve lung segment ventilation and perfusion but also effect secretion clearance, in combination with the normal mucociliary action of the lung.

If medically permitted and tolerated by a person with SCI, changes to the supine body position with alternate side lying positions +/- trendelenburg should be introduced and adequate time allocated eg. 10-20minutes for positioning effects. Pre-treatment nebulised medications can be given at the beginning of a positioning change before introducing other ACTs.

NOTE:

1. Positioning changes can be staffing intensive and exhausting for a person with SCI if acutely unwell so must be efficacious
2. Positioning for postural drainage must not compromise skin integrity so pressure relief needs must be considered
3. Positioning in partial to full sitting (head up) may be counterproductive if a person with SCI is acutely unwell due to the impact on the work of breathing
4. Positioning in trendelenberg (head down) is contraindicated in conditions that include but are not limited to heart failure, reflux and conditions with increased/poorly controlled intracranial pressure.
5. Consider targeting (L) middle and lower lobe positioning as there is a higher incidence of (L) sided pneumonias due to the

• compression atelectasis effect from the weight and positioning of the heart and mediastinum on the lung when supine
• greater angle of the (L) bronchus deviating from the main bronchus so that other ACT tends to bias the (R) lung

The Australian and New Zealand Physiotherapy Guidelines for people with SCI provides a consensus statement with a strong FOR recommendation that:                         

Intermittent Positive Pressure Breathing (IPPB)

IPPB has been a common physiotherapy method of improving lung volume inflation/recruitment for a person with SCI, normally breathing spontaneously or medically stable and ready for ventilation weaning. They must be able to voluntarily co-operate and communicate.

All IPPB strategies should be assessed and completed by a physiotherapist, or clinicians/carers who have been adequately trained by a physiotherapist.

IPPB aims to:

• augment inspiratory tidal volumes for improved 
  • lung oxygenation +/- ventilation
    • delivering homogeneous gas distribution in the lung
    • reversing atelectasis and recruiting collapsed alveoli
  • forced vital capacity and peak expiratory flow for coughing 
• improve pulmonary and chest wall compliance
• mobilise secretions and reduce the risk of pneumonia
• reduce the work of deep breathing and the risk of respiratory fatigue

For more information refer to Lung Volume Inflation/Recruitment: IPPB

Percussions and Vibrations

These physiotherapy techniques use a chest wall clapping or shaking technique. Alternatively if available, Intrapulmonary Percussive Ventilation (IPV) devices can also be used to provide high frequency airway oscillations. Either approach seeks to produce an energy wave, externally or internally, which is transmitted within the lung to mobilise secretions from a peripheral airway to a more central airway.

Percussion and vibrations are often performed in combination with postural drainage positioning and IPPB techniques to assist mobilisation of secretions. 

NOTE:

1. The use of percussion and vibration techniques are contraindicated in conditions that include but are not limited to:

• chest wall, thorax or abdominal injuries
• pulmonary embolus
• unstable spinal fractures

The Australian and New Zealand Physiotherapy Guidelines for people with SCI provides a consensus statement with a weak FOR recommendation:                         

Positive Expiratory Pressure (PEP) Devices

These physiotherapy devices are normally used to create positive oscillating pressure in the lungs but require a forcefully sustained exhalation into a mouthpiece. The oscillating pressure generated splint the airway and assist sputum mobilisation. 

Unfortunately, forcefully sustained exhalation is difficult to achieve for a person with a SCI due to the resultant weakened or paralysed abdominal muscles. Repeated use may accelerate respiratory fatigue in acute management and is often less effective in chronic management because expiratory flow rates/lung volumes are insufficient.

The Australian and New Zealand Physiotherapy Guidelines for people with SCI provides a consensus statement with a weak AGAINST recommendation that:

PROXIMAL ACT: Cough Augmentation

Following adequate hydration, humidification, medications, ventilation and peripheral ACT which have mobilized secretions to central airways, proximal ACT involving cough augmentation should be introduced.

Proximal ACT will be determined by airway access:

• ARTIFICIAL AIRWAY
  • Reflex Coughing via Suctioning
  • +/- Cough Augmentation/Assisted Coughing

• NORMAL AIRWAY
  • Cough Augmentation/Assisted Coughing
  • Yankauer Suctioning of Mouth

Reflex Coughing

This is effectively triggered by a suction catheter passed by clinicians/carers through a medically inserted endotracheal and tracheostomy/mini tracheostomy to just above the bifurcation of the trachea in the central airway.

NOTE:

1. Need to beware of risk of prolonged suctioning causing bradycardia in a person with SCI who already has a low heart rate, increasing the risk of cardiac arrest so ensure pulse oximetry is monitored
2. Consider the simultaneous use of cough augmentation/assisted coughing techniques or devices

Cough Augmentation/Assisted Coughing

Cough augmentation/assist strategies seek to replace the effect of weakened or paralysed abdominal muscles. The following can be trialled with varying effect:  

• manual assisted cough (MAC) technique
• mechanical insufflator-exsufflator (MI-E) device
• combination of both 

Cough augmentation/assist strategies can be performed in conjunction with ventilation airway suctioning, although it is more typically employed for a person who is spontaneously breathing.

Improvements in cough effectiveness can be assessed subjectively, but also objectively using spirometry to compare values with or without cough augmentation/assist strategies to determine effectiveness:

Ventilated person with SCI: measure PEF at the endotracheal tube (need >60L/min)              

Non ventilated person with SCI: measure PCF at the mouth (need >160-270L/min)

NOTE:

1. Variations of cough augmentation can be employed with any ventilation method interface:  endotracheal, tracheostomy and mouth. 
2. Precautions/safety considerations for a person with SCI receiving cough augmentation include conditions that include but are not limited to:

• chest wall/thoracic/abdominal injuries and surgery, paralytic ileus, pregnancy
• unstable spinal fractures and osteoporosis (lateral ribcage compression)
• recent food consumption (within 1.5-2hours) +/- risk of aspiration
• inducing fatigue from prolonged respiratory treatments, including repeated coughing efforts

3. Precautions/safety considerations for clinicians/carers providing cough augmentation include:

• appropriate PPE for encountering secretions and airborne particulates
  • eye goggles/face shield, face mask and gloves
• recognition that the MAC technique:
  • requires training to be performed safely, employing optimal ergonomics although repetitive strain injuries can still result over time
  • may be staffing intensive if more than 1 clinician is required to complete repeatedly, so it may be better practice to setup and use a MI-E device if available
  • may be used in an emergency for managing choking

Manual Assisted Coughing (MAC):

Essentially, a MAC, also known as a “quad cough”, is only effective when coordinated with the voluntary cough effort of a person with SCI:  the clinician/carer’s application of a firm thrust to the upper abdomen +/- compression to the chest wall aims to rapidly force air out of the lungs for expelling central airway debris or secretions.

The Australian and New Zealand Physiotherapy Guidelines for people with SCI provides a consensus statement for a strong FOR recommendation:

The MAC technique must be a firm thrust +/- compression and for effectiveness requires CORRECT hand positioning, directional force, co-ordination and cueing.

Instructions for performing a MAC technique are here.

The MAC is best performed when a maximal inspiratory lung volume can be achieved immediately prior to the cough. Use of a LVR bag and breath stacking techniques can augment the maximal inspiratory volume and thereby augment the cough further.

Improvements in cough effectiveness can be assessed subjectively, but also objectively using spirometry to compare values +/- MAC and +/- LVR bag.

NOTE:

1. The LVR bag only has a 1-way valve: will not allow exhalation.

DISCONNECT TO EXHALE: at risk of tension pneumothorax.                                                       

DO NOT USE as an EMERGENCY RESUSCITATION DEVICE

Mechanical Assisted Coughing:

Mechanical assisted coughing or “cough assist” is delivered by a mechanical insufflation-exsufflation (MI-E) device.

The device initially delivers a set of gradually increasing positive pressure breaths (insufflation- up to 40+cmH₂0), followed by passive exhalation. After the pre-determined final positive pressure breath, the device rapidly reverses the air flow to create negative pressure for air extraction (exsufflation up to negative 40cmH₂0). This simulates a cough for expelling central airway airway debris/secretion. 

The Australian and New Zealand Physiotherapy Guidelines for people with SCI provides a consensus statement with a strong FOR recommendation:

NOTE:

1. The MI-E device can be employed with any ventilation method interface: endotracheal, tracheostomy and mouth
2. If ventilated, the tubing cuff should be inflated to reduce airway leakage and maximise the insufflation delivered to the lung periphery; insufflation pressure may need to be more than 40cm H₂0 to accommodate the narrowed artificial airway aperture for equilibrium between the insufflation pressure and alveolar pressure
3. If spontaneously breathing, a face mask is normally recommended
4. t is important to ensure the maximal tidal volume/inspiratory positive airway pressure (IPAP) is first safely determined according to comfort and tolerance; the same also applies for expiratory pressure but it also needs to be effective
5. In the community, adequate training and regular use of the MI-E device by the user with their care team is very important to maintain familiarity and care team competency

General principles for using an MI-E are here https://www.ohri.ca/nivam/documents/MI-E%20Info%20V1.2.pdf

There are also many MI-E parameters to customise for use with a person with SCI, with exact features varying between devices:

• trigger type and sensitivity, inspiratory and expiratory flow rates, hold times and maximal pressures etc. 
• staging a set of inspiratory breaths of increasing inspiratory pressure
• incorporating the addition of pressure inspiratory and/or expiratory oscillations
• capacity to deliver aerosol medication and oxygen etc.

The supply and regular use of a MI-E devices, can significantly improve quality of life and become an important prophylaxis against respiratory complications and hospital readmission.

Although trialling of MI-E devices is often difficult to facilitate, especially in the community, all funding streams will require an evidence-based funding submission. Whether completed in the hospital or in the community, a trial of the potential MI-E device over a period of weeks should be undertaken by a person with SCI:

• facilitated by a suitably experienced physiotherapist
• incorporating respiratory specialist, GP and other health professionals
• involving relevant funding body support coordinator and care agency coordinator
• seeking necessary support from the supplier

Trial assessment considerations include:      

• respiratory benefits including spirometry and pulse oximetry values 
• quality of life indices including impact on sleep, ADL, cognition and hospitalization
• user and care team compliance, including incorporation into personal care plans
• user and care team education and training completed, including resources and protocols for use, cleaning and ordering consumables
• ongoing consideration for supplier customer service for maintenance and supply of consumables
• development of updated respiratory health plan and respiratory care plan in consultation with GP/specialist, funding supports coordinator and care agency coordinator

For more information refer to Community Respiratory Planning and SCI

In combination, these may justify the funding cost is reasonable and necessary to meet a person with SCI’s disability health-related respiratory needs for an MI-E device.

Combined Manual and Mechanical Assisted Coughing:

To maximise cough effectiveness and limit the adverse impact of fatigue, combining both cough augmentation strategies may be best practice using a:

• MAC technique if tolerated
• MI-E device if available

The Australian and New Zealand Physiotherapy Guidelines for people with SCI provides a consensus statement with a strong FOR recommendation: