#91: Clear the Air on Airway Clearance

August 16, 2023 | By Sam Masur

Audio

Summary:

Inhale the facts and exhale the myths about Airway Clearance! Dr. Ina St. Onge (UMass Chan) walks us through both pharmacologic and non pharmacologic airway clearance regimens, the patients who would benefit the most, and when to call your friendly neighborhood pulmonologist. After listening to this episode, you’ll never choke on airway clearance again!

Airway Clearance Pearls

1. To move mucus, you must have air flow!
2. To cough,  first, you must have the muscle strength to take a big breath in. Second, you must be able to hold your breath against a closed glottis. And third, you must have the chest wall strength to expel it.
3. To understand the level of sialorrhea, ask “how many shirts or bibs are getting soaked each day?” or “how frequently are you suctioning?”
4. When using insufflation/exsufflation devices, always end on a positive pressure breath to prevent lung derecruitment
5. The best device is the one your patient will tolerate.
6. For children with neuromuscular weakness, they won’t be able to show increased work of breathing, and so an early blood gas will determine whether NIPPV may be necessary

Airway Clearance Notes

Physiologic Airway Clearance

How Our Bodies Move Mucus Out of the Lung

• Alveolar macrophages remove particles from respiratory surfaces
• Cilia move mucus up the tracheobronchial tree
• Cough expels it out

A Few Physiology Pearls

• To cough,  first, you must have the muscle strength to take a big breath in. Second, you must be able to hold your breath against a closed glottis. And third, you must have the chest wall strength to expel it. Please remember, children with neuromuscular weakness often have impaired cough.
• The lung is not a digestive organ. All aspiration leads to some degree of inflammation.
• Theme of the day: To move mucus, you must have air flow!

Which Patients Need Assistance with Clearance?

• Most patients with neuromuscular weakness will need assistance. The degree of cough impairment can be obtained in the pulmonary function lab with Cough Peak Flow Testing. However, children must be able to follow instructions and coordinate breathing to complete the testing.
• In addition, children with bronchiectasis will likely need assistance. Bronchiectasis is most commonly seen with cystic fibrosis in the pediatric population, but there are also other forms of non-CF bronchiectasis.
• However, Dr. St. Onge also points out that you can often tell how well children can clear their airway from your physical exam. If their cough sounds weak, or you can continue to hear secretions rattling, they may need assistance. 
• There is no data to support use of the below devices in children without pulmonary comorbidities.

Non-Pharmacologic Adjuncts

• Suction
• Incentive Spirometry, Bubbles, or Pinwheels
  • Goal is to get air as distally as possible
  • To use, take a deep breath in and hold, allowing the air to reach the distal alveoli
• Positive Expiratory Pressure Flutter Devices
  • Goal is to increase air flow behind mucus
  • Patients must be able to generate their own flow rates
  • Example: Aerobika, Acapella
• Mechanical Insufflation Exsufflation Devices
  • Goal is to augment (and mimic) physiologic cough
  • Device provides a positive pressure breath in, followed by a brief pause, and then negative pressure out
  • Please remember, always end on a positive pressure breath to prevent lung derecruitment
  • Example: Cough Assist Device
• Chest Physiotherapy (PT)
  • Does not provided positive pressure
  • Helpful for patients with bronchiectasis
  • Forces the mucous off the airway wall and can help to move slightly proximally, but should be combined with another device
• High Frequency Chest Wall Oscillator
  • Same physiology as Chest PT
  • Example: Vest
• Intra-Pulmonary Percussive Ventilation with Superimposed High Frequency Ventilation
  • Combines high frequency chest wall oscillation with some level of positive pressure, providing alveolar distention and shear forces for mucus
  • Example: Volera
• Non-Invasive Positive Pressure Ventilation
  • Provides positive pressure to get air behind the mucus
  • Also used for hypoventilation and hypercapnia 
  • Example: BiPAP

Remember, the best device is the one your patient will tolerate. Most of the data for the above devices comes from the bronchiectasis population, mostly cystic fibrosis but also some non-CF bronchiectasis. Our most compelling data for decreasing hospital length of stay and improving quality of life is for mechanical insufflation-exsufflation devices in neuromuscular weakness (Pediatric Pulmonology, 2020). Although there may not be much data for some of the others, there is little harm from these devices/methods.

For many of these devices, obtaining insurance approval can be challenging. Demonstrating bronchiectasis (via either chest CT or bronchoscopy) is often necessary for devices such as the high frequency chest wall oscillator.

Pharmacologic Adjuncts

• Bronchodilators
  • Beta agonists
  • Used to dilate the airway prior to giving mucolytics
  • Beta agonists also improve ciliary beat frequency (American Journal of Resp and Critical Care Medicine, 1996)
• Mucolytics
  • Hypertonic saline (3% or up to 7% with CF), normal saline (0.9%), or Dornase Alpha (CF only)
  • Often bronchospastic, so often given with bronchodilator as above
  • Hypertonic saline works by using the tonicity gradient to draw water into the airways to moisten the secretions. It is commonly used twice daily and should not be given more than every 6 hours due to lung irritation. 
  • Do not combine hypertonic saline with dornase alpha
  • Note: N-Acetylcysteine is not commonly given in pediatrics
• Anticholinergics
  • Glycopyrrolate, Scopolamine, Ipratropium
  • Used to treat sialorrhea, which can increase risk for aspiration
  • To understand the level of sialorrhea, ask “how many shirts or bibs are getting soaked each day?” or “how frequently are you suctioning?”
  • However, be mindful about the risks of overdrying, which can lead to dental caries or tracheostomy plugging

• Acid Suppression
  • Acidic refluxing material is thought to cause inflammation in the lungs, although the data isn’t strong to support this
  • Although controversial, pulmonologists will use PPIs to decrease the acidity of any aspirated material when all other treatments have been trialed
• Anti-Inflammatory
  • Inhaled corticosteroids should only be used for comorbid asthma. There is no indication to use for other types of inflammation, such as from acidic reflux
  • Azithromycin (given Mon, Wed, Fri) is supported in the CF population for anti-inflammatory purposes.

How to Prescribe an Airway Clearance Regimen

This example uses our case from Kashlak Children’s Hospital, a 4 year old ex 32-week male with a history of IVH and resulting cerebral palsy, global developmental delay, G tube dependence due to aspiration, and hypotonia, who presents with cough, congestion, and respiratory distress in the setting of an adenovirus infection.

Inpatient (Acute Illness)

• Trial oscillatory device followed by mechanical insufflation-exsufflation device (as frequently as every 1-2 hours if resources available)
• Dr. St. Onge would recommend saline nebulizer twice daily (with albuterol pre-medication if necessary) if the secretions are hard to move, or ipratropium if they are copious.
• Generally, the recommendation is to use the nebs before the device when using them together
• Remember to be mindful of G tube feeds and overdistention of the abdomen with all the positive pressure
• For children with neuromuscular weakness, they won’t be able to show increased work of breathing, and so an early blood gas will determine whether NIPPV may be necessary

Outpatient (Daily Regimen)

• Mechanical insufflation-exsufflation device twice daily 
  • When sick, it can be increased up to every 4 hours. If needed more frequently, the patient should come into the hospital
• Don’t forget to make sure your patients have nebulizer and suction machines at home

Links

Check out Pulmonary Fellowship!

Goal

Listeners will learn the basic physiology, pharmacologic and non-pharmacologic adjuncts behind airway clearance to improve inpatient and outpatient management of various respiratory conditions.

Learning Objectives

After listening to this episode listeners will…  

1. Recall the basic physiology of airway clearance. 
2. Be familiar with pharmacologic and non-pharmacologic adjuncts for airway clearance.
3. Practice prescribing a basic airway clearance regimen. 
4. Learn about neuromuscular weakness in relation to airway clearance.

Disclosures

Dr St. Onge reports no relevant financial disclosures. The Cribsiders report no relevant financial disclosures. 

Citation

Masur S, St Onge I, Chiu C, Berk J. “#91: Clear the Air on Airway Clearance”. The Cribsiders Pediatric Podcast. https:/www.thecribsiders.com/ August 16, 2023.