The lungs require the strength of many muscles to help a person to breathe and cough. As people with Duchenne grow older, the respiratory muscles, like the skeletal muscles, become weaker. Like the heart, every person with Duchenne will have pulmonary issues of some type.
The goal of pulmonary care is to allow both the prevention and management of respiratory complications. This is such an important area of care and concern that we pulled together pulmonary experts from across the US to address these important issues.
This fall, PPMD will present a three part series on the pulmonary care of patients living with Duchenne. The first webinar in the series addressed early pulmonary care on September 24th.
- Dr. Hemant Sawnani (Cincinnati Children's Hosptial Medical Center)
- Dr. Richard Shell (Nationwide Children’s Hospital)
- Dr. Oscar Henry (“Hank”) Mayer (Children’s Hospital of Philadelphia)
Recording & Summary
Preventive Pulmonary Care
Dr. Oscar Henry (“Hank”) Mayer (Children’s Hospital of Philadelphia)
Preventive Pulmonary Care
- Immunizations: make sure they are up to date
- Flu shots: be sure to get these annually
Proactive Pulmonary Care
- Protect and preserve your cough! Cough early and often!
- Support weak coughs early
- Inspiratory assistance:
- Can include “breath stacking,” possibly with the use of intermittent positive pressure breaths (inspiratory pressure applied – hold 1-2 seconds – complete exhalation at the capacity of the patient)
- ONLY useful in patients who are relatively strong
- Expiratory assistance:
- Can include chest wall compression, abdominal compression or a combination of the two
- Inspiratory and expiratory assistance:
- Breath stacking manually or with assisted cough
- Mechanical insufflator/exsufflator (Cough Assist)
- Evidence shows that receiving both inspiratory and expiratory assistance greatly enhances the ability to effectively generate forced expiratory flow
- How to use a Cough Assist
- Cycle Pi (inspiratory pressure) 15-50cm H2O
- Hold target Pi for 1-2 seconds
- Pe (expiratory pressure) 15-50cm H2O 1-2 seconds
- 5 cycles then suction
- Repeat x 5 sets total (25 breaths)
- This can be varied in both number of breaths and frequency based on a patient’s need
- Remember – how often does one cough when sick?
- As much as you to. So patients/families need to adjust the frequency of testing based on patient need.
- Ventilatory assistance (intrapulmonary percussive ventilation, IPV)
- Delivers high frequency oscillation under pressure with nebulization (to break up secretions/mucus)
- A useful addition to Cough Assist, but NOT an equivalent alternative
Emergency Care and Anesthesia
Richard Shell (Nationwide Children’s Hospital)
- Do NOT use without checking end tidal carbon dioxide (CO2) levels
- If CO2 is high, it may indicate the need for assisted cough or airway clearance rather than oxygen
- Pre-op (before surgery)
- Pulmonary, cardiac assessments
- Anesthesia consultation
- Pulmonary evaluation should include spirometery (pulmonary function test or PFT), oxygen (O2) level, CO2 levels, nutrition evaluation
- Ask about the need for cough assist, non-invasive positive pressure ventilation (NIV), and the need to assess nutrition/swallowing
- Ask about risk for pulmonary complications with anesthesia
- FVC (forced vital capacity
- FVC <50% normal increased risk
- FVC<30% high risk
- PCF (peak cough flow)
- <270 L/min increased risk
- <160 L/min high risk
- MEP (mean expiratory pressure)
- Op (during surgery)
- Type of anesthesia to be used
- May be increased risk with inhaled anesthesias; use IV if possible
- Do NOT use succinylcholine
- Discuss ventilation during surgery
- Post-op (after surgery)
- If BiPAP was used before, stay on after
- If BiPAP was not used before, stay on until fully awake
- Airway clearance
- Appropriate monitoring of O2 if needed
- Optimize pain control
- Dental anesthesia
- Less is best
- Nitrous oxide, local anesthesia are safe
- Nitrous oxide with oxygen wash-out is safe
Hypoventilation and Sleep Disordered Breathing
Dr. Hemant Sawnani (Cincinnati Children's Hosptial Medical Center)
- Pulmonary function decreases slowly
- Progression begins with muscle weakness – need for nocturnal (night time) ventilation - need for daytime ventilation
- Respiratory weakness leads to atelectasis (lung collapse) and neuromuscular spinal changes (kyphosis or scoliosis); these lead to changes in lung compliance, chest wall compliance and ventilatory drive – this can be a vicious cycle
- Predictors of hypoventilation
- End tidal CO2 >45
- Ventilatory capacity <680 ml
- Sleep disordered breathing
- Important to know prevalence and relationship to pulmonary function
- Young patients: most common finding is obstructive sleep apnea, generally occurring with increased weight
- Forced vital capacity (FVC) : decreases as muscle strength decreases and as age increases; decreased FVC increases the risk of hypoventilation; sleep architecture is well preserved despite REM sleep related sleep disordered breathing
- Recumbent muscle strength: more difficult to breath lying down; recumbent muscle strength is very important
- There is a 5-20% decrease in lung volume when lying down; muscle weakness decreases this even further
- Cycle of tachypnea (shortness of breath) and fatigue – lead to muscle weakness – lead to rotational deficiencies – lead to diaphragm dysfunction – lead to impaired cough – lead again to tachypnea and fatigue. The cycle is ongoing.
- Very important to optimize cough and to mobilize secretions – it is very important to stay hydrated (hydration thins secretions)
- Chest x-rays demonstrate a change in rib angles over time and has been an indicator of the need for sleep studies and nocturnal assisted ventilation
- Future pulmonary directions:
- Understand the “new natural history” of Duchenne
- Need to better understand cardio-pulmonary interactions
- We need sensitive indicators for sleep disordered breathing in Duchenne
1) Might intrapulmonary percussive ventilation (IPV) be a substitute for BiPAP if a child (autistic) cannot tolerate BiPAP?
- No, IPV and BiPAP are 2 separate things. IPV might be a substitute for a cough assist, as it provides both expiratory and inspiratory assistance, as well as nebulization. This effort will help to thin secretions and to cough them out. The BiPAP, rather than assist with cough, assists with continuous ventilation.
2) What is the difference between BiPAP and CPAP, and why would CPAP be preferable in an emergent situation?
- CPAP stands for “continuous positive airway pressure.” This means that the machine delivers a constant inspiratory and expiratory pressure. This constant pressure keeps the airway open, and is a perfect tool for a person suffering from obstructive sleep apnea. For patients with Duchenne, and weakened pulmonary muscles, the expiratory pressure needs to be lower than the inspiratory pressure. For patients with Duchenne, who have weakened respiratory muscles, and who have sleep hypoventilation (not obstructive sleep apnea), BiPAP (or bilevel positive airway pressure) is preferable. With BiPAP, the inspiratory pressure can be set higher than the expiratory pressure. If a patient presents to the emergency room in respiratory distress, respiratory assistance should be provided by BiPAP.
3) We can tell from DuchenneConnect that only 37% of ambulatory patients age 6 and older have had pulmonary function tests. Why are pulmonary function tests important?
- According to the CDC Care Considerations, pulmonary function tests should be performed annually from age 6yo. These are very important tests that demonstrate the breathing capacity of the lungs, both inspiratory and expiratory, and generally include an evaluation of cough (cough peak flow). Evaluating these tests over time, and managing challenges as early as possible, will benefit the patient. Without these tests, it is difficult to know when assistive devices (cough assist, BiPAP, non-invasive ventilation, etc.) might be necessary. Pulmonary dysfunction progresses very slowly and often without symptoms. Regularly evaluating the lung function of patients is critical to their overall health and management.
Save the Date for Upcoming Webinars in This Series