1. Approach to Respiratory
Complications with
Neuromuscular Disorders
Nahid Sherbini
Consultant IM &Pulmonary
KFH Medina

2. DMD
• Most prevalent childhood muscular dystrophy,
every 1 in 3000-6000 male births
• X-linked recessive ,Deficiency of the muscle
protein Dystrophin
• Shortened lifespan due to progressive muscle
weakness and complications- mean age is 19
without intervention, mid-to-late twenties with
proper care.

3. Dystrophin
• Provides mechanical reinforcement
to the sarcolemmal membrane of
muscle fibers; protects muscle fibers
from being damaged while stressed
during muscle contraction.

4. Associated Pathologies:
Weakness
• Progressive weakness of hip and
shoulder girdle musculature
• Weakness in paraspinals make
walking difficult
• Leads to:
• Waddling gait
• Lumbar lordosis
• Forward thrusting of the
abdomen
• Scapular winging
• AP scoliotic curve
• Joint contractures
• Respiratory impairment
• Weight gain

6. CLINICAL MANIFESTATIONS
1. Insufficient ventilation : dyspnea, orthopnea, rapid shallow
breathing ,hypercapnia, or hypoxemia.
2. Nocturnal hypoventilation may induce choking, insomnia,
daytime hypersomnolence, morning headaches, fatigue, or
impaired cognition.
3. Bulbar dysfunction dysarthria, dysphagia, weak
mastication, facial weakness, nasal speech, or a protruding
tongue.
4. Ineffective cough aspiration, retention of secretions, or
pneumonia.

8. EVALUATION
1. Confirm respiratory muscle weakness
2. Assess cough
3. Assess need for ventilatory support
Degree of respiratory muscle weakness cannot be predicted by
the degree of peripheral muscle weakness. *
-->tests of respiratory muscle function are essential to identify
the patient who is at risk for respiratory failure.
*Respiratory muscle weakness in peripheral neuropathies Burakgazi AZ,
Höke A J Peripher Nerv Syst. 2010 Dec;15(4):307-13

9. Confirm respiratory muscle weakness
by PFT - No single abnormality is diagnostic of respiratory muscle
weakness*; Typical abnormalities include:
1.A Restrictive pattern
2.Expiratory muscle weakness increased (RV)
3.FVC measured in the supine position is >10 % lower than in the
upright position.
4.MVV is reduced
5.DLCO is normal
*The value of multiple tests of respiratory muscle strength. Steier J, Kaul S, Seymour J, Jolley C,
Rafferty G, Man W, Luo YM, Roughton M, Polkey MI, Moxham J Thorax. 2007;62(11):975.

10. 1. Confirm respiratory muscle
weakness
•Maximal inspiratory pressure (MIP) or maximal expiratory
pressure (MEP) is reduced.
The MIP reflects the strength of the diaphragm and other
inspiratory muscles, while
the MEP reflects the strength of the abdominal muscles and
other expiratory muscles.
•IN bulbar dysfunction the sniff nasal inspiratory pressure
(SNIP)

11. 2-Assess cough
1. Peak cough flow — The peak cough flow (PCF) is measured by.
A PCF l< 160 L/min =an ineffective cough ,between 160 -- 270
L/min are at risk for respiratory tract infections, which can
further reduce muscle strength .
2. MEP — <60 cm H2O suggests
3. Expiratory cough flow tracings — The absence of transient
increases in expiratory flow above the maximal flow-volume
loop (ie, cough spikes)

12. 3-Assess need for ventilatory
support
• MIP and MEP –
1.MIP < -30 cm H2O a high risk for hypercapnia
2.MEP <40 cm H2O  inadequate cough strength and risk for
secretion retention.
3.VC < 20 mL/kg, 60%, or 1 L*. Or 30 - 50 % compared to a prior
measurement.
The repeated measurement of vital capacity is a poor predictor of the need for mechanical
ventilation in myasthenia gravis. Rieder P, Louis M, Jolliet P, Chevrolet JC Intensive Care
Med. 1995;21(8):663.

13. Assess need for ventilatory
support
• A "20-30-40 rule" has been proposed .
The rule advocates the initiation of ventilatory support when
VC < 20 mL/kg,
MIP < -30 cm H2O
or MEP < 40 cm H2O.

14. MECHANICAL VENTILATION
NPPV may benefit patients who require:
1.Continuous MV for a short duration (ie, days), such as patients
with an acute neuromuscular disease (eg, Guillain-Barré
syndrome)
2.Intermittent MV for a long duration (ie, years), such as
patients with nocturnal hypoventilation or early chronic
respiratory failure.

15. The likelihood that NPPV will be
unsuccessful or cause a complication is
increased when any of the following exist:
1.Bulbar dysfunction
2.Upper airway obstruction
3.Retention of respiratory secretions
4.Poor cooperation
5.Inadequate cough.

16. • An observational study compared 14 patients with
neuromuscular disease who received NPPV for acute
respiratory failure to 14 historical controls who received
invasive MV .
The NPPV group  lower mortality
 a shorter length of ICU stay
& decrease needing invasive MV.*
Non-invasive ventilatory approach to treatment of acute respiratory failure in
neuromuscular disorders. A comparison with endotracheal intubation. Vianello A,
Bevilacqua M, Arcaro G, Gallan F, Serra E Intensive Care Med. 2000;26(4):384.

17. Invasive MV
Should be initiated early for the following reasons:
•Intubation itself has risks that are best managed in a controlled
setting
dysautonomia increases the risk of severe hypotension and
bradycardia .
•decrease the risk of early-onset pneumonia*.
Prognosis and risk factors of early onset pneumonia in ventilated patients with Guillain-
Barrésyndrome.Orlikowski D, Sharshar T, Porcher R, Annane D, Raphael JC, Clair B Intensive Care
Med. 2006;32(12):1962.

18. PROGNOSIS
• Among intubated patients with GBS
mortality UP 20 %
median duration of MV is UP 29 days *.
• Among intubated patients with myasthenia gravis,
mortality is UP 8 %
duration of is 14 days .
• Among intubated patients admitted to ICU, diaphragmatic
dysfunction 64 % . Mortality (26 %) .
Long-term outcome in patients with Guillain-Barrésyndrome requiring mechanical ventilation.
Fletcher DD, Lawn ND, Wolter TD, Wijdicks EF Neurology. 2000;54(12):2311.

19. Predictors of successful Extubation
• (MIP) more negative
than -50 cm H2O
• Improvement VC by > 4
mL/kg from
preintubation to pre-
extubation.
Predictors of failed extubation
• dysautonomia
• Advanced age
• pulmonary
complications
(pneumonia, atelectasis)
were associated with
extubation failure
Factors predicting extubation success in patients with Guillain Barrésyndrome. Nguyen TN,
Badjatia N, Malhotra A, Gibbons FK, Qureshi MM, Greenberg SA Neurocrit Care.
2006;5(3):230.

20. COUGH ASSISTANCE
1.Mechanical insufflation-exsufflation APPLY PRESSURE
2.Manually-assisted coughing ABD TRUST
3.Hyperinflation maneuvers Inc TV by Glossopharyngeal
breathing (ie, repetitive air gulping) ,Delivery of stacked breaths
and Mechanical inspiration using a mechanical insufflator or a
volume cycled ventilator
4.Secretion mobilization techniques.
By High frequency chest-wall oscillation and Intrapulmonary
percussive ventilation.

21. TRACHEOSTOMY
1. Difficulty clearing their secretions.
2. Intermittent long-term mechanical ventilation, but in whom
NPPV is contraindicated (eg, severe bulbar dysfunction).
3. Intermittent long-term NPPV is no longer sufficient.
4. Fail to wean from invasive MV.

22. GENERAL CARE
•Correct electrolyte abnormalities
•Avoid neuromuscular blocking agents, aminoglycosides, and
glucocorticoids.
•Nutritional status should be maintained
•Prophylaxis for DVT and stress gastric ulcers should be provided
when indicated.
•The head of the bed should be elevated by 45º to decrease the
risk for ventilator-associated pneumonia .

23. GENERAL CARE
• Decisions regarding long-term support.
Progressive neuromuscular diseases of childhood, such as spinal
muscular atrophy and Duchenne muscular dystrophy present
different challenges, as parents are often the main decision
makers. [ long-term ventilatory support is more common and
often associated with good quality of life].