Chapter 29 Neuromuscular and Other Diseases of the Chest Wall Copyright © 2013, 2009, 2003, 1999, 1995, 1990, 1982, 1977, 1973, 1969 by Mosby, an imprint of Elsevier Inc.

2 Learning Objectives  List the potential respiratory complications associated with neuromuscular disease.  Identify the clinical signs and symptoms associated with respiratory muscle weakness.

Copyright © 2013, 2009, 2003, 1999, 1995, 1990, 1982, 1977, 1973, 1969 by Mosby, an imprint of Elsevier Inc. 3 Learning Objectives (cont.)  Describe techniques for monitoring the patient with respiratory muscle weakness.  Describe the general respiratory care management of patients with respiratory muscle weakness.

Learning Objectives (cont.)  Describe the clinical findings and treatment for each of the following neuromuscular disorders: Duchennes muscular dystrophy, Myotonic dystrophy, Polymyositis, Myasthenia gravis, Lambert-Eaton syndrome, Guillain-Barre syndrome, Unilateral diaphragmatic paralysis, Amyotrophic lateral sclerosis, Critical illness myopathy and polyneuropathy, Spinal cord injury, Stroke, Traumatic brain injury, Kyphoscoliosis, Flail chest Copyright © 2013, 2009, 2003, 1999, 1995, 1990, 1982, 1977, 1973, 1969 by Mosby, an imprint of Elsevier Inc. 4

5 Introduction  Pulmonary consequences of NMD may include:  Hyperventilation  Central apnea  Atelectasis leading to hypoxemia  Hypertension

Introduction (cont.) Copyright © 2013, 2009, 2003, 1999, 1995, 1990, 1982, 1977, 1973, 1969 by Mosby, an imprint of Elsevier Inc. 6

7 All of the following are consequences of Neuromuscular disorder, except: A.Atelactasis leading to hypoxemia B.Hypertension C.Central Apnea D.Stroke

Principles of Neuromuscular Weakness of Ventilatory Muscles  Pathophysiology & pulmonary function testing  Monitoring & assessing patients for respiratory insufficiency  Management of respiratory muscle weakness Copyright © 2013, 2009, 2003, 1999, 1995, 1990, 1982, 1977, 1973, 1969 by Mosby, an imprint of Elsevier Inc. 8

Pathophysiology & PFTs  NMD normal lung parenchyma reveals restrictive defect  Decreased VC, FEV 1, TLC  Normal or increased RV & diffusing capacity corrected for V A  Positional changes suggest diaphragmatic weakness  Seated to supine: >20% decline in FEV 1 & VC  Decreased PI max & Pe max  ABG: ⇓ PaO 2, ⇓ PaCO 2, but deterioration leads to ⇑ PaCO 2 Copyright © 2013, 2009, 2003, 1999, 1995, 1990, 1982, 1977, 1973, 1969 by Mosby, an imprint of Elsevier Inc. 9.

Pathophysiology & PFTs (cont.) Copyright © 2013, 2009, 2003, 1999, 1995, 1990, 1982, 1977, 1973, 1969 by Mosby, an imprint of Elsevier Inc. 10

Copyright © 2013, 2009, 2003, 1999, 1995, 1990, 1982, 1977, 1973, 1969 by Mosby, an imprint of Elsevier Inc. 11 All of the following reveal a restrictive lung defect, except: A.Increased RV B.Decreased FVC C.Decreased FEV1 D.Decreased TLC

Copyright © 2013, 2009, 2003, 1999, 1995, 1990, 1982, 1977, 1973, 1969 by Mosby, an imprint of Elsevier Inc. 12 Monitoring & Assessing Patients for Respiratory Insufficiency  Respiratory muscle weakness leads to fatigue & respiratory failure  May necessitate MV, so monitor carefully to determine when to initiate  Monitoring involves serial measurements of PI max, VC, & ABG values  May monitor maximal nasal sniff inspiratory force & nocturnal oximetry  Close monitoring of all respiratory function is important

Copyright © 2013, 2009, 2003, 1999, 1995, 1990, 1982, 1977, 1973, 1969 by Mosby, an imprint of Elsevier Inc. 13 Management of Respiratory Muscle Weakness  Weakness leads to respiratory insufficiency & retained secretions  Consider NIV or MV via tracheostomy  Augmentation of secretion clearance & assist with cough  NIV increasingly used for short-term & intermittent ventilatory support  i.e., Pneumonia or surgical event  Diaphragmatic pacing for spinal injuries FDA approved  May be useful to treat NMD as well

Specific Neuromuscular Diseases  Disorders of muscle:  Duchenne Muscular Dystrophy  Myotinic Dystrophy  Polymyositis Copyright © 2013, 2009, 2003, 1999, 1995, 1990, 1982, 1977, 1973, 1969 by Mosby, an imprint of Elsevier Inc. 14

Copyright © 2013, 2009, 2003, 1999, 1995, 1990, 1982, 1977, 1973, 1969 by Mosby, an imprint of Elsevier Inc. 15 Duchenne Muscular Dystrohpy  Genetic muscle-wasting disorder  Manifests early by waddling gait, lordosis, frequent falls  Most affected children are wheelchair dependent by age 12  Point of significant respiratory function decline  Adapt rapid shallow breathing pattern  Progression leads to PPV, initially only nocturnal  Death occurs by age 20, usually result of declining respiratory muscle strength & subsequent infection

Copyright © 2013, 2009, 2003, 1999, 1995, 1990, 1982, 1977, 1973, 1969 by Mosby, an imprint of Elsevier Inc. 16 Myotonic Dystrophy  Most common MD in adults  Respiratory dysfunction is common  Respiratory muscle weakness  OSA & CSA, very common even at early age  Bulbar muscle dysfunction  Aspiration  Tend to be sensitive to anesthesia & respiratory depressants so prolonged postoperative monitoring is required  Nocturnal NIV for oxygen & ventilation issues, while central hypoventilation requires tracheostomy & MV

Copyright © 2013, 2009, 2003, 1999, 1995, 1990, 1982, 1977, 1973, 1969 by Mosby, an imprint of Elsevier Inc. 17 Polymyositis  Inflammatory myopathy of unknown cause  Ventilatory insufficiency & failure are usual  If occurs, parallel progression of limb weakness  Corticosteroids are mainstay of initial management  10–30% develop interstitial lung disease, with diffuse infiltrates predominantly in bases

Disorders of the Neuromuscular Junction  Myasthenia gravis (MG)  Lambert-Eaton syndrome (LES) Copyright © 2013, 2009, 2003, 1999, 1995, 1990, 1982, 1977, 1973, 1969 by Mosby, an imprint of Elsevier Inc. 18

Disorders of the Neuromuscular Junction Copyright © 2013, 2009, 2003, 1999, 1995, 1990, 1982, 1977, 1973, 1969 by Mosby, an imprint of Elsevier Inc. 19

Copyright © 2013, 2009, 2003, 1999, 1995, 1990, 1982, 1977, 1973, 1969 by Mosby, an imprint of Elsevier Inc. 20 Myasthenia Gravis  Characterized by intermittent muscle weakness  Worsens with repetition  Improves with anticholinesterase medications  Caused by antibodies that inactivate ACh-R, blocking electrical impulse transmission  Neoplastic growth within the thymus gland is common  Typically occurs earlier in life in women & later in men

Copyright © 2013, 2009, 2003, 1999, 1995, 1990, 1982, 1977, 1973, 1969 by Mosby, an imprint of Elsevier Inc. 21 Myasthenia Gravis (cont.)  Characterized by progressive loss of muscle function often starting with eye muscles  Vary through day or progress, especially with repetitive use  Diagnosis is by presence of anti–ACh-R antibodies & improvement with use of edrophonium  Treatment includes  Thymectomy & anticholinesterase drugs  Plasmapheresis to remove anti–ACh-R antibodies

Copyright © 2013, 2009, 2003, 1999, 1995, 1990, 1982, 1977, 1973, 1969 by Mosby, an imprint of Elsevier Inc. 22 Myasthenia Gravis (cont.)  Pulmonary complications depend on affected muscles  Upper airway obstruction  Exertional dyspnea  Ventilatory failure  Typically display  Decreased TLC, VC, PImax, PEmax Sensitive markers of early respiratory muscle weakness  Myasthenic crisis is acute respiratory insufficiency caused by infection, surgery or excess anticholinesterase inhibitors

Myasthenia Gravis (cont.) Copyright © 2013, 2009, 2003, 1999, 1995, 1990, 1982, 1977, 1973, 1969 by Mosby, an imprint of Elsevier Inc. 23

Myasthenia Gravis (cont.) Copyright © 2013, 2009, 2003, 1999, 1995, 1990, 1982, 1977, 1973, 1969 by Mosby, an imprint of Elsevier Inc. 24

Copyright © 2013, 2009, 2003, 1999, 1995, 1990, 1982, 1977, 1973, 1969 by Mosby, an imprint of Elsevier Inc. 25 Lambert-Eaton Syndrome  More than fifty percent of cases associated with cancer, most of those with small cell carcinoma of lung  Autoantibodies interfere with release of ACh  Presence is supported by nerve conduction studies  Increasing strength with repetition differentiates LES from MG  Respiratory failure is rare

Disorders of the Nerves  Guillain-Barre Syndrome (GBS)  Phrenic Nerve & Diaphragmatic Paralysis Copyright © 2013, 2009, 2003, 1999, 1995, 1990, 1982, 1977, 1973, 1969 by Mosby, an imprint of Elsevier Inc. 26

Disorders of the Nerves (cont.) Copyright © 2013, 2009, 2003, 1999, 1995, 1990, 1982, 1977, 1973, 1969 by Mosby, an imprint of Elsevier Inc. 27

Copyright © 2013, 2009, 2003, 1999, 1995, 1990, 1982, 1977, 1973, 1969 by Mosby, an imprint of Elsevier Inc. 28 Guillain-Barre Syndrome  Most common peripheral neuropathy  Characterized by paralysis & hyporeflexia, self- limiting  Thought to be caused by antimyelin antibodies  Diagnosis: High CSF protein levels & slow impulse transmission

Copyright © 2013, 2009, 2003, 1999, 1995, 1990, 1982, 1977, 1973, 1969 by Mosby, an imprint of Elsevier Inc. 29 Patient has a sigh mechanism compromised with Atelactasis,mild hypoxemia and VC of 30 mL/kg. Which would be most appropriate? A.Chest physical therapy B.Incentive Spirometry C.Positive pressure ventilation D.Full ventilation

Phrenic Nerve Damage & Diaphragmatic Paralysis  Phrenic nerve arises from C3 to C5  Damage to one phrenic nerve affects one hemidiaphragm  Bilateral interruption in high cervical injuries results in complete diaphragmatic paralysis  Reversible unilateral paralysis can occur due to pneumonia  Typically asymptomatic, diagnosed by radiography Copyright © 2013, 2009, 2003, 1999, 1995, 1990, 1982, 1977, 1973, 1969 by Mosby, an imprint of Elsevier Inc. 30

Phrenic Nerve Damage & Diaphragmatic Paralysis Copyright © 2013, 2009, 2003, 1999, 1995, 1990, 1982, 1977, 1973, 1969 by Mosby, an imprint of Elsevier Inc. 31

Copyright © 2013, 2009, 2003, 1999, 1995, 1990, 1982, 1977, 1973, 1969 by Mosby, an imprint of Elsevier Inc. 32 Which of the following does the phrenic nerve arise from?: A.C1 to C3 B.C3 to C5 C.T1 to T3 D.T3 to T5

Disorders of the Spinal Cord  Amytrophic Lateral Sclerosis (ALS): Lou Gehrig Disease  Spinal Cord Trauma Copyright © 2013, 2009, 2003, 1999, 1995, 1990, 1982, 1977, 1973, 1969 by Mosby, an imprint of Elsevier Inc. 33

Copyright © 2013, 2009, 2003, 1999, 1995, 1990, 1982, 1977, 1973, 1969 by Mosby, an imprint of Elsevier Inc. 34 Amyotrophic Lateral Sclerosis (ALS): Lou Gehrig Disease  Characterized by progressive deterioration of upper & lower motor neurons  Male-to-female ratio for ALS is approximately 1.2:1  80% of patients have died by 5 years  Medical treatment is essentially ineffective  Riluzole: trials shown extended life 4.2 months

Amyotrophic Lateral Sclerosis (ALS): Lou Gehrig Disease (cont.)  Supportive therapy central theme in managing ALS  Key strategies: Prevent respiratory complications & assess need for MV  If PEmax <40 cm H 2 O patient has ineffective cough Treat with assisted cough, postural drainage  Consider instituting MV if: PImax 45 mm Hg, VC –40 cm H 2 O Many patients opt not to prolong life with MV Copyright © 2013, 2009, 2003, 1999, 1995, 1990, 1982, 1977, 1973, 1969 by Mosby, an imprint of Elsevier Inc. 35

Copyright © 2013, 2009, 2003, 1999, 1995, 1990, 1982, 1977, 1973, 1969 by Mosby, an imprint of Elsevier Inc. 36 All of the following would lead to initiation mechanical ventilation in ALS patients, except: A.VC >20 ml/kg B.PaCO 2 >45 mm Hg C.PImax <60 cm H 2 O D.NSIF >–40 cm H 2 O

Spinal Cord Trauma  Respiratory impact of spinal injury depends on level of injury & if complete or partial  High cervical injuries (C1-2) result in complete paralysis & death unless immediate MV is instituted  Middle-low cervical injury (C3-C8): though diaphragm is impacted at C3-C5, many can come off MV  Adapt rapid shallow breathing pattern by use of accessory muscles Copyright © 2013, 2009, 2003, 1999, 1995, 1990, 1982, 1977, 1973, 1969 by Mosby, an imprint of Elsevier Inc. 37

Disorders of the Brain  Trauma, stroke, hemorrhage, & infection can all impact respiration by:  Abnormalities in lungs themselves, such as neurogenic pulmonary edema Copyright © 2013, 2009, 2003, 1999, 1995, 1990, 1982, 1977, 1973, 1969 by Mosby, an imprint of Elsevier Inc. 38

Stroke  Interruption of blood flow to portion of brain, which results in persistent dysfunction  Could be thrombotic, embolic or hemorrhagic  Impairment related to which structures were damaged  Treatment  Early (3–4.5 hours) use of thrombolytic agents after thrombotic event improves survival & function  Physical & occupational therapy  Speech therapy if indicated Copyright © 2013, 2009, 2003, 1999, 1995, 1990, 1982, 1977, 1973, 1969 by Mosby, an imprint of Elsevier Inc. 39

Stroke (cont.) Copyright © 2013, 2009, 2003, 1999, 1995, 1990, 1982, 1977, 1973, 1969 by Mosby, an imprint of Elsevier Inc. 40

Copyright © 2013, 2009, 2003, 1999, 1995, 1990, 1982, 1977, 1973, 1969 by Mosby, an imprint of Elsevier Inc. 41 Traumatic Brain Injury  Blunt or penetrating injury resulting in brain lesions  May cause direct trauma to respiratory centers  Cause neurogenic pulmonary edema, hypersecretion of mucus, leading to respiratory failure

Disorders of the Thoracic Cage  Kyphoscoliosis  Flail chest Copyright © 2013, 2009, 2003, 1999, 1995, 1990, 1982, 1977, 1973, 1969 by Mosby, an imprint of Elsevier Inc. 42

Copyright © 2013, 2009, 2003, 1999, 1995, 1990, 1982, 1977, 1973, 1969 by Mosby, an imprint of Elsevier Inc. 43 Kyphoscoliosis  Posterior angulation of thorax (kyphosis) & lateral curature of spine (scoliosis) occur together  Kyphoscoliosis may result in hypoventilation, hypercapnia, & pulmonary HTN  Decreased compliance seen with these patients Result in ⇓ TLC & VC & restrictive disorder May have impaired diaphragmatic function  Spinal fixation may improve compliance, prevent further pulmonary dysfunction, preexisting conditions will not be reversed

Kyphoscoliosis (cont.) Copyright © 2013, 2009, 2003, 1999, 1995, 1990, 1982, 1977, 1973, 1969 by Mosby, an imprint of Elsevier Inc. 44

Kyphoscoliosis (cont.) Copyright © 2013, 2009, 2003, 1999, 1995, 1990, 1982, 1977, 1973, 1969 by Mosby, an imprint of Elsevier Inc. 45

Copyright © 2013, 2009, 2003, 1999, 1995, 1990, 1982, 1977, 1973, 1969 by Mosby, an imprint of Elsevier Inc. 46 Flail Chest  Multiple rib fractures result in portion of chest wall becoming free-floating, moving in paradoxic motion during respiratory cycle  Bows out during expiration, in during inspiration  Often accompanied by pneumothorax, pulmonary contusion, hemothorax, which require emergent care