1. Copyright © 2006 by Mosby, Inc. Slide 1 Chapter 30 Myasthenia Gravis Figure 30-1. Myasthenia gravis. Inset, Atelectasis, a common secondary anatomic alteration of the lungs.

2. Copyright © 2006 by Mosby, Inc. Slide 2 In Severe Cases, Diaphragmatic Paralysis and Ventilatory Failure May Develop

3. Copyright © 2006 by Mosby, Inc. Slide 3 Anatomic Alterations of the Lungs (Associated with Ventilatory Failure Not Properly Managed)  Mucus accumulation  Airway obstruction  Alveolar consolidation  Atelectasis

4. Copyright © 2006 by Mosby, Inc. Slide 4 Etiology  It is believed that antibodies disrupt the chemical transmission of the ACh at the neuromuscular junction  It is believed that the antibodies disrupt the chemical transmission of ACh by:  Blocking the ACh from the receptor sites of the muscular cell  Accelerating the breakdown of ACh  Destroying the receptor sites

5. Copyright © 2006 by Mosby, Inc. Slide 5 Etiology  Myasthenia gravis affects between 20,000 and 70,000 people in the United States annually  Most common in:  Young women (15 to 35 years of age)  Older men (40 to 70 years of age)  Clinical manifestations are often provoked by: Emotional upset Emotional upset Physical stress Physical stress Exposure to extreme temperature changes Exposure to extreme temperature changes Febrile illness Febrile illness Pregnancy Pregnancy

6. Copyright © 2006 by Mosby, Inc. Slide 6 Screening and Diagnosis 1.The clinical history 2.Neurologic examination 3.Electromyography 4.Blood analysis 5.Edrophonium test 6.Computed tomography or magnetic resonance imaging

7. Copyright © 2006 by Mosby, Inc. Slide 7 Common Noncardiopulmonary Manifestations (Weakness of Striated Muscles) (Weakness of Striated Muscles)  Eye muscles  Drooping of the upper eyelids  Extraocular muscles  Double vision  Muscles of the lower portion of the face  Speech impairment  Chewing and swallowing muscles  Muscles of the arms and legs

8. Copyright © 2006 by Mosby, Inc. Slide 8 Overview of the Cardiopulmonary Clinical Manifestations Associated with MYASTHENIA GRAVIS The following clinical manifestations result from the pathophysiologic mechanisms caused (or activated) by Atelectasis (see Figure 9-7), Alveolar Consolidation (see Figure 9-8), and Excessive Bronchial Secretions (see Figure 9-11)—the major anatomic alterations of the lungs associated with myasthenia gravis (when ventilatory failure is not properly managed) (see Figure 30-1)

9. Copyright © 2006 by Mosby, Inc. Slide 9 Figure 9-7. Atelectasis clinical scenario.

10. Copyright © 2006 by Mosby, Inc. Slide 10 Figure 9-8. Alveolar consolidation clinical scenario.

11. Copyright © 2006 by Mosby, Inc. Slide 11 Figure 9-11. Excessive bronchial secretions clinical scenario.

12. Copyright © 2006 by Mosby, Inc. Slide 12 Clinical Data Obtained at the Patient’s Bedside Clinical Data Obtained at the Patient’s Bedside  Cyanosis  Chest assessment findings  Diminished breath sounds  Crackles and rhonchi

13. Copyright © 2006 by Mosby, Inc. Slide 13 Clinical Data Obtained from Laboratory Tests and Special Procedures

14. Copyright © 2006 by Mosby, Inc. Slide 14 Pulmonary Function Study: Expiratory Maneuver Findings FVC FEV T FEF 25%-75% FEF 200-1200     PEFR MVV FEF 50% FEV 1%     FVC FEV T FEF 25%-75% FEF 200-1200     PEFR MVV FEF 50% FEV 1%    

15. Copyright © 2006 by Mosby, Inc. Slide 15 Pulmonary Function Study: Lung Volume and Capacity Findings V T RV FRC TLC   VC IC ERV RV/TLC%    N V T RV FRC TLC   VC IC ERV RV/TLC%    N

16. Copyright © 2006 by Mosby, Inc. Slide 16 Arterial Blood Gases Acute Ventilatory Failure with Hypoxemia pH PaCO 2 HCO 3 - PaO 2    (Slightly)  pH PaCO 2 HCO 3 - PaO 2    (Slightly) 

17. Copyright © 2006 by Mosby, Inc. Slide 17 Oxygenation Indices Q S /Q T D O 2 V O 2 C(a-v) O 2   Normal Normal O 2 ER Sv O 2   Q S /Q T D O 2 V O 2 C(a-v) O 2   Normal Normal O 2 ER Sv O 2  

18. Copyright © 2006 by Mosby, Inc. Slide 18 Radiologic Findings Chest radiograph  Normal  Increased density  When atelectasis or consolidation is present

19. Copyright © 2006 by Mosby, Inc. Slide 19 General Management of Myasthenia Gravis  Frequent measurements of the patient’s:  Vital capacity  Blood pressure  Oxygen saturation  Blood gases

20. Copyright © 2006 by Mosby, Inc. Slide 20 General Management of Myasthenia Gravis  Mechanical ventilation should be initiated when the clinical data demonstrate:  Impending ventilatory failure  Acute ventilatory failure  Bronchopulmonary hygiene and hyperinflation therapy protocol should be instituted to prevent mucus accumulation, airway obstruction, alveolar consolidation, and atelectasis

21. Copyright © 2006 by Mosby, Inc. Slide 21 General Management of Myasthenia Gravis  Cholinesterase inhibitors  Immunosuppressants  Adrenocorticotropic hormone therapy  Thymectomy  Plasmapheresis

22. Copyright © 2006 by Mosby, Inc. Slide 22 General Management of Myasthenia Gravis Respiratory care treatment protocols  Oxygen therapy protocol  Bronchopulmonary hygiene therapy protocol  Hyperinflation therapy protocol  Mechanical ventilation protocol

23. Copyright © 2006 by Mosby, Inc. Slide 23 Classroom Discussion Case Study: Myasthenia Gravis