Copyright © 2006 by Mosby, Inc. Slide 1 Chapter 30 Myasthenia Gravis Figure Myasthenia gravis. Inset, Atelectasis, a common secondary anatomic alteration of the lungs.
Copyright © 2006 by Mosby, Inc. Slide 2 In Severe Cases, Diaphragmatic Paralysis and Ventilatory Failure May Develop
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
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
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
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
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
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)
Copyright © 2006 by Mosby, Inc. Slide 9 Figure 9-7. Atelectasis clinical scenario.
Copyright © 2006 by Mosby, Inc. Slide 10 Figure 9-8. Alveolar consolidation clinical scenario.
Copyright © 2006 by Mosby, Inc. Slide 11 Figure Excessive bronchial secretions clinical scenario.
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
Copyright © 2006 by Mosby, Inc. Slide 13 Clinical Data Obtained from Laboratory Tests and Special Procedures
Copyright © 2006 by Mosby, Inc. Slide 14 Pulmonary Function Study: Expiratory Maneuver Findings FVC FEV T FEF 25%-75% FEF PEFR MVV FEF 50% FEV 1% FVC FEV T FEF 25%-75% FEF PEFR MVV FEF 50% FEV 1%
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
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)
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
Copyright © 2006 by Mosby, Inc. Slide 18 Radiologic Findings Chest radiograph Normal Increased density When atelectasis or consolidation is present
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
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
Copyright © 2006 by Mosby, Inc. Slide 21 General Management of Myasthenia Gravis Cholinesterase inhibitors Immunosuppressants Adrenocorticotropic hormone therapy Thymectomy Plasmapheresis
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
Copyright © 2006 by Mosby, Inc. Slide 23 Classroom Discussion Case Study: Myasthenia Gravis