Diaphragm disorder Dr Kantam Chakraborthy disorders.pptx

Diaphragmatic disorder

1. CONGENITAL AND ACQUIRED DISORDERS OF DIAPHRAGM DR KANTAM D CHAKRABORTY

2. BACKGROUND The diaphragm is the dome-shaped muscle that separates the thoracic and abdominal cavities; it is the major muscle of respiration. Dysfunction of the diaphragm may be an asymptomatic incidental finding, or it may be associated with dyspnea, decreased exercise tolerance, sleep disturbances, respiratory failure, and death. Diaphragmatic dysfunction may result from disease processes in the central nervous system, the phrenic nerves, the neuromuscular junction, or anatomically.

3. BACKGROUND Dysfunction may range in severity from a partial loss of muscle contraction to complete paralysis, and it may involve one or both hemidiaphragms. The workup for suspected diaphragm dysfunction includes chest radiography, pulmonary function testing, fluoroscopy, phrenic nerve conduction studies (NCS), needle electromyogram (EMG) of the diaphragm, and transdiaphragmatic pressure measurements.

4. ETIOLOGY Anatomic defects Congenital defects: Bochdalek hernia, Morgagni hernia, eventration of the diaphragm, and diaphragmatic agenesis Acquired defects: Blunt traumatic rupture, penetrating injuries, and iatrogenic injury during surgery or other invasive procedures Neurologic defects Brainstem stroke Spinal cord disorders: Trauma to the cervical spinal cord, syringomyelia, poliomyelitis, anterior horn cell disease Cervical spondylosis

5. ETIOLOGY Cervical chiropractic manipulation Trauma to the phrenic nerve from surgery, radiation, or a tumor Guillain-Barré syndrome Diabetic neuropathy Alcoholic neuropathy Viral and postviral neuropathy (polio, West Nile virus, herpes zoster, human immunodeficiency virus ) Heavy metal toxicity (lead, arsenic) Multiple sclerosis Amyotrophic lateral sclerosis Connective-tissue disease (eg, systemic lupus erythematosus [SLE], rheumatoid arthritis)

6. ETIOLOGY Myopathic causes Disuse atrophy due to mechanical ventilation Malnutrition Electrolyte disturbances (hypophosphatemia, hypokalemia, hypocalcemia) Limb-girdle dystrophy Hyperthyroidism or hypothyroidism Acid maltase deficiency SLE Dermatomyositis Mixed connective-tissue disease Amyloidosis Myasthenia gravis Muscular disorders: Myotonic dystrophies, Duchenne muscular dystrophy, and metabolic myopathies

7. DISORDERS OF NEUROMUSCULATURE During normal respiration, the brainstem sends action potentials to the third through fifth cervical spine levels, which then give off dorsal rami that join to form the phrenic nerves bilaterally. The phrenic nerves then traverse the neck and thorax and innervate the diaphragm. Traumatic injury to the head or brainstem prevents nerve signals from reaching the phrenic nerve. Other etiologies of central nervous system damage that may affect the brainstem include multiple sclerosis, stroke, Arnold-Chiari malformations, and poliomyelitis.

8. PHRENIC NERVE DIRECT INVOLVEMENT Numerous clinical entities can affect the phrenic nerve directly, including trauma, external compression from a tumor, cardiac or thoracic surgery, chiropractic cervical spine manipulation, radiation therapy, demyelinating diseases (eg, Guillain-Barré syndrome, chronic inflammatory demyelinating polyneuropathy, Charcot-Marie-Tooth), uremia, lead neuropathy, and postinfectious neuropathies.

9. NMJ DISEASES Diseases of the neuromuscular junction can inhibit the production, release, or binding of neurotransmitters at phrenic-diaphragmatic synapses. These processes include myasthenia gravis, Lambert-Eaton syndrome, botulism, organophosphate poisoning.

10. MYOPATHIES Diseases that affect the muscle fibers of the diaphragm may result in decreased muscle strength resulting in a decreased ability to generate transdiaphragmatic pressure gradients and thereby less negative maximal inspiratory pressures. These processes include muscular dystrophies, glucocorticoid myopathy, statin myopathy, malnutrition, thyroid disorders, and disuse atrophy in mechanically ventilated patients.

11. ANATOMICAL - CONGENITAL Congenital diaphragmatic hernias occur when the muscular entities of the diaphragm do not develop normally, usually resulting in displacement of the abdominal components into the thorax. Association with maternal vitamin A deficiency.

12. CDH Congenital diaphragmatic hernias are classified by the position of the defect. Bochdalek hernias, which represent between 80% and 90% of congenital diaphragmatic hernias, are posterolateral defects of the diaphragm that result in either failure in the development of the pleuroperitoneal folds or improper or absent migration of the diaphragmatic musculature. Morgagni hernias involve the anterior portion of the diaphragm. Congenital diaphragmatic hernias involving the central portion of the diaphragm are rare.

13. ANATOMICAL - ACQUIRED The most common cause of acquired diaphragmatic disorders is trauma. Traumatic diaphragmatic rupture can occur secondary to both blunt and penetrating trauma. Up to 65% of diaphragmatic ruptures are a result of penetrating injury from stab or gunshot wounds. The remainder of traumatic diaphragmatic injury is blunt trauma sustained from motor vehicle accidents, falls, or direct impacts. Left-sided rupture is more common, occurring in 65%-75% of blunt trauma cases.

14. INCIDENCE Congenital diaphragmatic hernia (CDH) affects 1 in 3500 live-born infants. Coronary artery bypass grafting (CABG) surgery is associated with lesions of the phrenic nerves resulting in postoperative diaphragmatic paralysis, with reported incidences varying from 1% to 5%. Internal mammary artery harvesting during cardiac surgery increase the risk of phrenic nerve injury.

15. PROGNOSIS Patients with congenital diaphragmatic hernias generally present in the neonatal period, with associated postsurgical survival rates of 60%-80%. Despite improvements in surgical correction over the years, complications and comorbidities still affect 20%-40% of the treated children. These include both surgical complications (recurrence, postoperative adhesions and obstruction, stenosis, strictures, and recurrent fistulae) as well as pulmonary problems (chronic lung disease, obstructive and restrictive pulmonary dysfunction), gastrointestinal problems (dysphagia, gastroesophageal reflux, impaired intestinal motility), and failure to thrive.

16. PROGNOSIS Patients with diaphragmatic disorders due to transient neuropathies such as postviral neuropathy or Guillain-Barré syndrome as well as patients with iatrogenic phrenic nerve injury from cardiac or thyroid surgery generally have a favorable prognosis, with functional recovery in up to 69% of patients within 2 years. In the intensive care unit, ventilator-induced diaphragm dysfunction is a negative prognostic marker, with clinical impact on the weaning outcome, length of mechanical ventilation, survival, and long-term outcome. The mechanisms underlying this process include weakness of the diaphragm from defective contractility and reduced diaphragm muscle mass, as well as oxidative loads, structural damage, and muscle fiber remodeling.

17. PROGNOSIS Persons with high cervical spine fractures generally fare worse than individuals with transient neuropathies. Trauma to the cervical spine at C1-C2 results in complete diaphragmatic paralysis. Trauma to C3 and C4 may lead to substantial loss of diaphragm function. Trauma to C4 and C5 are much less likely to require ventilatory support.

18. PRESENTATION Congenital hernias Respiratory distress and/or cyanosis may occur within the first 24 hours of life. If the defect is small enough, patients often remain asymptomatic for years or even decades. Traumatic rupture The acute phase of a traumatic diaphragmatic rupture manifests with abdominal pain, concurrent intra-abdominal and intrathoracic injuries, respiratory distress, and cardiac dysfunction. Latent-phase symptoms include gastrointestinal complaints, pain in the left upper quadrant or chest, pain in the left shoulder, dyspnea, and orthopnea. The gastrointestinal obstructive phase manifests with nausea and vomiting with unrelenting abdominal pain, prostration, and respiratory distress.

19. PRESENTATION Neurologic causes Most patients with unilateral diaphragm dysfunction are asymptomatic, and they are generally found with incidental unilateral elevation of a hemidiaphragm on chest imaging. When symptoms are present, they include mild exertional dyspnea, generalized muscle fatigue, chest wall pain, and resting dyspnea while lying with the paralyzed side down or when the abdomen is submerged under water. Symptoms are generally more severe in patients with concomitant lung disease.

20. UNILATERAL PARALYSIS

21. PRESENTATION Bilateral dysfunction is more severe and manifests with shortness of breath, severe exertional dyspnea, poor sleep quality, and marked orthopnea. The orthopnea of bilateral diaphragmatic dysfunction is dramatic and occurs within minutes after assuming the recumbent position; it is caused by cephalad movement of the abdominal viscera against the weakened diaphragm. Orthopnea is associated with tachypnea and rapid, shallow breathing. Chest radiographs in patient with bilateral diaphragmatic disorder may be interpreted as “small lung volumes” or “poor inspiratory effort.”

22. BILATERAL PARALYSIS

23. PHYSICAL EXAMINATION Congenital hernia findings include the following: Right-sided heart Decreased breath sounds on the affected side Scaphoid abdomen Auscultation of bowel sounds in the thorax

24. PHYSICAL EXAMINATION Traumatic diaphragmatic rupture findings include the following: Marked respiratory distress Decreased breath sounds on the affected side Palpation of abdominal contents in the chest when inserting a chest tube Auscultation of bowel sounds in the chest Paradoxical movement of the abdomen with breathing

25. PHYSICAL EXAMINATION Neurologic findings include the following: Decreased breath sounds Generalized or focal neurologic deficits Dullness on the lower chest upon percussion on the involved side Decreased excursion of the involved hemithorax compared to the healthy side Paralysis Paradoxical abdominal wall retraction during inspiration (this is best appreciated in the supine position) Hypoxemia, secondary to atelectasis-induced ventilation-perfusion mismatch, exacerbated in the supine position Signs of cor pulmonale (occasionally present)

26. DIFFERENTIAL DIAGNOSIS Alveolar hypoventilation caused by brainstem or higher cervical spinal injury Anterior horn cell or neuromuscular junction disease to differentiate from phrenic nerve dysfunction Cerebral hemorrhage or ischemia Cervical fracture Cervical spine fractures Decreased pulmonary or abdominal compliance Guillain-Barre Syndrome Injury to phrenic nerve from trauma, neoplasm, or surgery Myasthenia Gravis Peripheral neuropathies Pleural adhesions

27. WORKUP Diagnostic evaluation may include chest radiography, supine and upright pulmonary function testing, video fluoroscopy, phrenic nerve conduction studies (NCS), needle electromyography (EMG) of the diaphragm, and transdiaphragmatic pressure measurements. Laboratory studies are limited to evaluation of underlying neuropathic causes of diaphragmatic dysfunction and include viral titers and heavy metal levels. Arterial blood gas determinations may show hypoxemia with underlying ventilation-perfusion (V/Q) mismatch and progressive hypercapnia as respiratory failure develops.

28. IMAGING STUDIES - CXR Unilateral diaphragm paralysis appears as an abnormally elevated hemidiaphragm on a chest radiograph, which can be defined as a right hemidiaphragm sitting more than 2 cm higher than its left counterpart or a left hemidiaphragm sitting at or higher than the right hemidiaphragm. Congenital defect or traumatic rupture is demonstrated roentgenographically with abdominal contents in the thorax on the affected side. Chest radiographs may exhibit a cervical or thoracic mass that encompasses the phrenic nerve. Small lung volume and atelectasis are also common features.

29. FLUOROSCOPY Fluoroscopy is generally performed with two to three resting tidal respirations, two to three deep respirations, and two to three hard, deep, and fast inhalations through the nose (sniff maneuvers) in both the anteroposterio and lateral views. Fluoroscopy is considered positive if a 2-cm or greater excursion is present and the whole leaf of the hemidiaphragm is involved during the sniff maneuver. Although fluoroscopy is positive in 90% of cases of unilateral diaphragmatic paralysis, it should not be used to diagnose bilateral diaphragm weakness. In bilateral paralysis, the sniff test result may be misleading because the cephalad movement of the ribs and accessory muscle contraction gives the false appearance of caudal displacement of the diaphragm.

30. OTHER IMAGING MODALITIES USG The main variables that can be assessed using this technique include the static measurement of diaphragm thickness and the more dynamic evaluation of inspiratory diaphragm thickening fraction and excursion. CT, MRI Computed tomography (CT) scanning is usually not very helpful in bilateral paralysis. Dynamic magnetic resonance imaging (MRI), however, has evolved with new techniques for quantitative evaluation of excursion, synchronicity, and velocity of diaphragm motion.

31. PULMONARY FUNCTION TESTS Pulmonary function tests, including maximum inspiratory pressures, transdiaphragmatic pressure measurement, and vital capacity (VC), in both the upright and supine positions to check whether diaphragmatic dysfunction is present and/or the degree of respiratory compromise experienced by the patient in different positions. In healthy individuals, a 10% decrease in VC in the supine position when compared to the upright postion is typically present. In patients with unilateral diaphragmatic paralysis, VC is typically decreased by 15%-20% in the supine position. In patients with bilateral diaphragmatic paralysis, VC decreases 30%-50% in the supine position.

32. MAXIMAL INSPIRATORY PRESSURE Easy, noninvasive test with well-established normal ranges. Limitations - effort dependent, less reproducible than lung volumes, and of minimal benefit in the assessment of unilateral diaphragmatic weakness. Normal values of MIP are generally considered above 80 cm H2O in men, and more than 70 cm H2O in women. Bilateral diaphragmatic paralysis decreases MIP by approximately 60%, and unilateral diaphragmatic weakness decreases MIP by approximately 30%.

33. TRANSDIAPHRAGMATIC PRESSURE Measurement of transdiaphragmatic pressure (Pdi) is the considered gold standard for the diagnosis of diaphragmatic dysfunction and paralysis. It is measured by placing balloon catheters in the lower esophagus and stomach, and then calculating the difference in pressures. Measurements can be made during tidal breathing, during maximum inspiratory effort (Pdi-max), and during the sniff maneuver (Pdi-sniff). Pdi may also be augmented by transcutaneous electrical or magnetic stimulation of the phrenic nerves (twitch Pdi) to eliminate variability due to patient effort.

34. PDI Pdi-sniff has been shown to have a narrower normal range and less susceptibility to variations. Normal values of Pdi-sniff are approximately more than 90 cm H2O in men and over 80 cm H2O in women, with a standard deviation of 20 cm H2O Pdi-sniff above 40 cm H2O or twitch Pdi above 15 cm H2O virtually excludes clinically significant diaphragmatic weakness. Limitations of Pdi measurements include invasiveness, patient discomfort, and requirement of specialized equipment and expertise in their use and interpretation.

35. OTHER INVESTIGATIONS Nerve Conduction Study Phrenic nerve conduction studies are used to assess the latency of conducting nervous impulses along the course of the nerve. This helps localize lesions to one side or the other as well as helps the clinician to decipher whether the condition is a bilateral phenomenon. Electromyography An electromyogram (EMG) is useful to show neuropathic or myopathic patterns, and the test can be complemented by phrenic nerve stimulation at the neck. Diaphragm EMG can detect evidence of denervation and differentiate between neuropathic and myopathic causes of paralysis.

36. MEDICAL MANAGEMENT Many patients with severe bilateral diaphragmatic dysfunction require ventilatory support. This may range from nocturnal to continuous, and from noninvasive to invasive. General indications for initiating nocturnal noninvasive ventilator support include a daytime partial pressure of carbon dioxide above 45 mm Hg, nocturnal oxygen saturations of 88% or lower for five consecutive minutes, a maximal inspiratory pressure (MIP) below 60 cm H2O or a forced vital capacity of less than 50% predicted. In the case of patients with concomitant chronic respiratory or cardiac disease, transient ventilatory support may be required in situations of cardiac or respiratory instability, such as with respiratory infections, pulmonary edema, or bronchospasm.

37. MEDICAL MANAGEMENT If the patient does not respond to nasal or oral positive-pressure ventilation, alternative forms of therapy such as negative-pressure cuirass ventilation or jacket ventilator/airtight body suit (eg, Pulmo-Wrap), rocking bed, or positive-pressure pulmo-belt can be used. Diaphragmatic pacing may be of benefit to patients with bilateral diaphragmatic weakness who have intact phrenic nerves, such as patients with high-level cervical spinal injuries or patients with central hypoventilation. This therapy is limited, and often diaphragmatic pacing does not result in sustained, independent ventilation. Progressive reconditioning is recommended when using a diaphragmatic pacer. High stimulating frequencies and a prolonged period of pacing may lead to irreversible muscle dysfunction. Patients with diaphragmatic pacing require tracheotomies, because pacer-induced breathing is not synchronized with the upper airway.

38. DIAPHRAGMATIC PACING

39. SURGICAL MANAGEMENT Manage congenital diaphragmatic defects through transabdominal primary surgical repair. Acquired diaphragmatic defects (ie, traumatic rupture, late-onset congenital diaphragmatic defect) are typically managed by thoracoscopic plication of the hemidiaphragm. Plication usually results in improved lung function and exercise endurance, and less dyspnea. Plication of the diseased diaphragm improves ventilation to the well-perfused lung and improves gas exchange, which improves static lung mechanics.

40. PLICATION VIA THORACOSCOPY

41. SURGICAL MANAGEMENT Primary repair of phrenic nerve damage from trauma can be attempted but does not generally restore function. With expectant treatment, few patients regain phrenic nerve function. Manage injury from a tumor by resection of the tumor encasing the phrenic nerve. Most patients regain function of the nerve. Cold phrenic nerve injury during cardiac surgery generally resolves with conservative management.

42. THANK YOU