Diaphragm Disorders (Diaphragmatic Dysfunction) 

Updated: Nov 18, 2021
Author: Garrett L Rampon, MD; Chief Editor: Zab Mosenifar, MD, FACP, FCCP 

Overview

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.[1, 2, 3, 4]

Diaphragmatic dysfunction may result from disease processes in the central nervous system, the phrenic nerves, the neuromuscular junction, or anatomically. Dysfunction may range in severity from a partial loss of muscle contraction to complete paralysis, and it may involve one or both hemidiaphragms.

The diagnosis and management of unilateral and bilateral diaphragm dysfunction may be challenging for the clinician because of its relative rarity and subtle clinical manifestations, and it is likely underdiagnosed.[5] 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. Each modality has strengths and weaknesses, but all of these produce false-positive and false-negative findings.[6]

Pathophysiology

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. The successful impulse of respiratory stimulus from the brain to the diaphragm can be compromised by an interruption of the phrenic nerve at any point along this course.

Traumatic injury to the head or brainstem prevents nerve signals from reaching the phrenic nerve. Generally, injuries that affect the brain and brainstem are catastrophic, with the chance of survival being poor.[7] Other etiologies of central nervous system damage that may affect the brainstem include multiple sclerosis, stroke, Arnold-Chiari malformations, and poliomyelitis.

Injuries or disease processes that affect the phrenic nerves along their course are well described and impair the transmission of action potentials from the brainstem to the diaphragm. 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.

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.

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.[8, 9, 10]

Disorders of anatomy

Anatomic disorders of the diaphragm are typically classified into two broad categories, congenital and acquired.

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 (see the image below).[11] The underlying etiologies of these diaphragmatic hernias are not well understood, but a number of studies implicate abnormalities of the retinoid system which may result from maternal vitamin A deficiency.[12, 13, 7]

Diaphragm Disorders (Diaphragmatic dysfunction). C Diaphragm Disorders (Diaphragmatic dysfunction). Congenital diaphragmatic hernia is shown in this coronal obstetric ultrasound (the patient's head is to the right of the image; the thorax is center, and the abdomen is left). The stomach (st) and heart (hrt) are both within the thorax. Courtesy of Wikipedia (https://en.wikipedia.org/wiki/File:Cdh0002.jpg), author Dr Laughlin Dawes.

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.[14, 15, 16] Morgagni hernias involve the anterior portion of the diaphragm (see the following image). Congenital diaphragmatic hernias involving the central portion of the diaphragm are rare.

Diaphragm Disorders (Diaphragmatic dysfunction). S Diaphragm Disorders (Diaphragmatic dysfunction). Sagittal computed tomography scan of the chest with intravenous contrast demonstrates a Morgagni hernia (red arrow) containing abdominal fat. Courtesy of Wikipedia (https://en.wikipedia.org/wiki/File:Morgagni_Hernia.PNG), author Jason Robert Young, MD.

The most common cause of acquired diaphragmatic disorders is trauma.[17, 18] 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.[19, 20, 21]

Etiology

The etiology of diaphragmatic dysfunction is most easily separated into anatomic, neurologic, neuromuscular junction, and myopathic disorders.

Anatomic defects include the following:

  • 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 are include the following:

  • Brainstem stroke
  • Spinal cord disorders: Trauma to the cervical spinal cord, syringomyelia, poliomyelitis, anterior horn cell disease
  • Cervical spondylosis
  • Cervical chiropractic manipulation [22]
  • Trauma to the phrenic nerve from surgery, [23] radiation, [24] or a tumor
  • Guillain-Barré syndrome [25]
  • Diabetic neuropathy
  • Alcoholic neuropathy
  • Viral and postviral neuropathy (polio, West Nile virus, herpes zoster, human immunodeficiency virus [26] )
  • Heavy metal toxicity (lead, arsenic) [27]
  • Multiple sclerosis
  • Amyotrophic lateral sclerosis
  • Connective-tissue disease (eg, systemic lupus erythematosus [SLE], rheumatoid arthritis)

Myopathic causes of diaphragmatic paralysis are include the following:

  • Disuse atrophy due to mechanical ventilation [9]
  • Malnutrition
  • Electrolyte disturbances (hypophosphatemia, hypokalemia, hypocalcemia) [28]
  • 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

Epidemiology

The exact frequency of diaphragmatic disorders is not known and is difficult to estimate. It is likely that diaphragmatic disorders are underdiagnosed due to subtle clinical findings and varying etiologies. However, the incidence of many specific causes of diaphragmatic disorders is known.

For example, congenital diaphragmatic hernia (CDH) affects 1 in 3500 live-born infants.[29] 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%, with some reports as high as 60%. Internal mammary artery harvesting and the use of frozen slurry during cardiac surgery increase the risk of phrenic nerve injury.[5, 30, 31] Up to 25% of patients with Guillain-Barre disease will develop diaphragmatic weakness requiring mechanical ventilation.[25]

Prognosis

The prognostic and clinical evolution of diaphragm dysfunction are variable and related to the underlying etiology and the extent of the dysfunction.

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.[29]

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.[32, 30, 33]

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.[34, 35] 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.[34, 36]

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 whereas trauma to C4 and C5 are much less likely to require ventilatory support.[7] In the context of degenerative myopathies or neurologic diseases, respiratory muscle weakness frequently progresses relentlessly with the underlying disease and may progress to fulminate respiratory failure. Patients with amyotrophic lateral sclerosis have universally fatal outcomes, but respiratory muscle strength has been demonstrated to be a predictive marker for prognosis.[37]

 

Presentation

History

Background information is of prime importance when considering dysfunction of the diaphragm. An adequate history is essential to help identify potential causes. Even so, an etiology for diaphragmatic dysfunction is not ascertained in 50%-60% of patients. Note the conditions discussed below.

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.

The development of a ventral hernia is a relatively common complication of abdominal surgery. If large enough, a ventral abdominal hernia may lead to diaphragm dysfunction accompanied by complaints of dyspnea and platypnea. Because diaphragm dysfunction is more commonly associated with orthopnea and not platypnea, these symptoms can be misattributed to deconditioning or atelectasis.[38]

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.[5] 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.

Bilateral dysfunction is more severe and manifests with shortness of breath, severe exertional dyspnea, poor sleep quality, and marked orthopnea.[39] 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.”

Physical Examination

Physical findings upon examination in patients with diaphragm disorders vary depending on the etiology.

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

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

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)
 

DDx

Differential Diagnoses

  • 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

 

Workup

Approach Considerations

Diaphragm dysfunction can be difficult to diagnose, particularly when paralysis is bilateral. Workup may be triggered by unexplained dyspnea or by discovery of unilateral hemidiaphragmatic elevation on imaging. 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. Each modality has its strengths and weaknesses, and all produce false-positive and false-negative findings.[6]

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.

Imaging Studies

Chest radiography

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. However, it should not be taken as a decisive indication of diaphragmatic paralysis. Although chest radiography has high sensitivity (90%), there can be false-positive findings (positive predictive value of 33%), and there is relatively poor specificity (44%) for the diagnosis of diaphragm dysfunction.[5, 40]

Congenital defect or traumatic rupture is demonstrated roentgenographically with abdominal contents in the thorax on the affected side. A nasogastric tube that radiographically appears to be in the thorax may be misinterpreted as a massive hemothorax. Thus, it is always important to palpate the lung parenchyma and/or abdominal viscus within the thorax before inserting a chest tube into a patient with trauma.[41] ​

Chest radiographs may exhibit a cervical or thoracic mass that encompasses the phrenic nerve. Small lung volume and atelectasis are also common features. Often, a chest plain film may be interpreted as “poor inspiratory effort.”

Note the image below.

Diaphragm Disorders (Diaphragmatic dysfunction). R Diaphragm Disorders (Diaphragmatic dysfunction). Radiograph of a man who fell 45 ft from scaffolding, through plate glass windows, and onto the ground. Intraoperatively, he had a completely avulsed diaphragm on the left side. The patient subsequently recovered after a 45-day hospital course of treatment.

Fluoroscopy

Fluoroscopy is well validated for evaluation of unilateral diaphragmatic dysfunction. 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. It should be noted, however, that up to 6% of the healthy population has paradoxical movement of a hemidiaphragm on a deep inspiration or during a sniff maneuver.[40]

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.[41, 42]

Ultrasonography

Ultrasound evaluation of the diaphragm is noninvasive and readily available at the bedside.[43, 44] 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.[45, 43, 44] In patients with serial ultrasound measurements after diaphragm paralysis, an increase in thickness of the diaphragm during inspiration, which probably correlates with reinnervation, has been associated with improvement in inspiratory function and increases in vital capacity over time.[6]

In a prospective study, 66 patients with dyspnea were evaluated with B-mode ultrasonography for possible diaphragm dysfunction due to neuromuscular respiratory failure. Results were compared to the diagnosis of diaphragm dysfunction using other diagnostic tests, including chest radiography, fluoroscopy, phrenic nerve conduction studies, diaphragm electromyography, and/or pulmonary function tests. Compared to 82 abnormal hemidiaphragms, 76 had abnormal sonographic findings (size < 2mm or decreased thickening with inspiration); compared to 49 normal hemidiaphragms, there were no false-positive ultrasound findings. Diaphragmatic ultrasound was 93% sensitive and 100% specific for the diagnosis of neuromuscular diaphragmatic dysfunction.[46]

CT scanning and 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.[6]

MRI of the neck may be useful to determine if the presence of pathologic conditions involving the spinal column and nerve roots are causing diaphragmatic paralysis.

Other Tests

Pulmonary function tests

Pulmonary function tests, including maximum inspiratory pressures, transdiaphragmatic pressure measurement, and vital capacity (VC), in both the upright and supine positions help the clinician determine 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. A decrease of less than 10% in the supine position when compared to upright effectively excludes clinically significant diaphragmatic weakness.[47, 48]

Maximal inspiratory pressure (MIP) is also a useful test, although like VC, it is more useful in the assessment of bilateral diaphragmatic weakness. The benefits of MIP are that it is an easy, noninvasive test with well-established normal ranges. Limitations of assessing MIP include the fact that it is 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. However, it is recognized that the normal range is wide and varies with age, sex, and body habitus.[37] For this reason, some pulmonary function testing laboratories will use a calculated lower limit of normal that calculates a more narrow range based on specific patient demographics.[49] Bilateral diaphragmatic paralysis decreases MIP by approximately 60%, and unilateral diaphragmatic weakness decreases MIP by approximately 30%. Normal MIPs can generally exclude clinically significant diaphragmatic weakness.[50]

Transdiaphragmatic pressure measurements

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.

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, in which a Pdi-sniff above 40 cm H2O or twitch Pdi above 15 cm H2O virtually excludes clinically significant diaphragmatic weakness.[5, 51, 49] Limitations of Pdi measurements include invasiveness, patient discomfort, and requirement of specialized equipment and expertise in their use and interpretation.

Nerve conduction and electromyography

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. This test is not generally available and may require referral to a center that is able to provide this service.

An electromyogram (EMG) is useful to show neuropathic or myopathic patterns, and the test can be complemented by phrenic nerve stimulation at the neck.[52]

Diaphragm EMG can detect evidence of denervation and differentiate between neuropathic and myopathic causes of paralysis with high sensitivity and specificity, and it can be performed in patients on full ventilator support. However, it is uncomfortable, can be technically challenging to perform and interpret, and carries the risk of pneumothorax.[6]

Sleep studies

Sleep-disordered breathing (SDB) is common in patients with diaphragmatic dysfunction. Results of lung function tests and daytime symptoms have been reported to be poor predictors of the presence of SDB in this population, and polysomnography should be considered early in the evaluation of diaphragm dysfunction.[53]

 

Treatment

Approach Considerations

The treatment of patients with diaphragmatic dysfunction is dependent on the underlying etiology as well as the presence or absence of symptoms. Patients with unilateral diaphragmatic paralysis are typically asymptomatic and do not need treatment. These patients may have some dyspnea with exertion or if they have an underlying pulmonary disease. Treatment should be considered when dyspnea is out of proportion to the physical exertion. Bilateral diaphragmatic weakness is much more severe and may require treatment.

In cases involving anatomic causes and defects, the only treatment option is surgical repair. Neuromuscular processes, depending on the etiology, can generally be treated medically. If diaphragmatic disease is secondary to an underlying medical etiology, treatment of that disease often improves diaphragmatic weakness. For example, bilateral diaphragm dysfunction due to shrinking lung syndrome, connective-tissue disease, hypothyroidism, or malnutrition may improve with treatment of the primary disease.

The use of medication is limited to the etiology of neurologic involvement.

Medical Care

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.[4] 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.[5]

Patients with cor pulmonale also may manifest improvement in function and correction of blood gas abnormalities with nighttime or intermittent daytime noninvasive ventilation.[54]

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.

Patients undergoing pulmonary rehabilitation have been shown to have improved diaphragmatic contractility,[55] and it may be of benefit to patients who suffer from diaphragmatic dysfunction.[56]

Tracheotomy with positive-pressure intermittent or permanent ventilation is reserved for patients with life-threatening or irreversible disease such as amyotrophic lateral sclerosis.

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.[57] 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.[58]

Intraperitoneal diaphragm pacing has been evaluated in the use of patients with amyotrophic lateral sclerosis with poor results. A multicenter, randomized controlled trail to evaluate the safety and efficacy of the use of intraperitoneal diaphragm pacing across seven centers in the United Kingdom was terminated early following a statistically significant excessive mortality in the group receiving diaphragm pacing.[59]

Surgical Care

Surgery is indicated in the management of anatomic defects in the diaphragm. The type of surgical intervention depends on the anatomic defect or problem.

Congenital defects

Manage congenital diaphragmatic defects through transabdominal primary surgical repair.

Acquired defects

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.

In a selected group of patients, plication of the diaphragm improved vital capacity by 10%-20% as well as improved the partial pressure of arterial oxygen (PaO2) by 10%.[60]

A surgical series reported improvement in forced tidal volume from 216 mm/GHz to 415 mm/GHz postplication, and mechanical ventilatory support could be discontinued 2-12 days after plication. Plication can also be achieved by video-assisted thoracoscopy.[13]

Phrenic nerve injury

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.

Spinal cord injury or phrenic nerve injury

Diaphragmatic pacing is an investigational technology that allows the placement of electrodes within the diaphragm that stimulate the diaphragm to contract. This can be performed either transthoracically or transabdominally. The more recent studies support the use of laparoscopy and thoracoscopy.

Consultations

A multidisciplinary approach to the diagnosis and management of diaphragmatic dysfunction is best. Note the following:

  • Pulmonologists trained in diaphragmatic assessments are vital to perform and interpret diagnostic studies to ascertain the presence and severity of diaphragmatic dysfunction.
  • Thoracic surgeons should be consulted for evaluation of surgical plication or placement of diaphragmatic pacing.
  • Neurologists should be consulted when electromyography or diaphragmatic pacing is considered.
  • Surgical procedures require postprocedural monitoring in an intensive care unit.

Diet and Activity

Diet

No specific dietary modifications have been shown to benefit patients with diaphragmatic dysfunction.

For obese patients, weight reduction has been shown to improve respiratory function.[56]

Malnutrition and electrolyte disturbances related to poor nutritional status in patients in the intensive care unit have been shown to worsen ventilator-induced diaphragmatic dysfunction.[61]

Activity

In general, patients should have no activity restrictions and should have activity as tolerated. Early mobilization, particularly after invasive procedures or during a stay in the intensive care unit, is beneficial for diaphragmatic strength and recovery. Mechanical ventilation alone should not be a contraindication for mobilization. Patients undergoing pulmonary rehabilitation have been shown to have improved diaphragmatic contractility,[62]  and it may be of benefit to patients who suffer from diaphragmatic dysfunction.[55]

Long-Term Monitoring

Once an anatomic defect is corrected, the patient should undergo periodic chest radiography and assessment of pulmonary function, including upright and supine pulmonary function testing (PFTs) and maximal inspiratory pressures (MIPs). Although the rate of spontaneous recurrence of a repaired diaphragmatic hernia is low, small defects in the repair site have been reported.

Patients with progressing disease should be routinely monitored for the development of nocturnal desaturations or daytime hypercarbia.

If diaphragmatic dysfunction was secondary to a tumor encroaching on the phrenic nerve, maintaining close follow-up contact with the patient is important to ensure that the neoplasm has not recurred.