Approach Considerations
Unilateral diaphragmatic paralysis
Most patients with unilateral diaphragmatic paralysis are asymptomatic and do not require treatment. If the underlying causes are discovered, they can be treated. Even when the etiology is not known, many times paralysis resolves on its own, albeit slowly over a period of months to more than a year. In a select group of patients with unilateral diaphragmatic paralysis who have severe dyspnea upon excursion, surgical treatment has been shown to be beneficial.
Diaphragmatic plication
Stabilization from surgical plication of the paralyzed diaphragm provides good results in selected patients. Following plication, the paralyzed diaphragm does not paradoxically move cephalad into the thorax during inspiration and, therefore, improves ventilation to the affected site. Furthermore, the procedure also favors the healthy diaphragm, which now performs less work.
In a select group of patients, diaphragmatic plication decreased breathlessness, improved vital capacity by 10-20%, and improved PaO2 by 10%. In one surgical series, the mean forced tidal volume improved dramatically from 216 mL to 415 mL after plication and it was possible to discontinue mechanical ventilation within 2-12 days of plication. [21] Functional and physiologic results of diaphragm plication have been shown to endure over long-term follow-up. In another study, 41 patients underwent plication of the hemidiaphragm. Patients were followed up for at least 48 months. Mean forced vital capacity, forced expiratory volume at 1 second, functional residual capacity, and total lung capacity all improved by 17%, 21%, 20%, and 20% (P< .005), respectively, at 48 months. These mean values had remained constant when compared with the 6-month follow-up. [22]
Plication of the diaphragm can be performed using a number of techniques through a thoracotomy, video-assisted thoracoscopic surgery (VATS), or laparoscopy. The VATS approach can have similar results as the thoracotomy series, with fewer complications. [23]
A common relative contraindication to plication is morbid obesity, as surgical plication is technically more difficult in these patients. This group of patients should be evaluated for bariatric surgery and may be able to avoid plication with improvement of pulmonary function after significant weight loss. [9] Patients with certain neuromuscular disorders (ie, amyotrophic lateral sclerosis and muscular dystrophy) should be approached with caution as plication provides only modest benefit with more complications. [9]
Bilateral diaphragmatic paralysis
The treatment of bilateral diaphragmatic paralysis mainly depends on the etiology and severity of the paralysis. Invasive ventilation was historically the main treatment for patients who developed respiratory failure as a result of bilateral diaphragmatic paralysis. Later, a subset of these patients who did not have intrinsic lung pathology became candidates for noninvasive ventilation.
Currently phrenic pacing is increasingly being used in patients with central respiratory paralysis and upper cervical spinal cord injury (lesions above C3) to wean them off the ventilators. [24] These patients ideally should not have any intrinsic lung disease. Electrodes can be implanted intrathoracically via thoracotomy and, more recently, with VATS. Alternatively, electrodes can be placed intramuscularly via a laparoscopic approach. [25] In this approach, intramuscular electrodes are placed near the entrance points of the phrenic nerves using motor-point mapping techniques.
Diaphragm pacing allows patients to speak again and use their olfaction system. It reduces the occurrence of respiratory infections, provides more natural breathing, and avoids dependency on a mechanical ventilator. [24] The phrenic nerve should be tested with a phrenic nerve conduction study before planning for diaphragmatic pacing. Deconditioning and atrophy of the diaphragm prior to pacing is the main limiting factor in weaning patients off the ventilators.
Negative-pressure systems may induce obstruction of the upper airway, particularly if the upper airway dilators are weak and unable to counteract the negative pressure generated by the ventilator. Therefore, sleep studies are required for patients who are being considered for negative-pressure ventilation. [26] Consideration of positive-pressure ventilation lessens the need for screening sleep studies.
Most patients with mild-to-moderate diaphragmatic weakness maintain daytime gas exchange but worsen during sleep. Sleep studies and ventilatory-assist device treatments may identify this condition. Nighttime noninvasive ventilation could be used in this group of patients.
Patients in whom nasal or oral positive-pressure ventilation is unsuccessful may need other forms of noninvasive ventilation (eg, negative-pressure cuirass, pulmonary wrap, rocking bed, positive-pressure pneumobelt).
Tracheostomy with positive-pressure intermittent or permanent ventilation is reserved for patients who are not candidates for less invasive methods or in whom less invasive methods fail.
Nerve reconstruction techniques
In a select group of patients, nerve surgery may be used to restore function to the paralyzed hemidiaphragm. [27, 28] Neurolysis, nerve grafting, and neurotization have demonstrated promise in returning function to unilateral phrenic nerve injury that occurred as a result of anesthetic procedures and operative and nonoperative trauma to the neck. With microscopic neurolysis, fibrous tissue from the compressed portion of the phrenic nerve is removed.
Inspiratory muscle strength and endurance training
Daily inspiratory muscle strength and endurance training can lead to increased nondiaphragmatic inspiratory muscle recruitment and help those with mild symptoms from diaphragmatic paralysis. [29]
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Acute unilateral left diaphragmatic paralysis in a patient with moderately severe chronic obstructive pulmonary disease. The patient previously was asymptomatic but developed class III dyspnea following the new event.
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Fluoroscopy of elevated left hemidiaphragm in a patient with unilateral diaphragmatic paralysis. The diaphragm moves paradoxically upward during inspiration.
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Fluoroscopy of elevated left hemidiaphragm in a patient with unilateral diaphragmatic paralysis. The diaphragm does not move during expiration. For confirmation, a sniff test is required.
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Radiograph of a patient with bilateral diaphragmatic paralysis displaying low lung volumes.
