Most patients with unilateral diaphragmatic paralysis are
asymptomatic and do not require treatment. If the underlying cause is
found, 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 decreases breathlessness, improves vital capacity by 10-20%,
and improves PaO
2 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.
[12] 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.
[13]
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.
[14]
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.
[4] 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.
[4]
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.
[15] 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.
[16] 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.
[15] 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.
[17] 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 can 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.
[18, 19] 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.
[20