History
Bilateral diaphragmatic paralysis is characterized by profound abnormalities of pulmonary and respiratory muscle function. Patients develop severe restrictive ventilatory impairment, and the vital capacity and total lung capacity frequently are below 50% of predicted for that patient. Lung capacity is reduced further when the patient assumes the supine position. Symptoms depend on whether the paralysis is unilateral or bilateral, how rapid the paralysis occurs, and the presence of underlying pulmonary disease.
Unilateral diaphragmatic paralysis
Unilateral diaphragmatic paralysis is often discovered incidentally in patients undergoing chest radiography for some other reason. Patients usually are asymptomatic at rest but may experience dyspnea upon exertion and may have a decrease in exercise performance. [12]
If the patient has an underlying lung disease, dyspnea may occur at rest.
Some patients may develop orthopnea, which is generally less intense than patients bilateral diaphragmatic paralysis.
Bilateral diaphragmatic paralysis
Patients typically present with respiratory failure or dyspnea (should be distinguished from right-sided heart failure [fluid retention and dyspnea]) that worsens in the supine position. [1] Tachypnea and rapid, shallow breathing occur when the patient adopts the recumbent position.
Patients also report anxiety, insomnia, morning headache, excessive daytime somnolence and fatigue, and poor sleep habits. In some patients, nonspecific GI symptoms such as heartburn, regurgitation, nausea, and epigastric pain can also develop. [9]
In bilateral diaphragmatic paralysis, additional clues to diagnosis include dyspnea further exacerbated in a swimming pool or sleep that only occurs in the sitting position. The duration of symptoms prior to diagnosis can be quite long because of a lack of suspicion for the condition.
Physical Examination
Physical examination findings depend on whether the paralysis is unilateral or bilateral. Generally, a breathing pattern of paradoxical abdominal wall retraction during inspiration occurs. The physician can evaluate the patient further by palpating under the costal margin and feeling for the descending hemidiaphragms during inspiration.
Unilateral diaphragmatic paralysis
Patients reveal dullness to percussion and absent breath sounds over the lower chest on the involved side. Excursion on the involved hemithorax is decreased when compared with the healthy side.
Bilateral diaphragmatic paralysis
Chest examination reveals limitation of diaphragmatic excursions and bilateral lower chest dullness with absent breath sounds. Patients are tachypneic and use accessory respiration muscles. The diagnostic finding is a paradoxical inward movement of the abdomen with inspiration.
Complications
Diaphragmatic dysfunction following cardiac surgery
Phrenic nerve injury commonly occurs from cold cardioplegia or mechanical stretching during open-heart surgery.
Diaphragmatic dysfunction often occurs postoperatively in patients undergoing cardiac surgery. This has been attributed to pleurotomy in order to harvest internal mammary artery (IMA) grafts, which results in greater chest wall and parenchymal trauma, greater pain, and impairment of cough and deep breathing. In addition, IMA dissection may reduce blood supply to ipsilateral intercostal muscles and may cause mechanical injury to the phrenic nerve.
In the past, studies have confirmed phrenic nerve injury from cold-induced injury during myocardial protection, although in current practice most centers use warm cardioplegia.
The consequences of post–cardiac surgery diaphragm dysfunction vary from asymptomatic radiographic abnormalities to severe pulmonary dysfunction requiring prolonged mechanical ventilation and increased morbidity and mortality.
In one study, the incidence of diaphragmatic dysfunction was 11% (5 of 44 patients). But only one patient had phrenic nerve palsy.
Most patients with post–cardiac surgery diaphragmatic dysfunction improve with conservative measures such as chest physiotherapy, prevention and treatment of pneumonia, treatment of underlying chronic obstructive pulmonary disease (if present), and overall care. Rarely, diaphragmatic plication may also be required in such patients.
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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.
