Diaphragmatic paralysis other diagnostic studies

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Editor-In-Chief: C. Michael Gibson, M.S., M.D. [1]; Associate Editor(s)-in-Chief:

Overview

There are no other diagnostic studies associated with [disease name].

OR

[Diagnostic study] may be helpful in the diagnosis of [disease name]. Findings suggestive of/diagnostic of [disease name] include [finding 1], [finding 2], and [finding 3].

OR

Other diagnostic studies for [disease name] include [diagnostic study 1], which demonstrates [finding 1], [finding 2], and [finding 3], and [diagnostic study 2], which demonstrates [finding 1], [finding 2], and [finding 3].

Other Diagnostic Studies

Pulmonary function test:

• Spirometry in the supine and sitting positions may be helpful in the diagnosis of diaphragmatic paralysis. Findings suggestive of diaphragmatic paralysis include:
  • Unilateral diaphragmatic paralysis:
    • Mild decrease in vital capacity (VC): 75% of the predicted value and further decrease (10% to 20% in the supine position)
    • Functional residual capacity (FRC) and total lung capacity (TLC) are usually unchanged.
  • Bilateral diaphragmatic paralysis:
    • Decrease in vital capacity (VC): 50 % of the predicted value and further decrease (30% to 50% in the supine position )
    • Total lung capacity may be reduced
      • Residual volume (RV) may be elevated

Maximal inspiratory pressure (MIP) :

• MIP < −80 cmH2O exclude diaphragmatic paralysis
• MIP can be decreased:
  • Less than 60% of the predicted value in unilateral diaphragmatic paralysis
  • Less than 30% of the predicted value in bilateral diaphragmatic paralysis

• Maximal expiratory pressure (MEP) is normal.
• MEP/MIP >2 is supportive of thediagnosis of diaphragmatic paralysis.

The maximal inspiratory pressure (MIP) is usually decreased to values of 60 percent of predicted (normal values are more negative than -60 cm H2O). The maximal expiratory pressure (MEP) is usually normal. An MEP to MIP ratio (MEP/MIP) >2 is supportive of the diagnosis [20]. We do not routinely obtain maximum voluntary ventilation (MVV), unless needed for cardiopulmonary exercise testing. Similarly, we have not found sniff nasal pressures measured at the nose to provide additional information, although other authors use this test [21].

The measurement of inspiratory pressure at the mouth during a maximal inspiratory effort against a closed mouthpiece (maximal inspiratory pressure (MIP)) is widely used as a test of respiratory muscle function [98]. It has the advantages of being simple to perform and well tolerated. However, this measurement is effort dependent [99,100], represents the combined action of all inspiratory muscles rather than isolated diaphragmatic contraction and is associated with widely-variable predicted values [100,101,102,103,104] that limit its use as a tool to evaluate and follow diaphragmatic contractility. A MIP < −80 cmH2O is generally thought to exclude clinically-significant inspiratory muscle weakness [98], and unilateral and bilateral diaphragm paralysis can be expected to decrease MIP in the ranges of 60% [105] and <30% [90] of the predicted values, respectively. However, these values may be greatly impacted by the presence of underlying obstructive or restrictive lung disease [86].

• [Diagnostic study] may be helpful in the diagnosis of [disease name]. Findings suggestive of/diagnostic of [disease name] include:
  • [Finding 1]
  • [Finding 2]
  • [Finding 3]
• Other diagnostic studies for [disease name] include:
  • [Diagnostic study 1], which demonstrates:
    • [Finding 1]
    • [Finding 2]
    • [Finding 3]
  • [Diagnostic study 2], which demonstrates:
    • [Finding 1]
    • [Finding 2]
    • [Finding 3]