Diaphragmatic paralysis diagnostic study of choice

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

Diagnostic Study of Choice

Study of choice:

Unilateral diaphragmatic paralysis

• Fontal upright chest radiograph:
  • Elevated hemidiaphragm in paralysed side
  • Chest xray is then confirmed with fluoroscopic sniff test

• Fluoroscopic sniff test:
  • Observation of diaphragamtic movement when patient sniffs forcefully
  • Paradoxical elevation of the paralyzed hemidiaphragm during inspiration

Bilateral diaphragmatic paralysis

• Measurement of transdiaphragmatic pressure (Pdi) is the gold standard test for the diagnosis of bilateral diaphragmatic paralysis.
  • This test is performed with two catheters. One of them is placed in esophagus and it assesses changing pleural pressure (Ppl) and another one is placed in stomach and it detects changing abdominal or gastric pressure (Pga).
  • Pdi is the difference between Ppl and Pga (Pdi = Ppl – Pga).
  • Normal transdiaphragmatic pressure:
    • Men: 148 cm water
    • Women: 122 cm water
• The following result of transdiaphragmatic pressure (Pdi) is confirmatory of bilateral diaphragmatic paralysis:
  • Unilateral diaphragmatic paralysis:
    • Maximal transdiaphragmatic pressure is more than 70 cm water and it does not effect normal ventilatory behaviors but it may compromise coughing or sneezing.
  • Bilateral diaphragmatic paralysis:
    • Maximal transdiaphragmatic pressure is less than 40 cm water and it effects normal ventilatory behaviors.
• his test is performed via the transnasal placement of two thin-walled balloon-tipped catheters (waveform 1). One is placed in the lower third of the esophagus above the diaphragm to assess changing pleural pressure (Ppl); the location is adjusted to avoid cardiac contraction signals that can modify the tracing [31]. The second balloon is placed in the stomach, to reflect changing abdominal or gastric pressure (Pga) (waveform 1). In adults, the distance between the nostril and the tip of the balloon is 35 to 40 cm for the esophageal balloon and 50 to 60 cm for the gastric balloon [31]. The Pdi is the difference between Ppl and Pga (Pdi = Ppl – Pga). The Pdi can be measured at rest, during tidal breathing (Pdi) at end inspiration or end expiration, with voluntary maneuvers such as a deep breath [32], a sniff (sniff Pdi) [33,34], or a maximal inspiratory force maneuver with airflow limited by a partially closed shutter (Pdi-max) [11,35]. At peak tidal volume inspiration, the value for Pdi is negative in diaphragm paralysis, but positive if the diaphragm is working normally (waveform 1). The normal value for Pdi depends upon the method used to obtain it. Reliability is also an issue since there is great variation even in the same individual. In an attempt to avert this problem, Pdi may be measured independent of the patient's effort. This is done by electrically stimulating the phrenic nerve and measuring the twitch Pdi [36].
• Normal transdiaphragmatic pressure is approximately 148 cm water in men and 122 cm water in women. ^{null 14} Unilateral diaphragmatic paralysis is associated with a maximal transdiaphragmatic pressure of greater than 70 cm water, and thus does not significantly effect transdiaphragmatic pressure generation during normal ventilatory behaviors, but can compromise higher-force, nonventilatory, behaviors like coughing or sneezing. Bilateral diaphragmatic paralysis, however, can impair normal ventilatory behaviors as it is associated with a maximal transdiaphragmatic pressure of less than 40 cm water. ^{[[null 15], [null 16], [null 17]]}
  • Result 1
  • Result 2
• The [name of the investigation] should be performed when:
  • The patient presented with symptoms/signs 1. 2, 3.
  • A positive [test] is detected in the patient.
• [Name of the investigation] is the gold standard test for the diagnosis of [disease name].
• The diagnostic study of choice for [disease name] is [name of the investigation].
• There is no single diagnostic study of choice for the diagnosis of [disease name].
• There is no single diagnostic study of choice for the diagnosis of [disease name], but [disease name] can be diagnosed based on [name of the investigation 1] and [name of the investigation 2].
• [Disease name] is mainly diagnosed based on clinical presentation.
• Investigations:
  • Among patients who present with clinical signs of [disease name], the [investigation name] is the most specific test for the diagnosis.
  • Among patients who present with clinical signs of [disease name], the [investigation name] is the most sensitive test for diagnosis.
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The comparison table for diagnostic studies of choice for [disease name]

	Sensitivity	Specificity
Test 1	✔	...%
Test 2	...%	✔

✔= The best test based on the feature

Diagnostic results

The following result of [investigation name] is confirmatory of [disease name]:

• Result 1
• Result 2

Sequence of Diagnostic Studies

The [name of investigation] should be performed when:

• The patient presented with symptoms/signs 1, 2, and 3 as the first step of diagnosis.
• A positive [test] is detected in the patient, to confirm the diagnosis.

Diagnostic Criteria

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• [Disease name] may be diagnosed at any time if one or more of the following criteria are met:
  • Criteria 1
  • Criteria 2
  • Criteria 3

IF there are clear, established diagnostic criteria:

• The diagnosis of [disease name] is made when at least [number] of the following [number] diagnostic criteria are met: [criterion 1], [criterion 2], [criterion 3], and [criterion 4].
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IF there are no established diagnostic criteria: 

• There are no established criteria for the diagnosis of [disease name].