Chest
Volume 133, Issue 3, March 2008, Pages 737-743
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ORIGINAL RESEARCH
NONINVASIVE IMAGING
Monitoring Recovery From Diaphragm Paralysis With Ultrasound

https://doi.org/10.1378/chest.07-2200Get rights and content

Background

Diaphragmatic paralysis is an uncommon, yet underdiagnosed cause of dyspnea. Data regarding the time course and potential for recovery has come from a few small case series. The methods that have been traditionally employed to diagnose diaphragmatic weakness or paralysis are either invasive or limited in sensitivity and specificity. A new technique utilizing two-dimensional, B-mode ultrasound (US) measurements of diaphragm muscle thickening during inspiration (Δtdi%) has been validated in the diagnosis of diaphragm paralysis (DP). The purpose of this study was to assess whether serial US evaluation might be utilized to monitor the potential recovery of diaphragm function.

Methods

Twenty-one consecutive patients with clinically suspected DP were referred to the pulmonary physiology laboratory. Sixteen patients were found to have DP by US (unilateral, 10 patients; bilateral, 6 patients). Subjects were followed up for up to 60 months. On initial and subsequent visits, Δtdi% was measured by US. Additional measurements included upright and supine vital capacity (VC), maximal inspiratory pressure (Pimax), and maximal expiratory pressure.

Results

Eleven of 16 patients functionally recovered from DP. The mean (± SD) recovery time was 14.9 ± 6.1 months. No diaphragm thickening was noted in those patients who did not recover. Positive correlations were found between improvement in Δtdi% and interval changes in VC, Pimax, and end-expiratory measurements of diaphragm thickness.

Conclusions

US may be used to assess for potential functional recovery from diaphragm weakness or DP. As in previous series, recovery occurs in a substantial number of individuals, but recovery time may be prolonged.

Section snippets

Subjects

Twenty-one consecutive patients who were referred between January 1997 and February 2007 for the evaluation of unexplained dyspnea or the confirmation of the clinical diagnosis of DP were assessed for inclusion in this study. The patients were referred by pulmonary specialists from the surrounding region. The initial diagnoses of DP were made on the basis of clinical symptoms, chest radiograph findings, and/or fluoroscopy of the diaphragm dome. Subjects with a diagnosis of DP made or confirmed

Patient Characteristics

Sixteen subjects (13 men and 3 women) met the inclusion criteria for the study (mean [± SD] age, 52.6 ± 12.3 years). As shown in Table 1, UDP was diagnosed in 10 patients, and BDP was diagnosed in 6 patients. An etiology was identifiable in five patients. Three patients had brachial plexus neuritis, which is also known as neuralgic amyotrophy. Two patients were thought to have iatrogenic DP, one following aortic valve replacement surgery, the other following exploratory laparotomy. Idiopathic

Discussion

Traditionally employed techniques for the diagnosis and follow-up of diaphragmatic weakness and paralysis all have significant inherent limitations. The measurement of maximal Pdi during a maximal inspiratory effort or during phrenic nerve stimulation is generally considered the “gold standard” in establishing the diagnosis of BDP.1171819202122 However, these tests are invasive and uncomfortable as they require the placement of esophageal and gastric probes. Electrical (rather than voluntary)

ACKNOWLEDGMENT

The authors thank Bradley Shapiro, MD, and Hervé Germain for their generous technical support; Carol Garber, PhD, for her assistance with the statistical analyses; and Vadim Fayngersh, MD, and Taro Minami, MD, for assistance with figures.

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    The authors have reported to the ACCP that no significant conflicts of interest exist with any companies/organizations whose products or services may be discussed in this article.

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