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Diaphragm depth in normal subjects

Authors

  • Leili Shahgholi MD,

    1. Department of Physical Medicine and Rehabilitation, Mayo Clinic and Foundation, Rochester, Minnesota, USA
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  • Michael R. Baria MD,

    1. Department of Physical Medicine and Rehabilitation, Mayo Clinic and Foundation, Rochester, Minnesota, USA
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  • Eric J. Sorenson MD,

    1. Division of Clinical Neurophysiology, Department of Neurology, Mayo Clinic and Foundation, Rochester, Minnesota, USA
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  • Caitlin J. Harper BS,

    1. Mayo Medical School, Mayo Clinic, Rochester, Minnesota, USA
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  • James C. Watson MD,

    1. Division of Clinical Neurophysiology, Department of Neurology, Mayo Clinic and Foundation, Rochester, Minnesota, USA
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  • Jeffrey A. Strommen MD,

    1. Department of Physical Medicine and Rehabilitation, Mayo Clinic and Foundation, Rochester, Minnesota, USA
    2. Division of Clinical Neurophysiology, Department of Neurology, Mayo Clinic and Foundation, Rochester, Minnesota, USA
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  • Andrea J. Boon MBChB

    Corresponding author
    1. Department of Physical Medicine and Rehabilitation, Mayo Clinic and Foundation, Rochester, Minnesota, USA
    2. Division of Clinical Neurophysiology, Department of Neurology, Mayo Clinic and Foundation, Rochester, Minnesota, USA
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  • This publication was made possible by CTSA Grant UL1 TR000135 from the National Center for Advancing Translational Sciences (NCATS), a component of the National Institutes of Health (NIH). Its contents are solely the responsibility of the authors and do not necessarily represent the official view of NIH.

ABSTRACT

Introduction: Needle electromyography (EMG) of the diaphragm carries the potential risk of pneumothorax. Knowing the approximate depth of the diaphragm should increase the test's safety and accuracy. Methods: Distances from the skin to the diaphragm and from the outer surface of the rib to the diaphragm were measured using B mode ultrasound in 150 normal subjects. Results: When measured at the lower intercostal spaces, diaphragm depth varied between 0.78 and 4.91 cm beneath the skin surface and between 0.25 and 1.48 cm below the outer surface of the rib. Using linear regression modeling, body mass index (BMI) could be used to predict diaphragm depth from the skin to within an average of 1.15 mm. Conclusions: Diaphragm depth from the skin can vary by more than 4 cm. When image guidance is not available to enhance accuracy and safety of diaphragm EMG, it is possible to reliably predict the depth of the diaphragm based on BMI. Muscle Nerve 49: 666–668, 2014

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