CHEST Guidelines-Ultrasound-Assessment-of-the-Diaphragm-in-Patients

Ultrasound-Assessment-of-the-Diaphragm-in-Patients

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In their correspondence published in CHEST, Drs. Sachin Kumar and Sandipan Chandra respond to Baria et al.'s study on diaphragm thickness (Tdi) and thickening ratio in COPD patients using B-mode ultrasound. They highlight concerns before these measurements become clinical practice standards.<br /><br />First, Kumar and Chandra challenge the hypothesis that COPD leads to diaphragmatic hypertrophy due to compensatory overuse. They argue that oxidative stress in COPD actually triggers proteolytic activity resulting in muscle atrophy, not hypertrophy. Despite diminished diaphragm muscle length in COPD, its pressure-generating capacity is largely preserved, but the firing rate of diaphragmatic motor units increases by about 70% compared to healthy individuals.<br /><br />Second, they critique the method of measuring Tdi at end-expiration and maximal inspiration, as Tdi relates non-linearly to lung volume and is more pronounced above 50% of vital capacity. They suggest that diaphragm function might be better interpreted through changes in diaphragm thickness during breathing or thickening fraction (TF).<br /><br />Kumar and Chandra emphasize that TF accounts for volume changes and may better differentiate between a paralyzed atrophic diaphragm and a functional one. They propose comparing diaphragm shortening and changes in thickness to distinguish between COPD patients and the general population further.<br /><br />In response, Baria et al. express gratitude for the feedback and engagement, indicating a willingness to explore these dimensions further in future research. This discourse underscores the necessity of intricate understanding and precise measurements when evaluating diaphragm function and structure in COPD through ultrasound, suggesting potential refinements in clinical diagnostic practices.

Keywords

diaphragm thickness

COPD

B-mode ultrasound

diaphragmatic hypertrophy

muscle atrophy

thickening fraction

diaphragm function

clinical practice

proteolytic activity

diagnostic practices