Comparative evaluation of diaphragmatic excursion in ICU patients: ultrasonography assessment via the conventional M-mode versus the anatomical M-mode

Diaphragmatic function is central to respiration, and its evaluation is critical in intensive care unit (ICU) settings.Ultrasonography is a reliable bedside tool to assess diaphragmatic excursion (DE). [1,2]The conventional M-mode (MM) offers high-resolution imaging but requires precise alignment, which can be diffi cult in ICU patients. [3][4][5] Anatomical M-mode (AMM) allows flexible line adjustment, enabling accurate DE measurements despite poor acoustic windows. [6]However, comparative data between MM and AMM are limited.This retrospective study evaluated the concordance between MM and AMM for assessing right DE.A retrospective study was conducted in a medicalsurgical ICU of a tertiary care center over six months (from December 2023 to June 2024).We used existing data collected during routine clinical evaluations to perform this analysis.Adults (18 years) who were breathing spontaneously and not receiving mechanical ventilation were included.Additionally, no patients required non-invasive ventilation or high-flow nasal cannulas.The study was not related to spontaneous breathing trials.The exclusion criteria were as follows: pre-existing diaphragmatic paralysis, neuromuscular disease, poor-quality images, and irregular breathing patterns.Data on age, sex, diagnosis, mean arterial pressure (MAP), heart rate (HR), respiratory rate (RR), and peripheral oxygen saturation (SpO 2 ) were extracted.All patients had DE measured by MM and AMM.Ultrasound assessments were performed using a Philips Sparq system (Philips Healthcare, USA) equipped with a phased-array transducer.With the patient in a