Exacerbations of chronic obstructive pulmonary disease (ECOPD) are a major cause of acute hypercapnic respiratory failure. Diaphragmatic dysfunction is common, often accompanied by compensatory recruitment of parasternal intercostal (IC) and sternocleidomastoid (SCM) muscles. While diaphragm ultrasound (US) is established, evidence on extra-diaphragmatic and accessory muscle activity in this context is limited.
