Sonographic evaluation of the diaphragm in critically ill patients. Technique and clinical

The use of ultrasonogra- phy has become increasingly popular in the everyday management of crit- ically ill patients. It has been demonstrated to be a safe and handy bedside tool that allows rapid hemo- dynamic assessment and visualization of the thoracic, abdominal and major vessels structures. More recently, M-mode ultrasonography has been used in the assessment of diaphragm kinetics. Ultrasounds provide a sim- ple, non-invasive method of quantifying diaphragmatic movement in a variety of normal and pathologi- cal conditions. Ultrasonography can assess the characteristics of dia- phragmatic movement such as amplitude, force and velocity of contraction, special patterns of motion and changes in diaphragmatic thickness during inspiration. These sonographic diaphragmatic parame- ters can provide valuable information in the assessment and follow up of patients with diaphragmatic weakness or paralysis, in terms of patient-ven- tilator interactions during controlled or assisted modalities of mechanical ventilation, and can potentially help to understand post-operative pul- monary dysfunction or weaning failure from mechanical ventilation. This article reviews the technique and the clinical applications of ultraso- nography in the evaluation of diaphragmatic function in ICU patients.