Interest of thoracic ultrasound after cardiac surgery or interventional cardiology

Abstract

Thoracic ultrasound has attracted much interest in detecting pleural effusion or pulmonary consolidation after cardiac surgery. In 2016, Trovato reported, in the World Journal of Cardiology, the interest of using, in addition to echocardiography, thoracic ultrasound. In this editorial, we highlight the value of assessing diaphragm function after cardiac surgery and interventional cardiology procedures. Various factors are able to impair diaphragm function after such interventions. Diaphragm motion may be decreased by chest pain secondary to sternotomy, pleural effusion or impaired muscle function. Hemidiaphragmatic paralysis may be secondary to phrenic nerve damage complicating cardiac surgery or atrial fibrillation ablation. Diagnosis may be delayed. Indeed, respiratory troubles induced by diaphragm dysfunction are frequently attributed to pre-existing heart disease or pulmonary complications secondary to surgery. In addition, elevated hemidiaphragm secondary to diaphragm dysfunction is sometimes not observed on chest X-ray performed in supine position in the intensive care unit. Analysis of diaphragm function by ultrasound during the recovery period appears essential. Both hemidiaphragms can be studied by two complementary ultrasound methods. The mobility of each hemidiaphragms is measured by M-mode ultrasonography. In addition, recording the percentage of inspiratory thickening provides important information about the quality of muscle function. These two approaches make it possible to detect hemidiaphragm paralysis or dysfunction. Such a diagnosis is important because persistent diaphragm dysfunction after cardiac surgery has been shown to be associated with adverse respiratory outcome. Early respiratory physiotherapy is able to improve respiratory function through strengthening of the inspiratory muscles i.e. diaphragm and accessory inspiratory muscles.

Keywords: Diaphragm; Hemidiaphragm; Phrenic nerve; Physiotherapy; Thickening fraction; Ultrasonography.