 Recently, ultrasound artifacts mimicking lung sliding have been described in absence of the visceral pleura, in a group of patients who underwent pneumonectomy. In these patients, lung sliding was clearly absent during mechanical ventilation in the operated hemithorax. During spontaneous breathing, although of lower intensity compared to the unoperated hemithorax, some artifacts mimicking lung sliding and seashore sign were found during each deep spontaneous breath. These findings have led to the hypothesis that these artifacts may be due to the contraction of the intercostal muscles. 