 The recognition of cardiac origin of weaning failure is of vital importance. Unfortunately, the clinical signs of patients who fail weaning because of acute heart failure tachypnea, tachycardia, anxiety, etc are often difficult to distinguish from signs of respiratory failure. Reliable bedside minimally invasive monitoring tools and tests need to be developed to help the clinician in identifying these patients and help titrate cardiovascular therapies during weaning trials. Currently, the list of such tools is short and the validity of each technique in different situations is unknown 2. 