Echocardiography by the subcostal route.
IVC: inferior vena cava. This view visualizes the inferior vena cava from its suprarenal path to its entry in the right atrium. This film was recorded in a spontaneously breathing dyspneic patient. Note the large changes in caliber of the inferior vena cava during respiration (inspiratory collapse). The measurement of the inferior vena cava diameter must be done at the end of expiration, whether the patient is breathing spontaneously or is mechanically ventilated. This film well illustrates the difficulty of using the inferior vena cava diameter for hemodynamic purposes, as it differs considerably depending on the site of measurement. Certain authors have proposed calculating the percentage change in diameter during ventilation (spontaneous or in positive pressure) to evaluate central venous pressure or to predict the efficacy of volume expansion.
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