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Fig. 3 | Annals of Intensive Care

Fig. 3

From: Ultrasonographic assessment of parasternal intercostal muscles during mechanical ventilation

Fig. 3

A simplified diagram of respiratory muscular ultrasound during weaning trial from mechanical ventilation. Once a pressure support (PS) trial or a spontaneous breathing trial (SBT) is started and patients failed a termination of the weaning process within 24 h a diaphragm evaluation exploring the diaphragmatic thickening fraction (TFdi) should be performed. At the same time, the parasternal intercostal muscle should be evaluated. The simplest method is to evaluate the thickness and the thickening fraction (TFic) as calculated for the diaphragm (TF = ((TH end inspiration – TH end expiration)/TH end expiration)) * 100. A value of TFic less than 10%, associated with a TFdi greater than 20% indicates a pattern of breathing in which respiratory muscles are not recruited, and is then suggestive of a successful weaning trial. All these measurements should be integrated with other routinely used predictive parameters of weaning failure, such as rapid shallow breathing index (RSBI), negative inspiratory function (NIF), forced vital capacity (VFC) and the tidal change in esophageal pressure (Δpes). In any case, consider optimizing muscular load acting on pharmacological intervention, metabolic supply, and respiratory muscular in/activity

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