الفهرس 
THE DIAPHRAGMOnly 14 pages are availabe for public view
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Abstract
Predictive indices of weaning from mechanical ventilation are often inaccurate especially in patients with sepsis. Among the many indices used in clinical practice, the rapid shallow breathing index is one of the most accurate. We evaluated a new weaning index consisting in the diaphragm thickening fraction (DTF) and diaphragm excursion (DE) assessed by ultrasound.
Sixty patients were prospectively enrolled. All patients were ventilated in pressure support. Patients underwent a spontaneous breathing trial (SBT) when they met all the following criteria: FiO2 < 0.6, PEEP ≤5 cmH2O, PaO2/FiO2 > 200, respiratory rate < 30 breath/min, RSBI <105, absence of fever, alert and cooperative, and hemodynamic stability with low dose or without vasoactive therapy support. Then SBT was continued on T-piece for 2 hours and diaphragm measurements were done after 30 minutes from start of T-piece. The patient was then instructed to perform breathing to total lung capacity (TLC) and then exhaling to residual volume (RV). Then by using curved probe 1- to 5-MHz in M-mode diaphragmatic excursion (DE) was measured on the right and left hemi-diaphragm in the posterior third. And by using linear probe 7- to 11MHz in M-mode diaphragmatic thickness (DT) was measured on the right hemi-diaphragm at zone of apposition (ZOA). Diaphragm thickness was recorded at TLC and RV, and the DTF was calculated as percentage from the following formula: Thickness at end inspiration − Thickness at end expiration / Thickness at end expiration. Weaning failure was defined as the inability to maintain spontaneous breathing for at least 48 h, without any form of ventilatory support.
DE was significantly different between patients who failed and patients who succeeded SBT. A cutoff value of Rt and Lt DE > 6.1 and 5.4 cm respectively was associated with a successful SBT with a sensitivity of 58.33 and 62.5% respectively, a specificity of 83.33%, a positive predictive value (PPV) of 93.3 and 93.7 respectively, and a negative predictive value (NPV) of 33.3 and 35.7 respectively. DTF was significantly different between patients who failed and patients who succeeded SBT. A cutoff value of a DTF >37% was associated with a successful SBT with a sensitivity of 58.33%, a specificity of 100%, a positive predictive value (PPV) of 100, and a negative predictive value (NPV) of 37.5.
In conclusion, this study shows that in our cohort of patients, the assessment of DE and DTF by diaphragm ultrasound may perform similarly to other weaning indices. If validated by other studies, this method may be used in clinical practice.