Application of Lung Ultrasound for Predicting Outcome of Weaning From Mechanical Ventilation

Patients should be assessed daily for their readiness to be weaned from mechanical ventilation, sedation must be withdrawn and all patients will be put on a spontaneous breathing trial (SBT), via T-piece, for 60 -120 minutes period, when they fulfil the weaning criteria. Patients who succeed to tolerate SBT will be extubated and monitored for signs of respiratory distress.

Clinical assessment during and after SBT:

• The ability of maintaining a respiration rate of less than 35/min, and keeping oxygen saturation more than 90%.
• Arterial blood gases (ABGs) will be done 30-60 minutes after SBT and after extubation.
• To detect signs of respiratory distress: diaphoresis, tachypnea (RR> 35/min), increase activity of accessory muscles of respiration, tachycardia (heart rate > 140 beats per minute), systolic blood pressure > 180 mmHg or <90 mmHg, appearance of new arrhythmia, or alteration in mental status (drowsiness or anxiety). ABGs: PaO2 ≤ 60 mmHg or oxygen saturation < 90% on FiO2 ≥ 0.4, PaCO2 > 50 mmHg, or an increase in by ≥ 8 mmHg, pH < 7.32 or a decrease in pH by ≥ 0.07 pH units.

Clinical assessment will be done by an intensivist who will be blinded to the LUS score results.

Lung ultrasound (LUS): will be performed while patients in supine position, with a curved probe on B- mode, using longitudinal view, to assess the amount of lung aeration. Each lung will be divided into anterior, lateral and posterior regions, each part will be divided to upper and lower zone, with total of 12 zones to undergo examination. Examination will be done by an expert physician in US.