Ultrasound-Guided Diaphragmatic Thickness Assessment as an Indicator of Successful Extubation in Mechanically Ventilated
Condition: Successful Weaning; Weaning Failure
Study type: Observational

Summary: 
      Weaning of mechanically ventilated patient is a daily challenge in Intensive Care units.
      Several indexes have been employed to assess the patient's ability to recover efficient
      spontaneous breathing. As the diaphragm is the main respiratory muscle, direct measurement of
      diaphragmatic function as predictors of extubation success or failure have not been
      extensively evaluated. Ultrasound can easily access diaphragm thickness (tdi) in its zone of
      apposition during, tdi can represent the contractile activity of the diaphragm and the
      efficiency of its function.
    

Detailed description: 
      Each patient will have an orotracheal tube, and will be mechanically ventilated in pressure
      support ventilation (PSV) mode according to the clinical needs. Local guidelines for sedation
      of postoperative patients prescribe the use of an intravenous (iv) continuous infusion of
      propofol, starting at 1.5 mg/kg/h and titrated to obtain a Richmond agitation-sedation scale
      (RASS) score of 0/-1. Analgesia is provided as a 6- to 8-ml/h continuous epidural infusion of
      bupivacaine 0.125% + fentanyl 2-mcg/ml solution, aiming at a verbal numerical rating <4 or a
      behavioral pain scale <7. If epidural analgesia is not feasible, patients receive 0.5 to 1
      mg/kg/h continuous iv infusion of morphine + iv acetaminophen 1 g three/four times per day.
      Patients enrolled when judged to be eligible for a test of weaning from mechanical
      ventilation, following the local weaning guidelines, that is, adequate cough, absence of
      excessive tracheobronchial secretion, clinical stability, heart rate (HR) <140/min, systolic
      blood pressure between 90 and 140 mmHg, arterial partial pressure of oxygen/inspired oxygen
      fraction (PaO2/FIO2) ≥150 mmHg, respiratory rate <35/min, maximal inspiratory pressure < -20
      cmH2O, respiratory rate/tidal volume ratio <105 breaths/(min/l) [19]. Weaning trials
      consisted of spontaneous breathing(SB) trials on PS mode (reducing PS by 5 cm H2O until a PS
      level of Δ5/5 was obtained). A successful extubation will be defined as SB for >48 h
      following extubation. A failed extubation will be defined as reintubation within 48 h. The
      RSBI (f in breaths/minute (f)/tidal volume in liters (VT)will be calculated simultaneously
      with ultrasound measurements of tdi and simultaneously with other criteria for weaning.

      TECHNIQUE Diaphragm thickness (tdi) was measured using a 6-13 MHz linear ultrasound probe set
      to B mode (SonoSite M-turbo ultrasound machine). The right hemidiaphragm was imaged at the
      zone of apposition of the diaphragm and rib cage in the midaxillary line between the 8th and
      10th intercostal spaces as previously described.[18] All patients were studied with the head
      of bed elevated between 20° and 40°. The tdi was measured at end-expiration and
      end-inspiration. The percent change in tdi between end-expiration and end-inspiration (Δtdi%)
      was calculated as (tdi end-inspiration-tdi end-expiration/tdi end-expiration) ×100. The Δtdi%
      for each patient represented the mean of three to five breaths. Images were obtained within
      the first 5 min of the PS trial and immediate before extubation. Data will be collected: 1.
      Diaphragmatic thickness. 2. The percent change in tdi between end-expiration and
      end-inspiration Δtdi%. 3. Arterial blood gases (ABG). 4. Rapid Shallow Breathing Index (RSBI)
      = Respiratory rate/Tidal volume. 5. Duration of ventilator treatment. 6. Success and failure
      rate of weaning. 7. Body mass index (BMI).
    

Intervention name(s): Ultrasound assessment of diaphragm thickness in B-mode
Intervention type(s): Combination Product
Intervention description(s): assess the thickness of diaphragm needed as a tool for prediction of extubation and proper timing of weaning from mechanical ventilation in the ICU which is measured by B mode ultrasound in ventilated cancer patients
Other intervention name(s): Rapid shallow breathing index; Arterial blood gases
Observational model: Case-Crossover
Time perspective: Cross-Sectional
Sampling method: Probability Sample
Study population: 
        Fifty patients were recruited during the immediate postoperative period after major
        elective cancer surgery who needed mechanical ventilation (MV) due to a respiratory cause
        and met criteria for a spontaneous breathing trial with pressure support ventilation and
        diaphragm thickness is assessed by using b-mode ultrasound.