Spontaneous Ventilation Versus Controlled Ventilation on Lung Atelectasis in Children.
Condition: Lung Collapse
MeSH terms: Pulmonary Atelectasis
Study type: Observational

Summary: 
      This is an observational study to compare the effect of spontaneous ventilation versus
      controlled ventilation on lung atelectasis using lung score measured by lung ultrasound. the
      study will be conducted in children hospital of Cairo University Hospitals and study
      population will be : children aged from one to eight years of age. primary outcome will be
      the lung score measured by lung ultrasound.
    

Detailed description: 
      Randomization will be done by computer generated numbers and concealed by serially
      numbered,opague and sealed envelopes. The details of the series will be unknown to the
      investigators and the group assignment will be kept in asset of sealed envelopes each bearing
      only the case number on the outside. Prior to surgery the appropriate numbered envelopes will
      be opened by the nurse, the card inside will determine the patient group. All children will
      be premedicated with oral midazolam 0.5mg/kg half hour before procedure and atropine at a
      dose of 0.01-0.02 mg/kg (IM). Continuous electrocardiogram (ECG), pulse oximetry,
      non-invasive arterial blood pressure, and temperature monitoring will be applied and all
      patients will be induced with inhalational anesthetic using Sevoflurane+ oxygen (O2) with mac
      6%. After deepening of the anesthesia, intravenous (I.V.) line will be inserted and fentanyl
      1μg/kg. Patient will be divided into two groups; group S (spontaneous) will be intubated and
      maintained spontaneously with Ayres T piece circuit on isoflurane + oxygen with mac 2% and
      with fresh gas flow 2 times minute ventilation of patient to avoid co2 rebreathing . Group C
      (controlled) will receive muscle given in the form of atracurium 0.5mg/kg and patients will
      be intubated by appropriate size of endotracheal tube. Patients in controlled group will be
      ventilated at 6 ml/ kg tidal volume, Inspiratory to expiratory (I: E) ratio 1:2, Fio2 1 and
      PEEP 5 cmH2o.

      10 minutes after induction lung ultrasound will be done to assess lung score and arterial
      blood gases will be withdrawn. At the end of surgery lung ultrasound (LUS) will be done again
      and another blood gases will be taken.

      LUS will be performed with the portable echograph MicroMax (SonoSite, M-turbo) using a linear
      probe of 3 to 6 MHz. Each hemithorax will be divided into six sections using three
      longitudinal lines (parasternal, anterior, and posterior axillary) and two axial lines, one
      above the diaphragm and another one 1 cm above the nipples.

      As LUS provides regional information, we will repeat the following examination sequence in
      each hemithorax and in all patients: (1) anterior, (2) lateral, and (3) posterior regions
      starting from the diaphragm (caudal lung) and moving toward the apex (cranial lung). Each
      hemithorax will be assessed using the two-dimensional classical view placing the probe
      parallel to the ribs .The LUS of a normal lung shows a lung sliding (caused by the
      respiratory movement of the visceral pleura relative to the fixed parietal pleura) and A
      lines (repetitive horizontal reverberation artifacts generated by air within the lungs
      separated by regular intervals, the distances of which being equal that between the skin and
      the pleural line).

      The lung ultrasound (LUS) assessment will be segmented in anterior , lateral (L) and
      posterior (P) regions in both lungs. The dotted black axial line separated the lungs in
      superior and inferior portions. Ovals depicted where the probe is placed in the classical LUS
      approach: mid-clavicular, lateral and posterior axillary lines.

      Anesthesia-induced atelectasis would be associated with the following LUS signs:

        -  Localized iso- or hypoechoic areas as compared with the highly reflective or anechoic
           normally aerated lung tissue.21-25 This consolidation or tissue-like pattern is caused
           by a loss of lung aeration. It commonly arises from the pleural line and thus can be
           described as Juxtapleural consolidations of various sizes.

        -  Static air bronchograms are observed as bright echogenic branching structures within
           these lung consolidations.

        -  The juxtapleural consolidations commonly erases the typical normal A lines and a few
           focal B lines (vertical, laser-like lines that erase normal A lines) can be observed
           below them.

        -  The lack of local respiratory movement or lung sliding and the presence of the pulse
           sign (a small motion within the lungs caused by the transmission of heart beats through
           the atelectatic area) are sometimes observed in large atelectatic areas.

      Patients' demographic data will be collected; age, gender, weight, height, type of surgery
      and duration of surgery.

      Lung ultrasound examinations will be performed at different time-points 10 minutes after
      induction of general anesthesia and before extubation to detect lung atelectasis. Arterial
      blood samples will be collected simultaneously to measure Pao2.

      Atelectasis will be assessed by ultrasound using lung aeration score applied for each region.
      Lung score is four points (0 = normal lung, 1 = moderate aeration loss, 2 = severe aeration
      loss, 3 = complete aeration loss and consolidation) so, applying score for 12 regions
      bilateral will result in maximum score 36 and lowest score 0.

      Assessment of postoperative pulmonary complications like; postoperative lung collapse,
      postoperative pneumonia.
    

Intervention name(s): Lung ultrasound
Intervention type(s): Diagnostic Test
Intervention description(s): we will perform lung ultrasound for both groups to calculate lung score.
Observational model: Case-Control
Time perspective: Prospective
Sampling method: Non-Probability Sample
Study population: 
        children undergoing anesthesia for non-major surgical procedures in Cairo Univesity
        children hospital.