Selective Lobar Blockade and Bronchial Blockers
Condition: Elective Thoracic Surgery; One Lung Ventilation
Study type: Interventional

Summary: 
      Selective lobar blockade (SLB) is a specific technique that allows collapse of the operated
      lobe during thoracic surgery while the other lobes are ventilated. It is associated with the
      improvement of arterial oxygenation during one lung ventilation (OLV) for thoracic with
      providing adequate surgical access. The purpose of this study is to compare the efficacy of
      three bronchial blockers, namely an Arndt® wire-guided endobronchial blocker, a Cohen
      Flexi-tip endobronchial blocker or a Fuji Uni-blocker, for achieving selective lobar
      collapse.
    

Detailed description: 
      Prevention of hypoxemia associated with one-lung ventilation (OLV) during video-assisted
      thoracoscopic surgery (VATS) or open thoracotomy has a priority for anesthetists.

      Selective lobar blockade (SLB) is a specific technique that allows collapse of the operated
      lobe during thoracic surgery while the other lobes are ventilated. SLB has been recommended
      to enhance the safety of OLV in patients with previous pulmonary resection requiring
      subsequent resection or in patients with limited pulmonary reserve resulting from severe
      pulmonary disease.1

      One of the advantages of SLB is the improvement of arterial oxygenation in patients
      undergoing lobectomy with providing adequate lobar collapse for surgical access.2 Similarly,
      selective left lower lobar blockade during lower esophageal surgery provides a lower
      intraoperative intrapulmonary shunt and a better perioperative arterial oxygenation.3

      SLB can be achieved with a Coopdech endobronchial blocker tube (COOPDECH™, Osaka, Japan),3an
      Arndt® wire-guided endobronchial blocker (Cook Inc., Bloomington, IN)4-6 or with an
      embolectomy catheter,7 can be used through a single-lumen endotracheal tube (ETT), attached
      to a single-lumen ETT with a sided channel (Univent tube),2 or placed under direct
      laryngoscopy.7

      Up to best of the authors' knowledge, there is no consensus on the best technique for
      selective lobar blockade for thoracic surgery.

      The purpose of this study is to compare the efficacy of three bronchial blockers, namely an
      Arndt® wire-guided endobronchial blocker, a Cohen Flexi-tip endobronchial blocker (Cook
      Critical Care, Bloomington, IN) or a Fuji Uni-blocker (Fuji Systems, Tokyo, Japan), for
      achieving selective lobar collapse. It is generally accepted that bronchial blockers perform
      better clinically when positioned in the longer left mainstem bronchus versus the shorter
      right bronchus.9 However, this could not be extended for the SLB. Thus, the present study
      will include both sides thoracic procedures and studied patients will be stratified to the
      side on which their surgery will be performed, right or left.

      An independent investigator who will be blind to the study groups and who will not be
      involved in the patients' management will collect the saved recorded patient data by the
      attending anesthesiologists.

      The surgeons, who will be absent from the operating room during DLT or bronchial blocker
      placement, will be blind to randomization and to the isolation device by means of an opaque
      sheet placed over the lung isolation device.

      In all patients, standard monitoring, including radial arterial catheterization, and state
      and response entropy (SE and RE, respectively) will be applied. Patients will received either
      a thoracic epidural or a paravertebral catheter before the induction of anesthesia for open
      thoracotomy or patient-controlled systemic morphine after VATS, for postoperative analgesia.

      Anesthetic technique will be standardized in all studied patients. The same senior
      anesthesiologists (> 5 years' experience), who are experienced in thoracic surgery, OLV, and
      the use of a FOB for DLT and bronchial blockers placement, will give the anesthetic, will
      place all of the isolation devices in the studied groups and will not be involved in the
      patient's assessment.

      General anesthesia will be induced with propofol (2-3 mg/kg) and fentanyl (2-3 µg/kg).
      Cisatracurium (0.2 mg/kg) will be given to facilitate the placement of the isolation device.
      Anesthesia will be maintained with 0.7-1.5 minimum alveolar concentration (MAC) of
      sevoflurane or total intravenous anesthesia according to each center's protocol to maintain
      the SE values < 50 and the difference between RE and SE < 10. fentanyl 0.5µg/kg increments
      will be administered when the SE values > 50, the difference between RE and SE >10, and the
      heart rate and MAP are >20% of the baseline values despite a target sevoflurane MAC ≥ 1.5.
      Cisatracurium increments will be used to maintain surgical relaxation as indicated by
      train-of-4 monitoring.

      Patients' two lungs will be ventilated, with a fraction of inspired oxygen (FiO2) of 0.5 in
      air, tidal volume (VT) of 8 mL/kg predicted body weight (PBW), inspiratory to expiratory [I:
      E] ratio of 1:2.5 and positive end expiratory pressure (PEEP) of 5 cm H2O, and respiratory
      rate adjusted to achieve an arterial carbon dioxide tension of 35-45 mm Hg. Peak airway
      pressure will be limited to 35 cm H2O and a fresh gas flow (FGF) < 2 L/min will be used.

      The patients' tracheas will be intubated using a Macintosh laryngoscope with either an
      appropriately sized left-sided DLT (DLT group)10 or a minimum 7.5-mm internal diameter (ID)
      ETT for women and 8.0-mm ID ETT for men, which will be connected to a dedicated multiport
      airway adapter to allow continuous ventilation of the patients during the placement of the
      bronchial blockers (bronchial blockers groups).

      In the DLT group; the correct placement of the DLT will be assessed by using an FOB. Then,
      the lumen of the nondependent lung will be clamped and left open to air to facilitate
      unilateral lung collapse.

      In the bronchial blockers groups; all bronchial blockers will be placed via the ETT according
      to the manufacturers' recommended instructions. To achieve selective lobe collapse during
      surgery, the bronchial blocker will be advanced and directed to block selectively the desired
      operated lobe (or lobes) only; under vision with a pediatric FOB. The bronchial blocker will
      be placed deeply into the desired bronchus to minimize the chance of dislodgment back into
      the mainstem bronchus or trachea. If surgery will be performed in either the right middle or
      lower lobe, both lobes will be collapsed while the right upper lobe will be ventilated. If
      surgery will be performed in either the left lower or upper lobe, the left upper or lower
      lobe will be collapsed, respectively, while the remaining lobe will be ventilated. For the
      Arndt® blocker, once the blocker will be in an optimal position, the wire loop will be
      removed to use the wire channel for suction. To facilitate the selected lobar collapse, a
      barrel part of a 1-mL insulin syringe will be attached to the suction port of the bronchial
      blocker, and will be connected to suction.

      OLV will be initiated using a VT of 6 mL/kg PBW, FiO2 of 0.3-1.0 to maintain SaO2 > 92%,
      whereas the I: E ratio, PEEP, respiratory rate, and FGF will be maintained as during two-lung
      ventilation. Recruitment maneuvers for the dependent lung will be repeated at 30-minute
      intervals by raising the inspiratory pressure up to 40 cmH2O for 10 seconds.

      The patients will be then turned to the lateral decubitus position for surgery, the position
      of the DLT or the bronchial blocker will be checked with FOB. All operations were performed
      by the same surgeons.

      If the lung collapse is not satisfactory or if any ventilation problem occurs during surgery,
      such as an increase of peak pressure, the FOB will be passed to reposition the bronchial cuff
      of the DLT or the bronchial blocker; if it is not appropriately positioned in the desired
      bronchus.

      Patient will be withdrawn from the study and total operative lung collapse will be considered
      if the surgeon rates the VAS of the operative field conditions as 30 mm or less despite the
      confirmation of the appropriate position of the isolation device with FOB.

      Intraoperative hypoxemia will be defined as decreases in SaO2 less than 90% will be treated
      with increasing of FiO2 to 1.0. Addition of low level of 2 cm H2O of CPAP to the ventilated
      lung (or lobes) will be considered if the former fails to correct hypoxemia.

      At the end of surgery, the operative lung will be re-expanded, two-lung ventilation will be
      resumed, sevoflurane will be discontinued and the residual neuromuscular block will be
      antagonized.

      Before extubation, FOB will be performed in all patients to observe whether there was any
      damage to the tracheal or bronchial mucosa. For the Arndt® blocker group, the bronchial
      blocker will be deflated and then withdrawn together with the multiport connector to prevent
      shredding the plastic balloon over the blocker port.

      Each of the four lung isolation groups will be further subdivided into two subgroups
      according to the side of surgery to right-sided and left-sided subgroups.

      Sample Size Calculation:

      A power analysis of data from our pilot study on a similar surgical population indicated that
      we need to study 14 subjects in each group to detect a 15-mm true difference in the mean
      visual analog scale (VAS) rating of the to rate the deflation of the target lung lobe with a
      standard deviation (S.D.) of 1.22, a type-I error of 0.0083 (0.05 / 6 possible comparisons)
      and a power of 90%. We will add 10% more patients for a final sample size of 60 patients to
      account for patients dropping out during the study.
    

Intervention name(s): Endobronchial double lumen tube; Arndt® blocker; Cohen blocker; Fuji Uni-blocker
Intervention type(s): Device; Device; Device; Device
Intervention description(s): Endobronchial double lumen tube for one lug ventilation; Arndt® blocker for selective lobar deflation; Cohen blocker for selective lobar deflation; Fuji Uni-blocker foe selective lobar deflation
Allocation: Randomized
Intervention model: Parallel Assignment
Masking: Quadruple (Participant, Care Provider, Investigator, Outcomes Assessor)
Primary purpose: Treatment