Techniques for Lung Deflation With Arndt® Blocker

Overview

The use of wire-guided Arndt® endobronchial blocker does not gain widespread acceptance during video-assisted thoracoscopy (VATS) because it takes longer time to collapse the operative lung especially in patients with chronic obstructive lung disease (COPD). The use of a disconnection technique for deflation of Arndt® blocker had a comparable degree of lung collapse with the use of double-lumen tubes. However, it carries a risk of blood or infected secretions contaminating the dependent lung. We hypothesise that the use bronchial suction of through a barrel part of a 1-mL insulin syringe attached to the suction port of the bronchial blocker would be associated with comparable time to optimum lung collapse with the disconnection technique. After ethical approval, 58 patients with spontaneous pneumothorax scheduled for elective VATS using Arndt blocker® for lung separation will be included in this prospective, randomized, double-blind study. Patients will be randomly assigned to deflate the blocker with either disconnecting the endotracheal tube from the ventilator for 60 s. prior to inflation of the bronchial blocker allowing both lungs to collapse, or attaching -20 cm H2O of suction to the suction port of the blocker through the barrel part of a 1-mL insulin syringe (n = 29 for each group).

Most Middle Eastern and British thoracic anesthesiologists (100% and 98%, respectively) are using a double-lumen endobronchial tube (DLT) as the first-choice lung separation technique, 1-2 although the intubation with a single lumen tube (SLT) could be easier. However, the use of a bronchial blocker has a special concern as it takes longer time to collapse the operative lung,3 which precludes its widespread acceptance for video-assisted thoracoscopic (VATS) procedures because of delayed insertion of the trocars. The wire-guided Arndt® endobronchial blocker (Cook® Critical Care, Bloomington, IN) takes longer time for lung collapse than the Univent® tube (approximately, 26 min vs. 19 min, respectively; P\<0.006),3 that may be due to its narrower inner lumen (1.4 mm vs. 2.0 mm, respectively). There are different techniques described to speed of lung collapse during the use of Arndt® endobronchial blocker. These include the disconnecting of the SLT from the ventilator and allowing both lungs to collapse before inflation of the bronchial blocker cuff, 4-5 or bronchial suction either through the fiberoptic bronchoscope after deflation of the bronchial cuff and cessation of ventilation before re-inflation of the bronchial cuff, or through a barrel part of a 3-mL syringe attached to the suction port of the bronchial blocker.3 The use of a modified disconnection technique for deflation of Arndt® endobronchial blocker had a comparable degree of lung collapse with the use of DLT during VATS procedures in patients presented with pneumothorax.5 However, compared with the bronchial suction, the disconnection technique may carry a risk of blood or infected secretions contaminating the dependent lung.6 To the best of our knowledge, the comparison of the efficacy of disconnection and bronchial suction techniques to facilitate the deflation of Arndt® blocker during thoracoscopic surgery has not yet been studied. In all patients, standard monitors and state and response entropy (SE and RE, respectively) based-depth of anaesthesia will be applied. The radial artery will be catheterized. Anesthetic technique is standardized in all studied patients. The experienced attending anesthesiologist (\>10 yrs.), who will give the anesthetic and places the Arndt® blocker will not be blinded to group assignment and will not be involved in the collection of outcome data. After preoxygenation, anesthesia will be induced using propofol 1.5-3 mg/kg and target-controlled infusion (TCI) of remifentanil at an effect-site concentration (Ce) of 4 ng/mL, to achieve the SE values below 50 and the difference between RE and SE below 10. Cisatracurium (0.2 mg/kg) will be given to facilitate the tracheal intubation with a SLT, size 8.0 mm for women and 8.5 mm for men. Then a 9.0 F, 78-cm Arndt® blocker will be advanced through the blocker port of its multiport adapter and the wire loop will be coupled with a pediatric fiberoptic bronchoscope (FOB) that has been introduced through the fiberoptic port. The Arndt® blocker will be introduced to the targeted bronchus. The correct position of the Arndt® blocker wil be confirmed with a FOB. Anesthesia will be maintained with 0.7-1.5 minimum alveolar concentration (MAC) of sevoflurane and remifentanil Ce of 2-4 ng/ml to maintain the SE values below 50, the difference between RE and SE below 10 and the mean arterial blood pressure (MA) and heart rate \<20% of baseline values. Cisatracurium increments will be used to maintain surgical relaxation. Patients' two lungs (TLV) will be mechanically ventilated with fraction of inspired oxygen (FiO2) of 0.4 in air, tidal volume (VT) of 8 mL/kg, inspiratory to expiratory (I: E) ratio of 1:2.5 and PEEP of 5 cm H2O, and respiratory rate will be adjusted to achieve a PaCO2 of 35-45 mm Hg. After the positioning of the patient in the lateral decubitus position, the position of the blocker will be reconfirmed, the blocker cuff will be inflated with a titrated amount of air to create a seal under direct visualization of FOB and the wire loop will be removed. All surgical procedures will be performed by the same surgeons who are blinded for the lung collapse technique and who are absent from the operating room during placement of the BB and deflation of the lung. The VATS procedure begins with the exploration of the pleural cavity using a 30° video thoracoscopic camera through a 1.5 cm single skin incision with the use of 1-3 trocars which enabled the thoracoscopic instruments to move the lung.