The VivaSight-DL double-lumen tube with integrated camera

Editor, Lung isolation for thoracic surgery is commonly achieved by endobronchial intubation with a double-lumen endotracheal tube (DLT).1 The correct placement of a DLT is usually evaluated, by clinical confirmation, after blind intubation of the bronchus,2 but blind placement alone can be incorrect in 32 to 48% of cases.3 A misplaced tube can result in incomplete collapse of the operative lung, hypoventilation and an increased incidence of postoperative respiratory infections.4 A flexible fibrescope is therefore recommended to accurately guide the endobronchial lumen into position or confirm the correct position under direct vision, following blind intubation of the bronchus.5 The VivaSight-DL (ETView Ltd, M P Misgav 20174, Israel) is a novel single-use DLT with an integrated high-resolution camera situated at the end of the tracheal lumen. This camera allows real-time images of the airway to be viewed during intubation of the trachea and bronchus, perioperatively, and the tube has a flushing channel for secretion clearance (Fig. 1). We describe its use in eight patients undergoing elective thoracic surgery, to evaluate the success of correct endobronchial intubation, the quality of the camera view and lung isolation, and any adverse events.Fig. 1: VivaSight integrated camera.Ethical approval for this study (National Research Ethics Service number 13/NW/0204) was provided by the NRES Committee North West Haydock (Chairperson Professor R.S. Gulati) on 25 March 2013, and the study was commenced on 28 August 2013. Written informed consent was obtained from the eight patients. At the time of the study, only the 37F left-sided VivaSight-DL was manufactured. Therefore, female patients for elective thoracic surgery suitable for a 37F left-sided DLT for lung isolation were recruited. Patients with known or predicted difficult laryngoscopy or intubation were excluded (Table 1).Table 1: Patient demographics and factors that affect endobronchial tube placementStandard monitoring [(ECG, non-invasive blood pressure, pulse oximetry and Bispectral Index (Covidien-Medtronic, Dublin, Ireland)] was started before induction of the anaesthetic. Following preoxygenation of the patient's lungs, anaesthesia was induced with intravenous alfentanil (15–20 μg kg−1) and propofol (10 mg ml−1) by target-controlled infusion (Alaris PK, Marsh model; CareFusion UK 306 Ltd, Basingstoke, UK) titrated to a BIS measurement of 40–45, and rocuronium 0.5 mg kg−1. All the patients underwent conventional laryngoscopy and tracheal intubation by a single operator, an experienced thoracic anaesthetist. Intubation times were recorded, from the cessation of bag-mask ventilation before laryngoscopy and intubation to the following (Table 2): TR: Time to first view of tracheal rings through the VivaSight-DL camera. TB: Time to view correct endobronchial intubation through the VivaSight-DL camera. TV: Time to first ventilation of both lungs as confirmed with end-tidal carbon dioxide monitoring. Tc: Time to completion of clinical checks for lung isolation. Table 2: IntubationAn intubation of two or fewer attempts was classified as 'successful'. There were no Cormack and Lehane laryngoscopy views of grade III or IV. Tracheal intubation with the VivaSight-DL was successful in seven of the eight patients. In case 8, the distal tip of the VivaSight-DL could be passed below the vocal cords, but not below the subglottis on two attempts. Intubation with the VivaSight-DL was subsequently abandoned in this case and a conventional DLT (35F Rusch left sided) was easily passed into the correct bronchus. Closer inspection of the VivaSight-DL 37F tube when compared with a Mallinckrodt 37F DLT (Covidien, Boulder, Colorado, USA) (upon which the VivaSight-DL design is reportedly based) revealed that the external diameter of the former was 36% greater than the Mallinckrodt 37F DLT (15 vs 11 mm), owing to the profile of the camera (Fig. 2); we speculate that this may have impeded the passage of the tube into the trachea.Fig. 2: Profile features of (a) Mallinckrodt Broncho-cath (left, in both images) and the VivaSight-DL (right in both images); (b) external diameters of the Mallinckrodt Broncho-cath (left image) and Vivasight -DL (right image)Correct endobronchial intubation was successful on the first attempt in six out of seven cases. In case 5, a patient who had previously had a right lower lobectomy, the VivaSight-DL could not be directed into the left main bronchus on two attempts using the VivaSight-DL view alone; on the third attempt, it was eventually positioned by guiding it over a flexible fibrescope (Olympus LF-DP 3.1 mm; Olympus, Southend-on-Sea, UK) sited in the left main bronchus. The fibrescope easily passed down the bronchial lumen, but there was some resistance to passing it through the distal opening, which was overcome with the aid of further lubrication. The correct endobronchial intubation could be confirmed by the VivaSight-DL camera after 96 s. The lateral profile of the VivaSight-DL differs from that of the Mallinckrodt Broncho-cath (Fig. 2), and this may have influenced the passage of the fibrescope in the VivaSight. In the six cases in which correct placement occurred uneventfully, the mean time to confirmation of placement of the VivaSight-DL via the camera was 43.3 s (standard deviation (SD) 24.4 s) and with subsequent clinical assessment was 105.1 s (SD 22.1 s). The quality of the camera view of the VivaSight-DL was graded in both the supine and subsequent lateral positions for surgery (Tables 3 and 4). Secretion clearance was required in three out of seven cases, using a 10F dedicated curved suction catheter, under direct vision with the VivaSight camera, and by rapid 0.9% Normal saline lavage by injection through the flushing channel. In the majority of the views, although orientation could be satisfactorily identified, the trachealis muscle could not be visualised. This may be a result of the anterior curve of the VivaSight-DL. Bronchial cuff inflation could be viewed. Perioperative displacement of the tube occurred in three out of seven cases (43%) and, using the camera, the tube was replaced easily, without interruption of ventilation. No adverse effects to the patients were observed.Table 3: Grading of view through the VivaSight-DL cameraTable 4: View through VivaSight-DL camera and quality of lung isolationThe time to complete and confirm the correct placement of the VivaSight-DL was less than that for conventional DLTs. In conventional DLT placement, Cheong and Koh6 reported a mean time of 347 s to perform a blind insertion, clinical assessment and subsequent confirmation of placement with a fibrescope, and 105 s if a flexible fibrescopy was performed first, followed by clinical confirmation. If the method of DLT size prediction used by Brodsky et al.7 were applied to our series, four patients would be predicted to be suitable for a 39F left-sided DLT and four patients suitable for a 41 F left-sided DLT, and we have identified that this would not apply to the VivaSight-DLT. In conclusion, the VivaSight-DL allows monitoring of tube position and displacement detection, and may obviate the regular requirement of a flexible fibrescope. Further detailed evaluation in different patient groups and operators will be required. Acknowledgements relating to this article Assistance with the study: none. Financial support and sponsorship: VivaSight-DL were supplied from P3 Medical Ltd, Bristol, UK, free of charge, but no other external funding was received; no involvement in editing, design, evaluation or preparation of the manuscript. Conflict of interest: none. Trial registration: controlled-trials.com identifier: ISRCTN85628303.