Efficiency, Efficacy, and Safety of EZ-Blocker Compared with Left-sided Double-lumen Tube for One-lung Ventilation

LUNG isolation techniques are used to facilitate one-lung ventilation (OLV) in patients undergoing thoracic surgery, to protect one lung from contamination or hemorrhage in the contralateral lung, and for differential ventilation of the lungs. Commonly used for lung isolation is a double-lumen tube (DLT), which can be placed using only laryngoscopy and auscultation. It is recommended that bronchoscopy be used to verify the correct position because the incidence of malpositions is high.1–5The major disadvantage of DLTs is the often difficult placement because of the larger diameter; as a consequence, patients often complain of hoarseness or sore throat.6There is also a potential for minor laryngeal, tracheal, and bronchial trauma.6Major traumas such as bronchial ruptures have been described.7Compared with other techniques, a DLT has to be replaced by a single-lumen tube (SLT) if prolonged postoperative ventilation is necessary.Alternatively, a bronchial blocker (BB) can be used for lung isolation. This is a balloon-tipped semirigid catheter. Different types are available (e.g. , the wire-guided endobronchial Arndt blocker [Cook Critical Care, Bloomington, IN], the Cohen flex-tip blocker [Cook Critical Care], and the Univent torque control blocker [Vitaid, Lewiston, NY]. The BB is positioned in a bronchus with the aid of bronchoscopy. A BB is normally placed through the inside of an SLT. These types of blockers are not easy to position and frequently dislocate during repositioning of the patient or during surgical manipulation.8It is not easy to alternate OLV to either lung (e.g. , for protecting the contralateral lung from overinflation during reexpansion of the ipsilateral lung or during bilateral procedures).To solve these problems, a novel type of BB, the EZ-Blocker (Teleflex Life Sciences Ltd., Athlone, Ireland) (EZB) has been developed.9The EZB is also a semirigid catheter, but it has two distal extensions, both with an inflatable cuff and a central lumen (fig. 1). Advantages are believed to be the ease of placement through an SLT (minimum, 7-mm ID) and the ease of putting the distal extensions in the correct place, combined with fewer dislocations during repositioning the patient and during surgical manipulations. These improvements are attributable to the fact that the blocker anchors itself on the carina with the two extensions (fig. 2). Furthermore, one size of EZB will fit almost all adult patients, whereas selecting the best size for a DLT is rather complicated.10,11The cuff pressure of the EZB at adequate cuff volume is high and could be responsible for mucosal injury at the mainstem bronchi.The EZB has been evaluated in a clinical study.4This is the first clinical study to evaluate with a comprehensive examination of the airway both the efficacy and safety of the device. We hypothesize that the EZB performs clinically better than a DLT for lung isolation without causing more injury to the patient.This study was approved by the local ethical committee on research involving human subjects for the region of Arnhem-Nijmegen (Nijmegen, The Netherlands) (NL30799.091.09) and registered at ClinicalTrials.gov (NCT01073722). This single-site study took place at a university hospital in The Netherlands and started recruitment in March 2010, and final enrollment was in March 2011. Patients were recruited from the operation planning list. After informed written consent, American Society of Anesthesiologists physical status 1–3 patients aged 18 yr or older undergoing surgical procedures requiring a left-side DLT for OLV were included. Patients with known lesions along the path of the left-sided DLT or the EZB, anticipated difficult intubation (Mallampatti score ≥3), presence of tracheostomy, and patients requiring absolute lung separation or scheduled for bronchial sleeve resection or pneumonectomy were excluded from the study. The study was set up as a parallel design with the aim of identifying the superiority of the new device. Consecutive patients requiring surgery were allocated 1:1 into two groups—the DLT or the EZB group—using a computer-generated “simple” randomization. Codes were kept in numbered envelopes. An independent data safety monitoring board was not instituted. Patients were blinded with regard to the device used.All patients received midazolam and paracetamol orally for premedication. In the operating room, they received standard monitoring, intraarterial pressure monitoring, and bispectral index monitoring. Patients scheduled for thoracotomy received an epidural anesthetic at the T3–T4 or T4–T5 level using 20 mg bupivacaine and 20 μg sufentanil. After 3 min, preoxygenation patients received 1.5–3 mg/kg propofol, 0.6 mg/kg rocuronium, 10 μg sufentanil, and antibiotics IV. An I-gel®laryngeal mask airway (Intersurgical, Uden, The Netherlands) was inserted 2 min later. Anesthesia was maintained with propofol at 4–10 mg·kg−1·hr−1IV.Before intubation, a pulmonologist observed the status of the airway with an Olympus BF-3C40 or 3C160 bronchoscope (Olympus America Inc., Melville, NY) through the laryngeal mask airway. Injuries were classified6(table 1) and written on a chart. A video movie was stored for later comparison. Pulmonologists participated in this study because they are very experienced bronchoscopists. It was important for this study to avoid damaging the airway by the bronchoscopy itself. The pulmonologists had to judge the videos afterward and logically they produced the videos themselves.Four anesthesiologists experienced with both techniques performed placement of the devices after removal of the laryngeal mask airway. Surgeons were absent from the operating room during tube placement and were blinded to the device used.The correct size of DLT was extracted from the diameter of the left mainstem bronchus using computed tomography if available, or preoperative anteroposterior chest radiography using the diameter 1 cm beyond the carina with a −10% correction. If not clearly visible on radiography, the tracheal width at the level of the clavicles was measured and the following formula was used10: left mainstem bronchus diameter (mm) = (0.45) (tracheal width [mm]) + 3.3 mm. If the diameter of the left mainstem bronchus was 12, 13, or greater than 14 mm, a DLT size 35-, 37/39-, and 41-French, respectively, was chosen.12The estimated depth of insertion was derived from the following formula13: depth DLT (cm) = 12 + length patient (cm) × 10–1. The styletted DLT without a carinal hook (Broncho-cath; Mallinckrodt, Athlone, Ireland) was introduced into the glottis via direct laryngoscopy. After the bronchial cuff passed the vocal cords, the stylet was removed and the tube was rotated 90 degrees toward the left. The tube was advanced until slight resistance was encountered. The pulmonologist inserted a bronchoscope to verify the position of the DLT tube.Before EZB placement, a SLT (Hi-contour Tracheal Tube; Mallinckrodt), size 7 or 8 for women and size 8 or 9 for men, was introduced via direct laryngoscopy. The cuff of the tube had to be visible just below the vocal cords. A multiport adaptor (length, 11 cm) was attached to the tube. The EZB was lubricated with silicone spray and advanced through the tube until slight resistance was encountered after the tip emerged from the SLT. A pulmonologist verified the position of the SLT and the EZB using a bronchoscope.The primary outcome of the study is the incidence of malposition detected by bronchoscopy after initial insertion. A device was considered to be malpositioned when one of the following criteria was not observed: for DLT, the bronchial limb positioned in the left bronchus, unobstructed view of the tracheal carina (absence of bronchial cuff herniation), unobstructed view down the nonintubated bronchus, visualization of the proximal edge of the bronchial cuff below the tracheal carina, radiopaque line encircling the tube is seen above the tracheal carina, and unobstructed view of the left distal bronchial tree; for EZB, the extensions straddle the carina, the attachments of the extensions rests on the carina, unobstructed view down the carina (absence of balloon herniation), unobstructed view down the contralateral bronchus, and occlusion of all ostia of the mainstem bronchus after balloon inflation. Other study endpoints were the ease (1, excellent; 2, good; 3, average; and 4, poor) and duration (from visualization of vocal cords until initial positioning without bronchoscopy) of placement.The Cormack and Lehane classification14was used to quantify the view at laryngoscopy (grade I, visualization of entire laryngeal aperture; grade II, visualization of posterior part of the laryngeal aperture; grade III, visualization of epiglottis only; and grade IV, not even the epiglottis is visible).The ease (1, excellent; 2, good; 3, average; and 4, poor) and duration until correction of the malposition was also recorded. Once the devices were in the correct position, the cuffs or the balloons were successively insufflated under bronchoscopic view. The volume was recorded and the cuff pressure was measured with a handheld manometer (Endotest; Rüsch, Kernen, Germany) (upper limit, 130 cm H20). The bronchial cuff or the balloons were then deflated. After the patient was turned to the lateral position, the pulmonologist assessed the correct position of the DLT or EZB again with bronchoscopy.At least 3 min before initiation of OLV, the inspired oxygen concentration was increased to 100%. For a DLT, the bronchial cuff was insufflated and the appropriate channel was clamped and opened to air. For an EZB, the tube was disconnected from the ventilator for 60 s and then the correct balloon was insufflated with the same amount of air as determined previously. No further maneuvers were performed to facilitate lung collapse. During OLV, ventilator settings were adjusted to keep peak pressure below 25 cm H2O and a positive end-expiratory pressure of 5 cm H2O by increasing respiratory frequency and inspiratory/expiratory ratio and decreasing tidal volume. Where possible, arterial carbon dioxide tension was kept between 34 and 45 mmHg. The fraction of inspired oxygen was gradually reduced while aiming at an arterial saturation exceeding 95%. The surgeon, blinded to the technique, indicated when the collapse was halfway and scored the quality of lung collapse after 10 min and for the total period of OLV (1, excellent [complete collapse]; 2, good [some residual air]; 3, average [residual air interfering with surgical exposure]; and 4, poor [no collapse]).At the end of surgery, the tubes were removed and a laryngeal mask was inserted. Again, the pulmonologist observed the airway for possible damage caused by the DLT or EZB with the bronchoscope. Injuries were classified, written on a chart, and stored on video.Our second interest was the incidence of postoperative complaints of sore throat and hoarseness and of damage to laryngeal, tracheal, and bronchial structures. A blinded interrogator asked the patient postoperatively at the postanesthesia care unit and 24 h after the operation about sore throat (0, no sore throat; 1, mild [pain with deglutition]; and 2, moderate [pain constantly present and increasing with deglutition]) and postoperative hoarseness (0, no hoarseness; 1, noticed by patient; 2, noticed by observer; and 3, aphonia). Afterward, a pulmonologist (O.S. or E.H.), unaware of the device used, reviewed the videos before and after use of the devices for damage. Airway injuries were classified6as shown in table 1.A literature search for the incidence of malposition of left-side DLT1–3,5,15yielded a weighted mean incidence of malpositioning of the left-sided DLT(or proportion) of 55%. Using the Lehr formula,16we calculated that 50 patients in each group are required for the chi-square test to have an 80% chance of detecting a clinically important difference in malposition rate from 55% to 27% (a 50% decrease) at the two-side significance level of 5%.Statistical analysis was performed using SPSS Statistics 18.0 (IBM Corp., Armonk, NY). Results were considered statistically significant for values of P < 0.05. Data are expressed as mean (SD) or median (range). The difference in proportion of initial malpositions is reported with 95% CI, and for analysis, the Fisher’s exact test was used. Nonnormally divided data were analyzed using the Mann–Whitney rank sum test; otherwise, parametric independent Student t tests were used. Results based on ratings were tested using the Mann–Whitney rank sum test. Perioperative changes in airway injury were computed using the difference between postoperative and preoperative injuries, on which also a rank sum test was performed.Demographic data and sizes of the mainstem bronchi and trachea were not different between the groups (table 2). Type and side of the operation, duration of OLV, and sizes of the endotracheal tubes are listed in table 2. Figure 3shows the number of patients at each phase of the trial. In one patient, a 41-French DLT could not pass through the vocal cords. In another patient, it was not possible to position a 35-French DLT in the left mainstem bronchus. These patients received an SLT and an EZB successfully and were excluded from further analysis.The placement of an SLT and an EZB took a median of 25 s (range, 1.5–48 s), and placement of a DLT took a median of 13 s (range, 2.5–440 s) (P = 0.001). The placement of only an SLT was quicker than a DLT (table 3). The use of an SLT and an EZB is rated easier compared with a DLT (P = 0.02 and P = 0.011). Grade of intubation was equal in both groups (P = 0.374) (table 3).Only 15% of DLTs and 26% of EZBs were placed correctly without the need for repositioning the device during bronchoscopic inspection. The 11% increase in initially correct positions (95% CI, −4 to 27%) when an EZB was used was not statistically significant (P = 0.212). In three cases in each group, a description of the type of malposition was not documented. A majority (n = 29) of DLTs were positioned too deep and a majority (n = 24) of EZBs were placed with both the extensions in the right mainstem bronchus. An extension of one EZB entered in the of the SLT. A DLT could be than an EZB (table 3). The number of correct positions and the duration of repositioning of the malpositioned devices after the patient during lateral thoracotomy and during one-lung ventilation were not different (table or other were reported that could with collapse of the lung were excluded when both The to halfway collapse and the quality of collapse after 10 min and during the period of one-lung ventilation not between the groups (table A DLT to be during OLV = right = an EZB, = left = 2). and were 11 (range, and cm H2O (range, cm for the left balloon of the and 14 (range, and 130 cm H2O (range, cm for the right patients in the DLT group of sore throat at 1 (P = The incidence and of sore throat and hoarseness at 1 and 2 are listed in table Data for three patients in each group were the preoperative and postoperative of the bronchoscopic by the blinded In three cases in each group, the videos were for these the data from the that was after the bronchoscopic was a incidence of postoperative new or airway injury such as tracheal and and bronchial in the DLT was no difference in injuries at the vocal (P = and carina (P = but were more lesions at the tracheal (P < and bronchial (P = in the DLT settings (table and arterial analysis (table before and after one-lung ventilation were between the was a peak airway pressure and a during OLV in the EZB EZB and SLT were rated easier to place than the left-sided The to initial placement of an SLT an EZB was than a DLT, because an SLT and an EZB two of an SLT was than a DLT and was no statistically significant difference in the to place an EZB or a We that the are not clinically that above s (n = were observed in the DLT This that placement of DLTs in patients is easy but in a of patients is an that is not for the In two patients, it was not possible to place a left-sided DLT A technique, even if be Other that the to place the devices was but they the to control the A to place and to the position of the other a in the primary outcome is after only 15% of DLTs and 26% of EZBs were positioned The rate is in both The 95% for the difference in rate to 27%) that the difference is clinically a malposition was it be that OLV when left was not in which cases OLV have been because all malpositions were in both DLTs and of 1–3 cm were often OLV in such Other the incidence of malpositioning of left-sided DLTs to from of the than anticipated incidence of malposition of DLTs is that the number of patients is rather of device malposition be responsible for the high rate of malpositions malpositions with DLTs are attributable to positioning that is too This is in with other the left-sided DLT was positioned in the right mainstem bronchus. In one of these patients, it was not possible to correct the malposition and this patient was excluded from further Other were rated easy (95% were excellent or and 5 of the EZBs entered the right mainstem bronchus with both extensions when inserted are two possible for if the distal end of the SLT is than cm above the carina, the extensions of the EZB and the right mainstem bronchus because it is positioned more in line with the if the two extensions are advanced in a in the patient, the extensions will more the right mainstem bronchus. malpositions could be were excellent or and 11 s) under bronchoscopic it took more compared with the correction of a in thoracic high incidence of malpositions that the use of bronchoscopic control is If an EZB is initially placed under bronchoscopic correct placement in all patients, because all of were and number of DLTs or EZBs that after the patient to the lateral position were The number of malpositions during OLV was also between DLTs and EZBs and It had been shown that other such as the blocker not in place after the patient into lateral position or during that better when positioned in the left mainstem bronchus the We that the number of of an EZB during OLV was and divided between left and The balloon placed in the right mainstem bronchus had to be with 14 to whereas on the left side 11 was This to of the diameter of the right mainstem bronchus, which was The larger volume is also to the of the right not to DLTs or lung collapse was and rated excellent in the majority of patients with both collapse when using The use of preoxygenation and the SLT or the appropriate of the DLT, as had an EZB experienced sore throat on 1 compared with DLT was no difference between EZBs and DLTs in injury to vocal cords, which could have been an for Other also a number of with sore throat and vocal injury when using an Arndt blocker compared with a a study DLTs and was no difference in the incidence of sore throat and The incidence of sore throat at 1 was than reported by observed a high number of of with in the DLT could of the trachea on the the tip of the DLT the just below the vocal cords during insertion and then a of on the left side of the trachea caused by of the two types of damage caused by the could injury to the mainstem bronchus because of pressure by the We recorded of 11 and 14 during of air into the balloons to a of the bronchus. at that are above cm This is above the recommended pressure of cm H2O for endotracheal and that at to a to a positive pressure of 25 cm the pressure are than cm only a fraction is to the bronchial We a incidence of bronchial in the EZB group, that the used balloons is The incidence of bronchial in the DLT group was was the injury from the pressure by the EZB on the tracheal the EZB is between the carina and the at the proximal end of the endotracheal it in place during We could not that was more injury to the carina when using an EZB compared with a the EZB without of the study is that that postoperative injury to the airway also be caused by the bronchoscope itself. injury have been because experienced pulmonologists performed all bronchoscopic from sore throat at 1, the clinical of the injury to the We not the patients for more than 2 and are unaware of the all the EZB from the fact that it is easier to in the presence of a difficult airway or a If postoperative ventilation is is no need to the endotracheal which is with are were a DLT is such as pneumonectomy or bronchial sleeve the presence of the distal extension of a BB will the surgical or is at of in the a DLT is is absolute lung such as or in the distal bronchial and with because of the to the through the bronchial Furthermore, an EZB be used for which can be performed with other an EZB is an easy and device to OLV and injury to the tracheal and bronchial the patient sore throat than when a DLT is used. The quality of lung is and the EZB in place during The use of bronchoscopic control of the position of the EZB after initial placement and after repositioning the patient is but this also for the