Endobronchial Blocker Plus Laryngeal Mask Airway with Left-Sided Double-Lumen

Brazilian Journal of Medical and Biological Research (2018) 51(10): e6825retraction, http://dx.doi.org/10.1590/1414-431X20176825retraction ISSN 1414-431X Retraction 1/1

Retraction notice for: ‘‘Comparison of Arndt- endobronchial blocker plus laryngeal mask airway with left-sided double-lumen endobronchial tube in one-lung ventilation in thoracic surgery in the morbidly obese’’ [Braz J Med Biol Res (2018) 51(2): e6825]

Z.J. Zhang, M.L. Zheng, Y. Nie and Z.Q. Niu

Department of Anesthesiology, the Cangzhou Central Hospital, Cangzhou, Hebei, China

Retraction for: Braz J Med Biol Res | doi: 10.1590/1414-431X20176825 | PMID: 29267506 The Brazilian Journal of Medical and Biological Research was contacted by one specialist questioning the validity of this study. [Click here to view Specialist message] The authors were contacted on May 7 and 22, 2018 to answer the questions one-by-one. As of June 29, 2018, we did not receive an answer from the authors. The Editors decided to Retract the article: ‘‘Comparison of Arndt-endobronchial blocker plus laryngeal mask airway with left-sided double-lumen endobronchial tube in one-lung ventilation in thoracic surgery in the morbidly obese’’ that was published in volume 51 no. 2 (2018) (Epub Dec 18, 2017) in the Brazilian Journal of Medical and Biological Research ohttp://dx.doi.org/10.1590/1414-431X201768254 PMID: 29267506. The Brazilian Journal of Medical and Biological Research informed all authors before the publication of this Retraction.

Braz J Med Biol Res | doi: 10.1590/1414-431X20176825retraction Brazilian Journal of Medical and Biological Research (2018) 51(2): e6825, http://dx.doi.org/10.1590/1414-431X20176825 ISSN 1414-431X Research Article 1/9

Comparison of Arndt-endobronchial blocker plus laryngeal mask airway with left-sided double-lumen endobronchial tube in one-lung ventilation in thoracic surgery in the morbidly obese

Z.J. Zhang, M.L. Zheng, Y. Nie and Z.Q. Niu

Department of Anesthesiology, the Cangzhou Central Hospital, Cangzhou, Hebei, China

Abstract

This study aimed to evaluate the feasibility and performance of Arndt-endobronchial blocker (Arndt) combined with laryngeal mask airway (LMA) compared with left-sided double-lumen endobronchial tube (L-DLT) in morbidly obese patients in one-lung ventilation (OLV). In a prospective, randomized double-blind controlled clinical trial, 80 morbidly obese patients (ASA I-III, aged 20–70) undergoing general anesthesia for elective thoracic surgeries were randomly allocated into groups Arndt (n=40) and L-DLT (n=40). In group Arndt, a LMAt Proseal was placed followed by an Arndt-endobronchial blocker. In group L-DLT, patients were intubated with a left-sided double-lumen endotracheal tube. Primary endpoints were the airway establishment, ease of insertion, oxygenation, lung collapse and surgical field exposure. Results showed similar ease of airway establishment and fi tube/device insertion between the two groups. Oxygen arterial pressure (PaO2)ARTICLE of patients in the Arndt group was signi cantly higher than L-DLT (154±46 vs 105±52 mmHg; Po0.05). Quality of lung collapse and surgical field exposure in the Arndt group was significantly better than L-DLT (effective rate 100 vs 90%; Po0.05). Duration of surgery and anesthesia were significantly shorter in the Arndt group (2.4±1.7 vs 3.1±1.8 and 2.8±1.9 vs 3.8±1.8 h, respectively; Po0.05). Incidence of hoarseness of voice and incidence and severity of throat pain at the post-anesthesia care unit and 12, 24, 48, and 72 h after surgery were significantly lower in the Arndt group (Po0.05). Findings suggested that Arndt-endobronchial blocker combined with LMA can serve as a promising alternative for morbidly obese patients in OLV in thoracic surgery.

Key words: Laryngeal mask airway; Arndt-endobronchial blocker; L-DLT; One-lung ventilation; Thoracic surgery; Morbidly obese

Introduction

Management of one-lung ventilation (OLV) continues factors (6). Obese patients are also likely to have obstruc- to be a challenge in clinical practice (1). A double-lumen tive sleep apnea (7–9). Maintenance of airway for surgical endobronchial tube (DLT) or a bronchial blocker is usually procedures is difficult due to changing in pulmonary used to achieve one-lung ventilation (OLV) in thoracic sur- mechanics and circulation (10,11). Increased residual geries (2). However, DLT is not easy for nasal intubation in gastric volumes and gastric fluid acidity increase the need some cases due to its large outer diameter and distal for aspirations. Intubation with a DLT might be difficult curvature (3), particularly in patients with difficult airways due to its larger size and shape. At present, although tech- (Mallampati grade view 3 or 4), restricted mouth opening niques for lung isolation in thoracic surgery are increasing and limited neck extension, as it is bulkier and more rigid (12), reports on its optimal use in morbidly obese patients than a single-lumen endotracheal tube (4,5). Distortion of are still relatively scarce. A recent study by Campos et al. the tracheobronchial tree would cause difficulties in place- (13) on comparison between the use of L-DLT and Arndt ment of a DLT. An Arndt bronchial blocker might be better blocker in lung isolation in the morbidly obese found that in such cases. both techniques are clinically equivalent in terms of intuba- Obese patients are known to have increased risk of tion difficulty and time for lung collapse. complications in airway management due to altered air- Laryngeal mask airway (LMA) is a relatively new device. way anatomy. Short neck, limited neck extension and fat It is less invasive and causes less airway resistance. depositionRETRACTED in the pharyngeal wall are some of the causative However, its application is still limited in OLV (14). In the

Correspondence: Z.Q. Niu:

Received June 23, 2017 | Accepted October 16, 2017

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present study, we compared the outcome of the combina- tubes/devices, were taken care of by two experience tion of Arndt-endobronchial blocker and LMA with L-DLT anesthetists. All patients were informed before the pro- in the morbidly obese patients in OLV in thoracic surgery. cedure and were blinded to group allocation. This was done by evaluating the airway establishment, Exclusion criteria included an age of o20 years, ease of insertion, oxygenation, lung collapse, incidence of preoperative hoarseness, mouth opening of o2.5 cm, voice hoarseness and incidence and severity of throat symptomatic or untreated gastroesophageal reﬂux, preg- pain of the patients. nancy, surgery within 46h. We hypothesized that endotracheal intubation of the morbidly obese patients with Arndt-endobronchial blocker Methods of anesthesia combined with LMA would be more feasible and yield better All patients were premedicated with 0.01 mg/kg performance than L-DLT in OLV in elective thoracic surgery. intramuscular (im) injection of penehyclidine hydrochloride and 0.04 mg/kg of midazolam 30 min before induction Material and Methods of anesthesia. After arrival in the operation room, an intravenous (iv) cannula was placed and patients were Selection of patients maintained with infusion of Ringer’s solution at a rate The protocol for clinical investigation performed in of 5 mL Á kg-1 Á h-1. Induction of general anesthesia was this study was approved by the Ethics Committee of the achieved with 3–5 mg/kg fentanyl, 1.5–2 mg/kg propofol, Cangzhou Central Hospital, Cangzhou, Hebei (No. 2015- and 0.1–0.15 mg/kg vecuronium. Central venous pres- 063). Written informed consent was obtained from all sure of the right internal jugular vein was measured and participants. Eighty adult morbidly obese patients with a routine monitoring of heart rate (HR), respiratory rate (RR), 2 BMI 435 kg/m (age, 20–70 years; American Society of electrocardiography, oxygen arterial pressure (SpO2), oral Anesthesiologists physical status I–III) who were sched- temperature, radial artery pressure, and urine output were uled for elective thoracic surgery from September 2015 to performed continuously. December 2016 were randomly assigned into 2 groups, After theARTICLE patients were in full oxygen supply and Arndt group (Arndt-endobronchial blocker combined with complete muscle relaxation, a LMAt Proseal (size 4 for LMA) and L-DLT group, with 40 patients in each group female and size 5 for male; LMA North America, Inc., (Figure 1). USA) was placed followed by a 9 Fr Arndt endobronchial Sequence generation was achieved with a computer- blocker (Cooks Critical Care, USA) for those in the Arndt ized random number generator. Allocation concealment group. Patients in the L-DLT group were intubated with a was achieved by using sealed opaque envelopes. All left-sided [37–41] Fr double-lumen endobronchial tube aspects of anesthetic management, including placing the (L-DLT; Broncho-catht, Mallinckrodt Laboratories, Ireland).

Figure 1. CONSORT ﬂow diagram. Arndt: Arndt- endobronchial blocker association; L-DLT: left- sided double-lumen endobronchial tube.

RETRACTED

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Tube sizes were determined by measurement of the width and optimal position with FOB aid. A maximum of three of the tracheal diameter (in mm) from the preoperative placement attempts was allowed. Each attempt was defined chest radiographs (15). When the Arndt blocker was as withdrawing the bronchial lumen of the Arndt or L-DLT in optimal position, the wire loop was removed and the into the trachea and then attempting to reposition it. wire channel was used for suction. The cuff pressure was Correction of any inadequate seal of the LMA was per- maintained between 55 and 60 cmH2O with a manometer formed. In case of inability to intubate with a DLT, a single- (Mallinckrodt, Germany). All patients were given 1–2 mg Á lumen tube and exchange catheter (Cooks Critical Care) kg-1 Á min-1 of vecuronium with intermittent intravenous was used to place a DLT, and the time was added to the injection of fentanyl and inhalation anesthesia of 1–2% original attempt time. Criteria used to assess malposition isoflurane. Epidural lines were placed in all patients. are as shown in Table 1. Arterial blood gases, PaO2,PaCO2, and intrinsic positive Maintaining of patients end-expiratory pressure were collected during two-lung Accuracy of the Arndt or L-DLT was assessed by using ventilation (baseline data) and 30 min after OLV. a flexible fiberoptic bronchoscopy (FOB; BF type 3 C40; After the pleura was opened and the lung could be Olympus, Japan). Placements were confirmed by two seen, the quality of lung collapse was evaluated. The time experience thoracic anesthesiologists and were again for lung isolation/collapse was measured from the institu- checked after lateral positioning. Patients were carefully tion of one-lung ventilation to the time of total lung collapse. positioned for operation. The head was fixed and after Evaluation of surgical exposure (evaluation criteria as turning to the lateral decubitus position, OLV was initiated. referred to Campos et al. (16) method) were performed by During two-lung ventilation (TLV), patients were main- two thoracic surgeons independently who were blind to tained at tidal volume (Vt) of 8 mL/kg, inspiratory/expi- the group assignment. Collapse of the lung was assessed ratory ratio (I:E) of 1:1.5, fraction of inspired oxygen (FIO2) as follows: 1) spontaneous, 2) assisted with suction, or of 0.6 and RR of 12 breaths per min. During OLV, patients 3) manual. The conditions of surgery were ranked as were maintained at Vt of 6 mL/kg, I:E of 1:2, FIO2 of excellent, fair,ARTICLE or poor: 1) excellent: complete collapse with 0.6 and respiratory rate of 15 breaths per min. In order to perfect surgical exposure, 2) fair: total collapse, but the prevent ventilation/perfusion ratio imbalance due to pro- lung still had residual air, and 3) poor: no collapse was long OLV, suction was performed intermittently. Arterial achieved or partial collapse with interference in surgical blood gases were measured. Open thoracotomy or video- exposure. At the end of surgery, the surgeons gave the assisted thoracoscopic surgery (VATS) was performed. overall assessment of the lung isolation. Results were Tube/device position and adequacy of lung collapse were recorded and the average was calculated. evaluated each 30 min during surgery. An investigator blind to the group assignment of the After surgery, all patients were carefully extubated and patients asked the patients specific questions regarding received supplementary oxygen at 5 L/min via a facemask postoperative hoarseness and throat pain at the post- for 30 min. This was continued if SpO2 was less than 95% anesthesia care unit (PACU) and 12, 24, 48, 72, and 472 h whilst breathing room air. For postoperative pain therapy, after surgery. Throat pain score assessment was performed sufentanil and 0.25% bupivacaine were given upon request with a numerical rating scale (NRS) ranging from 1 to via the epidural catheter. Paracetamol and piritramide, 10 recorded by direct questioning of the patients. NRS=0 0.05 mg/kg intravenous, were given when analgesia was and NRS 40 were considered as painless and painful inappropriate. throat, respectively. All patients were trained on how to answer the NRS. Observation and data collection Intubation time was recorded with a stopwatch from Statistical analysis the time when the tubes or devices passed the vocal cords Primary endpoints were the number of times the tube/ until the anesthesiologists confirmed its correct placement devices were successfully position at the first intubation

Table 1. Criteria to assess endo-tracheal tube malpositions.

Bronchial cuff of the DLT herniated above tracheal carina (more than 50% of the cuff) Bronchial cuff edge of the DLT not visible in the entrance of mainstem bronchus such that it would potentially occlude a secondary bronchus ArndtRETRACTED blocker or DLT in the non-targeted bronchus Bronchial cuff of the Arndt blocker herniated into carina (more than 50% of the cuff), or the distal tip of the blocker above tracheal carina

DLT: double-lumen endobronchial tube

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Table 2. Demographic characteristics, preoperative pulmonary functions and preoperative arterial blood gas values of the patients in the Arndt and L-DLT groups.

Variables Arndt group (n=40) L-DLT group (n=40)

Age (year) 59±12 60±11 Gender (M/F) 34/6 34/6 Height (cm) 166±6 165±7 Weight (kg) 114±11 115±10 BMI (kg/m2) 41.4±3 42.2±3 Neck circumference (cm) 44±445±5 FEV1 (% predicted) 78±13 79±14 FRC (% predicted) 135±18 135±19 RV (% predicted) 142±20 141±21 TLC (% predicted) 105±15 102±16 Smoking history (n) 21 20 ± ± PaCO2 (mmHg, room air) 39 2402 ± ± PaO2 (mmHg, room air) 81 7808 ± ± O2sat (%) 95.9 0.6 96.4 0.8 ± ± PEEPi (cmH2O) 3.1 0.2 3.0 0.4 Pre-op BP (mmHg) 135±22 133±21 Pre-op HR (bpm) 75±676±5 Surgery duration (h) 2.4±1.7* ARTICLE3.1±1.8 Anesthesia duration (h) 2.8±1.9* 3.8±1.8

Data are reported as means±SD. n: number of patients; BMI: body mass index; FEV1: forced expiratory volume in 1s; FRC: functional residual capacity; RV: residual volume; TLC: total lung capacity; PEEPi: intrinsic positive end-expiratory pressure; Arndt: Arndt-endobronchial blocker association; L-DLT: left-sided double-lumen endobronchial tube. * Po0.05 Arndt group compared with L-DLT group (t-test). attempt, the number of malpositions, the time required Demographic characteristics to achieve optimal position verified by FOB, oxygena- Patients in the Arndt group and L-DLT group were tion, quality of lung collapse and surgical field exposure; equivalent in their basic characteristics with regard to age, Secondary outcome were incidence of hoarseness of male/female ratio, height, weight, BMI, neck circumference voice and incidence and severity of throat pain. (NC), pre-operative spirometry results and pre-operative The total number of patients recruited was based on hemodynamic parameters (Table 2). research of previous studies (17,18), to allow detection of at least 2 min difference between the two groups in the Duration of surgery and anesthesia time of tube or device placement, with an a of 0.05 and The duration of surgery and anesthesia for the Arndt power of 0.80. group was statistically shorter than the L-DLT group (2.4± Data are reported as means±SD. Comparison between 1.7 vs 3.1±1.8 and 2.8±1.9 vs 3.8±1.8 h, respectively; the two groups was performed using Student’s t-test. Po0.05; Table 2). Po0.05 was considered to be statistically significant. Surgical procedures performed in the Arndt and L-DLT Analysis was performed using SPSS statistical software group are shown in Table 3. The number of thoracotomies (version 19.0, SPSS Inc., USA). and VATS in the two groups were not significantly different (P=0.48), nor were the numbers of left- and right-sided Results surgeries (P=0.36).

No patient dropped out of the study. In the Arndt group, Number of intubation attempts RETRACTEDs sizes of the single-lumen tracheal tubes for the Arndt The number of intubation attempts and other airway blocker 9 Fr were 8.0 mm ID (n=6), 8.5 mm ID (n=22), and parameters for group Arndt and L-DLT are reported in 9.0 mm ID (n=12). In the L-DLT group, the tube sizes used Table 3. Parameters between the two groups were not were 37 Fr (n=19), 39 Fr (n=13), and 41 Fr (n=8). signiﬁcantly different.

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Table 3. Type of thoracic surgery and related outcomes of the 80 patients and airway parameters.

Type of procedure Arndt group (n-40) L-DLT group (n=40) P value

Lobectomy 0.36 Right-sided 16 14 Left-sided 8 10 Pneumonectomy Right-sided 1 0 Left-sided 1 2 Upper and middle esophageal resection 14 14 Airway parameters Mallampati grade 2.1±1.1 2.2±1.2 0.78 Cormack grade 2.2±1.3 2.3±1.2 0.68 Intubation attempts (n) 1.1±0.1 1.1±0.2 0.56 First attempt (n) 37 36 Second attempt (n) 3 3 Third attempt (n) 0 1 Intubation duration (min) 3.3±0.4 3.4±0.5 0.84 Positioning attempts (n) 1.1±0.1 1.1±0.1 0.81 Number of malpositions (n) 3 3 Positioning duration (min) 4.4±0.6 3.2±0.4 0.92 Adjustments (n) 0.6±0.2ARTICLE 0.4±0.1 0.35 Data are reported as mean±SD or number of patients. Arndt: Arndt-endobronchial blocker association; L-DLT: left-sided double-lumen endobronchial tube. Statistical analysis was done with the t-test.

In the Arndt group, the size of LMAt Proseal used was Lung collapse and surgical field exposure adequate with minimal secretions and without further com- The time required for lung collapse was 14.8±6.2 min plications. There was no dislodgement of mask, airway for the Arndt group and 17.0±6.4 min for the L-DLT group obstruction or pulmonary aspiration during anesthesia. (P=0.39). Quality of lung collapse and surgical field In the L-DLT group, for cases that failed to achieve exposure for the Arndt group was significantly better than successful tube intubation in the first attempt, a second or the L-DLT group (excellent n=40, fair n=0, poor n=0 for third attempt was performed. A single-lumen tracheal tube Arndt group; excellent n=36, fair n=0, poor n=4 for L-DLT followed by insertion of an 11 Fr Cooks airway exchange group; effective rate 100 vs 90%; Po0.05). catheter was used to advance a DLT without difficulties. Incidence of hoarseness of voice, incidence of throat Malpositions pain and throat pain score There were 3 malpositions reported in the Arndt group The incidence of hoarseness of voice and throat pain, and 3 in the L-DLT group in the first 30 min. This occurred and the mean score for throat pain among the patients when turning the patients from supine to the lateral posi- in the Arndt group at PACU and 12, 24, 48, 72 h after tion. For the 3 patients of the Arndt group, the tip of the thoracic surgery were significantly lower than the L-DLT blocker was dislodged above the tracheal carina, while for group (Po0.05; Table 5). No incidence of hoarseness of the 3 patients of the L-DLT group, the endobronchial cuff voice and throat pain occurred after 72 h of surgery. was herniated above the tracheal carina. All cases were repositioned with FOB aid with no further complications. Discussion The overall frequency of malpositions between the two groups was not significantly different (Table 3). Obesity is a worldwide health problem and the prevalence of morbid obesity is increasing over time. Thus, more patients Gas exchange data during OLV requiring anesthesia for thoracic surgery will be over- During OLV, PaO2 of the patients in the Arndt group weight or obese. Obese patients are at risk for difficulties (154±RETRACTED46 mmHg) was significantly higher than the L-DLT placing a DLT. For majority of cases, a left-sided DLT is ± group (105 52 mmHg; Po0.05) while P(A-a)O2 of the preferred over a right-sided DLT due to its greater margin patients in the Arndt group (194±42 mmHg) was sig- of safety. Increase in the NC could serves as a leading nificantly lower than the L-DLT group (243±45 mmHg; risk factor for difficult intubation (19,20), and it is neither Po0.05; Table 4). associated with increased BMI or absolute obesity (20).

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Table 4. Gas exchange data of the 80 patients during OLV.

Variables OLV

Arndt group (n=40) L-DLT group (n=40) ± ± Ppeak (cmH2O) 24 3234 ± ± Pplateau (cmH2O) 16 2152 ± ± PEEPi (cmH2O) 2.5 0.3 2.0 0.4 ± ± PaCO2 (mmHg) 39 5385 ± ± PaO2 (mmHg) 154 46* 105 52 ± ± P(A-a)O2 (mmHg) 194 42* 243 45

Data are reported as means±SD. n: number of patients; OLV: one lung ventilation; Ppeak: peak inspiratory airway pressure; Pplateau: end-inspiratory airway

pressure; PEEPi: intrinsic positive end-expiratory pressure; P(A-a)O2: alveolar- arterial oxygen tension difference; Arndt: Arndt-endobronchial blocker association; L-DLT: left-sided double-lumen endobronchial tube. * Po0.05 (t-test).

Table 5. Incidence of hoarseness of voice, incidence of throat pain and throat pain score among the 80 patients at PACU and 12, 24, 48, 72, and 472 h after thoracic surgery.

Hoarseness of voice Throat pain Throat pain score by numerical rating scale (NRS) Arndt L-DLT Arndt L-DLT ArndtARTICLE group L-DLT group (n, %) (n, %) (n, %) (n, %) Mean Maximum Mean Maximum

PACU 3 (7.5%)* 9 (22.5%) 6 (15%)* 13 (32.5%) 2* 3 5 6 12 h 4 (10%)* 12 (30%) 8 (20%)* 17 (42.5%) 3* 4 7 8 24 h 3 (7.5%)* 10 (25%) 7 (17.5%)* 15 (37.5%) 2* 3 5 7 48 h 2 (5%)* 7 (17.5%) 5 (12.5%)* 13 (32.5%) 1* 2 3 5 72 h 1 (2.5%)* 4 (10%) 1 (2.5%)* 7 (17.5%) 0.25* 1 2 3 472 h 0 (0%) 0 (0%) 0 (0%) 0 (0%) 0 0 0 0

Data are reported as number and percentage. PACU: Post anesthesia care unit; Arndt total number of patients = 40; L-DLT total number of patients = 40. Arndt: Arndt-endobronchial blocker association; L-DLT: left-sided double-lumen endobronchial tube. * Po0.05 (t-test).

Studies found similar difficulty of intubation for both Low functional residual capacity and expiratory reserve Arndt and DLT, however, DLT placements were exposed volume contribute, respectively, to hypoventilation and poor to additional risk such as potential for aspiration, progres- lung collapse in OLV (26). Decrease in lung and chest wall sive desaturation during the exchange and direct damage compliance may also result in intraoperative hypoventila- leading to tracheal or bronchial perforation or tension tion during mechanical ventilation and increased work pneumothorax (2,21). LMA could be a primary option in for breathing in the postoperative period when patients case of difficult and failed airways. However, LMA alone resume spontaneous ventilation (26). is not able to provide OLV in thoracic surgeries. Studies In the present study, we compared the ease and showed that combination of LMA with Arndt-endobronchial success of placement of tube/devices in the morbidly blocker could provide effective surgical exposure in OLV. obese patients in OLV for thoracic surgery between the The technique was also associated with reduced fluctua- Arndt and L-DLT group. In the Arndt group, selection of an tions in hemodynamic response (14). LMA causes less appropriate LMA size is important. First, the mask should airway resistance than endotracheal intubation which may, be able to provide an airtight seal during positive pressure in turn lead to decreased bronchoconstrictive reflex, fewer ventilation. Second, the mask should not produce exces- pulmonary infections and less atelectasis (22). sive pressure to the pharynx. Lastly, the mask should not ObesityRETRACTED is associated with restrictive lung disease due be too large (27). In a study done by Voyagis et al. (28) to increased intraabdominal pressure and decreased chest attempting to decide whether the patient’s age or weight wall compliance (23,24). A study showed that decreases was a better indicator for selecting the appropriate size in forced expiratory volume in 1 s and forced vital capacity of a laryngeal mask, it was found that the mean peak are inversely proportional to the increase in BMI (25). inspiratory pressure at which air leak occurred was greater

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using the sex-related method compared to the weight- Overall, in our study, difficult intubation was not sig- related method. In a study by Asai et al. (27), it was found nificantly different between the groups. The findings were that a larger size (size 4 in females and size 5 in males) comparable with the previous study done for comparison provided an airtight seal more frequently than smaller between Arndt and DLT in obese (13) and normal weight sizes, without producing a higher pressure on the pharynx. (14) patients, and either with (14) or without (13) com- The incidence of air leak was significantly lower when bination with LMA. a larger mask was used. Kagawa and Obara (29) pro- The number of malpositions was similar in both Arndt posed a formula for LMA size based on patient weight and L-DLT groups. Malpositioning might occur due to relationship. obese patients having shorter necks and decreased In our study, the size of LMA used (size 4 in females neck mobility than normal. With these patients, it might and size 5 in males) was adequate to provide a proper be difficult to support the head in the lateral decubitus seal for the patients. With the combination of Arndt blocker position with a flex-position bed. Patients in the Arndt and LMA, tracheal suctioning can be performed via the group required laryngeal mask manipulation resulting in internal channel of the FOB via direct visualization (14). the increase in the positioning duration by 1.2 min. There was seldom requirement for suctioning in patients However, the increase was not significantly different of the Arndt group. It has been reported in a previous from the L-DLT group. study that the oropharyngeal leak pressure of the LMA PaO2 of patients in the Arndt group was significantly ProSeal was 32 cmH2O (range, 12–40 cmH2O) (14,30). higher than the L-DLT during OLV. The time for lung In the present study, the peak airway pressure during collapse was similar in both groups, and was comparable ± OLV was 24 3 cmH2O in the Arndt group, which is far with the previous study done by Campos et al. (13) and below the leak pressure of the LMA ProSeal and this is Li et al. (14). Quality of lung collapse and surgical field comparable with the previous study (14). exposure in the Arndt group was significantly better than In the Arndt group, a second attempt was necessary the L-DLT group, which probably contributed to the shorter to achieve successful intubation in 3 patients. Securing duration of surgeryARTICLE and anesthesia for the Arndt group. the airway with a single-lumen tracheal tube is the Bronchial blockers have been considered the best most important step in patients with difficult airways. This device for patients with difficult airways. There is no need may have an advantage as it avoids the use of a tube to replace a tube if mechanical ventilation is required (36). exchanger (13). Risk of airway complications may increase when using In the L-DLT group, two or three attempts were a DLT compared to a bronchial blocker for achieving necessary to achieve successful intubation in 4 patients. OLV (37). Sore throat and hoarseness of voice are among Intubation with a single-lumen tracheal tube followed the well-known postoperative complications after tracheal by an airway exchange catheter is much easier than a intubation (38). standard laryngoscope with a DLT due to the larger size In the present study, the incidence of hoarseness and shape of a DLT (31). Besides, Dhonneur et al. of voice and the incidence and severity of throat pain in (32) described using a CTrach LMA as an alternative the Arndt group in the PACU and 12, 24, 48, and 72 h approach for morbidly obese patient. after thoracic surgery were significantly lower than the A study by Gonzalez et al. (33) found NC 443 cm L-DLT group (Po0.05), which were consistent with pre- as an indicator for increased risk of difficult intubation vious studies (14,37). Curved endobronchial lumen and while Neligan et al. (34) found no predictive association size of the L-DLT tubes could be the main risk factors for between NC and difficult intubation. Another study by postoperative hoarseness during intubation and extuba- Riad et al. (35) found BMI 450 and NC 442 cm as tion. There was no incidence of hoarseness of voice and the independent predictors for difficult intubation and throat pain after 72 h of surgery. BMI 450 and male gender as independent predictors for LMA may cause laryngopharyngeal mucosal injury in difficult mask ventilation. In our study, the mean NC of the a time-dependent manner. Studies found that prolonged patients in the Arndt group and L-DLT group was 44±4 use of LMA in pigs for o9 h was associated with no or and 45±5 cm, respectively, while the mean BMI was mild changes in the laryngopharyngeal mucosa while 41.4±3 and 42.2±3 kg, respectively. In the Arndt group, clear signs of mucosal injury were observed after X12 h the NC of the patients who failed the first intubation use (39). A previous study reported that injury scores attempt was 45.5, 45.8, and 46.2 cm, while the BMI of the bronchus and vocal cords in the DLT group were was 43.2, 43.7, and 44.1 kg, respectively, which was not significantly higher than Arndt combined with ProSealt, significantly different from the other patients in the same while the larynx injury score was significantly lower in the group.RETRACTED In the L-DLT group, the NC of the patients who DLT group (14). In the present study, surgeries of 46h failed first intubation attempt was 45.8, 46.3, and 47.0 cm, duration were excluded to minimize risk. while the BMI was 43.6, 43.9, and 44.3 kg, respectively, The use of an Arndt endobronchial blocker may which was also not significantly different from the other overcome some of the limitations of DLT, such as difficult patients in the L-DLT group. airway. When applied in combination with Prosealt LMA,

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the limitations of the traditional use of endobronchial morbidly obese patients in OLV for thoracic surgery with blockers can be further overcome. This novel combination similar ease of airway establishment as L-DLT, better can be very useful in many clinical scenarios, and make airway pressure, quality lung collapse and surgical ﬁeld thoracic anesthesia much easier (40). Combination of exposure, shorter duration of surgery and anesthesia, Arndt with LMA may exhibit more advantages over DLTs lower incidence of hoarseness of voice and less incidence particularly in less invasive day-case thoracic surgeries, and severity of throat pain. the number of which is rapidly increasing throughout the world (14). Development of newer designs of LMA would Acknowledgements help to improve its usage and provide optimal and better beneﬁts in the future. This study is supported by the Cangzhou City Science In conclusion, combination of the Arndt-endobronchial and Technology Research and Development Projects blockerwithLMAcanbeapromisingalternativefor (No. 151302063).

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