The Use Of Bronchial Blocker Versus Doublelumen Tube For One-lung Ventilation During Thoracoscope Assisted Mitral Valve Surgery

PurposePostoperative hoarseness, sore throat and vocal cord injuries are common complications after general anesthesia. The incidence of postoperative hoarseness is as frequent as 50% after short-term tracheal intubation. In the past, several risk factors for postoperative hoarseness and laryngeal injury have been identified, including demographic factors, quality of tracheal intubation and technical factors such as endotracheal tube size. One-lung ventilation during thoracotomy can be achieved via two basic techniques:(1) use of a double lumen endotracheal tube(DLT) consisting of an endotracheal and an endobronchial lumen allowing independent single-lung ventilation; or(2) use of an endobronchial blocker such as the arndt blocker, which allows lung collapse distal to the occlusion. It has been recently demonstrated that DLT and endobronchial blocker are similar in their efficacy to achieve lung isolation for elective thoracic surgery. No data are available yet about the influence of the chosen technique on postoperative hoarseness, vocal cord injuries, sore throat and bronchial injuries. Published data of Stout et al. imply that the incidence of postoperative hoarseness and vocal cord injury might be directly correlated with size of the used endotracheal tube. During thoracoscope assisted mitral valve replacement cardiac surgery, excellent lung isolated was not required. One-lung ventilation with the other lung collapsed is used to achieve a better exposure and assist the surgery. During the cardiac surgery under cardiopulmonary bypass, heparinization will lead to uncontrolled hemorrhage if there is endotracheal tube insertion associated injury. In addition, DLTs need to be exchanged for a single-lumen tube before the patient transferring to cardiac care unit for postoperative ventilatory support. This may result in second time injury. Investigators hypothesized that using a bronchial blocker to achieve one-lung ventilation may result in a lower incidence of clinically relevant laryngeal and bronchial morbidity after thoracoscope assisted mitral valve replacement cardiac surgery compared with a control group intubated with a DLT. MethodsWe conducted a prospective, randomized controlled trial involving adults who were scheduled for elective thoracoscope assisted mitral valve replacement cardiac surgery in Xijing Hospital from September 2015 to Feburary 2016. Patients were screened the day before surgery for eligibility and then written informed consent was obtained. Fifty-eight patients were randomly divided into double lumen endobronchial tube group(DLT group) or bronchial blocker group(BB group). The primary endpoint was a composite of clinically relevant laryngeal and bronchial morbidity, including postoperative hoarseness, laryngeal injury, hypoxia, atelectasis, and pulmonary infection. Secondary end points included the occurrence of any complications related to other organs, duration of mechanic ventilation, length of CCU stay, length of postoperative hospital stay, and all cause mortality at hospital discharge.Hemodynamic data(heart rate, central venous pressure, systolic blood pressure, diastolic blood pressure and mean arterial pressure) were recorded right before intubation(T1), immediate after intubation(T2), and three minutes after intubation(T3). Difficulty in intubation and endotracheal injury were assessed by recordings of the time needed for positing the endotracheal tube, the number of intubation attempts, the cuff pressure, the degree of lung collapse and the score of mucosal injury. clinically relevant laryngeal and bronchial complications was defined as the number of tube displacement and the degree of tracheal mucosal injury during the surgery. Simultaneously, the effects of one-lung ventilation was determined by the data of blood gas analysis and the respiratory related parameters at three different time points, that is before one-lung ventilation(T4), at the end of one-lung ventilation, at initiation of CPB(T5), and at the end of the surgery(T6).Comparisons between groups were made by using the Mann-Whitney U-test. Comparisons within groups were made by using the paired t-test. ResultsThere was 4 diaplacement in the BB group while none displacement as recorded in the DLT group; There was 11.11% and 21.43% postoperative pulmonary complications in BB and DLT group, respectively. However, due to the small sample size, statistic significance was not achieved. As refer to other laryngeal morbidities such as the incidecne of hoarseness, sore throat and the extent of mucosal injury, intubation with BB significantly reduced the laryngeal morbidities. Airway mucosal injury score in BB group(0.15 points) was significantly lower than the that of DLT group(0.68 points).The average time for positioning the endotracheal tube were 168 s and 145 s in BB and DLT group respectively. Only one case needed second intubation attempt to repalce the orginigal DLT due to cuff leakage. Mean main cuff pressures were 18.50 cm H2 O in BB group and 18.0 cmH2 O in DLT group. One case in BB group while two cases in DLT group with incidence of 3.57% and 7.14% did not achieve satisfactory lung collaspe.. The average pressure of blocker cuff exceeded 120 cm H2 O in BB Group while the average pressure of left bronchial cuff is 13cmH2 O in DLT.Intubation of DLT induced significant hemodynamic change with significantly increase of MAP at T3( 85 mmHg vs 70 mmHg, p <0.05), indicated the stimulation was much stronger when intubated with DLT.Both arterial carbon dioxide( mean value 38 mmHg vs 35 mmHg) and end-tidal carbon dioxide(mean value 33.5 mmHg vs 30.5 mm Hg)was significantly higher in DLT group with a lowered peak inspiratory pressure(mean value 16 cmH2 O vs 18 cm H2O) Conclusion1. Both of BB and DLT are effective in conducting one-lung ventilation without obvious hypoxia.2. Intubation of DLT associated with significantly higher incicent of clinically relevant laryngeal and bronchial complications, most of which are machanical injury related.3. In summary,in thoracoscopy assisted on cardiopulmonary bypass mitral valve replacement/plasty cardiac surgery, the use of bronchial blocker tube and double lumen tube have no difference in the effectiveness of conducting one-lung ventilation and lung isolation. However, the overall incidence of airway complications is significantly lower when bronchial blocker is chosed. Therefore, bronchial blocker is recommended in this particular procedure.