IPg2 Study: Left-sided Lung Isolation

Overview

Lung isolation is primordial in thoracic surgery. To achieve it, two techniques are used: the double lumen tube (DLT) and the bronchial blocker (BB). Left-sided DLT (L-DLT) is use by the majority of anesthesiologists for both left and right thoracic surgeries. Standard right-sided DLT (Rs-DLT) is rarely use since it is dif¬ficult to properly position it and that there is a risk of misalignment between the lateral orifice of the tube and the origin of the right upper lobe (RUL) bron¬chus. In 2007, the investigators have published results suggesting enlarging the Rs-DLT's lateral orifice. The modified R-DLT (Rm-DLT) was more frequently in an adequate position: 77% vs 37% of patients (p = 0.0121), and easier to reposition: 97% vs 74% of patients (p= 0.0109) in comparison to the standard R-DLT group. The data suggest the superiority of the Rm-DLT compared to Rs-DLT for optimal positioning to facilitate one-lung ventilation (OLV) during thoracic surgery. It is believed that DLT tend to provide quicker and better quality of lung collapse than BB. In 2013, investigators have demonstrated an equivalent quality of lung collapse (LC) between L-DLT and BB used with two apnea periods when initiating OLV. Complementary analysis showed a significative difference to obtain complete LC (CLC) between L-DLT for left thoracoscopy and L-DLT for right thoracoscopy and BB in right or left surgery. The investigator hypothesis is that, when using L-DLT for left video-assisted thoracoscopic surgery (VATS), LC of the isolated lung will be slower and of poorer quality compare to the use of the Rm-DLT. The primary objective is to compare the delay between pleural opening (PO) and CLC in left VATS when using three lung isolation devices: 1) L-DLT and 2) Rm-DLT. Secondary objectives are: 1) to evaluate quality of LC, 2) to evaluate the level of obstruction of the lumen of the left bronchus, 3) to evaluate the quality of OLV (PaO2) 4) To collect blind surgeon's opinion about de device used and 5) to measure the delay between OLV and PO for evaluating the role of absorption atelectasis in obtaining CLC. After obtaining IRB approval, the investigators propose a study of 40 patients undergoing an elective left VATS at IUCPQ involving one lung ventilation. They will have to be 21 years or more, to read, understand and sign an informed consent at their pre-operative evaluation. This study will be prospective, randomized, and blind to thoracic surgeons.

Background: Lung isolation is frequently used in thoracic surgery. The quality of the isolation is crucial, especially for video-assisted thoracoscopic surgery (VATS). Two techniques are principally used to obtain lung isolation: the double lumen tube (DLT) and the bronchial blocker (BB). The left-sided DLT (L-DLT) is used by the majority of anesthesiologists, as much for left as for right thoracic surgeries. The standard right-sided DLT (Rs-DLT) is rarely used since positioning its lateral orifice with the origin of the right upper lobe (RUL) can be difficult.(1-4) In 2007, the investigators have published their results suggesting an enlargement of the lateral orifice of the Rs-DLT.(5) They have demonstrated that the modified right-sided double lumen tube (Rm-DLT) remained more frequently in optimal position than the Rs-DLT (77% vs. 37%, p=0.0121) and that it was also easier to reposition the tube after turning the patient in lateral decubitus (97% vs. 74%, p=0.0109). More recently, investigators have demonstrated, with three dimensional reconstruction of computed tomography of 106 patients, that angulation between the RUL and the horizontal posterior plane varies from -26 to +58°, justifying the modification of the Rs-DLT proposed in 2007. (Unpublished data) The use of BB for lung isolation is believed to provide a slower and a poorer quality of lung collapse (LC) than DLT. Over the years, the investigators have demonstrated an equivalent quality of lung collapse between the L-DLT and BB when two apnea periods are used at the beginning of one-lung ventilation (OLV). (Unpublished data) Further to complementary analysis, investigators have noted a significant difference in time to get complete lung collapse between left and right thoracic surgery when using the L-DLT. Time to obtain complete lung collapse (CLC) was not different when comparing BB and L-DLT in left thoracic surgery. The hypothesis to explain these observations is that when the bronchial extremity of the L-DLT is inserted into the left main stem bronchus (LMSB), the LMSB and its relative superior position, associated to a progressive collapse of the left lung, could induce a dynamic obstruction of the distal extremity of the L-DLT lumen, and consequently slowing the lung collapse. Investigators have also regularly observed this type of obstruction during bronchoscopic examination when positioning the L-DLT. In past studies comparing L-DLT to BB, time to get CLC was measured from the beginning of OLV. Nevertheless, the interval between this time point and the pleural opening (PO) is sometime difficult to control. Technical incidents can prolong this period and induce a bias. Furthermore, in the last investigator's protocol, the second period of apnea is done at pleural opening. For these reasons, the authors consider that the time to get CLC should be measured from the pleural opening since it is the crucial moment for the surgical team. Investigators are proposing to evaluate the PO-CLC interval as a primary objective.(6) Hypothesis: The hypothesis of the proposed study is that the use of the L-DLT will allow for a slower and a poorer quality of CLC compared to the ones obtained with the Rm-DLT in left VATS.