Lung Collapse With Bronchial Blocker

Background:

Lung isolation is frequently used during thoracic surgery. Two techniques are principally used: the double lumen tube (DLT) and the bronchial blocker (BB). Today, the thoracic surgical technique with more perspective is the video-assisted thoracoscopy surgery (VATS), which requires an effective lung isolation technique

The DLT is the one that is widely used by the vast majority of anesthesiologists. It has been introduced in the eighties in its actual version of polyvinyl chloride. Its positioning with a fibrobronchoscope (FOB) is well established. Its efficiency is reproducible and it is used without major complication. Its use is limited in the presence of difficult airway.

The BB had appeared in its modern form at the end of the 1990. It is easy to use but its reputation is darken by the need of multiple repositioning during surgery and especially by a slower lung collapse than the DLT. The collapse of the isolated lung is the result of denitrogenation atelectasis and the draining of isolated lung through the inner channel of the BB. The diameter and the length of the internal channel vary depending of the model. The BB inner channel is very much smaller (Cook's Arndt: 1.3 mm; Cook's Cohen: 1.6 mm and Fuji's Uniblocker: 2.0 mm) than the lumen of a DLT, which varies from 6 to 9 mm (for a 35 to a 41 Fr tube).

A comparative study published in 2003 by Campos demonstrated results in favor of the inner channel draining hypothesis. Authors showed that the lung collapse with the Arndt BB is longer than with the Uniblocker BB or the BronchoCath DLT and that it needs more suction through the inner channel (p>0.06). The limitation of this report is that the number of thoracotomies and of video-assisted thoracoscopies surgery (VATS) was not mentioned. Furthermore, the side of surgery was not specified. This point is very important since the inflated cuff of a BB located into the right main bronchus may obstruct the origin the right upper lobe, and consequently impair its collapse.

In 2009, with a series of 45 thoracotomies and 22 VATS, Narayanaswamy and Slinger demonstrated that when both lung isolation and one lung ventilation (OLV) are started early, meaning immediately post-induction and intubation in dorsal decubitus position, and continuously maintained until the pleural is opened. Similar surgical exposure at 10 and 20 minutes post pleural opening was obtained with all three modern BB as with left DLT. In this report, the duration of the lung isolation period and of the one lung ventilation was not specified. We presume that this length was over 20 or 30 minutes before pleural opening, which created a lung collapse by denitrogenation, as shown by a later publication by the same research team. An early -20 cmH2O suction (at the start of OLV) through either a DLT or a Cohen's BB improved lung collapse quality compared to a late application (20 min after pleural opening). This advantage was not demonstrated with the Arndt BB or the Fuji's. Another limitation of this study is that it was done with only left unilateral surgeries to avoid inflating the BB cuff into the right main bronchus. This choice creates an important selection bias since these results cannot be applied to a universal use of BB.

In 2009, Ko and Slinger also published the following: the use of a fraction of inspired oxygen (FiO2) of 1.0 (denitrogenation) while ventilating before the initiation of OLV through a DLT gives a better surgical exposure at 10 and 20 minutes compared to a FiO2 of 0.4. These results are from 4 VATS and 100 thoracotomies.

Early initiation of OLV in dorsal decubitus is not recommended by any author for the following reasons: an additional OLV period of 15 to 30 minutes is not beneficial for the patient if desaturation occurs. Moreover, mobilization of patient in lateral decubitus could lead to complications related to an inflated BB. In fact, proximal movement of the BB's cuff can completely obstruct the trachea. There is also a risk of trauma to the airway. Note that these risks are theoretical since they were note described in this context. Since it is recommended to proceed to lung isolation when the patient in positioned in lateral decubitus, it is not surprising that these complications are not reported in the literature.

Reading recent literature on the subject and according to the vast experience of numerous hospital centers, it seems that the slowness of lung collapse remains without any solution. This slowness in lung deflation is detrimental to the initiation of VATS and could be exacerbated in COPD patients. For this reason, BB use is discredited in numerous centers.

However, at IUCPQ, the investigators rarely observe slow lung collapse when BB are used. For many years, the investigators have used a systematic denitrogenation of the lung before the initiation of OLV. Furthermore, when the patient is positioned in lateral decubitus, the investigators impose an apnea period of about 30 seconds to favor collapse of the isolated lung before inflating the cuff. This apnea is always limited by the occurrence of O2 desaturation (≤97%). The investigators also proceed to a second period of apnea of 30 seconds associated to a deflated BB's cuff at the pleural opening. Subsequently, the investigators inflate the BB's cuff to obtain definitive lung isolation.

Actual literature does not allow the anesthesiologists to conclude clearly on a choice of bronchial blocker. Thus, the investigators propose a study that will add up to essential data to make a better choice of lung isolation device.

Hypothesis:

The investigators hypothesis is that the use of two apnea periods, when isolating the lung with a BB, will allow the same quality of surgical exposure at 0, 5, 10, and 20 minutes post opening of the pleura compared to the one obtained with DLT. The investigators will use Fuji's BB and occlude its internal channel to be able to extrapolate the investigators results with other BB that are actually on the market.