Comparison of Endobronchial Intubation Versus Bronchial Blockade for Elective Pulmonary Lobectomy of Congenital Lung Anomalies in Small Children

Introduction

Congenital lung malformations (CLMs), such as congenital pulmonary airway malformations (CPAMs) and bronchopulmonary sequestrations (BPSs), have an estimated incidence of 4.15 per 10,000 births. ¹ Improved prenatal imaging modalities, namely ultrasonography and magnetic resonance imaging, have resulted in an increasing incidence in recent years.^2–6 Definitive treatment for asymptomatic CPAMs and intralobar BPSs involves pulmonary lobectomy and frequently occurs during the first year of life.^7–13 In the United States, pre-emptive resection, rather than observation, has become the standard of care to prevent future pulmonary complications, such as pneumonia, lung abscess, or malignant transformation. ¹⁴

Thoracoscopic lobectomy has been associated with a host of clinical benefits, such as decreased postoperative pain and shorter in-hospital length of stay, and, thus, this approach has continued to gain popularity over thoracotomy in many centers.^15,16 Given the small space within the infantile chest, single-lung ventilation is virtually always necessary to provide the surgeon with sufficient working space. For infants and small children, the two-lung isolation strategies available include either main stem intubation or utilization of a bronchial blocker. ¹⁷

However, little research exists on the ideal method of lung isolation for facilitating pulmonary lobectomy in infants and small children. We, therefore, set out to review our institutional outcomes to determine whether one method of lung isolation was associated with better clinical results for patients undergoing pulmonary lobectomy for CLMs.

Materials and Methods

A retrospective chart review of all pediatric patients under the age of 2 years undergoing elective pulmonary lobectomy for resection of a CLM at a tertiary-care pediatric hospital from 2011 through 2020 was performed. Demographics, diagnosis, method of lung isolation employed, perioperative data, and clinical outcomes were recorded. Perioperative data included estimated blood loss, transfusion requirements, operative time, anesthesia time, intraoperative hypoxemia, days until chest tube removal, hospital length of stay, 30-day readmissions, 30-day reoperations, surgical site infections, and mortality. Hypoxemia was defined as oxygen saturation rates of <90%.

Patients were split into two cohorts based on whether they were managed with a bronchial blocker or contralateral main stem bronchus intubation. Lung isolation methods employed were made on a case-by-case basis with input from both the pediatric surgery and pediatric anesthesiology teams. For the bronchial blocker group, a balloon-tipped blocker was inserted under fiberoptic bronchoscopy in all cases. Similarly, contralateral main stem intubation was confirmed with fiberoptic bronchoscopy for all patients.

Carbon dioxide (CO₂) insufflation to 4–6 mmHg was only employed if the surgeon felt that complete lung collapse had not been achieved with the initial method of lung isolation employed. All operations were performed by 1 of 4 fellowship-trained pediatric general surgeons, whereas all anesthetic care was managed by 1 of 7 fellowship-trained pediatric anesthesiologists. Continuous variables were then analyzed with Student's t-tests, whereas categorical variables were analyzed with Fisher's exact tests. The study was approved by the local Institutional Review Board Committee, registration number 21-00904.

Results

Thirty-two patients were identified—17 of whom were managed with a bronchial blocker, whereas 15 underwent main stem intubation. CO₂ insufflation was utilized for 76.5% (13/17) of the bronchial blocker group, but only for 20% (3/15) of the main stem intubation group. The most common diagnoses were CPAMs (53.3%) and intralobar BPSs (34.4%; Table 1). The most commonly affected anatomical sites were the right lower lobe (46.9%, 15/32) and left lower lobe (40.6%, 13/32).

Patients managed with main stem intubation were slightly younger (6.3 ± 4.4 months versus 10.4 ± 6.3 months, P = .06) than patients for whom a bronchial blocker was used. Thirty-one (96.9%) resections were initiated thoracoscopically. Among the 17 patients isolated with a bronchial blocker, 4 were eventually converted to a main stem intubation intraoperatively. None of the 15 patients initially isolated through main stem intubation underwent conversion to a bronchial blocker intraoperatively.

Main stem intubation was associated with shorter operative times (139.3 ± 61.8 minutes versus 202.9 ± 73.5 minutes, P = .01), shorter anesthetic times (259.5 ± 72.1 minutes versus 328.9 ± 76.5 minutes, P = .02), and less intaoperative blood loss (14.3 ± 12.5 mL versus 47.1 ± 56.9 mL, P = .04; Table 1). Review of the operative reports found that the surgeon stated that re-expansion of the lung being dissected in the bronchial blocker group was frequently encountered. This re-expansion, which was often found to be attributable to migration of the blocker, often led to poor visualization of the anatomy and inability to maintain a sufficient intrapleural working space.

No differences in length of stay (P = .64), conversation to thoracotomy (P = .35), intraoperative complications (P = .23), or postoperative complications (P = .49) were observed (Table 1). There were no mortalities. Although there was no difference observed between the two groups for the end-tidal CO₂ after intubation or before extubation, the average end-tidal CO₂ during surgery was slightly higher in the bronchial blocker group (52.5 ± 4.9 mmHg versus 48.3 ± 5.6 mmHg, P = .03). Blood transfusions were administered to 17.7% (3/17) of patients isolated with a bronchial blocker, whereas no patients in the main stem intubation group received a blood transfusion.

In the bronchial blocker group, 35.3% (6/17) of patients experienced at least one period of hypoxemia, whereas only 6.7% (1/15) of patients in the main stem intubation group experienced a similar level of desaturation. Two patients in the bronchial blocker group were inadvertently extubated when attempting to remove the blocker. In addition, position of the bronchial blocker had to be adjusted intraoperatively for 47.1% (8/17) of the patients in this group, either because it (1) retracted and blocked the trachea or (2) advanced and allowed for ipsilateral lung inflation. None of the patients in the main stem intubation group required intraoperative adjustment of their endotracheal tube.

Discussion

Increasingly, elective resections of CPAMs, BPSs, and other congenital lung anomalies are being performed in infants thoracoscopically.^15,16 Although it is possible to perform thoracoscopic lobectomies in infants while ventilating both lungs, single-lung ventilation is preferred to avoid CO₂ insufflation and potential hypercapnia.^18,19 Although the operative time of 202.9 ± 73.5 minutes in our bronchial blocker group is quite high, the operative time of 139.3 ± 61.8 minutes for the main stem intubation group is well within the range of what has been previously reported in the literature.^19–21

Our data show that although satisfactory outcomes can be achieved with either bronchial blockade or main stem intubation, the latter strategy is associated with better clinical outcomes, including shorter operative time, diminished anesthetic exposure, and less intraoperative blood loss. Although not statistically significant, patients undergoing main stem intubation were also less likely to necessitate a packed red blood cell transfusion and less likely to experience a postoperative complication in our experience.

The differences in clinical outcomes were universally due to abrupt loss of the working space and, thus, poor visualization of the intrathoracic anatomy. These instances were disproportionately encountered in the bronchial blocker group in this study. Some authors have previously reported using a Fogarty embolectomy catheter to provide bronchial blockade, although bronchial rupture has been reported with this technique.^22–25 However, no Fogarty embolectomy catheters were used in this study and, thus, we cannot draw any conclusions as to their efficacy.

Both methods of lung isolation have potential drawbacks. Criticisms of main stem intubation include both the relatively shorter length of the right main stem bronchus, as compared with the left, and the potential to occlude the right upper lobe bronchus, which could potentially hinder gas exchange and systemic oxygenation. ¹⁷ Furthermore, bronchial blockers can be deflated during surgery to ensure that the surgeon is not impinging upon any bronchial structures that are not meant to be divided. With a main stem intubation, performing a similar check would entail pulling the endobronchial tube back into the trachea.

To then subsequently advance the endotracheal tube back into the main stem bronchus, particularly with an infant in decubitus position, can be a challenging task even for an experienced anesthesiologist. ²⁶ Finally, main stem intubation does not allow for suctioning of the lung being dissected, although suctioning is not possible through smaller bronchial blockers either.

In contrast, bronchial blockers have the ability to migrate during surgery. Cranial migration can potentially lead to blockade of the entire trachea, whereas caudal migration can result in ipsilateral lung expansion and, thus, obliterate the surgeon's already-limited working space.^17,27 In this study, both of these migration events were observed among the patients for whom a bronchial blocker was utilized. Furthermore, due to the physical properties of their balloons, some blockers have caused airway rupture.^26–29 There have also been multiple reports of bronchial blockers being entrapped by endoscopic staplers, although no such events occurred in this study.^30–32

This study does have limitations, including its relatively small sample size. In addition, this was a retrospective study and, therefore, patients were not randomized to the method of lung isolation employed. Thus, there remains the possibility that there could have been other differences between the two groups that could account for the differing clinical outcomes observed.

Although not statistically significant, patients in the bronchial blockade group were somewhat older (10.4 months versus 6.3 months, P = .06) than patients in the main stem intubation group. It is, therefore, possible that the improved clinical outcomes observed could be due, in part, to the different age at which surgery was performed, rather than solely on the type of lung isolation utilized. To that point, at least one large study found operative times to be shorter when thoracoscopic lobectomy was performed in patients <3 months of age. ³³

Conclusions

In conclusion, utilization of main stem intubation, as opposed to bronchial blockers, was associated with shorter operative times, less time under anesthesia, and less intraoperative blood loss. These superior clinical outcomes are important findings, which argue that the potential benefits of bronchial blockers are actually outweighed by the longer operative time and more lengthy anesthetic exposure that results from their use. A randomized controlled trial would be best suited to determine whether one method of single-lung ventilation is conclusively better for facilitating thoracoscopic pulmonary lobectomies in infants and small children.