Mechanical ventilation strategy reduces atelectasis during bronchoscopy
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Atelectasis occurred less frequently when patients received ventilation through an endotracheal tube than through a laryngeal mask airway during bronchoscopy, according to study results published in CHEST.
The ventilatory strategy to prevent atelectasis (VESPA) also involved fraction of inspired oxygen (FiO2) less than 100% and positive end-expiratory pressure (PEEP) of 8 cm H2O to 10 cm H2O, according to researchers.
“We were able to demonstrate that VESPA significantly reduced the incidence of atelectasis, was well tolerated and had a sustained effect over time despite the pro-atelectatic maneuvers (obstruction of the airway caused by the bronchoscope and the balloon, suctioning, bleeding, etc) that occur during nodal staging with endobronchial ultrasound,” Moiz Salahuddin, MD, pulmonologist from the department of pulmonary medicine at The University of Texas MD Anderson Cancer Center, and colleagues wrote.
In a prospective, randomized, controlled trial, Salahuddin and colleagues analyzed 76 patients undergoing bronchoscopy with general anesthesia to assess if VESPA could safely decrease the occurrence of atelectasis. According to researchers, atelectasis is known to increase CT scan body divergence, keep targets from being seen and cause false-positive radial-probe endobronchial ultrasound (RP-EBUS) images.
Researchers randomly assigned 38 patients to receive standard mechanical ventilation via a laryngeal mask airway with 100% FiO2 and zero PEEP, whereas the other 38 received VESPA via an endotracheal tube with FiO2 titration (< 100%) and PEEP of 8 cm H2O to 10 cm H2O. VESPA patients also underwent a recruitment maneuver following endotracheal intubation.
Results
Researchers calculated the proportion of patients with atelectasis based on chest CT imaging and a RP-EBUS survey that evaluated both left and right bronchial segments 6, 9 and 10 after both artificial airway insertion (time 1) and 20 to 30 minutes later (time 2).
Chest CT scans taken after artificial airway insertion showed that a greater proportion of patients who received standard ventilation had either unilateral or bilateral atelectasis compared with those who received VESPA at both time 1 (23.7% vs. 10.5%) and time 2 (84.2% vs. 28.9%; P < .0001).
Similarly, standard ventilation also resulted in a greater proportion of patients with bilateral atelectasis than VESPA (time 1 = 10.5% vs. 2.6%; time 2 = 71.1% vs. 7.9%; P < .0001).
Researchers also found a more atelectatic bronchial segments in those receiving standard ventilation than those receiving VESPA at time 2 (mean, 3.84 ± 1.67 vs. 1.21 ± 1.63; P < .0001).
Between both groups, the rate of complications did not differ, and researchers reported no major complications.
“We achieved a significant reduction in atelectasis with VESPA, but we did not manage to eradicate it fully,” Salahuddin and colleagues wrote.
Future studies
According to Salahuddin and colleagues, their results were comparable to a previous study that included a more aggressive ventilator strategy, and this inspired them to consider another atelectasis reduction strategy that needs to be studied in the future.
“Our group recently reported an alternative strategy to overcome atelectasis based on patient positioning: bronchoscopy in the lateral decubitus position,” they wrote. “We briefly described our initial experience of robotic bronchoscopy (Ion, Intuitive Surgical) in the lateral decubitus position with mobile cone-beam CT scan guidance. ... This positional strategy may prove useful in patients with small posterior lesions, and we believe it warrants further studies.”
This study by Salahuddin and colleagues demonstrates that VESPA has potential to help patients undergoing bronchoscopy with general anesthesia, but it needs to be further investigated, according to an accompanying editorial by Robert J. Lentz, MD, and Samira Shojaee, MD, MPH, of the division of allergy, pulmonary and critical care medicine and the department of thoracic surgery at Vanderbilt University Medical Center.
“VESPA is a no-cost intervention that appears safe and should be considered when precision sampling of a peripheral lesion may be required,” Lentz and Shojaee wrote. “Rigorous future studies should focus on its impact on diagnostic yield, the study of different PEEP and FiO2 thresholds to further reduce the still-significant 29% rate of atelectasis in the VESPA group, the examination of its generalizability to wider populations and the detection of the length of time during which VESPA can retain its effect against atelectasis with an acceptable safety profile.
“In the era of fast-paced technologic innovation and slow-paced efficacy assessment through rigorous comparative prospective trials, we would do well to expand our focus to the less costly and more fundamental and overlooked concepts of peripheral bronchoscopy under general anesthesia,” they added.