Thoracic ultrasound is a viable alternative to fiber-optic bronchoscopy for verifying the correct position of a double-lumen endotracheal tube (DLET) before one-lung ventilation, a study has found.
Andrea Saporito, MD, a consultant anesthetist at Bellinzona Regional Hospital, in Bellinzona, Switzerland, and the study’s principal investigator, noted that thoracic ultrasound is noninvasive and cheaper than fiber-optic bronchoscopy. “Fiber-optic bronchoscopy is the gold standard, but it is expensive and has to be performed by an anesthetist,” he said. “The ultrasound does not have to be performed by an anesthetist with special skills; it can be performed by a nurse.”
The investigators conducted a case–control, crossover, blinded study in which 51 patients, with American Society of Anesthesiologists physical status 1 to 3 and a mean age of 62.6 years, were undergoing thoracic surgery using one-lung ventilation. After patient intubation with a DLET, the researchers evaluated correct lung isolation with bronchoscopy followed by thoracic ultrasound. Dr. Saporito and his colleagues presented a poster on the study at the International Symposium of Ultrasound for Regional Anesthesia, Pain Medicine & Perioperative Applications. The results were published in the Journal of Ultrasound (2013;16:195-199).
The researchers concluded that both approaches were equally sensitive and specific for confirming correct left DLET positioning, with only one discordant case. They also found a significant difference in execution time between the two procedures, with ultrasound being faster than bronchoscopy (2.08 vs. 7.70 min; P<0.05).
The time reduction, and the fact that a nurse could perform thoracic ultrasound, produced a net savings of about $7 US.
The results should be confirmed with a larger sample size of patients, Dr. Saporito noted. “It’s a pilot study, and thoracic ultrasound needs to be further evaluated,” he said.
Jerome M. Klafta, MD, professor and vice-chair for education and academic affairs, Department of Anesthesia and Critical Care, University of Chicago, felt the data were not robust enough to present thoracic ultrasound as a management option.
“It’s a bit of a stretch to think that [thoracic ultrasound] would play an important role in the modern management of double-lumen tubes,” Dr. Klafta said in an interview.
Dr. Klafta noted that the investigators failed to mention the method used for placing the double-lumen tubes. “If you want to talk about how effective your method is for confirming placement [of tubes], you also have to mention what your method of placement is,” he pointed out.
The results section of the study did not mention the percentage of tubes that were successfully placed, he noted. “If, in fact, there were a significant number that were malpositioned, then it would necessarily require the bronchoscope to achieve successful placement,” said Dr. Klafta, adding that the medical literature supports up to 30% of tubes that are placed without a bronchoscope being suboptimally positioned when placement is verified with a bronchoscope.
Although the authors of the study regard fiber-optic bronchoscopy as a rescue technique, Dr. Klafta said the data supported a limited clinical utility of thoracic ultrasound. “If you still need to use the bronchoscope in a significant number of patients, the utility of thoracic ultrasound is less impressive,” Dr. Klafta said.
The weight or body mass index of patients is also information that was absent in the study, Dr. Klafta noted. “Ultrasonographic examinations are more difficult in patients who are obese. Like with cardiac ultrasound, heavier patients make it a more technically difficult examination.”
The investigators also did not consider the use of bronchial blockers for lung separation, Dr. Klafta said. Several studies in the literature have described how double-lumen tubes and bronchial blockers move intraoperatively, he said. “There is a need, intraoperatively, to re-establish or reassess their position in the patient, which can only be done with a bronchoscope.”
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