Anika Turkiewicz, PGY1
Title: Confirmation of placement of endotracheal tube—a comparative observational pilot study of three ultrasound methods.
Sethi, A. K., Salhotra, R., Chandra, M., Mohta, M., Bhatt, S., & Kayina, C. A. (2019). Journal of anaesthesiology, clinical pharmacology, 35(3), 353.
Idea: ETT position confirmation is required to ventilate patients, and gold standard of EtCO2 is not always available. Three ultrasound-guided methods have been trialed to identify correct positioning: direct visualization via the trachea, inspection of chest wall movements by examining visceral-parietal pleural sliding, and bilateral diaphragmatic dome movement, with none of these methods having previously been directly compared to each other.
Study: This was a prospective, randomized, observational study. Inclusion criteria was patients age 18-60 with Mallampati Class I or II scheduled to undergo an elective surgical procedure requiring general anesthesia with endotracheal intubation. Exclusion criteria were those were pregnant, at risk of pulmonary aspiration or having neck swelling, cervical spine disease, pleural effusion, pneumothorax, intercostal drain in situ, and BMI >35. The primary objective was to evaluate the efficacy of the three USG techniques based on the time taken for confirmation of ETT position. The secondary objective was to compare the time to confirm ETT placement using USG with the time required for auscultation and capnography. Additionally the ability of USG techniques to correctly identify placement and accidental esophageal intubation was evaluated.
Results: A total of 98 patients were assessed for eligibility, with 90 becoming part of the study. Three statistically similar groups were created with 30 patients were group for each USG technique. The mean time for confirmation with USG was lowest in the tracheal group (3.8s), compared with the pleural (12.1s) and diaphragmatic group (13.8s). The time required for auscultation and capnography was comparable across all three groups. The tracheal method also took less time than both auscultation and capnography, while the pleural and diaphragmatic group took more time than auscultation but less than capnography. All three USG methods could correctly identify the presence of the ETT in the trachea, and there were no incidences of esophageal intubation.
Takeaway: This study was a single-center study conducted in a controlled setting, with time allocated prior to performance of the procedure to identify the appropriate landmarks for ultrasound, which can be difficulty in the emergency department setting. Although tracheal USG is the quickest, it cannot identify endotracheal compared with endobronchial intubation due to difficulty visualizing the carina. However, this could be verified by the presence of lung sliding bilaterally. The patients in which USG techniques would be most useful are the patients that were excluded from the study such as trauma victims, pregnant patients and those at high risk of aspiration. Additionally, the BMIs of patients included in the study were low and not representative of many patients that need emergent intubation. USG can be a useful adjunct in certain settings, but has limitations, and the time difference compared with capnography and auscultation may not be clinically significant.