Background Unrecognized malposition of the endotracheal tube (ETT) can lead to severe complications in patients under general anesthesia. The focus of this double-blinded randomized study was to assess the accuracy of point-of-care ultrasound in verifying the correct position of the ETT and to compare it with the accuracy of auscultation. Methods Forty-two adult patients requiring general anesthesia with ETT were consented. Patients were randomized to right main bronchus, left main bronchus, or tracheal intubation. After randomization, the ETT was placed via fiber-optic visualization. Next, the location of the ETT was assessed using auscultation by a separate blinded anesthesiologist, followed by an ultrasound performed by a third blinded anesthesiologist. Ultrasound examination included assessment of tracheal dilation via cuff inflation with air and evaluation of pleural lung sliding. Statistical analysis included sensitivity, specificity, positive predictive value, negative predictive value, and interobserver agreement for the ultrasound examination (95% CI). Results In differentiating tracheal versus bronchial intubations, auscultation showed a sensitivity of 66% (0.39 to 0.87) and a specificity of 59% (0.39 to 0.77), whereas ultrasound showed a sensitivity of 93% (0.66 to 0.99) and specificity of 96% (0.79 to 1). Identification of tracheal versus bronchial intubation was 62% (26 of 42) in the auscultation group and 95% (40 of 42) in the ultrasound group (P = 0.0005) (CI for difference, 0.15 to 0.52), and the McNemar comparison showed statistically significant improvement with ultrasound (P < 0.0001). Interobserver agreement of ultrasound findings was 100%. Conclusion Assessment of trachea and pleura via point-of-care ultrasound is superior to auscultation in determining the location of ETT.

Rad14 is a DNA damage recognition protein in yeast Nucleotide Excision Repair (NER) and believed to function early in the cascade of events. The function of Rad14 presumably precedes that of the Rad1-Rad10 endonuclease complex, which functions in a downstream step incising DNA 5′ to the site of DNA damage. We investigated whether recruitment of Rad10 to UV-induced DNA damage sites in live cells is dependent on Rad14 using fluorescence microscopy. Experiments were carried out using Saccharomyces cerevisiae strains in which the gene for Rad14 was fused to Cyan Fluorescent Protein (Rad14-CFP) and that of Rad10 was fused to Yellow Fluorescent Protein (Rad10-YFP). Rad14-CFP forms nuclear localized CFP fluorescent foci in response to UV-irradiation with the peak induction occurring 15 minutes post-irradiation. In contrast, Rad10-YFP foci form in response to UV with the peak induction occurring 2 hours post-irradiation. Recruitment of Rad14-CFP is not dependent on the RAD10 gene but Rad10-YFP is recruited to UV-induced YFP foci in a RAD14-dependent fashion. Time-lapse experiments indicate that Rad14-CFP foci are transient, typically persisting less than 6 minutes. Together these data support the model that yeast NER protein assembly is step-wise whereas Rad14 required to recruit Rad10 and Rad14 involvement is transient.

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