Background
Anesthesiologists rely on auscultation and clinical exam to determine correct endotracheal tube (ETT) placement since CXR or fluoroscopy are only rarely available. Several studies have shown that 18-19% of all the intubations result in inappropriate endotracheal tube placement and as high as 11% of malpositioned endotracheal tubes are not recognized after standard auscultation and clinical exam. {1,2} Recently the utility of point of care ultrasound (POCUS) to identify appropriate placement of the endotracheal tube in adults has been demonstrated. This is assessed by identifying the trachea motion secondary to adjustment of the ETT cuff,. {3} Importantly, similar utility has yet to be determined in pediatrics. This study sought to evaluate the utility of a POCUS exam to identify appropriate ETT position in a pediatric population by examining measurements of the ultrasound examination to those from routine fluoroscopy.
Methods
Pediatric patients (from birth to 10 years old) requiring general anesthesia for cardiac cath procedures involving chest fluoroscopy were consented for the study. The patient underwent induction with verification of appropriate ETT position via standard practice (auscultation and clinical exam). After ETT was deemed to be in appropriate position, an ultrasound linear probe was placed in a midline longitudinal tracheal view and the ETT cuff was identified by assessing for tracheal shape alteration during palpation of pilot balloon (occlude and release test). Once identified, the cuff location was marked on the US image and measurements were obtained to the sternal notch, cricoid cartilage, and thyroid cartilage’s. Transverse trachea view was also obtained to identify the location of the esophagus. Finally, bilateral pleural lung sliding was also evaluated. The patient then underwent chest fluoroscopy that was later reviewed to assess the location of ETT in relationship to the carina. Primary comparison was correlation assessment between the ultrasound measurements to the fluoroscopy measurements. Specifically, the fluoroscopy measurement of the carina to the ETT tip plus the measured distance of the balloon cuff to the tip of the ETT was compared to the ultrasound measurement of the thyroid cartilage to the cuff of the ETT. In addition, the incidence of inappropriate ETT location was also compared between the auscultation/clinical exam and both the ultrasound and fluoroscopy examinations. Finally time to perform the POCUS exam was also recorded
Results
Preliminary results indicate 100% detection/visualization of the ETT cuff with the POCUS exam. Average time to perform the exam was 163 secs (stdev = 67sec). A strong correlation (R=0.98) was demonstrated between the fluoroscopy measurements to the ultrasound measurements (p=0.024). Currently, all exams (auscultation, fluoroscopy, and ultrasound) have demonstrated appropriate ETT placement. Additionally, the POCUS exams have demonstrated 100% visualization of the esophagus, with 80% demonstrating the esophagus to be to the left of the trachea.
Conclusion
Preliminary data suggests that airway POCUS is a fast and reliable modality to verify adequate depth of the ETT in the pediatric population.
