|Year : 2020 | Volume
| Issue : 4 | Page : 163-165
Upper airway ultrasound: A promising tool in the management of pediatric airways
Department of Pediatric Intensive Care Unit, Rainbow Children's Hospital, Banjara Hills, Hyderabad, Telangana, India
|Date of Submission||21-May-2020|
|Date of Acceptance||26-May-2020|
|Date of Web Publication||13-Jul-2020|
Dr. Farhan Shaikh
Department of Pediatric Intensive Care Unit, Rainbow Children's Hospital, Banjara Hills, Hyderabad, Telangana
Source of Support: None, Conflict of Interest: None
|How to cite this article:|
Shaikh F. Upper airway ultrasound: A promising tool in the management of pediatric airways. J Pediatr Crit Care 2020;7:163-5
Confirmation of endotracheal intubation is commonly done by chest auscultation and capnograph executed only after the endotracheal tube (ETT) is placed in the trachea. Over the last 15 years, there are many studies in adult population on use of ultrasound to confirm endotracheal intubation with real-time images by placing a linear ultrasound probe transversely on the anterior aspect of the neck at the level of the cricothyroid membrane.
As per numerous studies in adult population, transtracheal ultrasound is a useful tool to confirm endotracheal intubation with an acceptable degree of sensitivity and specificity. It can be used in emergency situations as a preliminary test before final confirmation by capnography. Ultrasonography can differentiate tracheal, esophageal, and endobronchial intubation. Ultrasonography of the neck can accurately localize the cricothyroid membrane for emergency airway access and similarly identify tracheal rings for ultrasonography-guided tracheostomy.
In addition, ultrasonography can identify vocal cord dysfunction and pathology before induction of anesthesia.
A rapidly growing body of evidence showing ultrasonography used in conjunction with hands-on management of the airway may benefit patient care. Increasing awareness and use of point-of-care ultrasonography (POCUS) for many indications have resulted in technologic advancements and increased accessibility and portability. Upper airway POCUS has the potential to become the first-line noninvasive adjunct assessment tool in airway management. Very few studies in pediatric and neonatal population have been published. Until the year 2017, only six studies in neonates and infants while just five studies in children from 1 year to 18 years of age were published on use of ultrasonography for the detection of position of ETT during intubation.
In ideal circumstances, the ETT position can be assessed by ultrasonography using three windows: (1) transverse suprasternal/tracheal view to observe modification of vocal cords or glottis structures during ETT insertion or visualization of a saline-inflated ETT cuff (T. R. U. S. T.), (2) sagittal mid-axillary intercostal view to observe lung motion bilaterally (“sliding lung sign”), and (3) transverse substernal/subxiphoid view to assess bilateral diaphragm motion. These imaging strategies have been adopted from adult studies reporting successful clinical utility and feasibility. The studies reviewed by Jaeel et al. suggest similar efficacy of ultrasound and X-ray for all the three techniques in children. The techniques of assessing pleural sliding and diaphragmatic movements require ventilation of the patient and may be affected by underlying lung diseases, such as pneumothorax, pneumonia, or malignancy.
In this issue of Journal of Pediatric Critical Care, Sarangi et al. have shared a prospective study on utility of upper airway ultrasound for confirmation of ETT placement in the Pediatric Intensive Care Unit (PICU) Setting. Children between 1 month and 18 years of age were included in the study. Airway ultrasonography was done during intubation by placing the probe transversely over the suprasternal notch and the confirmation of tube in the trachea was done by visualizing the absence of double trachea sign, later confirmed by capnography. The average time taken for confirmation by ultrasound and capnography was determined. The authors have used ultrasonography only on trachea to confirm entry of ETT in the trachea. They have not used ultrasonography to assess sliding pleural signs on both the lungs or movements of diaphragm on both sides. Thus, they will not be able to discover if there was endobronchial intubation. They were able to only detect whether ETT was in trachea or not.
Very few studies have compared the time taken for confirmation by ultrasonography and capnography. Hao-Chang et al. demonstrated that tracheal ultrasound is not inferior to capnography in identifying correct tracheal intubation. Indeed, quantitative capnography itself might not be reliable in some cardiac arrest patients because of low pulmonary flow. Galicinao et al. investigated the usefulness of ultrasonography for ETT placement in 99 pediatric patients in emergency department and PICU.
The investigators underwent an American College of Emergency Physician-sponsored training course on ultrasonography and had more than 1-year experience of ultrasonography. All of them were credentialed through their institutional program. In 50 patients, ultrasonography was compared to capnography and X-ray. The mean time to determine ETT position by ultrasonography was 17 s, compared to 14 min by X-ray. Ultrasonography had a sensitivity, specificity, positive predictive value, and negative predictive value of 100% in confirming ETT placement. Ultrasonography even detected ETT position where capnography failed to detect proper ETT placement (two cases) or did not clearly detect improper placement (one case). The authors reported difficulty in ultrasonographic imaging in patients with subjectively shorter necks and those with small cervical collars.
From the available literature, however, it seems that the training and acquisition of skills in ultrasonography for the detection of endotracheal intubation does not take very long time to learn. Dennington et al. and Kerrey et al. involved respiratory therapists who presumably had little previous ultrasonography experience and reported good ETT detection and good concordance between ultrasonography-X-ray after a short training period., Galicinao et al. suggest that ultrasonography may be advantageous over capnography in children with pulmonary and gastrointestinal-related pathologies.
With few studies, and the need for an ultrasonography machine as well as operator training, it is unlikely that ultrasonography will completely replace capnography in the near future for the detection of correct placement of ETT during intubation. Ultrasonography, however, has its role in procedure of endotracheal intubation in various situations. It can complement resuscitative measures with capnography as capnography provides limited information on ETT depth and may have a false positive rate (ETT in esophagus but capnography reports trachea) as high as 3%.
Ultrasonography can be used as an effective training tool for residents learning intubation using conventional direct laryngoscopy. Ultrasonography is the fastest method to confirm correct ETT placement compared to capnograph and chest auscultation. The trainer can guide the trainee resident to direct ETT toward trachea and can promptly detect esophageal intubation by double trachea sign much before AMBU bagging and inflating the stomach. Intubated patients in PICU undergo multiple X-rays just for the confirmation of position of the ETT during their stay in PICU. With the concern for ionizing radiation exposure in pediatric population, the safety of ultrasonography for routine monitoring of ETT positioning with less X-ray verification looks an attractive option which needs to be determined by some well-designed studies.
Effective training regimens for doctors and even respiratory therapists and nurses interested in using bedside ultrasonography would increase proliferation of this evolving imaging modality.
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