17: ULTRASOUND EVALUATION OF THE NECK AND UPPER RESPIRATORY SYSTEM

Introduction

Ultrasound of the neck and upper respiratory system has many potentially useful clinical applications.¹ Aside from vascular access (see Chapter 27), some of these indications include confirmation of satisfactory endotracheal tube (ETT) placement, evaluation of the larynx, guidance for percutaneous tracheostomy, evaluation of the paranasal sinuses, and assessment of vocal cord disorders. The data demonstrating improved outcomes by using ultrasound for imaging the upper airway remain scarce. However, there are important opportunities to improve care for the intensive care unit (ICU) patient that can be derived from its use.

Paranasal Sinuses

Ultrasound use for the evaluation of the paranasal sinuses was recognized in Europe as technically feasible to confirm the presence of sinus disease as early as the 1960s.² However, widespread clinical application emerged only recently with the development of low-cost, high-quality bedside ultrasound imaging technology. Earlier studies established ultrasound as an alternative to computed tomography (CT) for the diagnosis of maxillary sinus disease and described the typical findings associated with sinusitis.^3,4 With improvements in imaging, more recent reports focused on improving the diagnostic accuracy of ultrasound by performing postural maneuvers.⁵ In 2006, Vargas et al. investigated the role of ultrasound for performing transnasal puncture of the maxillary sinus in intubated ICU patients. In patients suspected of having sinusitis, they found ultrasonographic evidence of maxillary sinusitis in 70% of patients, and of these, 93% had positive results from transnasal puncture, demonstrating the comparability of ultrasound to CT for the diagnosis and transnasal puncture of sinusitis.⁶ More recent studies investigated the characterization, or “staging,” of sinus fluid collections by noting the presence or absence of acoustic streaming in a model of sinusitis. More viscous collections (pus) are less likely to undergo acoustic streaming than less viscous collections.⁷

There are no studies that describe an improvement in ICU outcomes by using ultrasound instead of standard CT, even though a CT scan has more radiation, is more expensive, and requires the transportation of critically ill patients to and from the radiology department as well as the use of valuable critical care nursing time. There are important roles, however, for CT imaging of the sinuses that cannot be duplicated with ultrasonography. These include any planned surgical procedure involving the sinuses, suspected sinus trauma, and suspected malignant disease. This discussion focuses on the use of ultrasound for the evaluation of paranasal sinusitis.

Sinus disease is important to recognize in critically ill patients because it is a source of fever, which leads to costly diagnostic workups and empiric therapeutic regimens.^8,9 In addition, maxillary sinus disease is an independent risk factor for the development of nosocomial lung infections.¹⁰ Although not studied in any systematic fashion, it is also conceivable that undiagnosed sinusitis may lead to significant pain and agitation, resulting in the increased use of sedatives and analgesics, which could then ...