Article, Otolaryngology

Bedside ultrasonography as a safe and effective tool to diagnose acute epiglottitis

Case Report

Bedside ultrasonography as a safe and effective tool to diagnose acute epiglottitis

Abstract

Acute epiglottitis is a true airway emergency in the emergency department (ED). The patient may appear very toxic and rapidly progress to respiratory distress and life- threatening condition. The Inflammatory process includes not only epiglottis but also the rest of the supraglottic area including the vallecula, aryepiglottic folds, and arytenoids. soft tissue swelling over this windpipe area can be very dramatic. The criterion standard of diagnosis is direct inspection of cherry red and swollen epiglottis by laryngos- copy in the operation room with immediate access to anesthetists or ear, nose, and throat specialists. However, before the patients are well prepared, the clinical condition may critically go downhill; and any intention to visualize the throat can result in severe and fatal airway spasm. Thumbprint sign on lateral radiography of neck is typical, but it may be extremely risky to let a patient leave the consulting room for the study if respiratory distress has developed. We demonstrate a safe and practical way to investigate the epiglottis by bedside ultrasonography to visualize the “alphabet P sign” in a longitudinal view through thyrohyoid membrane by emergency physician in the ED.

The bedside ultrasonography is a safe and noninvasive study that is very useful in evaluating a patient in the ED when the diagnosis of acute epiglottitis is suspected. The “alphabet P sign,” which is formed by acoustic shadow of hyoid bone and swollen epiglottis at the level of thyrohyoid membrane in a longitudinal orientation, is easy to identify by emergency physicians.

A 49-year-old woman presented to emergency depart- ment (ED) for flu-like symptom lasting for 1 week, progressive severe sore throat, odynophagia, and lumping throat since the morning of her visit. Except for hepatitis B, she denied any systemic disease such as diabetes or hypertension. She was allergic to amoxicillin and nonste- roidal anti-inflammatory drugs. In the physical examination, the patient was calm and presented no respiratory distress. There were no drooling and no tripod position, and the initial oxygen saturation was 96% with pulse oxymeter at room air. Neck soft tissue x-ray was arranged, and

thumbprint sign with narrowed space between epiglottis and tongue base was found (Fig. 1). Under stable condition, the patient was given hydration, intravenous methylpred- nisolone, clindamycin, and gentamicin regarding previous allergy history. Results of laboratory studies were as follows: white blood cells, 10800/uL; aspartate aminotrans- ferase, 28 U/L; and C-reactive protein, 0.532 mg/dL. An ear, nose, and throat specialist was consulted; and cherry red swollen epiglottis with tongue base swelling was proven by laryngoscope (Figs. 2 and 3) Because of nontoxic appearance, the patient was observed at the ED. Ultraso- nography was performed gently at bedside in the ED by an emergency physician. The patient was placed with her head extended and neck flexed (sniffing position). The ultraso- nography machine was Toshiba SSA-550A with a PVM- 375AT curved transducer (3.75 MHz). The width of epiglottis was 3.1 cm in transverse view through thyrohyoid membrane. In longitudinal view, the swollen epiglottis was just by the side of hyoid bone with a hypoechogenicity halo comparing with normal people that epiglottis is barely seen by the same 3.75-MHz curved transducer (Figs. 4 and 5). The hyoid bone and its acoustic shadow, preepiglottic space, and the swollen epiglottis formed the “alphabet P sign” (Fig. 6). After 6 hours of observation at ED, patient felt better and the foreign body sensation over throat was reduced. The patient was discharged uneventfully and recovered after completing 7 days of oral clindamycin at follow-up ear, nose, and throat clinic.

After the Haemophilus influenzae type B vaccine era,

acute epiglottitis in children had been reduced greatly. However, the prevalence of acute epiglottitis remains the same [1]. The management of epiglottitis is a real challenge for emergency physicians because the progression of the disease can be very dramatic. Lateral radiography of the neck with the typical thumbprint sign is helpful in stable patient. Nonetheless, it is unwise to let the patient transfer for study if respiratory distress has developed. We demonstrated an easy and safe way to investigate the patient noninvasively by bedside ultrasonography.

Nowadays, ultrasonography is used widely in the ED. The assessment of anatomical structure of airway by sonography had been investigated by Singh et al [2]. The neck is best visualized by high-frequency transducer to gain the best quality of delicate structure of airway [3,4]. However, because the investigation by sonography in ED is focused

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Fig. 3 Cherry red swollen epiglottis under laryngoscope.

Fig. 1 Thumbprint sign on lateral radiography of neck.

mainly on trauma and on chest and Abdominal pathology, the lower-frequency transducer is more frequently equipped. The structure of acute epiglottitis was clearly presented in our case by a 3.5-Hz curved transducer in a linear orientation at bedside as the patient was placed supine in the sniffing

Fig. 2 Swollen tongue base under laryngoscope.

position. The thyrohyoid membrane between the hyoid bone and thyroid cartilage is the level where epiglottis can be visualized by the side and beneath the hyoid bone. The basic landmarks of this area are tongue base, preepiglottic space, hyoid bone, and thyroid cartilage (Fig. 5).

In the patient without acute epiglottitis, the epiglottis is a thin hypoechogenicity structure by the side of hyoid bone and preepiglottic space that may not be seen easily. Comparing with the pathologic condition in our patient (Fig. 4), the swollen epiglottis (white arrows) was well defined as a dark halo surrounding the high-density area of

Fig. 4 Under sniffing position, the transducer was placed on linear orientation at thyrohyoid membrane. The white arrows pointed at the swollen hypoechogenicity epiglottis. GG indicates genioglossus; TS, tongue surface; SLF, sublingual fat; HY, hyoid bone; PES, periepiglottic space; TC, thyroid cartilage. The white arrows pointed at the swollen hypo-echogenecity epiglottis.

Case Report

Fig. 5 Normal structure for comparison.

Fig. 6 “Alphabet P sign” formed by acoustic shadow of hyoid bone (HY), swollen epiglottis (pointed by white arrows).

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preepiglottic space. The acoustic shadow of hyoid bone and the swollen hypoechogenicity epiglottis formed an alphabet P figure (Fig. 6).

The bedside ultrasonography is a safe and noninvasive study that is very useful in evaluating patients in the ED when the diagnosis of acute epiglottitis is suspected. The “alphabet P sign” formed by acoustic shadow of hyoid bone and swollen epiglottis at thyrohyoid membrane is easy to identify by emergency physicians.

Tzu-Yao Hung MD Shang Li MD

Po-Shen Chen MD Liang-Ting Wu MD Yuh-Jeng Yang MD Li-Ming Tseng MD Kuo-Chih Chen MD

Emergency Department Shin-Kong Wu Ho-Su Memorial Hospital

Taipei, Taiwan

Tzong-Luen Wang PhD

Emergency Department Shin-Kong Wu Ho-Su Memorial Hospital

Taipei, Taiwan School of Medicine

Fu Jen Catholic University

Taipei, Taiwan

Tzu-Yao Hung MD

Emergency Department Shin-Kong Wu Ho-Su Memorial Hospital

Taipei, Taiwan

doi:10.1016/j.ajem.2010.05.001

References

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  3. Werner SL, Jones RA, Emerman CL. Sonographic assessment of the epiglottis. Acad Emerg Med 2004;11(12):1358-60.
  4. Bektas F, Soyuncu S, Yigit O, Turhan M. Sonographic diagnosis of epiglottal enlargement. Emerg Med J 2010;27(3):224-5.