Role of ultrasonography in determining the cricothyroid membrane localization in the predicted difficult airway

BACKGROUND: The aim of this study was to investigate the success rates of ultrasound (US) and palpation methods in identifying the cricothyroid membrane (CTM), and compare the results with the gold standard method—computed tomography (CT) scan.
METHODS: A total of 110 patients were included into the study. The midline was estimated by a single investigator using both the US and palpation methods from the prominence of the thyroid cartilage to the center of the sternal notch, and the distance was measured (in millimeters) between the two points: Point A (the midpoint of CTM) and Point B (the inferior process of thyroid cartilage). Furthermore, the distance between Point A and Point B was calculated using the CT images. Time taken to assess the CTM by using US and palpation methods were recorded. Moreover, difficulty in using the two methods was measured with the visual analog scale (VAS). In addition, demographic and morphometric characteristics of the patients were noted.
RESULTS: The CTM was detected accurately in 50 (45.5%) patients with palpation and 82 (74.5%) with US. In the Bland–Altman analysis, a better agreement was observed with US. The time to assess CTM was shorter with US than with palpation, p<0.001. The VAS scores for the palpation and US difficulty were 5.13±1.1 and 3.32±0.9 (p<0.001), respectively. While an increased neck circumference and thyromental distance were found to be independent risk factors for the success rates of determining the CTM by palpation, body mass index is an independent risk factor for US.
CONCLUSION: Localization of the CTM is more accurate and easier with US than palpation. Furthermore, the results gathered with US are in a closer range to CT scan.

Öngörülen zor havayolunda krikotiroit membran lokalizasyonunun belirlenmesinde ultrasonografinin rolü

AMAÇ: Bu çalýþmanýn amacý, ultrason (US) ve elle muayene yöntemlerinin baþarý oranlarýný araþtýrmak ve bilgisayarlý tomografiye (BT) karþý US ile elle muayenenin kýyaslanarak krikotiroid membranýn (KTM) tanýmlamak.
GEREÇ VE YÖNTEM: Çalýþmaya 110 hasta alýndý. Tiroit kartilajýn çýkýntýsýndan sternal çentiðin ortasýna kadar düzlemde orta hat belirlendikten sonra, iki nokta arasýndaki mesafe (milimetre) ölçüldü. A noktasý-KTM’nin orta noktasý ile B noktasý-tiroit kartilajýn inferiyor kýsmý arasýndaki mesafe (milimetre) US ve elle muayene ile tek bir araþtýrmacý tarafýndan iþaretlenerek ölçüldü. Ayrýca A noktasý ile B noktasý arasýndaki mesafe BT kullanýlarak hesaplandý. US ve elle muayene ile KTM’in belirlenmesi için geçen süre ve VAS skoru kullanýlarak her iki yöntemin kolaylýðý kaydedildi. Ek olarak hastalarýn demografik ve morfometrik karakteristikleri not edildi.
BULGULAR: Krikotiroit membran elle muayene ile 50 hastada (%45.5) ve US ile 82 (%74.5) hastada doðru olarak saptandý. Blant-Altman analizine göre US ile elle muayeneye göre daha iyi uyum gözlendi. KTM yerinin belirlenmesi için geçen süre US ile elle muayeneden daha kýsa idi (p<0.001). VAS deðerleri elle muayene ve US ile sýrasýyla 5.13±1.1, 3.32±0.9 bulundu (p<0.001). Artan boyun kalýnlýðý ve tiromental mesafe elle muayene baþarýsýný etkileyen risk faktörü olarak saptanýrken US için risk faktörü olarak vücut kitle indeksi (VKÝ) bulundu.
TARTIÞMA: Krikotiroit membranýn lokalizasyonu US ile elle muayeneden daha doðru ve kolay saptanmýþtýr. Ayrýca US ile bulunan sonuçlar BT’ye daha yakýn bulunmuþtur.