Hypothesis: Palpation of the cricothyroid membrane in female patients who are preoperatively expected to have difficult airway would be less accurate than in female patients with normal airway.
The first endpoint of the study is to compare the accuracy of surface landmark palpation for cricothyroid membrane identification in female patients who are preoperatively predicted to have difficult airway and normal airway.

Cricothyroidotomy is a way of emergent airway puncture to establish a patent airway during life-threatening situations such as "Can't intubate, can't ventilate (CICV)" or "Can't intubate, can't oxygenate (CICO)". Clinicians need to get familiar with relevant anatomy and develop the ability to identify the cricothyroid membrane (CTM). One way to improve familiarity with the anatomy is to palpate the structures of the anterior neck regularly when examining patients. The boundaries of the CTM are the thyroid cartilage superiorly, the cricoid cartilage inferiorly, and the cricothyroideus muscles laterally on both sides. Identifying the CTM is more confusing in women than in men because laryngeal prominence is less prominent. To get over this hardship, bedside ultrasound has been proposed as a method for identifying the cricothyroid membrane (CTM). In this study, we will examine the patients' airway before the induction of anesthesia and analyze the diffference of the CTM identification accuracy between difficult airway and normal airway,

Cohort/Group Label

difficult airway group

Cohort/Group Description

Based on a physical examination(Palpation) : If any of "3-3-2 rules" are applicable
** 3-3-2 rules : 
(a) Inter-incisor distance <3 finger breadths
(b) Hyoid-to-mental distance < 3 finger breadths
(c) Thyroid-to-hyoid distance <2 finger breadths

Cohort/Group Label

normal airway group

Cohort/Group Description

Based on a physical examination(Palpation) : If none of "3-3-2 rules" are applicable
** 3-3-2 rules : 
(a) Inter-incisor distance <3 finger breadths
(b) Hyoid-to-mental distance < 3 finger breadths
(c) Thyroid-to-hyoid distance <2 finger breadths

Not collect nor Archive

Female patients who undergo surgery under general anesthesia or regional anesthesia in the Eunpyeong St. Mary's Hospital.

Among female patients who undergo surgery under general anesthesia or regional anesthesia in the Eunpyeong St. Mary's Hospital during the study period, 30 patients who are preoperatively predicted to have difficult airway and 30 patients with normal airway will be enrolled prospectively.

Gender

Age

Description

1) Sex: Female
2) Adults: over 19 and under 75 years old
3) ASA(American Society of Anesthesiologists) physical status 1 or 2

1) Patients who disagree with the participation in this study
2) Patients with cognitive impairments, who can not understand this study
3) Pregnant women
4) Sex: Male
3) Age under 19 or over 75 
4) ASA(American Society of Anesthesiologists) physical status ≥3
5) Patients with pathologic lesion in the neck
6) Patients who undergo neck surgeries

Diffference of the cricothyroid membrane identification between difficult airway and normal airway

Before induction of an anesthesia

Ultrasonographic identification of the cricothyroid membrane

Before induction of an anesthesia