Neck Position and Ultrasound Landmark of Cricothyroid Membrane

2019-10-18 11:21:44 | BioPortfolio


Cricothyroid membrane (CTM) localization is a critical step prior to emergent surgical airway access. Ultrasound-guided localization of the CTM on the skin of the neck had been suggested prior to induction of general anesthesia so that a marked entry point can be used to quickly establish emergent front of neck access if required. In this prospective observational study, we aim to determine the potential for migration of the CTM markings in the sagittal plane during neck repositioning.


As defined in recent difficult airway guidelines, successful and rapid cricothyroidotomy depends on identification of the cricothyroid membrane (CTM), coupled with skillful and efficient technique (1,2). Unfortunately, identification of the CTM is often inaccurate and complicated by patient factors such as female gender and obesity (3,4,5). Further studies go on to demonstrate the rates for correct identification of the CTM using palpation methods are low and range between 11% and 42%, with even lower success of identifying the midline of the CTM (4,6). This traditional palpation method was demonstrated to be fraught with error by different users including: 2 finger palpation, 4 finger palpation, and neck crease successfully identified the CTM 62%, 46%, and 50% of the time at time intervals between 11-14 seconds in non emergency settings (7).

As a result of previously mentioned patient factors and multiple technical factors, including poor landmarking, cricothyrotomy has a failure rate as high as 60% (8), exposing patients to high risks of mortality and morbidity. Therefore, more accurate methods of CTM identification are greatly needed at present.

Suggestions of implementing ultrasound in airway management have been brought forth, with applications such as predicting airway difficulty prior to instrumentation, confirming endotracheal tube position, or marking the CTM prior to induction of anesthesia (3). There have been multiple studies addressing questions such as mean time to identification of CTM in obese subjects using ultrasound and comparison of transverse versus longitudinal scanning technique (7,9). One group assessed translational movement of the CTM in neutral neck position versus extended in 23 healthy volunteers, and found a difference in transverse and longitudinal markings of 0.91mm and 1.04mm respectively, with CTM length ranging from 10.6mm to 17mm (10).

Of interest to us is using ultrasound to predict CTM position accurately and ensuring ability to gain emergency airway access, as the accuracy of ultrasound identification of the CTM in different neck positions is unknown. What is specifically unknown is the translational movement of the cricoid between neck positions.

Therefore, we propose an observational prospective trial looking at cricoid cartilage translation with three different neck positions: neck neutral, neck extension, and neck sniffing. We will use GE Venue 50 (GE HealthcareTM) ultrasound machine, and a linear transducer probe with a frequency of 8-13MHz (GE LOGIQ 12L-SC) for measurements. The measurements will originate at the sternal notch to the superior border of the cricoid cartilage where the cricoid membrane inserts. These will also be referenced to exterior skin markings. Our outcomes will address if the airway significantly moves during manipulation by the degree of cricoid cartilage translation between neutral, sniffing and extended neck positions. Secondarily, we will also aim to address the directionality of a pre-marked neck and cricoid migration with neck manipulation.

Study Design


Cricothyroid Membrane




St Paul's Hospital
British Columbia
V6Z 1Y6




University of British Columbia

Results (where available)

View Results


Published on BioPortfolio: 2019-10-18T11:21:44-0400

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The Cricothyroid versus Spray-As-You-Go Method for Topical Anesthesia during Flexible Bronchoscopy: The CRISP Randomized Clinical Trial.

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Medical and Biotech [MESH] Definitions

The voltage difference, normally maintained at approximately -180mV, across the INNER MITOCHONDRIAL MEMBRANE, by a net movement of positive charge across the membrane. It is a major component of the PROTON MOTIVE FORCE in MITOCHONDRIA used to drive the synthesis of ATP.

Branches of the VAGUS NERVE. The superior laryngeal nerves originate near the nodose ganglion and separate into external branches, which supply motor fibers to the cricothyroid muscles, and internal branches, which carry sensory fibers. The RECURRENT LARYNGEAL NERVE originates more caudally and carries efferents to all muscles of the larynx except the cricothyroid. The laryngeal nerves and their various branches also carry sensory and autonomic fibers to the laryngeal, pharyngeal, tracheal, and cardiac regions.

The passive movement of molecules exceeding the rate expected by simple diffusion. No energy is expended in the process. It is achieved by the introduction of passively diffusing molecules to an enviroment or path that is more favorable to the movement of those molecules. Examples of facilitated diffusion are passive transport of hydrophilic substances across a lipid membrane through hydrophilic pores that traverse the membrane, and the sliding of a DNA BINDING PROTEIN along a strand of DNA.

A method used to study the lateral movement of MEMBRANE PROTEINS and LIPIDS. A small area of a cell membrane is bleached by laser light and the amount of time necessary for unbleached fluorescent marker-tagged proteins to diffuse back into the bleached site is a measurement of the cell membrane's fluidity. The diffusion coefficient of a protein or lipid in the membrane can be calculated from the data. (From Segen, Current Med Talk, 1995).

A basement membrane in the cochlea that supports the hair cells of the ORGAN OF CORTI, consisting keratin-like fibrils. It stretches from the SPIRAL LAMINA to the basilar crest. The movement of fluid in the cochlea, induced by sound, causes displacement of the basilar membrane and subsequent stimulation of the attached hair cells which transform the mechanical signal into neural activity.

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